neovim

quickfix.c (228145B)

---

// quickfix.c: functions for quickfix mode, using a file with error messages

#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "nvim/arglist.h"
#include "nvim/ascii_defs.h"
#include "nvim/autocmd.h"
#include "nvim/autocmd_defs.h"
#include "nvim/buffer.h"
#include "nvim/buffer_defs.h"
#include "nvim/change.h"
#include "nvim/charset.h"
#include "nvim/cursor.h"
#include "nvim/drawscreen.h"
#include "nvim/edit.h"
#include "nvim/errors.h"
#include "nvim/eval.h"
#include "nvim/eval/typval.h"
#include "nvim/eval/vars.h"
#include "nvim/eval/window.h"
#include "nvim/ex_cmds.h"
#include "nvim/ex_cmds2.h"
#include "nvim/ex_cmds_defs.h"
#include "nvim/ex_docmd.h"
#include "nvim/ex_eval.h"
#include "nvim/ex_eval_defs.h"
#include "nvim/ex_getln.h"
#include "nvim/extmark.h"
#include "nvim/fileio.h"
#include "nvim/fold.h"
#include "nvim/fuzzy.h"
#include "nvim/garray.h"
#include "nvim/garray_defs.h"
#include "nvim/gettext_defs.h"
#include "nvim/globals.h"
#include "nvim/help.h"
#include "nvim/highlight_defs.h"
#include "nvim/highlight_group.h"
#include "nvim/macros_defs.h"
#include "nvim/mark.h"
#include "nvim/mbyte.h"
#include "nvim/mbyte_defs.h"
#include "nvim/memline.h"
#include "nvim/memline_defs.h"
#include "nvim/memory.h"
#include "nvim/message.h"
#include "nvim/move.h"
#include "nvim/normal.h"
#include "nvim/ops.h"
#include "nvim/option.h"
#include "nvim/option_defs.h"
#include "nvim/option_vars.h"
#include "nvim/optionstr.h"
#include "nvim/os/fs.h"
#include "nvim/os/fs_defs.h"
#include "nvim/os/input.h"
#include "nvim/os/os.h"
#include "nvim/os/os_defs.h"
#include "nvim/path.h"
#include "nvim/pos_defs.h"
#include "nvim/quickfix.h"
#include "nvim/regexp.h"
#include "nvim/regexp_defs.h"
#include "nvim/search.h"
#include "nvim/strings.h"
#include "nvim/types_defs.h"
#include "nvim/ui.h"
#include "nvim/undo.h"
#include "nvim/vim_defs.h"
#include "nvim/window.h"

struct dir_stack_T {
 struct dir_stack_T *next;
 char *dirname;
};

// For each error the next struct is allocated and linked in a list.
typedef struct qfline_S qfline_T;
struct qfline_S {
 qfline_T *qf_next;      ///< pointer to next error in the list
 qfline_T *qf_prev;      ///< pointer to previous error in the list
 linenr_T qf_lnum;       ///< line number where the error occurred
 linenr_T qf_end_lnum;   ///< line number when the error has range or zero

 int qf_fnum;            ///< file number for the line
 int qf_col;             ///< column where the error occurred
 int qf_end_col;         ///< column when the error has range or zero
 int qf_nr;              ///< error number
 char *qf_module;        ///< module name for this error
 char *qf_fname;         ///< different filename if there're hard links
 char *qf_pattern;       ///< search pattern for the error
 char *qf_text;          ///< description of the error
 char qf_viscol;         ///< set to true if qf_col and qf_end_col is screen column
 char qf_cleared;        ///< set to true if line has been deleted
 char qf_type;           ///< type of the error (mostly 'E'); 1 for :helpgrep
 typval_T qf_user_data;  ///< custom user data associated with this item
 char qf_valid;          ///< valid error message detected
};

// There is a stack of error lists.
#define INVALID_QFIDX (-1)
#define INVALID_QFBUFNR (0)

/// Quickfix list type.
typedef enum {
 QFLT_QUICKFIX,  ///< Quickfix list - global list
 QFLT_LOCATION,  ///< Location list - per window list
 QFLT_INTERNAL,  ///< Internal - Temporary list used by
 //   getqflist()/getloclist()
} qfltype_T;

/// Quickfix/Location list definition
///
/// Usually the list contains one or more entries. But an empty list can be
/// created using setqflist()/setloclist() with a title and/or user context
/// information and entries can be added later using setqflist()/setloclist().
typedef struct {
 unsigned qf_id;         ///< Unique identifier for this list
 qfltype_T qfl_type;
 qfline_T *qf_start;     ///< pointer to the first error
 qfline_T *qf_last;      ///< pointer to the last error
 qfline_T *qf_ptr;       ///< pointer to the current error
 int qf_count;           ///< number of errors (0 means empty list)
 int qf_index;           ///< current index in the error list
 bool qf_nonevalid;      ///< true if not a single valid entry found
 bool qf_has_user_data;  ///< true if at least one item has user_data attached
 char *qf_title;         ///< title derived from the command that created
                         ///< the error list or set by setqflist
 typval_T *qf_ctx;       ///< context set by setqflist/setloclist
 Callback qf_qftf_cb;    ///< 'quickfixtextfunc' callback function

 struct dir_stack_T *qf_dir_stack;
 char *qf_directory;
 struct dir_stack_T *qf_file_stack;
 char *qf_currfile;
 bool qf_multiline;
 bool qf_multiignore;
 bool qf_multiscan;
 int qf_changedtick;
} qf_list_T;

/// Quickfix/Location list stack definition
/// Contains a list of quickfix/location lists (qf_list_T)
struct qf_info_S {
 // Count of references to this list. Used only for location lists.
 // When a location list window reference this list, qf_refcount
 // will be 2. Otherwise, qf_refcount will be 1. When qf_refcount
 // reaches 0, the list is freed.
 int qf_refcount;
 int qf_listcount;                 // current number of lists
 int qf_curlist;                   // current error list
 int qf_maxcount;                  // maximum number of lists
 qf_list_T *qf_lists;
 qfltype_T qfl_type;  // type of list
 int qf_bufnr;                     // quickfix window buffer number
};

static qf_info_T ql_info_actual;  // global quickfix list
static qf_info_T *ql_info;        // points to ql_info_actual after allocation
static unsigned last_qf_id = 0;   // Last Used quickfix list id

#define FMT_PATTERNS 14           // maximum number of % recognized

// Structure used to hold the info of one part of 'errorformat'
typedef struct efm_S efm_T;
struct efm_S {
 regprog_T *prog;        // pre-formatted part of 'errorformat'
 efm_T *next;        // pointer to next (NULL if last)
 char addr[FMT_PATTERNS];    // indices of used % patterns
 char prefix;                // prefix of this format line:
                             // 'D' enter directory
                             // 'X' leave directory
                             // 'A' start of multi-line message
                             // 'E' error message
                             // 'W' warning message
                             // 'I' informational message
                             // 'N' note message
                             // 'C' continuation line
                             // 'Z' end of multi-line message
                             // 'G' general, unspecific message
                             // 'P' push file (partial) message
                             // 'Q' pop/quit file (partial) message
                             // 'O' overread (partial) message
 char flags;                 // additional flags given in prefix
                             // '-' do not include this line
                             // '+' include whole line in message
 int conthere;                 // %> used
};

/// List of location lists to be deleted.
/// Used to delay the deletion of locations lists by autocmds.
typedef struct qf_delq_S {
 struct qf_delq_S *next;
 qf_info_T *qi;
} qf_delq_T;

enum {
 QF_FAIL = 0,
 QF_OK = 1,
 QF_END_OF_INPUT = 2,
 QF_NOMEM = 3,
 QF_IGNORE_LINE = 4,
 QF_MULTISCAN = 5,
 QF_ABORT = 6,
};

/// State information used to parse lines and add entries to a quickfix/location
/// list.
typedef struct {
 char *linebuf;
 size_t linelen;
 char *growbuf;
 size_t growbufsiz;
 FILE *fd;
 typval_T *tv;
 char *p_str;
 list_T *p_list;
 listitem_T *p_li;
 buf_T *buf;
 linenr_T buflnum;
 linenr_T lnumlast;
 vimconv_T vc;
} qfstate_T;

typedef struct {
 char *namebuf;
 int bnr;
 char *module;
 char *errmsg;
 size_t errmsglen;
 linenr_T lnum;
 linenr_T end_lnum;
 int col;
 int end_col;
 bool use_viscol;
 char *pattern;
 int enr;
 char type;
 typval_T *user_data;
 bool valid;
} qffields_T;

/// :vimgrep command arguments
typedef struct {
 int tomatch;          ///< maximum number of matches to find
 char *spat;          ///< search pattern
 int flags;             ///< search modifier
 char **fnames;       ///< list of files to search
 int fcount;            ///< number of files
 regmmatch_T regmatch;  ///< compiled search pattern
 char *qf_title;      ///< quickfix list title
} vgr_args_T;

#include "quickfix.c.generated.h"

static const char *e_no_more_items = N_("E553: No more items");
static const char *e_current_quickfix_list_was_changed =
 N_("E925: Current quickfix list was changed");
static const char *e_current_location_list_was_changed =
 N_("E926: Current location list was changed");

enum { QF_WINHEIGHT = 10, };  ///< default height for quickfix window

// Quickfix window check helper macro
#define IS_QF_WINDOW(wp) (bt_quickfix((wp)->w_buffer) && (wp)->w_llist_ref == NULL)
// Location list window check helper macro
#define IS_LL_WINDOW(wp) (bt_quickfix((wp)->w_buffer) && (wp)->w_llist_ref != NULL)

// Quickfix and location list stack check helper macros
#define IS_QF_STACK(qi)       ((qi)->qfl_type == QFLT_QUICKFIX)
#define IS_LL_STACK(qi)       ((qi)->qfl_type == QFLT_LOCATION)
#define IS_QF_LIST(qfl)       ((qfl)->qfl_type == QFLT_QUICKFIX)
#define IS_LL_LIST(qfl)       ((qfl)->qfl_type == QFLT_LOCATION)

// Return location list for window 'wp'
// For location list window, return the referenced location list
#define GET_LOC_LIST(wp) (IS_LL_WINDOW(wp) ? (wp)->w_llist_ref : (wp)->w_llist)

// Macro to loop through all the items in a quickfix list
// Quickfix item index starts from 1, so i below starts at 1
#define FOR_ALL_QFL_ITEMS(qfl, qfp, i) \
 for ((i) = 1, (qfp) = (qfl)->qf_start; \
      !got_int && (i) <= (qfl)->qf_count && (qfp) != NULL; \
      (i)++, (qfp) = (qfp)->qf_next)

// Looking up a buffer can be slow if there are many.  Remember the last one
// to make this a lot faster if there are multiple matches in the same file.
static char *qf_last_bufname = NULL;
static bufref_T qf_last_bufref = { NULL, 0, 0 };

static garray_T qfga;

/// Get a growarray to buffer text in.  Shared between various commands to avoid
/// many alloc/free calls.
static garray_T *qfga_get(void)
{
 static bool initialized = false;

 if (!initialized) {
   initialized = true;
   ga_init(&qfga, 1, 256);
 }

 // Reset the length to zero.  Retain ga_data from previous use to avoid
 // many alloc/free calls.
 qfga.ga_len = 0;

 return &qfga;
}

/// The "qfga" grow array buffer is reused across multiple quickfix commands as
/// a temporary buffer to reduce the number of alloc/free calls.  But if the
/// buffer size is large, then to avoid holding on to that memory, clear the
/// grow array.  Otherwise just reset the grow array length.
static void qfga_clear(void)
{
 if (qfga.ga_maxlen > 1000) {
   ga_clear(&qfga);
 } else {
   qfga.ga_len = 0;
 }
}

// Counter to prevent autocmds from freeing up location lists when they are
// still being used.
static int quickfix_busy = 0;
static qf_delq_T *qf_delq_head = NULL;

/// Process the next line from a file/buffer/list/string and add it
/// to the quickfix list 'qfl'.
static int qf_init_process_nextline(qf_list_T *qfl, efm_T *fmt_first, qfstate_T *state,
                                   qffields_T *fields)
{
 // Get the next line from a file/buffer/list/string
 int status = qf_get_nextline(state);
 if (status != QF_OK) {
   return status;
 }

 status = qf_parse_line(qfl, state->linebuf, state->linelen,
                        fmt_first, fields);
 if (status != QF_OK) {
   return status;
 }

 return qf_add_entry(qfl,
                     qfl->qf_directory,
                     (*fields->namebuf || qfl->qf_directory != NULL)
                     ? fields->namebuf
                     : ((qfl->qf_currfile != NULL && fields->valid)
                        ? qfl->qf_currfile : NULL),
                     fields->module,
                     fields->bnr,
                     fields->errmsg,
                     fields->lnum,
                     fields->end_lnum,
                     fields->col,
                     fields->end_col,
                     fields->use_viscol,
                     fields->pattern,
                     fields->enr,
                     fields->type,
                     fields->user_data,
                     fields->valid);
}

/// Read the errorfile "efile" into memory, line by line, building the error
/// list. Set the error list's title to qf_title.
///
/// @params  wp  If non-NULL, make a location list
/// @params  efile  If non-NULL, errorfile to parse
/// @params  errorformat  'errorformat' string used to parse the error lines
/// @params  newlist  If true, create a new error list
/// @params  qf_title  If non-NULL, title of the error list
/// @params  enc  If non-NULL, encoding used to parse errors
///
/// @returns -1 for error, number of errors for success.
int qf_init(win_T *wp, const char *restrict efile, char *restrict errorformat, int newlist,
           const char *restrict qf_title, char *restrict enc)
{
 qf_info_T *qi = wp == NULL ? ql_info : ll_get_or_alloc_list(wp);
 assert(qi != NULL);

 return qf_init_ext(qi, qi->qf_curlist, efile, curbuf, NULL, errorformat,
                    newlist, 0, 0, qf_title, enc);
}

// Maximum number of bytes allowed per line while reading an errorfile.
static const size_t LINE_MAXLEN = 4096;

/// Patterns used.  Keep in sync with qf_parse_fmt[].
static struct fmtpattern {
 char convchar;
 char *pattern;
} fmt_pat[FMT_PATTERNS] = {
 { 'f', ".\\+" },      // only used when at end
 { 'b', "\\d\\+" },    // 1
 { 'n', "\\d\\+" },    // 2
 { 'l', "\\d\\+" },    // 3
 { 'e', "\\d\\+" },    // 4
 { 'c', "\\d\\+" },    // 5
 { 'k', "\\d\\+" },    // 6
 { 't', "." },         // 7
#define FMT_PATTERN_M 8
 { 'm', ".\\+" },      // 8
#define FMT_PATTERN_R 9
 { 'r', ".*" },        // 9
 { 'p', "[-\t .]*" },  // 10
 { 'v', "\\d\\+" },    // 11
 { 's', ".\\+" },      // 12
 { 'o', ".\\+" }       // 13
};

/// Convert an errorformat pattern to a regular expression pattern.
/// See fmt_pat definition above for the list of supported patterns.  The
/// pattern specifier is supplied in "efmpat".  The converted pattern is stored
/// in "regpat".  Returns a pointer to the location after the pattern.
static char *efmpat_to_regpat(const char *efmpat, char *regpat, efm_T *efminfo, int idx, int round)
 FUNC_ATTR_NONNULL_ALL
{
 if (efminfo->addr[idx]) {
   // Each errorformat pattern can occur only once
   semsg(_("E372: Too many %%%c in format string"), *efmpat);
   return NULL;
 }
 if ((idx && idx < FMT_PATTERN_R
      && vim_strchr("DXOPQ", (uint8_t)efminfo->prefix) != NULL)
     || (idx == FMT_PATTERN_R
         && vim_strchr("OPQ", (uint8_t)efminfo->prefix) == NULL)) {
   semsg(_("E373: Unexpected %%%c in format string"), *efmpat);
   return NULL;
 }
 efminfo->addr[idx] = (char)++round;
 *regpat++ = '\\';
 *regpat++ = '(';
#ifdef BACKSLASH_IN_FILENAME
 if (*efmpat == 'f') {
   // Also match "c:" in the file name, even when
   // checking for a colon next: "%f:".
   // "\%(\a:\)\="
   STRCPY(regpat, "\\%(\\a:\\)\\=");
   regpat += 10;
 }
#endif
 if (*efmpat == 'f' && efmpat[1] != NUL) {
   if (efmpat[1] != '\\' && efmpat[1] != '%') {
     // A file name may contain spaces, but this isn't
     // in "\f".  For "%f:%l:%m" there may be a ":" in
     // the file name.  Use ".\{-1,}x" instead (x is
     // the next character), the requirement that :999:
     // follows should work.
     STRCPY(regpat, ".\\{-1,}");
     regpat += 7;
   } else {
     // File name followed by '\\' or '%': include as
     // many file name chars as possible.
     STRCPY(regpat, "\\f\\+");
     regpat += 4;
   }
 } else {
   char *srcptr = fmt_pat[idx].pattern;
   while ((*regpat = *srcptr++) != NUL) {
     regpat++;
   }
 }
 *regpat++ = '\\';
 *regpat++ = ')';

 return regpat;
}

/// Convert a scanf like format in 'errorformat' to a regular expression.
/// Returns a pointer to the location after the pattern.
static char *scanf_fmt_to_regpat(const char **pefmp, const char *efm, int len, char *regpat)
 FUNC_ATTR_NONNULL_ALL
{
 const char *efmp = *pefmp;

 if (*efmp == '[' || *efmp == '\\') {
   if ((*regpat++ = *efmp) == '[') {  // %*[^a-z0-9] etc.
     if (efmp[1] == '^') {
       *regpat++ = *++efmp;
     }
     if (efmp < efm + len) {
       *regpat++ = *++efmp;  // could be ']'
       while (efmp < efm + len && (*regpat++ = *++efmp) != ']') {}
       if (efmp == efm + len) {
         emsg(_("E374: Missing ] in format string"));
         return NULL;
       }
     }
   } else if (efmp < efm + len) {  // %*\D, %*\s etc.
     *regpat++ = *++efmp;
   }
   *regpat++ = '\\';
   *regpat++ = '+';
 } else {
   semsg(_("E375: Unsupported %%%c in format string"), *efmp);
   return NULL;
 }

 *pefmp = efmp;

 return regpat;
}

/// Analyze/parse an errorformat prefix.
static const char *efm_analyze_prefix(const char *efmp, efm_T *efminfo)
 FUNC_ATTR_NONNULL_ALL
{
 if (vim_strchr("+-", (uint8_t)(*efmp)) != NULL) {
   efminfo->flags = *efmp++;
 }
 if (vim_strchr("DXAEWINCZGOPQ", (uint8_t)(*efmp)) != NULL) {
   efminfo->prefix = *efmp;
 } else {
   semsg(_("E376: Invalid %%%c in format string prefix"), *efmp);
   return NULL;
 }

 return efmp;
}

// Converts a 'errorformat' string to regular expression pattern
static int efm_to_regpat(const char *efm, int len, efm_T *fmt_ptr, char *regpat)
 FUNC_ATTR_NONNULL_ALL
{
 // Build regexp pattern from current 'errorformat' option
 char *ptr = regpat;
 *ptr++ = '^';
 int round = 0;
 for (const char *efmp = efm; efmp < efm + len; efmp++) {
   if (*efmp == '%') {
     efmp++;
     int idx;
     for (idx = 0; idx < FMT_PATTERNS; idx++) {
       if (fmt_pat[idx].convchar == *efmp) {
         break;
       }
     }
     if (idx < FMT_PATTERNS) {
       ptr = efmpat_to_regpat(efmp, ptr, fmt_ptr, idx, round);
       if (ptr == NULL) {
         return FAIL;
       }
       round++;
     } else if (*efmp == '*') {
       efmp++;
       ptr = scanf_fmt_to_regpat(&efmp, efm, len, ptr);
       if (ptr == NULL) {
         return FAIL;
       }
     } else if (vim_strchr("%\\.^$~[", (uint8_t)(*efmp)) != NULL) {
       *ptr++ = *efmp;  // regexp magic characters
     } else if (*efmp == '#') {
       *ptr++ = '*';
     } else if (*efmp == '>') {
       fmt_ptr->conthere = true;
     } else if (efmp == efm + 1) {             // analyse prefix
       // prefix is allowed only at the beginning of the errorformat
       // option part
       efmp = efm_analyze_prefix(efmp, fmt_ptr);
       if (efmp == NULL) {
         return FAIL;
       }
     } else {
       semsg(_("E377: Invalid %%%c in format string"), *efmp);
       return FAIL;
     }
   } else {                    // copy normal character
     if (*efmp == '\\' && efmp + 1 < efm + len) {
       efmp++;
     } else if (vim_strchr(".*^$~[", (uint8_t)(*efmp)) != NULL) {
       *ptr++ = '\\';  // escape regexp atoms
     }
     if (*efmp) {
       *ptr++ = *efmp;
     }
   }
 }
 *ptr++ = '$';
 *ptr = NUL;

 return OK;
}

static efm_T *fmt_start = NULL;  // cached across qf_parse_line() calls

// callback function for 'quickfixtextfunc'
static Callback qftf_cb;

static void free_efm_list(efm_T **efm_first)
{
 for (efm_T *efm_ptr = *efm_first; efm_ptr != NULL; efm_ptr = *efm_first) {
   *efm_first = efm_ptr->next;
   vim_regfree(efm_ptr->prog);
   xfree(efm_ptr);
 }

 fmt_start = NULL;
}

/// Compute the size of the buffer used to convert a 'errorformat' pattern into
/// a regular expression pattern.
static size_t efm_regpat_bufsz(char *efm)
{
 size_t sz = (FMT_PATTERNS * 3) + (strlen(efm) << 2);
 for (int i = FMT_PATTERNS - 1; i >= 0;) {
   sz += strlen(fmt_pat[i--].pattern);
 }
#ifdef BACKSLASH_IN_FILENAME
 sz += 12;  // "%f" can become twelve chars longer (see efm_to_regpat)
#else
 sz += 2;  // "%f" can become two chars longer
#endif

 return sz;
}

/// Return the length of a 'errorformat' option part (separated by ",").
static int efm_option_part_len(const char *efm)
{
 int len;

 for (len = 0; efm[len] != NUL && efm[len] != ','; len++) {
   if (efm[len] == '\\' && efm[len + 1] != NUL) {
     len++;
   }
 }

 return len;
}

/// Parse the 'errorformat' option. Multiple parts in the 'errorformat' option
/// are parsed and converted to regular expressions. Returns information about
/// the parsed 'errorformat' option.
static efm_T *parse_efm_option(char *efm)
{
 efm_T *fmt_first = NULL;
 efm_T *fmt_last = NULL;

 // Get some space to modify the format string into.
 size_t sz = efm_regpat_bufsz(efm);
 char *fmtstr = xmalloc(sz);

 while (efm[0] != NUL) {
   // Allocate a new eformat structure and put it at the end of the list
   efm_T *fmt_ptr = (efm_T *)xcalloc(1, sizeof(efm_T));
   if (fmt_first == NULL) {        // first one
     fmt_first = fmt_ptr;
   } else {
     fmt_last->next = fmt_ptr;
   }
   fmt_last = fmt_ptr;

   // Isolate one part in the 'errorformat' option
   int len = efm_option_part_len(efm);

   if (efm_to_regpat(efm, len, fmt_ptr, fmtstr) == FAIL) {
     goto parse_efm_error;
   }
   if ((fmt_ptr->prog = vim_regcomp(fmtstr, RE_MAGIC + RE_STRING)) == NULL) {
     goto parse_efm_error;
   }
   // Advance to next part
   efm = skip_to_option_part(efm + len);       // skip comma and spaces
 }

 if (fmt_first == NULL) {      // nothing found
   emsg(_("E378: 'errorformat' contains no pattern"));
 }

 goto parse_efm_end;

parse_efm_error:
 free_efm_list(&fmt_first);

parse_efm_end:
 xfree(fmtstr);

 return fmt_first;
}

/// Allocate more memory for the line buffer used for parsing lines.
static char *qf_grow_linebuf(qfstate_T *state, size_t newsz)
{
 // If the line exceeds LINE_MAXLEN exclude the last
 // byte since it's not a NL character.
 state->linelen = newsz > LINE_MAXLEN ? LINE_MAXLEN - 1 : newsz;
 if (state->growbuf == NULL) {
   state->growbuf = xmalloc(state->linelen + 1);
   state->growbufsiz = state->linelen;
 } else if (state->linelen > state->growbufsiz) {
   state->growbuf = xrealloc(state->growbuf, state->linelen + 1);
   state->growbufsiz = state->linelen;
 }
 return state->growbuf;
}

/// Get the next string (separated by newline) from state->p_str.
static int qf_get_next_str_line(qfstate_T *state)
{
 // Get the next line from the supplied string
 char *p_str = state->p_str;

 if (*p_str == NUL) {  // Reached the end of the string
   return QF_END_OF_INPUT;
 }

 char *p = vim_strchr(p_str, '\n');
 size_t len = (p != NULL) ? (size_t)(p - p_str) + 1 : strlen(p_str);

 if (len > IOSIZE - 2) {
   state->linebuf = qf_grow_linebuf(state, len);
 } else {
   state->linebuf = IObuff;
   state->linelen = len;
 }
 memcpy(state->linebuf, p_str, state->linelen);
 state->linebuf[state->linelen] = NUL;

 // Increment using len in order to discard the rest of the line if it
 // exceeds LINE_MAXLEN.
 p_str += len;
 state->p_str = p_str;

 return QF_OK;
}

/// Get the next string from the List item state->p_li.
static int qf_get_next_list_line(qfstate_T *state)
{
 listitem_T *p_li = state->p_li;

 // Get the next line from the supplied list
 while (p_li != NULL
        && (TV_LIST_ITEM_TV(p_li)->v_type != VAR_STRING
            || TV_LIST_ITEM_TV(p_li)->vval.v_string == NULL)) {
   p_li = TV_LIST_ITEM_NEXT(state->p_list, p_li);  // Skip non-string items.
 }

 if (p_li == NULL) {  // End of the list.
   state->p_li = NULL;
   return QF_END_OF_INPUT;
 }

 size_t len = strlen(TV_LIST_ITEM_TV(p_li)->vval.v_string);
 if (len > IOSIZE - 2) {
   state->linebuf = qf_grow_linebuf(state, len);
 } else {
   state->linebuf = IObuff;
   state->linelen = len;
 }

 xstrlcpy(state->linebuf, TV_LIST_ITEM_TV(p_li)->vval.v_string,
          state->linelen + 1);

 state->p_li = TV_LIST_ITEM_NEXT(state->p_list, p_li);
 return QF_OK;
}

/// Get the next string from state->buf.
static int qf_get_next_buf_line(qfstate_T *state)
{
 // Get the next line from the supplied buffer
 if (state->buflnum > state->lnumlast) {
   return QF_END_OF_INPUT;
 }
 char *p_buf = ml_get_buf(state->buf, state->buflnum);
 size_t len = (size_t)ml_get_buf_len(state->buf, state->buflnum);
 state->buflnum += 1;

 if (len > IOSIZE - 2) {
   state->linebuf = qf_grow_linebuf(state, len);
 } else {
   state->linebuf = IObuff;
   state->linelen = len;
 }
 xstrlcpy(state->linebuf, p_buf, state->linelen + 1);

 return QF_OK;
}

/// Get the next string from file state->fd.
static int qf_get_next_file_line(qfstate_T *state)
{
retry:
 errno = 0;
 if (fgets(IObuff, IOSIZE, state->fd) == NULL) {
   if (errno == EINTR) {
     goto retry;
   }
   return QF_END_OF_INPUT;
 }

 bool discard = false;
 state->linelen = strlen(IObuff);
 if (state->linelen == IOSIZE - 1
     && !(IObuff[state->linelen - 1] == '\n')) {
   // The current line exceeds IObuff, continue reading using growbuf
   // until EOL or LINE_MAXLEN bytes is read.
   if (state->growbuf == NULL) {
     state->growbufsiz = 2 * (IOSIZE - 1);
     state->growbuf = xmalloc(state->growbufsiz);
   }

   // Copy the read part of the line, excluding null-terminator
   memcpy(state->growbuf, IObuff, IOSIZE - 1);
   size_t growbuflen = state->linelen;

   while (true) {
     errno = 0;
     if (fgets(state->growbuf + growbuflen,
               (int)(state->growbufsiz - growbuflen), state->fd) == NULL) {
       if (errno == EINTR) {
         continue;
       }
       break;
     }
     state->linelen = strlen(state->growbuf + growbuflen);
     growbuflen += state->linelen;
     if (state->growbuf[growbuflen - 1] == '\n') {
       break;
     }
     if (state->growbufsiz == LINE_MAXLEN) {
       discard = true;
       break;
     }

     state->growbufsiz = MIN(2 * state->growbufsiz, LINE_MAXLEN);
     state->growbuf = xrealloc(state->growbuf, state->growbufsiz);
   }

   while (discard) {
     // The current line is longer than LINE_MAXLEN, continue reading but
     // discard everything until EOL or EOF is reached.
     errno = 0;
     if (fgets(IObuff, IOSIZE, state->fd) == NULL) {
       if (errno == EINTR) {
         continue;
       }
       break;
     }
     if (strlen(IObuff) < IOSIZE - 1 || IObuff[IOSIZE - 2] == '\n') {
       break;
     }
   }

   state->linebuf = state->growbuf;
   state->linelen = growbuflen;
 } else {
   state->linebuf = IObuff;
 }

 // Convert a line if it contains a non-ASCII character
 if (state->vc.vc_type != CONV_NONE && has_non_ascii(state->linebuf)) {
   char *line = string_convert(&state->vc, state->linebuf, &state->linelen);
   if (line != NULL) {
     if (state->linelen < IOSIZE) {
       xstrlcpy(state->linebuf, line, state->linelen + 1);
       xfree(line);
     } else {
       xfree(state->growbuf);
       state->linebuf = line;
       state->growbuf = line;
       state->growbufsiz = MIN(state->linelen, LINE_MAXLEN);
     }
   }
 }
 return QF_OK;
}

/// Get the next string from a file/buffer/list/string.
static int qf_get_nextline(qfstate_T *state)
{
 int status = QF_FAIL;

 if (state->fd == NULL) {
   if (state->tv != NULL) {
     if (state->tv->v_type == VAR_STRING) {
       // Get the next line from the supplied string
       status = qf_get_next_str_line(state);
     } else if (state->tv->v_type == VAR_LIST) {
       // Get the next line from the supplied list
       status = qf_get_next_list_line(state);
     }
   } else {
     // Get the next line from the supplied buffer
     status = qf_get_next_buf_line(state);
   }
 } else {
   // Get the next line from the supplied file
   status = qf_get_next_file_line(state);
 }

 if (status != QF_OK) {
   return status;
 }

 if (state->linelen > 0 && state->linebuf[state->linelen - 1] == '\n') {
   state->linebuf[state->linelen - 1] = NUL;
#ifdef USE_CRNL
   if (state->linelen > 1 && state->linebuf[state->linelen - 2] == '\r') {
     state->linebuf[state->linelen - 2] = NUL;
   }
#endif
 }

 remove_bom(state->linebuf);

 return QF_OK;
}

/// Returns true if the specified quickfix/location stack is empty
static bool qf_stack_empty(const qf_info_T *qi)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 return qi == NULL || qi->qf_listcount <= 0;
}

/// Returns true if the specified quickfix/location list is empty.
static bool qf_list_empty(qf_list_T *qfl)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 return qfl == NULL || qfl->qf_count <= 0;
}

/// Returns true if the specified quickfix/location list is not empty and
/// has valid entries.
static bool qf_list_has_valid_entries(qf_list_T *qfl)
{
 return !qf_list_empty(qfl) && !qfl->qf_nonevalid;
}

/// Return a pointer to a list in the specified quickfix stack
static qf_list_T *qf_get_list(qf_info_T *qi, int idx)
 FUNC_ATTR_NONNULL_ALL
{
 return &qi->qf_lists[idx];
}

/// Parse a line and get the quickfix fields.
/// Return the QF_ status.
static int qf_parse_line(qf_list_T *qfl, char *linebuf, size_t linelen, efm_T *fmt_first,
                        qffields_T *fields)
{
 efm_T *fmt_ptr;
 int idx = 0;
 char *tail = NULL;
 int status;

restofline:
 // If there was no %> item start at the first pattern
 if (fmt_start == NULL) {
   fmt_ptr = fmt_first;
 } else {
   // Otherwise start from the last used pattern.
   fmt_ptr = fmt_start;
   fmt_start = NULL;
 }

 // Try to match each part of 'errorformat' until we find a complete
 // match or no match.
 fields->valid = true;
 for (; fmt_ptr != NULL; fmt_ptr = fmt_ptr->next) {
   idx = (uint8_t)fmt_ptr->prefix;
   status = qf_parse_get_fields(linebuf, linelen, fmt_ptr, fields,
                                qfl->qf_multiline, qfl->qf_multiscan,
                                &tail);
   if (status == QF_NOMEM) {
     return status;
   }
   if (status == QF_OK) {
     break;
   }
 }
 qfl->qf_multiscan = false;

 if (fmt_ptr == NULL || idx == 'D' || idx == 'X') {
   if (fmt_ptr != NULL) {
     // 'D' and 'X' directory specifiers.
     status = qf_parse_dir_pfx(idx, fields, qfl);
     if (status != QF_OK) {
       return status;
     }
   }
   status = qf_parse_line_nomatch(linebuf, linelen, fields);
   if (status != QF_OK) {
     return status;
   }
   if (fmt_ptr == NULL) {
     qfl->qf_multiline = qfl->qf_multiignore = false;
   }
 } else {
   // honor %> item
   if (fmt_ptr->conthere) {
     fmt_start = fmt_ptr;
   }

   if (vim_strchr("AEWIN", idx) != NULL) {
     qfl->qf_multiline = true;     // start of a multi-line message
     qfl->qf_multiignore = false;  // reset continuation
   } else if (vim_strchr("CZ", idx) != NULL) {
     // continuation of multi-line msg
     status = qf_parse_multiline_pfx(idx, qfl, fields);
     if (status != QF_OK) {
       return status;
     }
   } else if (vim_strchr("OPQ", idx) != NULL) {
     // global file names
     status = qf_parse_file_pfx(idx, fields, qfl, tail);
     if (status == QF_MULTISCAN) {
       goto restofline;
     }
   }
   if (fmt_ptr->flags == '-') {  // generally exclude this line
     if (qfl->qf_multiline) {
       // also exclude continuation lines
       qfl->qf_multiignore = true;
     }
     return QF_IGNORE_LINE;
   }
 }

 return QF_OK;
}

// Allocate the fields used for parsing lines and populating a quickfix list.
static void qf_alloc_fields(qffields_T *pfields)
 FUNC_ATTR_NONNULL_ALL
{
 pfields->namebuf = xmalloc(CMDBUFFSIZE + 1);
 pfields->module = xmalloc(CMDBUFFSIZE + 1);
 pfields->errmsglen = CMDBUFFSIZE + 1;
 pfields->errmsg = xmalloc(pfields->errmsglen);
 pfields->pattern = xmalloc(CMDBUFFSIZE + 1);
}

// Free the fields used for parsing lines and populating a quickfix list.
static void qf_free_fields(qffields_T *pfields)
 FUNC_ATTR_NONNULL_ALL
{
 xfree(pfields->namebuf);
 xfree(pfields->module);
 xfree(pfields->errmsg);
 xfree(pfields->pattern);
}

// Setup the state information used for parsing lines and populating a
// quickfix list.
static int qf_setup_state(qfstate_T *pstate, char *restrict enc, const char *restrict efile,
                         typval_T *tv, buf_T *buf, linenr_T lnumfirst, linenr_T lnumlast)
 FUNC_ATTR_NONNULL_ARG(1)
{
 pstate->vc.vc_type = CONV_NONE;
 if (enc != NULL && *enc != NUL) {
   convert_setup(&pstate->vc, enc, p_enc);
 }

 if (efile != NULL
     && (pstate->fd = (strequal(efile, "-")
                       ? fdopen(os_open_stdin_fd(), "r")
                       : os_fopen(efile, "r"))) == NULL) {
   semsg(_(e_openerrf), efile);
   return FAIL;
 }

 if (tv != NULL) {
   if (tv->v_type == VAR_STRING) {
     pstate->p_str = tv->vval.v_string;
   } else if (tv->v_type == VAR_LIST) {
     pstate->p_li = tv_list_first(tv->vval.v_list);
   }
   pstate->tv = tv;
 }
 pstate->buf = buf;
 pstate->buflnum = lnumfirst;
 pstate->lnumlast = lnumlast;

 return OK;
}

// Cleanup the state information used for parsing lines and populating a
// quickfix list.
static void qf_cleanup_state(qfstate_T *pstate)
 FUNC_ATTR_NONNULL_ALL
{
 if (pstate->fd != NULL) {
   fclose(pstate->fd);
 }
 xfree(pstate->growbuf);
 if (pstate->vc.vc_type != CONV_NONE) {
   convert_setup(&pstate->vc, NULL, NULL);
 }
}

/// Read the errorfile "efile" into memory, line by line, building the error
/// list.
/// Alternative: when "efile" is NULL read errors from buffer "buf".
/// Alternative: when "tv" is not NULL get errors from the string or list.
/// Always use 'errorformat' from "buf" if there is a local value.
/// Then "lnumfirst" and "lnumlast" specify the range of lines to use.
/// Set the title of the list to "qf_title".
///
/// @param newlist  true: start a new error list
/// @param lnumfirst  first line number to use
/// @param lnumlast  last line number to use
///
/// @return  -1 for error, number of errors for success.
static int qf_init_ext(qf_info_T *qi, int qf_idx, const char *restrict efile, buf_T *buf,
                      typval_T *tv, char *restrict errorformat, bool newlist, linenr_T lnumfirst,
                      linenr_T lnumlast, const char *restrict qf_title, char *restrict enc)
 FUNC_ATTR_NONNULL_ARG(1)
{
 qfstate_T state = { 0 };
 qffields_T fields = { 0 };
 qfline_T *old_last = NULL;
 static efm_T *fmt_first = NULL;
 static char *last_efm = NULL;
 int retval = -1;                      // default: return error flag

 // Do not used the cached buffer, it may have been wiped out.
 XFREE_CLEAR(qf_last_bufname);

 qf_alloc_fields(&fields);
 if (qf_setup_state(&state, enc, efile, tv, buf, lnumfirst, lnumlast) == FAIL) {
   goto qf_init_end;
 }

 qf_list_T *qfl;
 bool adding = false;
 if (newlist || qf_idx == qi->qf_listcount) {
   // make place for a new list
   qf_new_list(qi, qf_title);
   qf_idx = qi->qf_curlist;
   qfl = qf_get_list(qi, qf_idx);
 } else {
   // Adding to existing list, use last entry.
   adding = true;
   qfl = qf_get_list(qi, qf_idx);
   if (!qf_list_empty(qfl)) {
     old_last = qfl->qf_last;
   }
 }

 // Use the local value of 'errorformat' if it's set.
 char *efm = (errorformat == p_efm && tv == NULL && buf && *buf->b_p_efm != NUL)
             ? buf->b_p_efm
             : errorformat;

 // If the errorformat didn't change between calls, then reuse the previously
 // parsed values.
 if (last_efm == NULL || (strcmp(last_efm, efm) != 0)) {
   // free the previously parsed data
   XFREE_CLEAR(last_efm);
   free_efm_list(&fmt_first);

   // parse the current 'efm'
   fmt_first = parse_efm_option(efm);
   if (fmt_first != NULL) {
     last_efm = xstrdup(efm);
   }
 }

 if (fmt_first == NULL) {      // nothing found
   goto error2;
 }

 // got_int is reset here, because it was probably set when killing the
 // ":make" command, but we still want to read the errorfile then.
 got_int = false;

 // Read the lines in the error file one by one.
 // Try to recognize one of the error formats in each line.
 while (!got_int) {
   int status = qf_init_process_nextline(qfl, fmt_first, &state, &fields);
   if (status == QF_END_OF_INPUT) {  // end of input
     break;
   }
   if (status == QF_FAIL) {
     goto error2;
   }

   line_breakcheck();
 }
 if (state.fd == NULL || !ferror(state.fd)) {
   if (qfl->qf_index == 0) {
     // no valid entry found
     qfl->qf_ptr = qfl->qf_start;
     qfl->qf_index = 1;
     qfl->qf_nonevalid = true;
   } else {
     qfl->qf_nonevalid = false;
     if (qfl->qf_ptr == NULL) {
       qfl->qf_ptr = qfl->qf_start;
     }
   }
   // return number of matches
   retval = qfl->qf_count;
   goto qf_init_end;
 }
 emsg(_(e_readerrf));
error2:
 if (!adding) {
   // Error when creating a new list. Free the new list
   qf_free(qfl);
   qi->qf_listcount--;
   if (qi->qf_curlist > 0) {
     qi->qf_curlist--;
   }
 }
qf_init_end:
 if (qf_idx == qi->qf_curlist) {
   qf_update_buffer(qi, old_last);
 }
 qf_cleanup_state(&state);
 qf_free_fields(&fields);

 return retval;
}

/// Set the title of the specified quickfix list. Frees the previous title.
/// Prepends ':' to the title.
static void qf_store_title(qf_list_T *qfl, const char *title)
 FUNC_ATTR_NONNULL_ARG(1)
{
 XFREE_CLEAR(qfl->qf_title);

 if (title == NULL) {
   return;
 }

 size_t len = strlen(title) + 1;
 char *p = xmallocz(len);

 qfl->qf_title = p;
 xstrlcpy(p, title, len + 1);
}

/// The title of a quickfix/location list is set, by default, to the command
/// that created the quickfix list with the ":" prefix.
/// Create a quickfix list title string by prepending ":" to a user command.
/// Returns a pointer to a static buffer with the title.
static char *qf_cmdtitle(const char *cmd)
 FUNC_ATTR_NONNULL_ALL
{
 static char qftitle_str[IOSIZE];

 snprintf(qftitle_str, IOSIZE, ":%s", cmd);

 return qftitle_str;
}

/// Return a pointer to the current list in the specified quickfix stack
static qf_list_T *qf_get_curlist(qf_info_T *qi)
 FUNC_ATTR_NONNULL_ALL
{
 return qf_get_list(qi, qi->qf_curlist);
}

/// Pop a quickfix list from the quickfix/location list stack
/// Automatically adjust qf_curlist so that it stays pointed
/// to the same list, unless it is deleted, if so then use the
/// newest created list instead. qf_listcount will be set correctly.
/// The above will only happen if <adjust> is true.
static void qf_pop_stack(qf_info_T *qi, bool adjust)
{
 qf_free(&qi->qf_lists[0]);
 for (int i = 1; i < qi->qf_listcount; i++) {
   qi->qf_lists[i - 1] = qi->qf_lists[i];
 }

 // fill with zeroes now unused list at the top
 memset(qi->qf_lists + qi->qf_listcount - 1, 0, sizeof(*qi->qf_lists));

 if (adjust) {
   qi->qf_listcount--;
   if (qi->qf_curlist == 0) {
     qi->qf_curlist = qi->qf_listcount - 1;
   } else {
     qi->qf_curlist--;
   }
 }
}

/// Prepare for adding a new quickfix list. If the current list is in the
/// middle of the stack, then all the following lists are freed and then
/// the new list is added.
static void qf_new_list(qf_info_T *qi, const char *qf_title)
{
 // If the current entry is not the last entry, delete entries beyond
 // the current entry.  This makes it possible to browse in a tree-like
 // way with ":grep".
 while (qi->qf_listcount > qi->qf_curlist + 1) {
   qf_free(&qi->qf_lists[--qi->qf_listcount]);
 }

 // When the stack is full, remove to oldest entry
 // Otherwise, add a new entry.
 if (qi->qf_listcount == qi->qf_maxcount) {
   qf_pop_stack(qi, false);
   qi->qf_curlist = qi->qf_listcount - 1;  // point to new empty list
 } else {
   qi->qf_curlist = qi->qf_listcount++;
 }

 qf_list_T *qfl = qf_get_curlist(qi);
 CLEAR_POINTER(qfl);
 qf_store_title(qfl, qf_title);
 qfl->qfl_type = qi->qfl_type;
 qfl->qf_id = ++last_qf_id;
 qfl->qf_has_user_data = false;
}

/// Parse the match for filename ('%f') pattern in regmatch.
/// Return the matched value in "fields->namebuf".
static int qf_parse_fmt_f(regmatch_T *rmp, int midx, qffields_T *fields, int prefix)
{
 if (rmp->startp[midx] == NULL || rmp->endp[midx] == NULL) {
   return QF_FAIL;
 }

 // Expand ~/file and $HOME/file to full path.
 char c = *rmp->endp[midx];
 *rmp->endp[midx] = NUL;
 expand_env(rmp->startp[midx], fields->namebuf, CMDBUFFSIZE);
 *rmp->endp[midx] = c;

 // For separate filename patterns (%O, %P and %Q), the specified file
 // should exist.
 if (vim_strchr("OPQ", prefix) != NULL
     && !os_path_exists(fields->namebuf)) {
   return QF_FAIL;
 }

 return QF_OK;
}

/// Parse the match for buffer number ('%b') pattern in regmatch.
/// Return the matched value in "fields->bnr".
static int qf_parse_fmt_b(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 int bnr = (int)atol(rmp->startp[midx]);
 if (buflist_findnr(bnr) == NULL) {
   return QF_FAIL;
 }
 fields->bnr = bnr;
 return QF_OK;
}

/// Parse the match for error number ('%n') pattern in regmatch.
/// Return the matched value in "fields->enr".
static int qf_parse_fmt_n(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->enr = (int)atol(rmp->startp[midx]);
 return QF_OK;
}

/// Parse the match for line number ('%l') pattern in regmatch.
/// Return the matched value in "fields->lnum".
static int qf_parse_fmt_l(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->lnum = (linenr_T)atol(rmp->startp[midx]);
 return QF_OK;
}

/// Parse the match for end line number ('%e') pattern in regmatch.
/// Return the matched value in "fields->end_lnum".
static int qf_parse_fmt_e(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->end_lnum = (linenr_T)atol(rmp->startp[midx]);
 return QF_OK;
}

/// Parse the match for column number ('%c') pattern in regmatch.
/// Return the matched value in "fields->col".
static int qf_parse_fmt_c(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->col = (int)atol(rmp->startp[midx]);
 return QF_OK;
}

/// Parse the match for end line number ('%e') pattern in regmatch.
/// Return the matched value in "fields->end_lnum".
static int qf_parse_fmt_k(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->end_col = (int)atol(rmp->startp[midx]);
 return QF_OK;
}

/// Parse the match for error type ('%t') pattern in regmatch.
/// Return the matched value in "fields->type".
static int qf_parse_fmt_t(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->type = *rmp->startp[midx];
 return QF_OK;
}

/// Copy a non-error line into the error string.  Return the matched line in
/// "fields->errmsg".
static int copy_nonerror_line(const char *linebuf, size_t linelen, qffields_T *fields)
 FUNC_ATTR_NONNULL_ALL
{
 if (linelen >= fields->errmsglen) {
   // linelen + null terminator
   fields->errmsg = xrealloc(fields->errmsg, linelen + 1);
   fields->errmsglen = linelen + 1;
 }
 // copy whole line to error message
 xstrlcpy(fields->errmsg, linebuf, linelen + 1);

 return QF_OK;
}

/// Parse the match for error message ('%m') pattern in regmatch.
/// Return the matched value in "fields->errmsg".
static int qf_parse_fmt_m(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL || rmp->endp[midx] == NULL) {
   return QF_FAIL;
 }
 size_t len = (size_t)(rmp->endp[midx] - rmp->startp[midx]);
 if (len >= fields->errmsglen) {
   // len + null terminator
   fields->errmsg = xrealloc(fields->errmsg, len + 1);
   fields->errmsglen = len + 1;
 }
 xstrlcpy(fields->errmsg, rmp->startp[midx], len + 1);
 return QF_OK;
}

/// Parse the match for rest of a single-line file message ('%r') pattern.
/// Return the matched value in "tail".
static int qf_parse_fmt_r(regmatch_T *rmp, int midx, char **tail)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 *tail = rmp->startp[midx];
 return QF_OK;
}

/// Parse the match for the pointer line ('%p') pattern in regmatch.
/// Return the matched value in "fields->col".
static int qf_parse_fmt_p(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL || rmp->endp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->col = 0;
 for (char *match_ptr = rmp->startp[midx]; match_ptr != rmp->endp[midx];
      match_ptr++) {
   fields->col++;
   if (*match_ptr == TAB) {
     fields->col += 7;
     fields->col -= fields->col % 8;
   }
 }
 fields->col++;
 fields->use_viscol = true;
 return QF_OK;
}

/// Parse the match for the virtual column number ('%v') pattern in regmatch.
/// Return the matched value in "fields->col".
static int qf_parse_fmt_v(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL) {
   return QF_FAIL;
 }
 fields->col = (int)atol(rmp->startp[midx]);
 fields->use_viscol = true;
 return QF_OK;
}

/// Parse the match for the search text ('%s') pattern in regmatch.
/// Return the matched value in "fields->pattern".
static int qf_parse_fmt_s(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL || rmp->endp[midx] == NULL) {
   return QF_FAIL;
 }
 size_t len = (size_t)(rmp->endp[midx] - rmp->startp[midx]);
 len = MIN(len, CMDBUFFSIZE - 5);
 STRCPY(fields->pattern, "^\\V");
 xstrlcat(fields->pattern, rmp->startp[midx], len + 4);
 fields->pattern[len + 3] = '\\';
 fields->pattern[len + 4] = '$';
 fields->pattern[len + 5] = NUL;
 return QF_OK;
}

/// Parse the match for the module ('%o') pattern in regmatch.
/// Return the matched value in "fields->module".
static int qf_parse_fmt_o(regmatch_T *rmp, int midx, qffields_T *fields)
{
 if (rmp->startp[midx] == NULL || rmp->endp[midx] == NULL) {
   return QF_FAIL;
 }
 size_t len = (size_t)(rmp->endp[midx] - rmp->startp[midx]);
 size_t dsize = strlen(fields->module) + len + 1;
 dsize = MIN(dsize, CMDBUFFSIZE);
 xstrlcat(fields->module, rmp->startp[midx], dsize);
 return QF_OK;
}

/// 'errorformat' format pattern parser functions.
/// The '%f' and '%r' formats are parsed differently from other formats.
/// See qf_parse_match() for details.
/// Keep in sync with fmt_pat[].
static int (*qf_parse_fmt[FMT_PATTERNS])(regmatch_T *, int, qffields_T *) = {
 NULL,  // %f
 qf_parse_fmt_b,
 qf_parse_fmt_n,
 qf_parse_fmt_l,
 qf_parse_fmt_e,
 qf_parse_fmt_c,
 qf_parse_fmt_k,
 qf_parse_fmt_t,
 qf_parse_fmt_m,
 NULL,  // %r
 qf_parse_fmt_p,
 qf_parse_fmt_v,
 qf_parse_fmt_s,
 qf_parse_fmt_o
};

/// Parse the error format matches in 'regmatch' and set the values in 'fields'.
/// fmt_ptr contains the 'efm' format specifiers/prefixes that have a match.
/// Returns QF_OK if all the matches are successfully parsed. On failure,
/// returns QF_FAIL or QF_NOMEM.
static int qf_parse_match(char *linebuf, size_t linelen, efm_T *fmt_ptr, regmatch_T *regmatch,
                         qffields_T *fields, int qf_multiline, int qf_multiscan, char **tail)
{
 char idx = fmt_ptr->prefix;

 if ((idx == 'C' || idx == 'Z') && !qf_multiline) {
   return QF_FAIL;
 }
 if (vim_strchr("EWIN", (uint8_t)idx) != NULL) {
   fields->type = idx;
 } else {
   fields->type = 0;
 }

 // Extract error message data from matched line.
 // We check for an actual submatch, because "\[" and "\]" in
 // the 'errorformat' may cause the wrong submatch to be used.
 for (int i = 0; i < FMT_PATTERNS; i++) {
   int status = QF_OK;
   int midx = (int)fmt_ptr->addr[i];
   if (i == 0 && midx > 0) {  // %f
     status = qf_parse_fmt_f(regmatch, midx, fields, idx);
   } else if (i == FMT_PATTERN_M) {
     if (fmt_ptr->flags == '+' && !qf_multiscan) {  // %+
       status = copy_nonerror_line(linebuf, linelen, fields);
     } else if (midx > 0) {  // %m
       status = qf_parse_fmt_m(regmatch, midx, fields);
     }
   } else if (i == FMT_PATTERN_R && midx > 0) {  // %r
     status = qf_parse_fmt_r(regmatch, midx, tail);
   } else if (midx > 0) {  // others
     status = (qf_parse_fmt[i])(regmatch, midx, fields);
   }

   if (status != QF_OK) {
     return status;
   }
 }

 return QF_OK;
}

/// Parse an error line in 'linebuf' using a single error format string in
/// 'fmt_ptr->prog' and return the matching values in 'fields'.
/// Returns QF_OK if the efm format matches completely and the fields are
/// successfully copied. Otherwise returns QF_FAIL or QF_NOMEM.
static int qf_parse_get_fields(char *linebuf, size_t linelen, efm_T *fmt_ptr, qffields_T *fields,
                              int qf_multiline, int qf_multiscan, char **tail)
{
 if (qf_multiscan && vim_strchr("OPQ", (uint8_t)fmt_ptr->prefix) == NULL) {
   return QF_FAIL;
 }

 fields->namebuf[0] = NUL;
 fields->bnr = 0;
 fields->module[0] = NUL;
 fields->pattern[0] = NUL;
 if (!qf_multiscan) {
   fields->errmsg[0] = NUL;
 }
 fields->lnum = 0;
 fields->end_lnum = 0;
 fields->col = 0;
 fields->end_col = 0;
 fields->use_viscol = false;
 fields->enr = -1;
 fields->type = 0;
 *tail = NULL;

 regmatch_T regmatch;
 // Always ignore case when looking for a matching error.
 regmatch.rm_ic = true;
 regmatch.regprog = fmt_ptr->prog;
 bool r = vim_regexec(&regmatch, linebuf, 0);
 fmt_ptr->prog = regmatch.regprog;
 int status = QF_FAIL;
 if (r) {
   status = qf_parse_match(linebuf, linelen, fmt_ptr, &regmatch, fields,
                           qf_multiline, qf_multiscan, tail);
 }

 return status;
}

/// Parse directory error format prefixes (%D and %X).
/// Push and pop directories from the directory stack when scanning directory
/// names.
static int qf_parse_dir_pfx(int idx, qffields_T *fields, qf_list_T *qfl)
{
 if (idx == 'D') {  // enter directory
   if (*fields->namebuf == NUL) {
     emsg(_("E379: Missing or empty directory name"));
     return QF_FAIL;
   }
   qfl->qf_directory = qf_push_dir(fields->namebuf, &qfl->qf_dir_stack, false);
   if (qfl->qf_directory == NULL) {
     return QF_FAIL;
   }
 } else if (idx == 'X') {  // leave directory
   qfl->qf_directory = qf_pop_dir(&qfl->qf_dir_stack);
 }

 return QF_OK;
}

/// Parse global file name error format prefixes (%O, %P and %Q).
static int qf_parse_file_pfx(int idx, qffields_T *fields, qf_list_T *qfl, char *tail)
{
 fields->valid = false;
 if (*fields->namebuf == NUL || os_path_exists(fields->namebuf)) {
   if (*fields->namebuf && idx == 'P') {
     qfl->qf_currfile = qf_push_dir(fields->namebuf, &qfl->qf_file_stack, true);
   } else if (idx == 'Q') {
     qfl->qf_currfile = qf_pop_dir(&qfl->qf_file_stack);
   }
   *fields->namebuf = NUL;
   if (tail && *tail) {
     STRMOVE(IObuff, skipwhite(tail));
     qfl->qf_multiscan = true;
     return QF_MULTISCAN;
   }
 }

 return QF_OK;
}

/// Parse a non-error line (a line which doesn't match any of the error
/// format in 'efm').
static int qf_parse_line_nomatch(char *linebuf, size_t linelen, qffields_T *fields)
{
 fields->namebuf[0] = NUL;   // no match found, remove file name
 fields->lnum = 0;           // don't jump to this line
 fields->valid = false;

 return copy_nonerror_line(linebuf, linelen, fields);
}

/// Parse multi-line error format prefixes (%C and %Z)
static int qf_parse_multiline_pfx(int idx, qf_list_T *qfl, qffields_T *fields)
{
 if (!qfl->qf_multiignore) {
   qfline_T *qfprev = qfl->qf_last;

   if (qfprev == NULL) {
     return QF_FAIL;
   }
   if (*fields->errmsg) {
     size_t textlen = strlen(qfprev->qf_text);
     size_t errlen = strlen(fields->errmsg);
     qfprev->qf_text = xrealloc(qfprev->qf_text, textlen + errlen + 2);
     qfprev->qf_text[textlen] = '\n';
     STRCPY(qfprev->qf_text + textlen + 1, fields->errmsg);
   }
   if (qfprev->qf_nr == -1) {
     qfprev->qf_nr = fields->enr;
   }
   if (vim_isprintc(fields->type) && !qfprev->qf_type) {
     // only printable chars allowed
     qfprev->qf_type = fields->type;
   }

   if (!qfprev->qf_lnum) {
     qfprev->qf_lnum = fields->lnum;
   }
   if (!qfprev->qf_end_lnum) {
     qfprev->qf_end_lnum = fields->end_lnum;
   }
   if (!qfprev->qf_col) {
     qfprev->qf_col = fields->col;
     qfprev->qf_viscol = fields->use_viscol;
   }
   if (!qfprev->qf_end_col) {
     qfprev->qf_end_col = fields->end_col;
   }
   if (!qfprev->qf_fnum) {
     qfprev->qf_fnum = qf_get_fnum(qfl, qfl->qf_directory,
                                   *fields->namebuf || qfl->qf_directory
                                   ? fields->namebuf
                                   : qfl->qf_currfile && fields->valid
                                   ? qfl->qf_currfile : 0);
   }
 }
 if (idx == 'Z') {
   qfl->qf_multiline = qfl->qf_multiignore = false;
 }
 line_breakcheck();

 return QF_IGNORE_LINE;
}

/// Queue location list stack delete request.
static void locstack_queue_delreq(qf_info_T *qi)
{
 qf_delq_T *q = xmalloc(sizeof(qf_delq_T));
 q->qi = qi;
 q->next = qf_delq_head;
 qf_delq_head = q;
}

/// Return the global quickfix stack window buffer number.
int qf_stack_get_bufnr(void)
{
 assert(ql_info != NULL);
 return ql_info->qf_bufnr;
}

/// Wipe the quickfix window buffer (if present) for the specified
/// quickfix/location list.
static void wipe_qf_buffer(qf_info_T *qi)
 FUNC_ATTR_NONNULL_ALL
{
 if (qi->qf_bufnr == INVALID_QFBUFNR) {
   return;
 }

 buf_T *const qfbuf = buflist_findnr(qi->qf_bufnr);
 if (qfbuf != NULL && qfbuf->b_nwindows == 0) {
   bool buf_was_null = false;
   // can happen when curwin is going to be closed e.g. curwin->w_buffer
   // was already closed in win_close(), and we are now closing the
   // window related location list buffer from win_free_mem()
   // but close_buffer() calls CHECK_CURBUF() macro and requires
   // curwin->w_buffer == curbuf
   if (curwin->w_buffer == NULL) {
     curwin->w_buffer = curbuf;
     buf_was_null = true;
   }

   // If the quickfix buffer is not loaded in any window, then
   // wipe the buffer.
   close_buffer(NULL, qfbuf, DOBUF_WIPE, false, false);
   qi->qf_bufnr = INVALID_QFBUFNR;
   if (buf_was_null) {
     curwin->w_buffer = NULL;
   }
 }
}

/// Free all lists in the stack (not including the stack)
static void qf_free_list_stack_items(qf_info_T *qi)
{
 for (int i = 0; i < qi->qf_listcount; i++) {
   qf_free(qf_get_list(qi, i));
 }
}

/// Free a qf_info_T struct completely
static void qf_free_lists(qf_info_T *qi)
{
 qf_free_list_stack_items(qi);

 xfree(qi->qf_lists);
 xfree(qi);
}

/// Free a location list stack
static void ll_free_all(qf_info_T **pqi)
{
 qf_info_T *qi = *pqi;
 if (qi == NULL) {
   return;
 }
 *pqi = NULL;          // Remove reference to this list

 // If the location list is still in use, then queue the delete request
 // to be processed later.
 if (quickfix_busy > 0) {
   locstack_queue_delreq(qi);
   return;
 }

 qi->qf_refcount--;
 if (qi->qf_refcount < 1) {
   // No references to this location list.
   // If the quickfix window buffer is loaded, then wipe it
   wipe_qf_buffer(qi);

   qf_free_lists(qi);
 }
}

/// Free all the quickfix/location lists in the stack.
void qf_free_all(win_T *wp)
{
 qf_info_T *qi = ql_info;

 if (wp != NULL) {
   // location list
   ll_free_all(&wp->w_llist);
   ll_free_all(&wp->w_llist_ref);
 } else if (qi != NULL) {
   qf_free_list_stack_items(qi);  // quickfix list
 }
}

/// Delay freeing of location list stacks when the quickfix code is running.
/// Used to avoid problems with autocmds freeing location list stacks when the
/// quickfix code is still referencing the stack.
/// Must always call decr_quickfix_busy() exactly once after this.
static void incr_quickfix_busy(void)
{
 quickfix_busy++;
}

/// Safe to free location list stacks. Process any delayed delete requests.
static void decr_quickfix_busy(void)
{
 quickfix_busy--;
 if (quickfix_busy == 0) {
   // No longer referencing the location lists. Process all the pending
   // delete requests.
   while (qf_delq_head != NULL) {
     qf_delq_T *q = qf_delq_head;

     qf_delq_head = q->next;
     ll_free_all(&q->qi);
     xfree(q);
   }
 }
#ifdef ABORT_ON_INTERNAL_ERROR
 if (quickfix_busy < 0) {
   emsg("quickfix_busy has become negative");
   abort();
 }
#endif
}

#if defined(EXITFREE)
void check_quickfix_busy(void)
{
 if (quickfix_busy != 0) {
   semsg("quickfix_busy not zero on exit: %" PRId64, (int64_t)quickfix_busy);
# ifdef ABORT_ON_INTERNAL_ERROR
   abort();
# endif
 }
}
#endif

/// Add an entry to the end of the list of errors.
///
/// @param  qfl      quickfix list entry
/// @param  dir      optional directory name
/// @param  fname    file name or NULL
/// @param  module   module name or NULL
/// @param  bufnum   buffer number or zero
/// @param  mesg     message
/// @param  lnum     line number
/// @param  end_lnum  line number for end
/// @param  col      column
/// @param  end_col  column for end
/// @param  vis_col  using visual column
/// @param  pattern  search pattern
/// @param  nr       error number
/// @param  type     type character
/// @param  user_data  custom user data or NULL
/// @param  valid    valid entry
///
/// @return  QF_OK on success or QF_FAIL on failure.
static int qf_add_entry(qf_list_T *qfl, char *dir, char *fname, char *module, int bufnum,
                       char *mesg, linenr_T lnum, linenr_T end_lnum, int col, int end_col,
                       char vis_col, char *pattern, int nr, char type, typval_T *user_data,
                       char valid)
{
 buf_T *buf;
 qfline_T *qfp = xmalloc(sizeof(qfline_T));
 char *fullname = NULL;
 char *p = NULL;

 if (bufnum != 0) {
   buf = buflist_findnr(bufnum);
   qfp->qf_fnum = bufnum;
   if (buf != NULL) {
     buf->b_has_qf_entry |=
       IS_QF_LIST(qfl) ? BUF_HAS_QF_ENTRY : BUF_HAS_LL_ENTRY;
   }
 } else {
   qfp->qf_fnum = qf_get_fnum(qfl, dir, fname);
   buf = buflist_findnr(qfp->qf_fnum);
 }
 if (fname != NULL) {
   fullname = fix_fname(fname);
 }
 qfp->qf_fname = NULL;
 if (buf != NULL && buf->b_ffname != NULL && fullname != NULL) {
   if (path_fnamecmp(fullname, buf->b_ffname) != 0) {
     p = path_try_shorten_fname(fullname);
     if (p != NULL) {
       qfp->qf_fname = xstrdup(p);
     }
   }
 }
 xfree(fullname);
 qfp->qf_text = xstrdup(mesg);
 qfp->qf_lnum = lnum;
 qfp->qf_end_lnum = end_lnum;
 qfp->qf_col = col;
 qfp->qf_end_col = end_col;
 qfp->qf_viscol = vis_col;
 if (user_data == NULL || user_data->v_type == VAR_UNKNOWN) {
   qfp->qf_user_data.v_type = VAR_UNKNOWN;
 } else {
   tv_copy(user_data, &qfp->qf_user_data);
   qfl->qf_has_user_data = true;
 }
 if (pattern == NULL || *pattern == NUL) {
   qfp->qf_pattern = NULL;
 } else {
   qfp->qf_pattern = xstrdup(pattern);
 }
 if (module == NULL || *module == NUL) {
   qfp->qf_module = NULL;
 } else {
   qfp->qf_module = xstrdup(module);
 }
 qfp->qf_nr = nr;
 if (type != 1 && !vim_isprintc(type)) {  // only printable chars allowed
   type = 0;
 }
 qfp->qf_type = type;
 qfp->qf_valid = valid;

 qfline_T **lastp = &qfl->qf_last;
 if (qf_list_empty(qfl)) {
   // first element in the list
   qfl->qf_start = qfp;
   qfl->qf_ptr = qfp;
   qfl->qf_index = 0;
   qfp->qf_prev = NULL;
 } else {
   assert(*lastp);
   qfp->qf_prev = *lastp;
   (*lastp)->qf_next = qfp;
 }
 qfp->qf_next = NULL;
 qfp->qf_cleared = false;
 *lastp = qfp;
 qfl->qf_count++;
 if (qfl->qf_index == 0 && qfp->qf_valid) {
   // first valid entry
   qfl->qf_index = qfl->qf_count;
   qfl->qf_ptr = qfp;
 }

 return QF_OK;
}

/// Resize quickfix stack to be able to hold n amount of lists.
void qf_resize_stack(int n)
{
 assert(ql_info != NULL);
 qf_resize_stack_base(ql_info, n);
}

/// Resize location list stack for window 'wp' to be able to hold n amount of lists.
void ll_resize_stack(win_T *wp, int n)
{
 // check if given window is a location list window;
 // if so then sync its 'lhistory' to the parent window or vice versa
 if (IS_LL_WINDOW(wp)) {
   qf_sync_llw_to_win(wp);
 } else {
   qf_sync_win_to_llw(wp);
 }

 qf_info_T *qi = ll_get_or_alloc_list(wp);
 qf_resize_stack_base(qi, n);
}

/// Resize quickfix/location lists stack to be able to hold n amount of lists.
static void qf_resize_stack_base(qf_info_T *qi, int n)
 FUNC_ATTR_NONNULL_ALL
{
 int amount_to_rm = 0;
 size_t lsz = sizeof(*qi->qf_lists);

 if (n == qi->qf_maxcount) {
   return;
 } else if (n < qi->qf_maxcount && n < qi->qf_listcount) {
   // We have too many lists to store them all in the new stack,
   // pop lists until we can fit them all in the newly resized stack
   amount_to_rm = qi->qf_listcount - n;

   for (int i = 0; i < amount_to_rm; i++) {
     qf_pop_stack(qi, true);
   }
 }

 qf_list_T *new = xrealloc(qi->qf_lists, lsz * (size_t)n);

 // fill with zeroes any newly allocated memory
 if (n > qi->qf_maxcount) {
   memset(new + qi->qf_maxcount, 0, lsz * (size_t)(n - qi->qf_maxcount));
 }

 qi->qf_lists = new;
 qi->qf_maxcount = n;

 qf_update_buffer(qi, NULL);
}

/// Initialize quickfix list, should only be called once.
void qf_init_stack(void)
{
 ql_info = qf_alloc_stack(QFLT_QUICKFIX, (int)p_chi);
}

/// Sync a location list window's 'lhistory' value to the parent window
static void qf_sync_llw_to_win(win_T *llw)
{
 win_T *wp = qf_find_win_with_loclist(llw->w_llist_ref);

 if (wp != NULL) {
   wp->w_p_lhi = llw->w_p_lhi;
 }
}

/// Sync a window's 'lhistory' value to its location list window, if any
static void qf_sync_win_to_llw(win_T *pwp)
{
 qf_info_T *llw = pwp->w_llist;

 if (llw != NULL) {
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
     if (wp->w_llist_ref == llw && bt_quickfix(wp->w_buffer)) {
       wp->w_p_lhi = pwp->w_p_lhi;
       return;
     }
   }
 }
}

/// Allocate a new quickfix/location list stack that is able to hold
/// up to n amount of lists
static qf_info_T *qf_alloc_stack(qfltype_T qfltype, int n)
 FUNC_ATTR_NONNULL_RET
{
 qf_info_T *qi;
 if (qfltype == QFLT_QUICKFIX) {
   qi = &ql_info_actual;
 } else {
   qi = xcalloc(1, sizeof(qf_info_T));
   qi->qf_refcount++;
 }
 qi->qfl_type = qfltype;
 qi->qf_bufnr = INVALID_QFBUFNR;
 qi->qf_lists = qf_alloc_list_stack(n);
 qi->qf_maxcount = n;

 return qi;
}

/// Allocate memory for qf_lists member of qf_info_T struct.
static qf_list_T *qf_alloc_list_stack(int n)
 FUNC_ATTR_NONNULL_RET
{
 return xcalloc((size_t)n, sizeof(qf_list_T));
}

/// Return the location list stack for window 'wp'.
/// If not present, allocate a location list stack
static qf_info_T *ll_get_or_alloc_list(win_T *wp)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
{
 if (IS_LL_WINDOW(wp)) {
   // For a location list window, use the referenced location list
   return wp->w_llist_ref;
 }

 // For a non-location list window, w_llist_ref should not point to a
 // location list.
 ll_free_all(&wp->w_llist_ref);

 if (wp->w_llist == NULL) {
   // new location list
   wp->w_llist = qf_alloc_stack(QFLT_LOCATION, (int)wp->w_p_lhi);
 }

 return wp->w_llist;
}

/// Get the quickfix/location list stack to use for the specified Ex command.
/// For a location list command, returns the stack for the current window.  If
/// the location list is not found, then returns NULL and prints an error
/// message if 'print_emsg' is true.
static qf_info_T *qf_cmd_get_stack(exarg_T *eap, bool print_emsg)
{
 qf_info_T *qi = ql_info;
 assert(qi != NULL);

 if (is_loclist_cmd(eap->cmdidx)) {
   qi = GET_LOC_LIST(curwin);
   if (qi == NULL) {
     if (print_emsg) {
       emsg(_(e_loclist));
     }
     return NULL;
   }
 }

 return qi;
}

/// Get the quickfix/location list stack to use for the specified Ex command.
/// For a location list command, returns the stack for the current window.
/// If the location list is not present, then allocates a new one.
/// For a location list command, sets 'pwinp' to curwin.
static qf_info_T *qf_cmd_get_or_alloc_stack(const exarg_T *eap, win_T **pwinp)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
{
 qf_info_T *qi = ql_info;

 if (is_loclist_cmd(eap->cmdidx)) {
   qi = ll_get_or_alloc_list(curwin);
   *pwinp = curwin;
 }

 return qi;
}

/// Copy location list entries from 'from_qfl' to 'to_qfl'.
static int copy_loclist_entries(const qf_list_T *from_qfl, qf_list_T *to_qfl)
 FUNC_ATTR_NONNULL_ALL
{
 int i;
 qfline_T *from_qfp;

 // copy all the location entries in this list
 FOR_ALL_QFL_ITEMS(from_qfl, from_qfp, i) {
   if (qf_add_entry(to_qfl,
                    NULL,
                    NULL,
                    from_qfp->qf_module,
                    0,
                    from_qfp->qf_text,
                    from_qfp->qf_lnum,
                    from_qfp->qf_end_lnum,
                    from_qfp->qf_col,
                    from_qfp->qf_end_col,
                    from_qfp->qf_viscol,
                    from_qfp->qf_pattern,
                    from_qfp->qf_nr,
                    0,
                    &from_qfp->qf_user_data,
                    from_qfp->qf_valid) == QF_FAIL) {
     return FAIL;
   }

   // qf_add_entry() will not set the qf_num field, as the
   // directory and file names are not supplied. So the qf_fnum
   // field is copied here.
   qfline_T *const prevp = to_qfl->qf_last;
   prevp->qf_fnum = from_qfp->qf_fnum;  // file number
   prevp->qf_type = from_qfp->qf_type;  // error type
   if (from_qfl->qf_ptr == from_qfp) {
     to_qfl->qf_ptr = prevp;  // current location
   }
 }

 return OK;
}

/// Copy the specified location list 'from_qfl' to 'to_qfl'.
static int copy_loclist(qf_list_T *from_qfl, qf_list_T *to_qfl)
 FUNC_ATTR_NONNULL_ALL
{
 // Some of the fields are populated by qf_add_entry()
 to_qfl->qfl_type = from_qfl->qfl_type;
 to_qfl->qf_nonevalid = from_qfl->qf_nonevalid;
 to_qfl->qf_has_user_data = from_qfl->qf_has_user_data;
 to_qfl->qf_count = 0;
 to_qfl->qf_index = 0;
 to_qfl->qf_start = NULL;
 to_qfl->qf_last = NULL;
 to_qfl->qf_ptr = NULL;
 if (from_qfl->qf_title != NULL) {
   to_qfl->qf_title = xstrdup(from_qfl->qf_title);
 } else {
   to_qfl->qf_title = NULL;
 }
 if (from_qfl->qf_ctx != NULL) {
   to_qfl->qf_ctx = xcalloc(1, sizeof(*to_qfl->qf_ctx));
   tv_copy(from_qfl->qf_ctx, to_qfl->qf_ctx);
 } else {
   to_qfl->qf_ctx = NULL;
 }
 callback_copy(&to_qfl->qf_qftf_cb, &from_qfl->qf_qftf_cb);

 if (from_qfl->qf_count) {
   if (copy_loclist_entries(from_qfl, to_qfl) == FAIL) {
     return FAIL;
   }
 }

 to_qfl->qf_index = from_qfl->qf_index;  // current index in the list

 // Assign a new ID for the location list
 to_qfl->qf_id = ++last_qf_id;
 to_qfl->qf_changedtick = 0;

 // When no valid entries are present in the list, qf_ptr points to
 // the first item in the list
 if (to_qfl->qf_nonevalid) {
   to_qfl->qf_ptr = to_qfl->qf_start;
   to_qfl->qf_index = 1;
 }

 return OK;
}

// Copy the location list stack 'from' window to 'to' window.
void copy_loclist_stack(win_T *from, win_T *to)
 FUNC_ATTR_NONNULL_ALL
{
 // When copying from a location list window, copy the referenced
 // location list. For other windows, copy the location list for
 // that window.
 qf_info_T *qi = IS_LL_WINDOW(from) ? from->w_llist_ref : from->w_llist;

 if (qi == NULL) {                 // no location list to copy
   return;
 }

 // allocate a new location list, set size of stack to 'from' window value
 to->w_llist = qf_alloc_stack(QFLT_LOCATION, (int)from->w_p_lhi);
 // set 'to' lhi to reflect new value
 to->w_p_lhi = to->w_llist->qf_maxcount;

 to->w_llist->qf_listcount = qi->qf_listcount;

 // Copy the location lists one at a time
 for (int idx = 0; idx < qi->qf_listcount; idx++) {
   to->w_llist->qf_curlist = idx;

   if (copy_loclist(qf_get_list(qi, idx),
                    qf_get_list(to->w_llist, idx)) == FAIL) {
     qf_free_all(to);
     return;
   }
 }

 to->w_llist->qf_curlist = qi->qf_curlist;  // current list
}

/// Get buffer number for file "directory/fname".
/// Also sets the b_has_qf_entry flag.
static int qf_get_fnum(qf_list_T *qfl, char *directory, char *fname)
{
 char *ptr = NULL;
 char *bufname;
 buf_T *buf;
 if (fname == NULL || *fname == NUL) {         // no file name
   return 0;
 }

#ifdef BACKSLASH_IN_FILENAME
 if (directory != NULL) {
   slash_adjust(directory);
 }
 slash_adjust(fname);
#endif
 if (directory != NULL && !vim_isAbsName(fname)) {
   ptr = concat_fnames(directory, fname, true);
   // Here we check if the file really exists.
   // This should normally be true, but if make works without
   // "leaving directory"-messages we might have missed a
   // directory change.
   if (!os_path_exists(ptr)) {
     xfree(ptr);
     directory = qf_guess_filepath(qfl, fname);
     if (directory) {
       ptr = concat_fnames(directory, fname, true);
     } else {
       ptr = xstrdup(fname);
     }
   }
   // Use concatenated directory name and file name.
   bufname = ptr;
 } else {
   bufname = fname;
 }

 if (qf_last_bufname != NULL
     && strcmp(bufname, qf_last_bufname) == 0
     && bufref_valid(&qf_last_bufref)) {
   buf = qf_last_bufref.br_buf;
   xfree(ptr);
 } else {
   xfree(qf_last_bufname);
   buf = buflist_new(bufname, NULL, 0, BLN_NOOPT);
   qf_last_bufname = (bufname == ptr) ? bufname : xstrdup(bufname);
   set_bufref(&qf_last_bufref, buf);
 }
 if (buf == NULL) {
   return 0;
 }
 buf->b_has_qf_entry =
   IS_QF_LIST(qfl) ? BUF_HAS_QF_ENTRY : BUF_HAS_LL_ENTRY;
 return buf->b_fnum;
}

// Push dirbuf onto the directory stack and return pointer to actual dir or
// NULL on error.
static char *qf_push_dir(char *dirbuf, struct dir_stack_T **stackptr, bool is_file_stack)
{
 struct dir_stack_T *ds_ptr;

 // allocate new stack element and hook it in
 struct dir_stack_T *ds_new = xmalloc(sizeof(struct dir_stack_T));

 ds_new->next = *stackptr;
 *stackptr = ds_new;

 // store directory on the stack
 if (vim_isAbsName(dirbuf)
     || (*stackptr)->next == NULL
     || is_file_stack) {
   (*stackptr)->dirname = xstrdup(dirbuf);
 } else {
   // Okay we don't have an absolute path.
   // dirbuf must be a subdir of one of the directories on the stack.
   // Let's search...
   ds_new = (*stackptr)->next;
   (*stackptr)->dirname = NULL;
   while (ds_new) {
     xfree((*stackptr)->dirname);
     (*stackptr)->dirname = concat_fnames(ds_new->dirname, dirbuf, true);
     if (os_isdir((*stackptr)->dirname)) {
       break;
     }

     ds_new = ds_new->next;
   }

   // clean up all dirs we already left
   while ((*stackptr)->next != ds_new) {
     ds_ptr = (*stackptr)->next;
     (*stackptr)->next = (*stackptr)->next->next;
     xfree(ds_ptr->dirname);
     xfree(ds_ptr);
   }

   // Nothing found -> it must be on top level
   if (ds_new == NULL) {
     xfree((*stackptr)->dirname);
     (*stackptr)->dirname = xstrdup(dirbuf);
   }
 }

 if ((*stackptr)->dirname != NULL) {
   return (*stackptr)->dirname;
 }
 ds_ptr = *stackptr;
 *stackptr = (*stackptr)->next;
 xfree(ds_ptr);
 return NULL;
}

// pop dirbuf from the directory stack and return previous directory or NULL if
// stack is empty
static char *qf_pop_dir(struct dir_stack_T **stackptr)
{
 // TODO(vim): Should we check if dirbuf is the directory on top of the stack?
 // What to do if it isn't?

 // pop top element and free it
 if (*stackptr != NULL) {
   struct dir_stack_T *ds_ptr = *stackptr;
   *stackptr = (*stackptr)->next;
   xfree(ds_ptr->dirname);
   xfree(ds_ptr);
 }

 // return NEW top element as current dir or NULL if stack is empty
 return *stackptr ? (*stackptr)->dirname : NULL;
}

// clean up directory stack
static void qf_clean_dir_stack(struct dir_stack_T **stackptr)
{
 struct dir_stack_T *ds_ptr;

 while ((ds_ptr = *stackptr) != NULL) {
   *stackptr = (*stackptr)->next;
   xfree(ds_ptr->dirname);
   xfree(ds_ptr);
 }
}

/// Check in which directory of the directory stack the given file can be
/// found.
/// Returns a pointer to the directory name or NULL if not found.
/// Cleans up intermediate directory entries.
///
/// TODO(vim): How to solve the following problem?
/// If we have this directory tree:
///     ./
///     ./aa
///     ./aa/bb
///     ./bb
///     ./bb/x.c
/// and make says:
///     making all in aa
///     making all in bb
///     x.c:9: Error
/// Then qf_push_dir thinks we are in ./aa/bb, but we are in ./bb.
/// qf_guess_filepath will return NULL.
static char *qf_guess_filepath(qf_list_T *qfl, char *filename)
{
 // no dirs on the stack - there's nothing we can do
 if (qfl->qf_dir_stack == NULL) {
   return NULL;
 }

 struct dir_stack_T *ds_ptr = qfl->qf_dir_stack->next;
 char *fullname = NULL;
 while (ds_ptr) {
   xfree(fullname);
   fullname = concat_fnames(ds_ptr->dirname, filename, true);

   if (os_path_exists(fullname)) {
     break;
   }

   ds_ptr = ds_ptr->next;
 }

 xfree(fullname);

 // clean up all dirs we already left
 while (qfl->qf_dir_stack->next != ds_ptr) {
   struct dir_stack_T *ds_tmp = qfl->qf_dir_stack->next;
   qfl->qf_dir_stack->next = qfl->qf_dir_stack->next->next;
   xfree(ds_tmp->dirname);
   xfree(ds_tmp);
 }

 return ds_ptr == NULL ? NULL : ds_ptr->dirname;
}

/// Returns true, if a quickfix/location list with the given identifier exists.
static bool qflist_valid(win_T *wp, unsigned qf_id)
{
 qf_info_T *qi = ql_info;

 if (wp) {
   if (!win_valid(wp)) {
     return false;
   }
   qi = GET_LOC_LIST(wp);  // Location list
 }
 if (!qi) {
   return false;
 }

 for (int i = 0; i < qi->qf_listcount; i++) {
   if (qi->qf_lists[i].qf_id == qf_id) {
     return true;
   }
 }

 return false;
}

/// When loading a file from the quickfix, the autocommands may modify it.
/// This may invalidate the current quickfix entry.  This function checks
/// whether an entry is still present in the quickfix list.
/// Similar to location list.
static bool is_qf_entry_present(qf_list_T *qfl, qfline_T *qf_ptr)
{
 qfline_T *qfp;
 int i;

 // Search for the entry in the current list
 FOR_ALL_QFL_ITEMS(qfl, qfp, i) {
   if (qfp == qf_ptr) {
     break;
   }
 }

 if (i > qfl->qf_count) {  // Entry is not found
   return false;
 }

 return true;
}

/// Get the next valid entry in the current quickfix/location list. The search
/// starts from the current entry. Returns NULL on failure.
static qfline_T *get_next_valid_entry(qf_list_T *qfl, qfline_T *qf_ptr, int *qf_index, int dir)
{
 int idx = *qf_index;
 int old_qf_fnum = qf_ptr->qf_fnum;

 do {
   if (idx == qfl->qf_count || qf_ptr->qf_next == NULL) {
     return NULL;
   }
   idx++;
   qf_ptr = qf_ptr->qf_next;
 } while ((!qfl->qf_nonevalid && !qf_ptr->qf_valid)
          || (dir == FORWARD_FILE && qf_ptr->qf_fnum == old_qf_fnum));

 *qf_index = idx;
 return qf_ptr;
}

/// Get the previous valid entry in the current quickfix/location list. The
/// search starts from the current entry. Returns NULL on failure.
static qfline_T *get_prev_valid_entry(qf_list_T *qfl, qfline_T *qf_ptr, int *qf_index, int dir)
{
 int idx = *qf_index;
 int old_qf_fnum = qf_ptr->qf_fnum;

 do {
   if (idx == 1 || qf_ptr->qf_prev == NULL) {
     return NULL;
   }
   idx--;
   qf_ptr = qf_ptr->qf_prev;
 } while ((!qfl->qf_nonevalid && !qf_ptr->qf_valid)
          || (dir == BACKWARD_FILE && qf_ptr->qf_fnum == old_qf_fnum));

 *qf_index = idx;
 return qf_ptr;
}

/// Get the n'th (errornr) previous/next valid entry from the current entry in
/// the quickfix list.
///   dir == FORWARD or FORWARD_FILE: next valid entry
///   dir == BACKWARD or BACKWARD_FILE: previous valid entry
static qfline_T *get_nth_valid_entry(qf_list_T *qfl, int errornr, int dir, int *new_qfidx)
{
 qfline_T *qf_ptr = qfl->qf_ptr;
 int qf_idx = qfl->qf_index;
 const char *err = e_no_more_items;

 while (errornr--) {
   qfline_T *prev_qf_ptr = qf_ptr;
   int prev_index = qf_idx;

   if (dir == FORWARD || dir == FORWARD_FILE) {
     qf_ptr = get_next_valid_entry(qfl, qf_ptr, &qf_idx, dir);
   } else {
     qf_ptr = get_prev_valid_entry(qfl, qf_ptr, &qf_idx, dir);
   }

   if (qf_ptr == NULL) {
     qf_ptr = prev_qf_ptr;
     qf_idx = prev_index;
     if (err != NULL) {
       emsg(_(err));
       return NULL;
     }
     break;
   }

   err = NULL;
 }

 *new_qfidx = qf_idx;
 return qf_ptr;
}

/// Get n'th (errornr) quickfix entry from the current entry in the quickfix
/// list 'qfl'. Returns a pointer to the new entry and the index in 'new_qfidx'
static qfline_T *get_nth_entry(qf_list_T *qfl, int errornr, int *new_qfidx)
{
 qfline_T *qf_ptr = qfl->qf_ptr;
 int qf_idx = qfl->qf_index;

 // New error number is less than the current error number
 while (errornr < qf_idx && qf_idx > 1 && qf_ptr->qf_prev != NULL) {
   qf_idx--;
   qf_ptr = qf_ptr->qf_prev;
 }

 // New error number is greater than the current error number
 while (errornr > qf_idx
        && qf_idx < qfl->qf_count
        && qf_ptr->qf_next != NULL) {
   qf_idx++;
   qf_ptr = qf_ptr->qf_next;
 }

 *new_qfidx = qf_idx;
 return qf_ptr;
}

/// Get a entry specified by 'errornr' and 'dir' from the current
/// quickfix/location list. 'errornr' specifies the index of the entry and 'dir'
/// specifies the direction (FORWARD/BACKWARD/FORWARD_FILE/BACKWARD_FILE).
/// Returns a pointer to the entry and the index of the new entry is stored in
/// 'new_qfidx'.
static qfline_T *qf_get_entry(qf_list_T *qfl, int errornr, int dir, int *new_qfidx)
{
 qfline_T *qf_ptr = qfl->qf_ptr;
 int qfidx = qfl->qf_index;

 if (dir != 0) {  // next/prev valid entry
   qf_ptr = get_nth_valid_entry(qfl, errornr, dir, &qfidx);
 } else if (errornr != 0) {  // go to specified number
   qf_ptr = get_nth_entry(qfl, errornr, &qfidx);
 }

 *new_qfidx = qfidx;
 return qf_ptr;
}

// Find a window displaying a Vim help file in the current tab page.
static win_T *qf_find_help_win(void)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
   if (bt_help(wp->w_buffer) && !wp->w_config.hide && wp->w_config.focusable) {
     return wp;
   }
 }
 return NULL;
}

/// Set the location list for the specified window to 'qi'.
static void win_set_loclist(win_T *wp, qf_info_T *qi)
{
 wp->w_llist = qi;
 qi->qf_refcount++;
}

/// Find a help window or open one. If 'newwin' is true, then open a new help
/// window.
static int jump_to_help_window(qf_info_T *qi, bool newwin, bool *opened_window)
{
 win_T *wp = (cmdmod.cmod_tab != 0 || newwin) ? NULL : qf_find_help_win();

 if (wp != NULL && wp->w_buffer->b_nwindows > 0) {
   win_enter(wp, true);
 } else {
   // Split off help window; put it at far top if no position
   // specified, the current window is vertically split and narrow.
   int flags = WSP_HELP;
   if (cmdmod.cmod_split == 0
       && curwin->w_width != Columns
       && curwin->w_width < 80) {
     flags |= WSP_TOP;
   }

   // If the user asks to open a new window, then copy the location list.
   // Otherwise, don't copy the location list.
   if (IS_LL_STACK(qi) && !newwin) {
     flags |= WSP_NEWLOC;
   }

   if (win_split(0, flags) == FAIL) {
     return FAIL;
   }

   *opened_window = true;

   if (curwin->w_height < p_hh) {
     win_setheight((int)p_hh);
   }

   // When using location list, the new window should use the supplied
   // location list. If the user asks to open a new window, then the new
   // window will get a copy of the location list.
   if (IS_LL_STACK(qi) && !newwin) {
     win_set_loclist(curwin, qi);
   }
 }

 restart_edit = 0;  // don't want insert mode in help file

 return OK;
}

/// Find a non-quickfix window using the given location list stack in the
/// current tabpage.
/// Returns NULL if a matching window is not found.
static win_T *qf_find_win_with_loclist(const qf_info_T *ll)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
   if (wp->w_llist == ll && !bt_quickfix(wp->w_buffer)) {
     return wp;
   }
 }
 return NULL;
}

/// Find a window containing a normal buffer in the current tab page.
static win_T *qf_find_win_with_normal_buf(void)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
   if (bt_normal(wp->w_buffer)) {
     return wp;
   }
 }
 return NULL;
}

// Go to a window in any tabpage containing the specified file.  Returns true
// if successfully jumped to the window. Otherwise returns false.
static bool qf_goto_tabwin_with_file(int fnum)
{
 FOR_ALL_TAB_WINDOWS(tp, wp) {
   if (wp->w_buffer->b_fnum == fnum) {
     goto_tabpage_win(tp, wp);
     return true;
   }
 }
 return false;
}

// Create a new window to show a file above the quickfix window. Called when
// only the quickfix window is present.
static int qf_open_new_file_win(qf_info_T *ll_ref)
{
 int flags = WSP_ABOVE;
 if (ll_ref != NULL) {
   flags |= WSP_NEWLOC;
 }
 if (win_split(0, flags) == FAIL) {
   return FAIL;  // not enough room for window
 }
 p_swb = empty_string_option;  // don't split again
 swb_flags = 0;
 RESET_BINDING(curwin);
 if (ll_ref != NULL) {
   // The new window should use the location list from the
   // location list window
   win_set_loclist(curwin, ll_ref);
 }
 return OK;
}

// Go to a window that shows the right buffer. If the window is not found, go
// to the window just above the location list window. This is used for opening
// a file from a location window and not from a quickfix window. If some usable
// window is previously found, then it is supplied in 'use_win'.
static void qf_goto_win_with_ll_file(win_T *use_win, int qf_fnum, qf_info_T *ll_ref)
{
 win_T *win = use_win;

 if (win == NULL) {
   // Find the window showing the selected file in the current tab page.
   FOR_ALL_WINDOWS_IN_TAB(win2, curtab) {
     if (win2->w_buffer->b_fnum == qf_fnum) {
       win = win2;
       break;
     }
   }
   if (win == NULL) {
     // Find a previous usable window
     win = curwin;
     do {
       if (bt_normal(win->w_buffer)) {
         break;
       }
       if (win->w_prev == NULL) {
         win = lastwin;      // wrap around the top
       } else {
         win = win->w_prev;  // go to previous window
       }
     } while (win != curwin);
   }
 }
 win_goto(win);

 // If the location list for the window is not set, then set it
 // to the location list from the location window
 if (win->w_llist == NULL && ll_ref != NULL) {
   // The new window should use the location list from the
   // location list window
   win_set_loclist(win, ll_ref);
 }
}

// Go to a window that shows the specified file. If a window is not found, go
// to the window just above the quickfix window. This is used for opening a
// file from a quickfix window and not from a location window.
static void qf_goto_win_with_qfl_file(int qf_fnum)
{
 win_T *win = curwin;
 win_T *altwin = NULL;
 while (true) {
   if (win->w_buffer->b_fnum == qf_fnum) {
     break;
   }
   if (win->w_prev == NULL) {
     win = lastwin;      // wrap around the top
   } else {
     win = win->w_prev;  // go to previous window
   }

   if (IS_QF_WINDOW(win)) {
     // Didn't find it, go to the window before the quickfix
     // window, unless 'switchbuf' contains 'uselast': in this case we
     // try to jump to the previously used window first.
     if ((swb_flags & kOptSwbFlagUselast) && win_valid(prevwin)
         && !prevwin->w_p_wfb) {
       win = prevwin;
     } else if (altwin != NULL) {
       win = altwin;
     } else if (curwin->w_prev != NULL) {
       win = curwin->w_prev;
     } else {
       win = curwin->w_next;
     }
     break;
   }

   // Remember a usable window.
   if (altwin == NULL
       && !win->w_p_pvw
       && !win->w_p_wfb
       && bt_normal(win->w_buffer)) {
     altwin = win;
   }
 }

 win_goto(win);
}

// Find a suitable window for opening a file (qf_fnum) from the
// quickfix/location list and jump to it.  If the file is already opened in a
// window, jump to it. Otherwise open a new window to display the file. If
// 'newwin' is true, then always open a new window. This is called from either
// a quickfix or a location list window.
static int qf_jump_to_usable_window(int qf_fnum, bool newwin, bool *opened_window)
{
 win_T *usable_wp = NULL;
 bool usable_win = false;

 // If opening a new window, then don't use the location list referred by
 // the current window.  Otherwise two windows will refer to the same
 // location list.
 qf_info_T *ll_ref = newwin ? NULL : curwin->w_llist_ref;
 if (ll_ref != NULL) {
   // Find a non-quickfix window with this location list
   usable_wp = qf_find_win_with_loclist(ll_ref);
   if (usable_wp != NULL) {
     usable_win = true;
   }
 }

 if (!usable_win) {
   // Locate a window showing a normal buffer
   win_T *win = qf_find_win_with_normal_buf();
   if (win != NULL) {
     usable_win = true;
   }
 }

 // If no usable window is found and 'switchbuf' contains "usetab"
 // then search in other tabs.
 if (!usable_win && (swb_flags & kOptSwbFlagUsetab)) {
   usable_win = qf_goto_tabwin_with_file(qf_fnum);
 }

 // If there is only one window and it is the quickfix window, create a
 // new one above the quickfix window.
 if ((ONE_WINDOW && bt_quickfix(curbuf)) || !usable_win || newwin) {
   if (qf_open_new_file_win(ll_ref) != OK) {
     return FAIL;
   }
   *opened_window = true;  // close it when fail
 } else {
   if (curwin->w_llist_ref != NULL) {  // In a location window
     qf_goto_win_with_ll_file(usable_wp, qf_fnum, ll_ref);
   } else {  // In a quickfix window
     qf_goto_win_with_qfl_file(qf_fnum);
   }
 }

 return OK;
}

/// Edit the selected file or help file.
/// @return  OK if successfully edited the file.
///          FAIL on failing to open the buffer.
///          QF_ABORT if the quickfix/location list was freed by an autocmd
///          when opening the buffer.
static int qf_jump_edit_buffer(qf_info_T *qi, qfline_T *qf_ptr, int forceit, int prev_winid,
                              bool *opened_window)
{
 qf_list_T *qfl = qf_get_curlist(qi);
 int old_changetick = qfl->qf_changedtick;
 int old_qf_curlist = qi->qf_curlist;
 qfltype_T qfl_type = qfl->qfl_type;
 int retval = OK;
 unsigned save_qfid = qfl->qf_id;

 if (qf_ptr->qf_type == 1) {
   // Open help file (do_ecmd() will set b_help flag, readfile() will
   // set b_p_ro flag).
   if (!can_abandon(curbuf, forceit)) {
     no_write_message();
     return FAIL;
   }
   retval = do_ecmd(qf_ptr->qf_fnum, NULL, NULL, NULL, 1,
                    ECMD_HIDE + ECMD_SET_HELP,
                    prev_winid == curwin->handle ? curwin : NULL);
 } else {
   int fnum = qf_ptr->qf_fnum;

   if (!forceit && curwin->w_p_wfb && curbuf->b_fnum != fnum) {
     if (qi->qfl_type == QFLT_LOCATION) {
       // Location lists cannot split or reassign their window
       // so 'winfixbuf' windows must fail
       emsg(_(e_winfixbuf_cannot_go_to_buffer));
       return FAIL;
     }

     if (win_valid(prevwin) && !prevwin->w_p_wfb
         && !bt_quickfix(prevwin->w_buffer)) {
       // 'winfixbuf' is set; attempt to change to a window without it
       // that isn't a quickfix/location list window.
       win_goto(prevwin);
     }
     if (curwin->w_p_wfb) {
       // Split the window, which will be 'nowinfixbuf', and set curwin
       // to that
       if (win_split(0, 0) == OK) {
         *opened_window = true;
       }
       if (curwin->w_p_wfb) {
         // Autocommands set 'winfixbuf' or sent us to another window
         // with it set, or we failed to split the window.  Give up,
         // but don't return immediately, as they may have messed
         // with the list.
         emsg(_(e_winfixbuf_cannot_go_to_buffer));
         retval = FAIL;
       }
     }
   }

   if (retval == OK) {
     retval = buflist_getfile(fnum, 1,
                              GETF_SETMARK | GETF_SWITCH, forceit);
   }
 }
 // If a location list, check whether the associated window is still
 // present.
 if (qfl_type == QFLT_LOCATION) {
   win_T *wp = win_id2wp(prev_winid);

   if (wp == NULL && curwin->w_llist != qi) {
     emsg(_("E924: Current window was closed"));
     *opened_window = false;
     return QF_ABORT;
   }
 }

 if (qfl_type == QFLT_QUICKFIX && !qflist_valid(NULL, save_qfid)) {
   emsg(_(e_current_quickfix_list_was_changed));
   return QF_ABORT;
 }

 if (old_qf_curlist != qi->qf_curlist
     || old_changetick != qfl->qf_changedtick
     || !is_qf_entry_present(qfl, qf_ptr)) {
   if (qfl_type == QFLT_QUICKFIX) {
     emsg(_(e_current_quickfix_list_was_changed));
   } else {
     emsg(_(e_current_location_list_was_changed));
   }
   return QF_ABORT;
 }

 return retval;
}

/// Go to the error line in the current file using either line/column number or
/// a search pattern.
static void qf_jump_goto_line(linenr_T qf_lnum, int qf_col, char qf_viscol, char *qf_pattern)
{
 if (qf_pattern == NULL) {
   // Go to line with error, unless qf_lnum is 0.
   linenr_T i = qf_lnum;
   if (i > 0) {
     i = MIN(i, curbuf->b_ml.ml_line_count);
     curwin->w_cursor.lnum = i;
   }
   if (qf_col > 0) {
     curwin->w_cursor.coladd = 0;
     if (qf_viscol == true) {
       coladvance(curwin, qf_col - 1);
     } else {
       curwin->w_cursor.col = qf_col - 1;
     }
     curwin->w_set_curswant = true;
     check_cursor(curwin);
   } else {
     beginline(BL_WHITE | BL_FIX);
   }
 } else {
   // Move the cursor to the first line in the buffer
   pos_T save_cursor = curwin->w_cursor;
   curwin->w_cursor.lnum = 0;
   if (!do_search(NULL, '/', '/', qf_pattern, strlen(qf_pattern), 1, SEARCH_KEEP, NULL)) {
     curwin->w_cursor = save_cursor;
   }
 }
}

/// Display quickfix list index and size message
static void qf_jump_print_msg(qf_info_T *qi, int qf_index, qfline_T *qf_ptr, buf_T *old_curbuf,
                             linenr_T old_lnum)
{
 garray_T *const gap = qfga_get();

 // Update the screen before showing the message, unless messages scrolled.
 if (!msg_scrolled) {
   update_topline(curwin);
   if (must_redraw) {
     update_screen();
   }
 }
 size_t IObufflen = vim_snprintf_safelen(IObuff, IOSIZE,
                                         _("(%d of %d)%s%s: "), qf_index,
                                         qf_get_curlist(qi)->qf_count,
                                         qf_ptr->qf_cleared ? _(" (line deleted)") : "",
                                         qf_types(qf_ptr->qf_type, qf_ptr->qf_nr));
 // Add the message, skipping leading whitespace and newlines.
 ga_concat_len(gap, IObuff, IObufflen);
 qf_fmt_text(gap, skipwhite(qf_ptr->qf_text));
 ga_append(gap, NUL);

 // Output the message.  Overwrite to avoid scrolling when the 'O'
 // flag is present in 'shortmess'; But when not jumping, print the
 // whole message.
 linenr_T i = msg_scroll;
 if (curbuf == old_curbuf && curwin->w_cursor.lnum == old_lnum) {
   msg_scroll = true;
 } else if ((msg_scrolled == 0 || (p_ch == 0 && msg_scrolled == 1))
            && shortmess(SHM_OVERALL)) {
   msg_scroll = false;
 }
 msg_ext_set_kind("quickfix");
 msg_keep(gap->ga_data, 0, true, false);
 msg_scroll = (int)i;

 qfga_clear();
}

/// Find a usable window for opening a file from the quickfix/location list. If
/// a window is not found then open a new window. If 'newwin' is true, then open
/// a new window.
/// @return  OK if successfully jumped or opened a window.
///          FAIL if not able to jump/open a window.
///          NOTDONE if a file is not associated with the entry.
///          QF_ABORT if the quickfix/location list was modified by an autocmd.
static int qf_jump_open_window(qf_info_T *qi, qfline_T *qf_ptr, bool newwin, bool *opened_window)
{
 qf_list_T *qfl = qf_get_curlist(qi);
 int old_changetick = qfl->qf_changedtick;
 int old_qf_curlist = qi->qf_curlist;
 qfltype_T qfl_type = qfl->qfl_type;

 // For ":helpgrep" find a help window or open one.
 if (qf_ptr->qf_type == 1 && (!bt_help(curwin->w_buffer) || cmdmod.cmod_tab != 0)) {
   if (jump_to_help_window(qi, newwin, opened_window) == FAIL) {
     return FAIL;
   }
 }
 if (old_qf_curlist != qi->qf_curlist
     || old_changetick != qfl->qf_changedtick
     || !is_qf_entry_present(qfl, qf_ptr)) {
   if (qfl_type == QFLT_QUICKFIX) {
     emsg(_(e_current_quickfix_list_was_changed));
   } else {
     emsg(_(e_current_location_list_was_changed));
   }
   return QF_ABORT;
 }

 // If currently in the quickfix window, find another window to show the
 // file in.
 if (bt_quickfix(curbuf) && !*opened_window) {
   // If there is no file specified, we don't know where to go.
   // But do advance, otherwise ":cn" gets stuck.
   if (qf_ptr->qf_fnum == 0) {
     return NOTDONE;
   }

   if (qf_jump_to_usable_window(qf_ptr->qf_fnum, newwin, opened_window)
       == FAIL) {
     return FAIL;
   }
 }
 if (old_qf_curlist != qi->qf_curlist
     || old_changetick != qfl->qf_changedtick
     || !is_qf_entry_present(qfl, qf_ptr)) {
   if (qfl_type == QFLT_QUICKFIX) {
     emsg(_(e_current_quickfix_list_was_changed));
   } else {
     emsg(_(e_current_location_list_was_changed));
   }
   return QF_ABORT;
 }

 return OK;
}

/// Edit a selected file from the quickfix/location list and jump to a
/// particular line/column, adjust the folds and display a message about the
/// jump.
/// @return  OK on success and FAIL on failing to open the file/buffer.
///          QF_ABORT if the quickfix/location list is freed by an autocmd when opening
///          the file.
static int qf_jump_to_buffer(qf_info_T *qi, int qf_index, qfline_T *qf_ptr, int forceit,
                            int prev_winid, bool *opened_window, int openfold, bool print_message)
{
 // If there is a file name, read the wanted file if needed, and check
 // autowrite etc.
 buf_T *old_curbuf = curbuf;
 linenr_T old_lnum = curwin->w_cursor.lnum;
 int retval = OK;

 if (qf_ptr->qf_fnum != 0) {
   retval = qf_jump_edit_buffer(qi, qf_ptr, forceit, prev_winid,
                                opened_window);
   if (retval != OK) {
     return retval;
   }
 }

 // When not switched to another buffer, still need to set pc mark
 if (curbuf == old_curbuf) {
   setpcmark();
 }

 qf_jump_goto_line(qf_ptr->qf_lnum, qf_ptr->qf_col, qf_ptr->qf_viscol, qf_ptr->qf_pattern);

 if ((fdo_flags & kOptFdoFlagQuickfix) && openfold) {
   foldOpenCursor();
 }
 if (print_message) {
   qf_jump_print_msg(qi, qf_index, qf_ptr, old_curbuf, old_lnum);
 }

 return retval;
}

/// Jump to a quickfix line and try to use an existing window.
void qf_jump(qf_info_T *qi, int dir, int errornr, int forceit)
{
 qf_jump_newwin(qi, dir, errornr, forceit, false);
}

// Jump to a quickfix line.
// If dir == 0 go to entry "errornr".
// If dir == FORWARD go "errornr" valid entries forward.
// If dir == BACKWARD go "errornr" valid entries backward.
// If dir == FORWARD_FILE go "errornr" valid entries files backward.
// If dir == BACKWARD_FILE go "errornr" valid entries files backward
// else if "errornr" is zero, redisplay the same line
// If 'forceit' is true, then can discard changes to the current buffer.
// If 'newwin' is true, then open the file in a new window.
static void qf_jump_newwin(qf_info_T *qi, int dir, int errornr, int forceit, bool newwin)
{
 char *old_swb = p_swb;
 unsigned old_swb_flags = swb_flags;
 const bool old_KeyTyped = KeyTyped;           // getting file may reset it

 if (qi == NULL) {
   assert(ql_info != NULL);
   qi = ql_info;
 }

 if (qf_stack_empty(qi) || qf_list_empty(qf_get_curlist(qi))) {
   emsg(_(e_no_errors));
   return;
 }

 incr_quickfix_busy();

 qf_list_T *qfl = qf_get_curlist(qi);

 qfline_T *qf_ptr = qfl->qf_ptr;
 qfline_T *old_qf_ptr = qf_ptr;
 int qf_index = qfl->qf_index;
 int old_qf_index = qf_index;

 qf_ptr = qf_get_entry(qfl, errornr, dir, &qf_index);
 if (qf_ptr == NULL) {
   qf_ptr = old_qf_ptr;
   qf_index = old_qf_index;
   goto theend;
 }

 qfl->qf_index = qf_index;
 qfl->qf_ptr = qf_ptr;

 // No need to print the error message if it's visible in the error window
 bool print_message = !qf_win_pos_update(qi, old_qf_index);

 int prev_winid = curwin->handle;

 bool opened_window = false;
 int retval = qf_jump_open_window(qi, qf_ptr, newwin, &opened_window);
 if (retval == FAIL) {
   goto failed;
 }
 if (retval == QF_ABORT) {
   qi = NULL;
   qf_ptr = NULL;
   goto theend;
 }
 if (retval == NOTDONE) {
   goto theend;
 }

 retval = qf_jump_to_buffer(qi, qf_index, qf_ptr, forceit, prev_winid,
                            &opened_window, old_KeyTyped, print_message);
 if (retval == QF_ABORT) {
   // Quickfix/location list was modified by an autocmd
   qi = NULL;
   qf_ptr = NULL;
 }

 if (retval != OK) {
   if (opened_window) {
     win_close(curwin, true, false);          // Close opened window
   }
   if (qf_ptr != NULL && qf_ptr->qf_fnum != 0) {
     // Couldn't open file, so put index back where it was.  This could
     // happen if the file was readonly and we changed something.
failed:
     qf_ptr = old_qf_ptr;
     qf_index = old_qf_index;
   }
 }
theend:
 if (qi != NULL) {
   qfl->qf_ptr = qf_ptr;
   qfl->qf_index = qf_index;
 }
 if (p_swb != old_swb && p_swb == empty_string_option) {
   // Restore old 'switchbuf' value, but not when an autocommand or
   // modeline has changed the value.
   p_swb = old_swb;
   swb_flags = old_swb_flags;
 }
 decr_quickfix_busy();
}

// Highlight ids used for displaying entries from the quickfix list.
static int qfFile_hl_id;
static int qfSep_hl_id;
static int qfLine_hl_id;

/// Display information about a single entry from the quickfix/location list.
/// Used by ":clist/:llist" commands.
/// 'cursel' will be set to true for the currently selected entry in the
/// quickfix list.
static void qf_list_entry(qfline_T *qfp, int qf_idx, bool cursel)
{
 char *fname = NULL;
 if (qfp->qf_module != NULL && *qfp->qf_module != NUL) {
   vim_snprintf(IObuff, IOSIZE, "%2d %s", qf_idx, qfp->qf_module);
 } else {
   buf_T *buf;
   if (qfp->qf_fnum != 0
       && (buf = buflist_findnr(qfp->qf_fnum)) != NULL) {
     fname = qfp->qf_fname == NULL ? buf->b_fname : qfp->qf_fname;
     if (qfp->qf_type == 1) {  // :helpgrep
       fname = path_tail(fname);
     }
   }
   if (fname == NULL) {
     snprintf(IObuff, IOSIZE, "%2d", qf_idx);
   } else {
     vim_snprintf(IObuff, IOSIZE, "%2d %s", qf_idx, fname);
   }
 }

 // Support for filtering entries using :filter /pat/ clist
 // Match against the module name, file name, search pattern and
 // text of the entry.
 bool filter_entry = true;
 if (qfp->qf_module != NULL && *qfp->qf_module != NUL) {
   filter_entry &= message_filtered(qfp->qf_module);
 }
 if (filter_entry && fname != NULL) {
   filter_entry &= message_filtered(fname);
 }
 if (filter_entry && qfp->qf_pattern != NULL) {
   filter_entry &= message_filtered(qfp->qf_pattern);
 }
 if (filter_entry) {
   filter_entry &= message_filtered(qfp->qf_text);
 }
 if (filter_entry) {
   return;
 }

 if (msg_col > 0) {
   msg_putchar('\n');
 }
 msg_outtrans(IObuff, cursel ? HLF_QFL : qfFile_hl_id, false);

 if (qfp->qf_lnum != 0) {
   msg_puts_hl(":", qfSep_hl_id, false);
 }
 garray_T *gap = qfga_get();
 if (qfp->qf_lnum != 0) {
   qf_range_text(gap, qfp);
 }
 ga_concat(gap, qf_types(qfp->qf_type, qfp->qf_nr));
 ga_append(gap, NUL);
 if (*(char *)gap->ga_data != NUL) {
   msg_puts_hl(gap->ga_data, qfLine_hl_id, false);
 }
 msg_puts_hl(":", qfSep_hl_id, false);
 if (qfp->qf_pattern != NULL) {
   gap = qfga_get();
   qf_fmt_text(gap, qfp->qf_pattern);
   ga_append(gap, NUL);
   msg_puts(gap->ga_data);
   msg_puts_hl(":", qfSep_hl_id, false);
 }
 msg_puts(" ");

 // Remove newlines and leading whitespace from the text.  For an
 // unrecognized line keep the indent, the compiler may mark a word
 // with ^^^^.
 gap = qfga_get();
 qf_fmt_text(gap, (fname != NULL || qfp->qf_lnum != 0) ? skipwhite(qfp->qf_text) : qfp->qf_text);
 ga_append(gap, NUL);
 msg_prt_line(gap->ga_data, false);
}

// ":clist": list all errors
// ":llist": list all locations
void qf_list(exarg_T *eap)
{
 char *arg = eap->arg;
 int all = eap->forceit;     // if not :cl!, only show recognised errors
 qf_info_T *qi = qf_cmd_get_stack(eap, true);

 if (qi == NULL) {
   return;
 }

 if (qf_stack_empty(qi) || qf_list_empty(qf_get_curlist(qi))) {
   emsg(_(e_no_errors));
   return;
 }

 bool plus = false;
 if (*arg == '+') {
   arg++;
   plus = true;
 }
 int idx1 = 1;
 int idx2 = -1;
 if (!get_list_range(&arg, &idx1, &idx2) || *arg != NUL) {
   semsg(_(e_trailing_arg), arg);
   return;
 }
 qf_list_T *qfl = qf_get_curlist(qi);
 int i;
 if (plus) {
   i = qfl->qf_index;
   idx2 = i + idx1;
   idx1 = i;
 } else {
   i = qfl->qf_count;
   if (idx1 < 0) {
     idx1 = (-idx1 > i) ? 0 : idx1 + i + 1;
   }
   if (idx2 < 0) {
     idx2 = (-idx2 > i) ? 0 : idx2 + i + 1;
   }
 }

 // Shorten all the file names, so that it is easy to read.
 shorten_fnames(false);

 // Get the attributes for the different quickfix highlight items.  Note
 // that this depends on syntax items defined in the qf.vim syntax file
 qfFile_hl_id = syn_name2id("qfFileName");
 if (qfFile_hl_id == 0) {
   qfFile_hl_id = HLF_D;
 }
 qfSep_hl_id = syn_name2id("qfSeparator");
 if (qfSep_hl_id == 0) {
   qfSep_hl_id = HLF_D;
 }
 qfLine_hl_id = syn_name2id("qfLineNr");
 if (qfLine_hl_id == 0) {
   qfLine_hl_id = HLF_N;
 }

 if (qfl->qf_nonevalid) {
   all = true;
 }
 msg_ext_set_kind("list_cmd");
 qfline_T *qfp;
 FOR_ALL_QFL_ITEMS(qfl, qfp, i) {
   if ((qfp->qf_valid || all) && idx1 <= i && i <= idx2) {
     qf_list_entry(qfp, i, i == qfl->qf_index);
   }
   os_breakcheck();
 }
 qfga_clear();
}

/// Remove newlines and leading whitespace from an error message.
/// Add the result to the grow array "gap".
static void qf_fmt_text(garray_T *gap, const char *restrict text)
 FUNC_ATTR_NONNULL_ALL
{
 const char *p = text;
 while (*p != NUL) {
   if (*p == '\n') {
     ga_append(gap, ' ');
     while (*++p != NUL) {
       if (!ascii_iswhite(*p) && *p != '\n') {
         break;
       }
     }
   } else {
     ga_append(gap, (uint8_t)(*p++));
   }
 }
}

/// Add the range information from the lnum, col, end_lnum, and end_col values
/// of a quickfix entry to the grow array "gap".
static void qf_range_text(garray_T *gap, const qfline_T *qfp)
{
 String buf = cbuf_as_string(IObuff, 0);

 buf.size = vim_snprintf_safelen(buf.data, IOSIZE, "%" PRIdLINENR, qfp->qf_lnum);

 if (qfp->qf_end_lnum > 0 && qfp->qf_lnum != qfp->qf_end_lnum) {
   buf.size += vim_snprintf_safelen(buf.data + buf.size, IOSIZE - buf.size,
                                    "-%" PRIdLINENR, qfp->qf_end_lnum);
 }
 if (qfp->qf_col > 0) {
   buf.size += vim_snprintf_safelen(buf.data + buf.size, IOSIZE - buf.size,
                                    " col %d", qfp->qf_col);
   if (qfp->qf_end_col > 0 && qfp->qf_col != qfp->qf_end_col) {
     buf.size += vim_snprintf_safelen(buf.data + buf.size, IOSIZE - buf.size,
                                      "-%d", qfp->qf_end_col);
   }
 }

 ga_concat_len(gap, buf.data, buf.size);
}

/// Display information (list number, list size and the title) about a
/// quickfix/location list.
static void qf_msg(qf_info_T *qi, int which, char *lead)
{
 char *title = qi->qf_lists[which].qf_title;
 int count = qi->qf_lists[which].qf_count;
 char buf[IOSIZE];

 vim_snprintf(buf, IOSIZE, _("%serror list %d of %d; %d errors "),
              lead,
              which + 1,
              qi->qf_listcount,
              count);

 if (title != NULL) {
   size_t len = strlen(buf);

   if (len < 34) {
     memset(buf + len, ' ', 34 - len);
     buf[34] = NUL;
   }
   xstrlcat(buf, title, IOSIZE);
 }
 trunc_string(buf, buf, Columns - 1, IOSIZE);
 msg(buf, 0);
}

/// ":colder [count]": Up in the quickfix stack.
/// ":cnewer [count]": Down in the quickfix stack.
/// ":lolder [count]": Up in the location list stack.
/// ":lnewer [count]": Down in the location list stack.
void qf_age(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 int count = (eap->addr_count != 0) ? (int)eap->line2 : 1;
 while (count--) {
   if (eap->cmdidx == CMD_colder || eap->cmdidx == CMD_lolder) {
     if (qi->qf_curlist == 0) {
       emsg(_("E380: At bottom of quickfix stack"));
       break;
     }
     qi->qf_curlist--;
   } else {
     if (qi->qf_curlist >= qi->qf_listcount - 1) {
       emsg(_("E381: At top of quickfix stack"));
       break;
     }
     qi->qf_curlist++;
   }
 }
 qf_msg(qi, qi->qf_curlist, "");
 qf_update_buffer(qi, NULL);
}

/// Display the information about all the quickfix/location lists in the stack.
void qf_history(exarg_T *eap)
{
 qf_info_T *qi = qf_cmd_get_stack(eap, false);

 if (eap->addr_count > 0) {
   if (qi == NULL) {
     emsg(_(e_loclist));
     return;
   }

   // Jump to the specified quickfix list
   if (eap->line2 > 0 && eap->line2 <= qi->qf_listcount) {
     qi->qf_curlist = eap->line2 - 1;
     qf_msg(qi, qi->qf_curlist, "");
     qf_update_buffer(qi, NULL);
   } else {
     emsg(_(e_invrange));
   }

   return;
 }

 if (qf_stack_empty(qi)) {
   msg(_("No entries"), 0);
 } else {
   for (int i = 0; i < qi->qf_listcount; i++) {
     qf_msg(qi, i, i == qi->qf_curlist ? "> " : "  ");
   }
 }
}

/// Free all the entries in the error list "idx". Note that other information
/// associated with the list like context and title are not freed.
static void qf_free_items(qf_list_T *qfl)
{
 bool stop = false;

 while (qfl->qf_count && qfl->qf_start != NULL) {
   qfline_T *qfp = qfl->qf_start;
   qfline_T *qfpnext = qfp->qf_next;
   if (!stop) {
     xfree(qfp->qf_fname);
     xfree(qfp->qf_module);
     xfree(qfp->qf_text);
     xfree(qfp->qf_pattern);
     tv_clear(&qfp->qf_user_data);
     stop = (qfp == qfpnext);
     xfree(qfp);
     if (stop) {
       // Somehow qf_count may have an incorrect value, set it to 1
       // to avoid crashing when it's wrong.
       // TODO(vim): Avoid qf_count being incorrect.
       qfl->qf_count = 1;
     } else {
       qfl->qf_start = qfpnext;
     }
   }
   qfl->qf_count--;
 }

 qfl->qf_start = NULL;
 qfl->qf_ptr = NULL;
 qfl->qf_index = 0;
 qfl->qf_start = NULL;
 qfl->qf_last = NULL;
 qfl->qf_ptr = NULL;
 qfl->qf_nonevalid = true;

 qf_clean_dir_stack(&qfl->qf_dir_stack);
 qfl->qf_directory = NULL;
 qf_clean_dir_stack(&qfl->qf_file_stack);
 qfl->qf_currfile = NULL;
 qfl->qf_multiline = false;
 qfl->qf_multiignore = false;
 qfl->qf_multiscan = false;
}

/// Free error list "idx". Frees all the entries in the quickfix list,
/// associated context information and the title.
static void qf_free(qf_list_T *qfl)
{
 qf_free_items(qfl);

 XFREE_CLEAR(qfl->qf_title);
 tv_free(qfl->qf_ctx);
 qfl->qf_ctx = NULL;
 callback_free(&qfl->qf_qftf_cb);
 qfl->qf_id = 0;
 qfl->qf_changedtick = 0;
}

/// Adjust error list entries for changed line numbers
///
/// Note: `buf` is the changed buffer, but `wp` is a potential location list
/// into that buffer, or NULL to check the quickfix list.
bool qf_mark_adjust(buf_T *buf, win_T *wp, linenr_T line1, linenr_T line2, linenr_T amount,
                   linenr_T amount_after)
{
 qf_info_T *qi = ql_info;
 assert(qi != NULL);
 int buf_has_flag = wp == NULL ? BUF_HAS_QF_ENTRY : BUF_HAS_LL_ENTRY;

 if (!(buf->b_has_qf_entry & buf_has_flag)) {
   return false;
 }
 if (wp != NULL) {
   if (wp->w_llist == NULL) {
     return false;
   }
   qi = wp->w_llist;
 }

 int i;
 qfline_T *qfp;
 bool found_one = false;
 for (int idx = 0; idx < qi->qf_listcount; idx++) {
   qf_list_T *qfl = qf_get_list(qi, idx);
   if (!qf_list_empty(qfl)) {
     FOR_ALL_QFL_ITEMS(qfl, qfp, i) {
       if (qfp->qf_fnum == buf->b_fnum) {
         found_one = true;
         if (qfp->qf_lnum >= line1 && qfp->qf_lnum <= line2) {
           if (amount == MAXLNUM) {
             qfp->qf_cleared = true;
           } else {
             qfp->qf_lnum += amount;
           }
         } else if (amount_after && qfp->qf_lnum > line2) {
           qfp->qf_lnum += amount_after;
         }
       }
     }
   }
 }

 return found_one;
}

// Make a nice message out of the error character and the error number:
//  char    number  message
//  e or E    0     " error"
//  w or W    0     " warning"
//  i or I    0     " info"
//  n or N    0     " note"
//  0         0     ""
//  other     0     " c"
//  e or E    n     " error n"
//  w or W    n     " warning n"
//  i or I    n     " info n"
//  n or N    n     " note n"
//  0         n     " error n"
//  other     n     " c n"
//  1         x     ""          :helpgrep
static char *qf_types(int c, int nr)
{
 static char cc[3];
 char *p;

 if (c == 'W' || c == 'w') {
   p = " warning";
 } else if (c == 'I' || c == 'i') {
   p = " info";
 } else if (c == 'N' || c == 'n') {
   p = " note";
 } else if (c == 'E' || c == 'e' || (c == 0 && nr > 0)) {
   p = " error";
 } else if (c == 0 || c == 1) {
   p = "";
 } else {
   cc[0] = ' ';
   cc[1] = (char)c;
   cc[2] = NUL;
   p = cc;
 }

 if (nr <= 0) {
   return p;
 }

 static char buf[20];
 snprintf(buf, sizeof(buf), "%s %3d", p, nr);
 return buf;
}

// When "split" is false: Open the entry/result under the cursor.
// When "split" is true: Open the entry/result under the cursor in a new window.
void qf_view_result(bool split)
{
 qf_info_T *qi = ql_info;
 assert(qi != NULL);

 if (IS_LL_WINDOW(curwin)) {
   qi = GET_LOC_LIST(curwin);
 }

 if (qf_list_empty(qf_get_curlist(qi))) {
   emsg(_(e_no_errors));
   return;
 }

 if (split) {
   // Open the selected entry in a new window
   qf_jump_newwin(qi, 0, (int)curwin->w_cursor.lnum, false, true);
   do_cmdline_cmd("clearjumps");
   return;
 }

 do_cmdline_cmd((IS_LL_WINDOW(curwin) ? ".ll" : ".cc"));
}

// ":cwindow": open the quickfix window if we have errors to display,
//             close it if not.
// ":lwindow": open the location list window if we have locations to display,
//             close it if not.
void ex_cwindow(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 qf_list_T *qfl = qf_get_curlist(qi);

 // Look for an existing quickfix window.
 win_T *win = qf_find_win(qi);

 // If a quickfix window is open but we have no errors to display,
 // close the window.  If a quickfix window is not open, then open
 // it if we have errors; otherwise, leave it closed.
 if (qf_stack_empty(qi)
     || qfl->qf_nonevalid
     || qf_list_empty(qfl)) {
   if (win != NULL) {
     ex_cclose(eap);
   }
 } else if (win == NULL) {
   ex_copen(eap);
 }
}

// ":cclose": close the window showing the list of errors.
// ":lclose": close the window showing the location list
void ex_cclose(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, false)) == NULL) {
   return;
 }

 // Find existing quickfix window and close it.
 win_T *win = qf_find_win(qi);
 if (win != NULL) {
   win_close(win, false, false);
 }
}

// Goto a quickfix or location list window (if present).
// Returns OK if the window is found, FAIL otherwise.
static int qf_goto_cwindow(const qf_info_T *qi, bool resize, int sz, bool vertsplit)
{
 win_T *const win = qf_find_win(qi);
 if (win == NULL) {
   return FAIL;
 }

 win_goto(win);
 if (resize) {
   if (vertsplit) {
     if (sz != win->w_width) {
       win_setwidth(sz);
     }
   } else if (sz != win->w_height
              && (win->w_height + win->w_hsep_height + win->w_status_height + tabline_height()
                  < cmdline_row)) {
     win_setheight(sz);
   }
 }

 return OK;
}

// Set options for the buffer in the quickfix or location list window.
static void qf_set_cwindow_options(void)
{
 // switch off 'swapfile'
 set_option_value_give_err(kOptSwapfile, BOOLEAN_OPTVAL(false), OPT_LOCAL);
 set_option_value_give_err(kOptBuftype, STATIC_CSTR_AS_OPTVAL("quickfix"), OPT_LOCAL);
 set_option_value_give_err(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL);
 RESET_BINDING(curwin);
 curwin->w_p_diff = false;
 set_option_value_give_err(kOptFoldmethod, STATIC_CSTR_AS_OPTVAL("manual"), OPT_LOCAL);
}

// Open a new quickfix or location list window, load the quickfix buffer and
// set the appropriate options for the window.
// Returns FAIL if the window could not be opened.
static int qf_open_new_cwindow(qf_info_T *qi, int height)
 FUNC_ATTR_NONNULL_ALL
{
 win_T *oldwin = curwin;
 const tabpage_T *const prevtab = curtab;
 int flags = 0;

 const buf_T *const qf_buf = qf_find_buf(qi);

 // The current window becomes the previous window afterwards.
 win_T *const win = curwin;

 // Default is to open the window below the current window or at the bottom,
 // except when :belowright or :aboveleft is used.
 if (cmdmod.cmod_split == 0) {
   flags = IS_QF_STACK(qi) ? WSP_BOT : WSP_BELOW;
 }
 flags |= WSP_NEWLOC;

 // Create a snapshot for quickfix window (not for location list)
 // so that when closing it, we can restore to the previous window
 if (IS_QF_STACK(qi)) {
   flags |= WSP_QUICKFIX;
 }

 if (win_split(height, flags) == FAIL) {
   return FAIL;  // not enough room for window
 }
 RESET_BINDING(curwin);

 if (IS_LL_STACK(qi)) {
   // For the location list window, create a reference to the
   // location list stack from the window 'win'.
   curwin->w_llist_ref = qi;
   qi->qf_refcount++;
 }

 if (oldwin != curwin) {
   oldwin = NULL;  // don't store info when in another window
 }
 if (qf_buf != NULL) {
   // Use the existing quickfix buffer
   if (do_ecmd(qf_buf->b_fnum, NULL, NULL, NULL, ECMD_ONE,
               ECMD_HIDE + ECMD_OLDBUF + ECMD_NOWINENTER, oldwin) == FAIL) {
     return FAIL;
   }
 } else {
   // Create a new quickfix buffer
   if (do_ecmd(0, NULL, NULL, NULL, ECMD_ONE, ECMD_HIDE + ECMD_NOWINENTER, oldwin) == FAIL) {
     return FAIL;
   }
   // save the number of the new buffer
   qi->qf_bufnr = curbuf->b_fnum;
 }

 // Set the options for the quickfix buffer/window (if not already done)
 // Do this even if the quickfix buffer was already present, as an autocmd
 // might have previously deleted (:bdelete) the quickfix buffer.
 if (!bt_quickfix(curbuf)) {
   qf_set_cwindow_options();
 }

 // Only set the height when still in the same tab page and there is no
 // window to the side.
 if (curtab == prevtab && curwin->w_width == Columns) {
   win_setheight(height);
 }
 curwin->w_p_wfh = true;  // set 'winfixheight'
 if (win_valid(win)) {
   prevwin = win;
 }
 return OK;
}

/// Set "w:quickfix_title" if "qi" has a title.
static void qf_set_title_var(qf_list_T *qfl)
{
 if (qfl->qf_title != NULL) {
   set_internal_string_var("w:quickfix_title", qfl->qf_title);
 }
}

/// ":copen": open a window that shows the list of errors.
/// ":lopen": open a window that shows the location list.
void ex_copen(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 incr_quickfix_busy();

 int height;
 if (eap->addr_count != 0) {
   height = (int)eap->line2;
 } else {
   height = QF_WINHEIGHT;
 }
 reset_VIsual_and_resel();  // stop Visual mode

 // Find an existing quickfix window, or open a new one.
 int status = FAIL;
 if (cmdmod.cmod_tab == 0) {
   status = qf_goto_cwindow(qi, eap->addr_count != 0, height,
                            cmdmod.cmod_split & WSP_VERT);
 }
 if (status == FAIL) {
   if (qf_open_new_cwindow(qi, height) == FAIL) {
     decr_quickfix_busy();
     return;
   }
 }

 qf_list_T *qfl = qf_get_curlist(qi);
 qf_set_title_var(qfl);
 // Save the current index here, as updating the quickfix buffer may free
 // the quickfix list
 int lnum = qfl->qf_index;

 // Fill the buffer with the quickfix list.
 qf_fill_buffer(qfl, curbuf, NULL, curwin->handle);

 decr_quickfix_busy();

 curwin->w_cursor.lnum = lnum;
 curwin->w_cursor.col = 0;
 check_cursor(curwin);
 update_topline(curwin);             // scroll to show the line
}

// Move the cursor in the quickfix window to "lnum".
static void qf_win_goto(win_T *win, linenr_T lnum)
{
 win_T *old_curwin = curwin;

 curwin = win;
 curbuf = win->w_buffer;
 curwin->w_cursor.lnum = lnum;
 curwin->w_cursor.col = 0;
 curwin->w_cursor.coladd = 0;
 curwin->w_curswant = 0;
 update_topline(curwin);              // scroll to show the line
 redraw_later(curwin, UPD_VALID);
 curwin->w_redr_status = true;  // update ruler
 curwin = old_curwin;
 curbuf = curwin->w_buffer;
}

/// :cbottom/:lbottom command.
void ex_cbottom(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 win_T *win = qf_find_win(qi);

 if (win != NULL && win->w_cursor.lnum != win->w_buffer->b_ml.ml_line_count) {
   qf_win_goto(win, win->w_buffer->b_ml.ml_line_count);
 }
}

// Return the number of the current entry (line number in the quickfix
// window).
linenr_T qf_current_entry(win_T *wp)
{
 qf_info_T *qi = ql_info;
 assert(qi != NULL);

 if (IS_LL_WINDOW(wp)) {
   // In the location list window, use the referenced location list
   qi = wp->w_llist_ref;
 }

 return qf_get_curlist(qi)->qf_index;
}

/// Update the cursor position in the quickfix window to the current error.
/// Return true if there is a quickfix window.
///
/// @param old_qf_index  previous qf_index or zero
static bool qf_win_pos_update(qf_info_T *qi, int old_qf_index)
{
 int qf_index = qf_get_curlist(qi)->qf_index;

 // Put the cursor on the current error in the quickfix window, so that
 // it's viewable.
 win_T *win = qf_find_win(qi);
 if (win != NULL
     && qf_index <= win->w_buffer->b_ml.ml_line_count
     && old_qf_index != qf_index) {
   win->w_redraw_top = MIN(old_qf_index, qf_index);
   win->w_redraw_bot = MAX(old_qf_index, qf_index);
   qf_win_goto(win, qf_index);
 }
 return win != NULL;
}

/// Checks whether the given window is displaying the specified
/// quickfix/location stack.
static int is_qf_win(const win_T *win, const qf_info_T *qi)
 FUNC_ATTR_NONNULL_ARG(2) FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 // A window displaying the quickfix buffer will have the w_llist_ref field
 // set to NULL.
 // A window displaying a location list buffer will have the w_llist_ref
 // pointing to the location list.
 if (buf_valid(win->w_buffer) && bt_quickfix(win->w_buffer)) {
   if ((IS_QF_STACK(qi) && win->w_llist_ref == NULL)
       || (IS_LL_STACK(qi) && win->w_llist_ref == qi)) {
     return true;
   }
 }

 return false;
}

/// Find a window displaying the quickfix/location stack 'qi' in the current tab
/// page.
static win_T *qf_find_win(const qf_info_T *qi)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 FOR_ALL_WINDOWS_IN_TAB(win, curtab) {
   if (is_qf_win(win, qi)) {
     return win;
   }
 }

 return NULL;
}

/// Find a quickfix buffer.
/// Searches in windows opened in all the tab pages.
static buf_T *qf_find_buf(qf_info_T *qi)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (qi->qf_bufnr != INVALID_QFBUFNR) {
   buf_T *const qfbuf = buflist_findnr(qi->qf_bufnr);
   if (qfbuf != NULL) {
     return qfbuf;
   }
   // buffer is no longer present
   qi->qf_bufnr = INVALID_QFBUFNR;
 }

 FOR_ALL_TAB_WINDOWS(tp, win) {
   if (is_qf_win(win, qi)) {
     return win->w_buffer;
   }
 }

 return NULL;
}

/// Process the 'quickfixtextfunc' option value.
const char *did_set_quickfixtextfunc(optset_T *args FUNC_ATTR_UNUSED)
{
 if (option_set_callback_func(p_qftf, &qftf_cb) == FAIL) {
   return e_invarg;
 }
 return NULL;
}

/// Update the w:quickfix_title variable in the quickfix/location list window in
/// all the tab pages.
static void qf_update_win_titlevar(qf_info_T *qi)
 FUNC_ATTR_NONNULL_ALL
{
 qf_list_T *const qfl = qf_get_curlist(qi);
 win_T *const save_curwin = curwin;

 FOR_ALL_TAB_WINDOWS(tp, win) {
   if (is_qf_win(win, qi)) {
     curwin = win;
     qf_set_title_var(qfl);
   }
 }
 curwin = save_curwin;
}

// Find the quickfix buffer.  If it exists, update the contents.
static void qf_update_buffer(qf_info_T *qi, qfline_T *old_last)
{
 // Check if a buffer for the quickfix list exists.  Update it.
 buf_T *buf = qf_find_buf(qi);
 if (buf == NULL) {
   return;
 }

 linenr_T old_line_count = buf->b_ml.ml_line_count;
 colnr_T old_endcol = ml_get_buf_len(buf, old_line_count);
 bcount_t old_bytecount = get_region_bytecount(buf, 1, old_line_count, 0, old_endcol);
 int qf_winid = 0;

 win_T *win;
 if (IS_LL_STACK(qi)) {
   if (curwin->w_llist == qi) {
     win = curwin;
   } else {
     // Find the file window (non-quickfix) with this location list
     win = qf_find_win_with_loclist(qi);
     if (win == NULL) {
       // File window is not found. Find the location list window.
       win = qf_find_win(qi);
     }
     if (win == NULL) {
       return;
     }
   }
   qf_winid = (int)win->handle;
 }

 // autocommands may cause trouble
 incr_quickfix_busy();

 aco_save_T aco;

 if (old_last == NULL) {
   // set curwin/curbuf to buf and save a few things
   aucmd_prepbuf(&aco, buf);
 }

 qf_update_win_titlevar(qi);

 qf_fill_buffer(qf_get_curlist(qi), buf, old_last, qf_winid);

 linenr_T new_line_count = buf->b_ml.ml_line_count;
 colnr_T new_endcol = ml_get_buf_len(buf, new_line_count);
 bcount_t new_byte_count = 0;
 linenr_T delta = new_line_count - old_line_count;

 if (old_last == NULL) {
   new_byte_count = get_region_bytecount(buf, 1, new_line_count, 0, new_endcol);
   extmark_splice(buf, 0, 0, old_line_count - 1, 0, old_bytecount, new_line_count - 1, new_endcol,
                  new_byte_count, kExtmarkNoUndo);
   changed_lines(buf, 1, 0, old_line_count > 0 ? old_line_count + 1 : 1, delta, true);
 } else if (delta > 0) {
   linenr_T start_lnum = old_line_count + 1;
   new_byte_count = get_region_bytecount(buf, start_lnum, new_line_count, 0, new_endcol);
   extmark_splice(buf, old_line_count - 1, old_endcol, 0, 0, 0, delta, new_endcol, new_byte_count,
                  kExtmarkNoUndo);
   changed_lines(buf, start_lnum, 0, start_lnum, delta, true);
 }
 buf->b_changed = false;

 if (old_last == NULL) {
   qf_win_pos_update(qi, 0);

   // restore curwin/curbuf and a few other things
   aucmd_restbuf(&aco);
 }

 // Only redraw when added lines are visible.  This avoids flickering when
 // the added lines are not visible.
 if ((win = qf_find_win(qi)) != NULL && old_line_count < win->w_botline) {
   redraw_buf_later(buf, UPD_NOT_VALID);
 }

 // always called after incr_quickfix_busy()
 decr_quickfix_busy();
}

// Add an error line to the quickfix buffer.
static int qf_buf_add_line(qf_list_T *qfl, buf_T *buf, linenr_T lnum, const qfline_T *qfp,
                          char *dirname, char *qftf_str, bool first_bufline)
 FUNC_ATTR_NONNULL_ARG(1, 2, 4, 5)
{
 garray_T *gap = qfga_get();

 // If the 'quickfixtextfunc' function returned a non-empty custom string
 // for this entry, then use it.
 if (qftf_str != NULL && *qftf_str != NUL) {
   ga_concat(gap, qftf_str);
 } else {
   buf_T *errbuf;
   if (qfp->qf_module != NULL) {
     ga_concat(gap, qfp->qf_module);
   } else if (qfp->qf_fnum != 0
              && (errbuf = buflist_findnr(qfp->qf_fnum)) != NULL
              && errbuf->b_fname != NULL) {
     if (qfp->qf_type == 1) {  // :helpgrep
       ga_concat(gap, path_tail(errbuf->b_fname));
     } else {
       // Shorten the file name if not done already.
       // For optimization, do this only for the first entry in a
       // buffer.
       if (first_bufline
           && (errbuf->b_sfname == NULL
               || path_is_absolute(errbuf->b_sfname))) {
         if (*dirname == NUL) {
           os_dirname(dirname, MAXPATHL);
         }
         shorten_buf_fname(errbuf, dirname, false);
       }
       ga_concat(gap, qfp->qf_fname == NULL ? errbuf->b_fname : qfp->qf_fname);
     }
   }

   ga_append(gap, '|');

   if (qfp->qf_lnum > 0) {
     qf_range_text(gap, qfp);
     ga_concat(gap, qf_types(qfp->qf_type, qfp->qf_nr));
   } else if (qfp->qf_pattern != NULL) {
     qf_fmt_text(gap, qfp->qf_pattern);
   }
   ga_append(gap, '|');
   ga_append(gap, ' ');

   // Remove newlines and leading whitespace from the text.
   // For an unrecognized line keep the indent, the compiler may
   // mark a word with ^^^^.
   qf_fmt_text(gap, gap->ga_len > 3 ? skipwhite(qfp->qf_text) : qfp->qf_text);
 }

 ga_append(gap, NUL);
 if (ml_append_buf(buf, lnum, gap->ga_data, gap->ga_len, false) == FAIL) {
   return FAIL;
 }

 return OK;
}

// Call the 'quickfixtextfunc' function to get the list of lines to display in
// the quickfix window for the entries 'start_idx' to 'end_idx'.
static list_T *call_qftf_func(qf_list_T *qfl, int qf_winid, int start_idx, int end_idx)
{
 Callback *cb = &qftf_cb;
 list_T *qftf_list = NULL;
 static bool recursive = false;

 if (recursive) {
   return NULL;  // this doesn't work properly recursively
 }
 recursive = true;

 // If 'quickfixtextfunc' is set, then use the user-supplied function to get
 // the text to display. Use the local value of 'quickfixtextfunc' if it is
 // set.
 if (qfl->qf_qftf_cb.type != kCallbackNone) {
   cb = &qfl->qf_qftf_cb;
 }
 if (cb->type != kCallbackNone) {
   typval_T args[1];
   typval_T rettv;

   // create the dict argument
   dict_T *const dict = tv_dict_alloc_lock(VAR_FIXED);

   tv_dict_add_nr(dict, S_LEN("quickfix"), IS_QF_LIST(qfl));
   tv_dict_add_nr(dict, S_LEN("winid"), qf_winid);
   tv_dict_add_nr(dict, S_LEN("id"), qfl->qf_id);
   tv_dict_add_nr(dict, S_LEN("start_idx"), start_idx);
   tv_dict_add_nr(dict, S_LEN("end_idx"), end_idx);
   dict->dv_refcount++;
   args[0].v_type = VAR_DICT;
   args[0].vval.v_dict = dict;

   textlock++;
   if (callback_call(cb, 1, args, &rettv)) {
     if (rettv.v_type == VAR_LIST) {
       qftf_list = rettv.vval.v_list;
       tv_list_ref(qftf_list);
     }
     tv_clear(&rettv);
   }
   textlock--;
   tv_dict_unref(dict);
 }

 recursive = false;
 return qftf_list;
}

/// Fill current buffer with quickfix errors, replacing any previous contents.
/// curbuf must be the quickfix buffer!
/// If "old_last" is not NULL append the items after this one.
/// When "old_last" is NULL then "buf" must equal "curbuf"!  Because ml_delete()
/// is used and autocommands will be triggered.
static void qf_fill_buffer(qf_list_T *qfl, buf_T *buf, qfline_T *old_last, int qf_winid)
 FUNC_ATTR_NONNULL_ARG(2)
{
 const bool old_KeyTyped = KeyTyped;

 if (old_last == NULL) {
   if (buf != curbuf) {
     internal_error("qf_fill_buffer()");
     return;
   }

   // delete all existing lines
   //
   // Note: we cannot store undo information, because
   // qf buffer is usually not allowed to be modified.
   //
   // So we need to clean up undo information
   // otherwise autocommands may invalidate the undo stack
   while ((curbuf->b_ml.ml_flags & ML_EMPTY) == 0) {
     // If deletion fails, this loop may run forever, so
     // signal error and return.
     if (ml_delete(1) == FAIL) {
       internal_error("qf_fill_buffer()");
       return;
     }
   }

   FOR_ALL_TAB_WINDOWS(tp, wp) {
     if (wp->w_buffer == curbuf) {
       wp->w_skipcol = 0;
     }
   }

   // Remove all undo information
   u_clearallandblockfree(curbuf);
 }

 // Check if there is anything to display
 if (qfl != NULL && qfl->qf_start != NULL) {
   char dirname[MAXPATHL];

   *dirname = NUL;

   linenr_T lnum;
   qfline_T *qfp;

   // Add one line for each error
   if (old_last == NULL) {
     qfp = qfl->qf_start;
     lnum = 0;
   } else {
     qfp = old_last->qf_next != NULL ? old_last->qf_next : old_last;
     lnum = buf->b_ml.ml_line_count;
   }

   list_T *qftf_list = call_qftf_func(qfl, qf_winid, lnum + 1, qfl->qf_count);
   listitem_T *qftf_li = tv_list_first(qftf_list);

   int prev_bufnr = -1;
   bool invalid_val = false;

   while (lnum < qfl->qf_count) {
     char *qftf_str = NULL;

     // Use the text supplied by the user defined function (if any).
     // If the returned value is not string, then ignore the rest
     // of the returned values and use the default.
     if (qftf_li != NULL && !invalid_val) {
       qftf_str = (char *)tv_get_string_chk(TV_LIST_ITEM_TV(qftf_li));
       if (qftf_str == NULL) {
         invalid_val = true;
       }
     }

     if (qf_buf_add_line(qfl, buf, lnum, qfp, dirname, qftf_str,
                         prev_bufnr != qfp->qf_fnum) == FAIL) {
       break;
     }
     prev_bufnr = qfp->qf_fnum;
     lnum++;
     qfp = qfp->qf_next;
     if (qfp == NULL) {
       break;
     }

     if (qftf_li != NULL) {
       qftf_li = TV_LIST_ITEM_NEXT(qftf_list, qftf_li);
     }
   }
   if (old_last == NULL) {
     // Delete the empty line which is now at the end
     ml_delete(lnum + 1);
   }

   qfga_clear();
 }

 // Correct cursor position.
 check_lnums(true);

 if (old_last == NULL) {
   // Set the 'filetype' to "qf" each time after filling the buffer.  This
   // resembles reading a file into a buffer, it's more logical when using
   // autocommands.
   curbuf->b_ro_locked++;
   set_option_value_give_err(kOptFiletype, STATIC_CSTR_AS_OPTVAL("qf"), OPT_LOCAL);
   curbuf->b_p_ma = false;

   curbuf->b_keep_filetype = true;  // don't detect 'filetype'
   apply_autocmds(EVENT_BUFREADPOST, "quickfix", NULL, false, curbuf);
   apply_autocmds(EVENT_BUFWINENTER, "quickfix", NULL, false, curbuf);
   curbuf->b_keep_filetype = false;
   curbuf->b_ro_locked--;

   // make sure it will be redrawn
   redraw_curbuf_later(UPD_NOT_VALID);
 }

 // Restore KeyTyped, setting 'filetype' may reset it.
 KeyTyped = old_KeyTyped;
}

static void qf_list_changed(qf_list_T *qfl)
{
 qfl->qf_changedtick++;
}

/// Return the quickfix/location list number with the given identifier.
///
/// @returns -1 if list is not found.
static int qf_id2nr(const qf_info_T *const qi, const unsigned qfid)
{
 for (int qf_idx = 0; qf_idx < qi->qf_listcount; qf_idx++) {
   if (qi->qf_lists[qf_idx].qf_id == qfid) {
     return qf_idx;
   }
 }
 return INVALID_QFIDX;
}

/// If the current list is not "save_qfid" and we can find the list with that ID
/// then make it the current list.
/// This is used when autocommands may have changed the current list.
/// Returns OK if successfully restored the list. Returns FAIL if the list with
/// the specified identifier (save_qfid) is not found in the stack.
static int qf_restore_list(qf_info_T *qi, unsigned save_qfid)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (qf_get_curlist(qi)->qf_id == save_qfid) {
   return OK;
 }

 const int curlist = qf_id2nr(qi, save_qfid);
 if (curlist < 0) {
   // list is not present
   return FAIL;
 }
 qi->qf_curlist = curlist;
 return OK;
}

// Jump to the first entry if there is one.
static void qf_jump_first(qf_info_T *qi, unsigned save_qfid, int forceit)
 FUNC_ATTR_NONNULL_ALL
{
 if (qf_restore_list(qi, save_qfid) == FAIL) {
   return;
 }

 if (!check_can_set_curbuf_forceit(forceit)) {
   return;
 }

 // Autocommands might have cleared the list, check for that
 if (!qf_list_empty(qf_get_curlist(qi))) {
   qf_jump(qi, 0, 0, forceit);
 }
}

// Return true when using ":vimgrep" for ":grep".
int grep_internal(cmdidx_T cmdidx)
{
 return (cmdidx == CMD_grep
         || cmdidx == CMD_lgrep
         || cmdidx == CMD_grepadd
         || cmdidx == CMD_lgrepadd)
        && strcmp("internal", *curbuf->b_p_gp == NUL ? p_gp : curbuf->b_p_gp) == 0;
}

// Return the make/grep autocmd name.
static char *make_get_auname(cmdidx_T cmdidx)
 FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 switch (cmdidx) {
 case CMD_make:
   return "make";
 case CMD_lmake:
   return "lmake";
 case CMD_grep:
   return "grep";
 case CMD_lgrep:
   return "lgrep";
 case CMD_grepadd:
   return "grepadd";
 case CMD_lgrepadd:
   return "lgrepadd";
 default:
   return NULL;
 }
}

// Form the complete command line to invoke 'make'/'grep'. Quote the command
// using 'shellquote' and append 'shellpipe'. Echo the fully formed command.
static char *make_get_fullcmd(const char *makecmd, const char *fname)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
{
 size_t len = strlen(p_shq) * 2 + strlen(makecmd) + 1;
 if (*p_sp != NUL) {
   len += strlen(p_sp) + strlen(fname) + 3;
 }
 char *const cmd = xmalloc(len);
 snprintf(cmd, len, "%s%s%s", p_shq, makecmd, p_shq);

 // If 'shellpipe' empty: don't redirect to 'errorfile'.
 if (*p_sp != NUL) {
   append_redir(cmd, len, p_sp, fname);
 }

 // Display the fully formed command.  Output a newline if there's something
 // else than the :make command that was typed (in which case the cursor is
 // in column 0).
 if (msg_col == 0) {
   msg_didout = false;
 }
 msg_start();
 msg_puts(":!");
 msg_outtrans(cmd, 0, false);  // show what we are doing

 return cmd;
}

// Used for ":make", ":lmake", ":grep", ":lgrep", ":grepadd", and ":lgrepadd"
void ex_make(exarg_T *eap)
{
 char *enc = (*curbuf->b_p_menc != NUL) ? curbuf->b_p_menc : p_menc;

 // Redirect ":grep" to ":vimgrep" if 'grepprg' is "internal".
 if (grep_internal(eap->cmdidx)) {
   ex_vimgrep(eap);
   return;
 }

 char *const au_name = make_get_auname(eap->cmdidx);
 if (au_name != NULL && apply_autocmds(EVENT_QUICKFIXCMDPRE, au_name,
                                       curbuf->b_fname, true, curbuf)) {
   if (aborting()) {
     return;
   }
 }

 win_T *wp = NULL;
 if (is_loclist_cmd(eap->cmdidx)) {
   wp = curwin;
 }

 autowrite_all();
 char *fname = get_mef_name();
 if (fname == NULL) {
   return;
 }
 os_remove(fname);  // in case it's not unique

 char *const cmd = make_get_fullcmd(eap->arg, fname);

 do_shell(cmd, 0);

 incr_quickfix_busy();

 char *errorformat = (eap->cmdidx != CMD_make && eap->cmdidx != CMD_lmake)
                     ? *curbuf->b_p_gefm != NUL ? curbuf->b_p_gefm : p_gefm
                     : p_efm;

 bool newlist = eap->cmdidx != CMD_grepadd && eap->cmdidx != CMD_lgrepadd;

 int res = qf_init(wp, fname, errorformat, newlist, qf_cmdtitle(*eap->cmdlinep), enc);

 qf_info_T *qi = ql_info;
 assert(qi != NULL);
 if (wp != NULL) {
   qi = GET_LOC_LIST(wp);
   if (qi == NULL) {
     goto cleanup;
   }
 }
 if (res >= 0) {
   qf_list_changed(qf_get_curlist(qi));
 }
 // Remember the current quickfix list identifier, so that we can
 // check for autocommands changing the current quickfix list.
 unsigned save_qfid = qf_get_curlist(qi)->qf_id;
 if (au_name != NULL) {
   apply_autocmds(EVENT_QUICKFIXCMDPOST, au_name, curbuf->b_fname, true,
                  curbuf);
 }
 if (res > 0 && !eap->forceit && qflist_valid(wp, save_qfid)) {
   // display the first error
   qf_jump_first(qi, save_qfid, false);
 }

cleanup:
 decr_quickfix_busy();
 os_remove(fname);
 xfree(fname);
 xfree(cmd);
}

// Return the name for the errorfile, in allocated memory.
// Find a new unique name when 'makeef' contains "##".
// Returns NULL for error.
static char *get_mef_name(void)
{
 char *name;
 static int start = -1;
 static int off = 0;

 if (*p_mef == NUL) {
   name = vim_tempname();
   if (name == NULL) {
     emsg(_(e_notmp));
   }
   return name;
 }

 char *p;

 for (p = p_mef; *p; p++) {
   if (p[0] == '#' && p[1] == '#') {
     break;
   }
 }

 if (*p == NUL) {
   return xstrdup(p_mef);
 }

 // Keep trying until the name doesn't exist yet.
 while (true) {
   if (start == -1) {
     start = (int)os_get_pid();
   } else {
     off += 19;
   }
   name = xmalloc(strlen(p_mef) + 30);
   STRCPY(name, p_mef);
   snprintf(name + (p - p_mef), strlen(name), "%d%d", start, off);
   strcat(name, p + 2);
   // Don't accept a symbolic link, it's a security risk.
   FileInfo file_info;
   bool file_or_link_found = os_fileinfo_link(name, &file_info);
   if (!file_or_link_found) {
     break;
   }
   xfree(name);
 }
 return name;
}

/// Returns the number of entries in the current quickfix/location list.
size_t qf_get_size(exarg_T *eap)
 FUNC_ATTR_NONNULL_ALL
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, false)) == NULL) {
   return 0;
 }
 return (size_t)qf_get_curlist(qi)->qf_count;
}

/// Returns the number of valid entries in the current quickfix/location list.
size_t qf_get_valid_size(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, false)) == NULL) {
   return 0;
 }

 int prev_fnum = 0;
 size_t sz = 0;
 qfline_T *qfp;
 int i;
 assert(qf_get_curlist(qi)->qf_count >= 0);
 qf_list_T *qfl = qf_get_curlist(qi);
 FOR_ALL_QFL_ITEMS(qfl, qfp, i) {
   if (!qfp->qf_valid) {
     continue;
   }

   if (eap->cmdidx == CMD_cdo || eap->cmdidx == CMD_ldo) {
     // Count all valid entries.
     sz++;
   } else if (qfp->qf_fnum > 0 && qfp->qf_fnum != prev_fnum) {
     // Count the number of files.
     sz++;
     prev_fnum = qfp->qf_fnum;
   }
 }

 return sz;
}

/// Returns the current index of the quickfix/location list.
/// Returns 0 if there is an error.
size_t qf_get_cur_idx(exarg_T *eap)
 FUNC_ATTR_NONNULL_ALL
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, false)) == NULL) {
   return 0;
 }

 assert(qf_get_curlist(qi)->qf_index >= 0);
 return (size_t)qf_get_curlist(qi)->qf_index;
}

/// Returns the current index in the quickfix/location list,
/// counting only valid entries.
/// Returns 1 if there are no valid entries.
int qf_get_cur_valid_idx(exarg_T *eap)
 FUNC_ATTR_NONNULL_ALL
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, false)) == NULL) {
   return 1;
 }

 qf_list_T *qfl = qf_get_curlist(qi);

 // Check if the list has valid errors.
 if (!qf_list_has_valid_entries(qfl)) {
   return 1;
 }

 int prev_fnum = 0;
 int eidx = 0;
 qfline_T *qfp;
 size_t i;
 assert(qfl->qf_index >= 0);
 for (i = 1, qfp = qfl->qf_start;
      i <= (size_t)qfl->qf_index && qfp != NULL;
      i++, qfp = qfp->qf_next) {
   if (!qfp->qf_valid) {
     continue;
   }

   if (eap->cmdidx == CMD_cfdo || eap->cmdidx == CMD_lfdo) {
     if (qfp->qf_fnum > 0 && qfp->qf_fnum != prev_fnum) {
       // Count the number of files.
       eidx++;
       prev_fnum = qfp->qf_fnum;
     }
   } else {
     eidx++;
   }
 }

 return eidx != 0 ? eidx : 1;
}

/// Get the 'n'th valid error entry in the quickfix or location list.
///
/// Used by :cdo, :ldo, :cfdo and :lfdo commands.
/// For :cdo and :ldo, returns the 'n'th valid error entry.
/// For :cfdo and :lfdo, returns the 'n'th valid file entry.
static size_t qf_get_nth_valid_entry(qf_list_T *qfl, size_t n, bool fdo)
 FUNC_ATTR_NONNULL_ALL
{
 // Check if the list has valid errors.
 if (!qf_list_has_valid_entries(qfl)) {
   return 1;
 }

 int prev_fnum = 0;
 size_t eidx = 0;
 int i;
 qfline_T *qfp;
 assert(qfl->qf_count >= 0);
 FOR_ALL_QFL_ITEMS(qfl, qfp, i) {
   if (qfp->qf_valid) {
     if (fdo) {
       if (qfp->qf_fnum > 0 && qfp->qf_fnum != prev_fnum) {
         // Count the number of files.
         eidx++;
         prev_fnum = qfp->qf_fnum;
       }
     } else {
       eidx++;
     }
   }

   if (eidx == n) {
     break;
   }
 }

 return i <= qfl->qf_count ? (size_t)i : 1;
}

/// ":cc", ":crewind", ":cfirst" and ":clast".
/// ":ll", ":lrewind", ":lfirst" and ":llast".
/// ":cdo", ":ldo", ":cfdo" and ":lfdo".
void ex_cc(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 int errornr;
 if (eap->addr_count > 0) {
   errornr = (int)eap->line2;
 } else {
   switch (eap->cmdidx) {
   case CMD_cc:
   case CMD_ll:
     errornr = 0;
     break;
   case CMD_crewind:
   case CMD_lrewind:
   case CMD_cfirst:
   case CMD_lfirst:
     errornr = 1;
     break;
   default:
     errornr = 32767;
     break;
   }
 }

 // For cdo and ldo commands, jump to the nth valid error.
 // For cfdo and lfdo commands, jump to the nth valid file entry.
 if (eap->cmdidx == CMD_cdo || eap->cmdidx == CMD_ldo
     || eap->cmdidx == CMD_cfdo || eap->cmdidx == CMD_lfdo) {
   size_t n;
   if (eap->addr_count > 0) {
     assert(eap->line1 >= 0);
     n = (size_t)eap->line1;
   } else {
     n = 1;
   }
   size_t valid_entry = qf_get_nth_valid_entry(qf_get_curlist(qi), n,
                                               eap->cmdidx == CMD_cfdo || eap->cmdidx == CMD_lfdo);
   assert(valid_entry <= INT_MAX);
   errornr = (int)valid_entry;
 }

 qf_jump(qi, 0, errornr, eap->forceit);
}

/// ":cnext", ":cnfile", ":cNext" and ":cprevious".
/// ":lnext", ":lNext", ":lprevious", ":lnfile", ":lNfile" and ":lpfile".
/// ":cdo", ":ldo", ":cfdo" and ":lfdo".
void ex_cnext(exarg_T *eap)
{
 qf_info_T *qi;

 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 int errornr;
 if (eap->addr_count > 0
     && (eap->cmdidx != CMD_cdo && eap->cmdidx != CMD_ldo
         && eap->cmdidx != CMD_cfdo && eap->cmdidx != CMD_lfdo)) {
   errornr = (int)eap->line2;
 } else {
   errornr = 1;
 }

 // Depending on the command jump to either next or previous entry/file.
 Direction dir;
 switch (eap->cmdidx) {
 case CMD_cprevious:
 case CMD_lprevious:
 case CMD_cNext:
 case CMD_lNext:
   dir = BACKWARD;
   break;
 case CMD_cnfile:
 case CMD_lnfile:
 case CMD_cfdo:
 case CMD_lfdo:
   dir = FORWARD_FILE;
   break;
 case CMD_cpfile:
 case CMD_lpfile:
 case CMD_cNfile:
 case CMD_lNfile:
   dir = BACKWARD_FILE;
   break;
 case CMD_cnext:
 case CMD_lnext:
 case CMD_cdo:
 case CMD_ldo:
 default:
   dir = FORWARD;
   break;
 }

 qf_jump(qi, dir, errornr, eap->forceit);
}

/// Find the first entry in the quickfix list 'qfl' from buffer 'bnr'.
/// The index of the entry is stored in 'errornr'.
/// Returns NULL if an entry is not found.
static qfline_T *qf_find_first_entry_in_buf(qf_list_T *qfl, int bnr, int *errornr)
{
 qfline_T *qfp = NULL;
 int idx = 0;

 // Find the first entry in this file
 FOR_ALL_QFL_ITEMS(qfl, qfp, idx) {
   if (qfp->qf_fnum == bnr) {
     break;
   }
 }

 *errornr = idx;
 return qfp;
}

/// Find the first quickfix entry on the same line as 'entry'. Updates 'errornr'
/// with the error number for the first entry. Assumes the entries are sorted in
/// the quickfix list by line number.
static qfline_T *qf_find_first_entry_on_line(qfline_T *entry, int *errornr)
{
 while (!got_int
        && entry->qf_prev != NULL
        && entry->qf_fnum == entry->qf_prev->qf_fnum
        && entry->qf_lnum == entry->qf_prev->qf_lnum) {
   entry = entry->qf_prev;
   (*errornr)--;
 }

 return entry;
}

/// Find the last quickfix entry on the same line as 'entry'. Updates 'errornr'
/// with the error number for the last entry. Assumes the entries are sorted in
/// the quickfix list by line number.
static qfline_T *qf_find_last_entry_on_line(qfline_T *entry, int *errornr)
{
 while (!got_int
        && entry->qf_next != NULL
        && entry->qf_fnum == entry->qf_next->qf_fnum
        && entry->qf_lnum == entry->qf_next->qf_lnum) {
   entry = entry->qf_next;
   (*errornr)++;
 }

 return entry;
}

// Returns true if the specified quickfix entry is
// after the given line (linewise is true)
// or after the line and column.
static bool qf_entry_after_pos(const qfline_T *qfp, const pos_T *pos, bool linewise)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (linewise) {
   return qfp->qf_lnum > pos->lnum;
 }
 return qfp->qf_lnum > pos->lnum
        || (qfp->qf_lnum == pos->lnum && qfp->qf_col > pos->col);
}

// Returns true if the specified quickfix entry is
// before the given line (linewise is true)
// or before the line and column.
static bool qf_entry_before_pos(const qfline_T *qfp, const pos_T *pos, bool linewise)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (linewise) {
   return qfp->qf_lnum < pos->lnum;
 }
 return qfp->qf_lnum < pos->lnum
        || (qfp->qf_lnum == pos->lnum && qfp->qf_col < pos->col);
}

// Returns true if the specified quickfix entry is
// on or after the given line (linewise is true)
// or on or after the line and column.
static bool qf_entry_on_or_after_pos(const qfline_T *qfp, const pos_T *pos, bool linewise)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (linewise) {
   return qfp->qf_lnum >= pos->lnum;
 }
 return qfp->qf_lnum > pos->lnum
        || (qfp->qf_lnum == pos->lnum && qfp->qf_col >= pos->col);
}

// Returns true if the specified quickfix entry is
// on or before the given line (linewise is true)
// or on or before the line and column.
static bool qf_entry_on_or_before_pos(const qfline_T *qfp, const pos_T *pos, bool linewise)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (linewise) {
   return qfp->qf_lnum <= pos->lnum;
 }
 return qfp->qf_lnum < pos->lnum
        || (qfp->qf_lnum == pos->lnum && qfp->qf_col <= pos->col);
}

/// Find the first quickfix entry after position 'pos' in buffer 'bnr'.
/// If 'linewise' is true, returns the entry after the specified line and treats
/// multiple entries on a single line as one. Otherwise returns the entry after
/// the specified line and column.
/// 'qfp' points to the very first entry in the buffer and 'errornr' is the
/// index of the very first entry in the quickfix list.
/// Returns NULL if an entry is not found after 'pos'.
static qfline_T *qf_find_entry_after_pos(int bnr, const pos_T *pos, bool linewise, qfline_T *qfp,
                                        int *errornr)
 FUNC_ATTR_NONNULL_ALL
{
 if (qf_entry_after_pos(qfp, pos, linewise)) {
   // First entry is after position 'pos'
   return qfp;
 }

 // Find the entry just before or at the position 'pos'
 while (qfp->qf_next != NULL
        && qfp->qf_next->qf_fnum == bnr
        && qf_entry_on_or_before_pos(qfp->qf_next, pos, linewise)) {
   qfp = qfp->qf_next;
   (*errornr)++;
 }

 if (qfp->qf_next == NULL || qfp->qf_next->qf_fnum != bnr) {
   // No entries found after position 'pos'
   return NULL;
 }

 // Use the entry just after position 'pos'
 qfp = qfp->qf_next;
 (*errornr)++;

 return qfp;
}

/// Find the first quickfix entry before position 'pos' in buffer 'bnr'.
/// If 'linewise' is true, returns the entry before the specified line and
/// treats multiple entries on a single line as one. Otherwise returns the entry
/// before the specified line and column.
/// 'qfp' points to the very first entry in the buffer and 'errornr' is the
/// index of the very first entry in the quickfix list.
/// Returns NULL if an entry is not found before 'pos'.
static qfline_T *qf_find_entry_before_pos(int bnr, const pos_T *pos, bool linewise, qfline_T *qfp,
                                         int *errornr)
 FUNC_ATTR_NONNULL_ALL
{
 // Find the entry just before the position 'pos'
 while (qfp->qf_next != NULL
        && qfp->qf_next->qf_fnum == bnr
        && qf_entry_before_pos(qfp->qf_next, pos, linewise)) {
   qfp = qfp->qf_next;
   (*errornr)++;
 }

 if (qf_entry_on_or_after_pos(qfp, pos, linewise)) {
   return NULL;
 }

 if (linewise) {
   // If multiple entries are on the same line, then use the first entry
   qfp = qf_find_first_entry_on_line(qfp, errornr);
 }

 return qfp;
}

/// Find a quickfix entry in 'qfl' closest to position 'pos' in buffer 'bnr' in
/// the direction 'dir'.
static qfline_T *qf_find_closest_entry(qf_list_T *qfl, int bnr, const pos_T *pos, Direction dir,
                                      bool linewise, int *errornr)
 FUNC_ATTR_NONNULL_ALL
{
 *errornr = 0;

 // Find the first entry in this file
 qfline_T *qfp = qf_find_first_entry_in_buf(qfl, bnr, errornr);
 if (qfp == NULL) {
   return NULL;  // no entry in this file
 }

 if (dir == FORWARD) {
   qfp = qf_find_entry_after_pos(bnr, pos, linewise, qfp, errornr);
 } else {
   qfp = qf_find_entry_before_pos(bnr, pos, linewise, qfp, errornr);
 }

 return qfp;
}

/// Get the nth quickfix entry below the specified entry.  Searches forward in
/// the list. If linewise is true, then treat multiple entries on a single line
/// as one.
static void qf_get_nth_below_entry(qfline_T *entry_arg, linenr_T n, bool linewise, int *errornr)
 FUNC_ATTR_NONNULL_ALL
{
 qfline_T *entry = entry_arg;

 while (n-- > 0 && !got_int) {
   int first_errornr = *errornr;

   if (linewise) {
     // Treat all the entries on the same line in this file as one
     entry = qf_find_last_entry_on_line(entry, errornr);
   }

   if (entry->qf_next == NULL
       || entry->qf_next->qf_fnum != entry->qf_fnum) {
     if (linewise) {
       *errornr = first_errornr;
     }
     break;
   }

   entry = entry->qf_next;
   (*errornr)++;
 }
}

/// Get the nth quickfix entry above the specified entry.  Searches backwards in
/// the list. If linewise is true, then treat multiple entries on a single line
/// as one.
static void qf_get_nth_above_entry(qfline_T *entry, linenr_T n, bool linewise, int *errornr)
 FUNC_ATTR_NONNULL_ALL
{
 while (n-- > 0 && !got_int) {
   if (entry->qf_prev == NULL
       || entry->qf_prev->qf_fnum != entry->qf_fnum) {
     break;
   }

   entry = entry->qf_prev;
   (*errornr)--;

   if (linewise) {
     entry = qf_find_first_entry_on_line(entry, errornr);
   }
 }
}

/// Find the n'th quickfix entry adjacent to position 'pos' in buffer 'bnr' in
/// the specified direction.  Returns the error number in the quickfix list or 0
/// if an entry is not found.
static int qf_find_nth_adj_entry(qf_list_T *qfl, int bnr, pos_T *pos, linenr_T n, Direction dir,
                                bool linewise)
 FUNC_ATTR_NONNULL_ALL
{
 int errornr;

 // Find an entry closest to the specified position
 qfline_T *const adj_entry = qf_find_closest_entry(qfl, bnr, pos, dir,
                                                   linewise, &errornr);
 if (adj_entry == NULL) {
   return 0;
 }

 if (--n > 0) {
   // Go to the n'th entry in the current buffer
   if (dir == FORWARD) {
     qf_get_nth_below_entry(adj_entry, n, linewise, &errornr);
   } else {
     qf_get_nth_above_entry(adj_entry, n, linewise, &errornr);
   }
 }

 return errornr;
}

/// Jump to a quickfix entry in the current file nearest to the current line or
/// current line/col.
/// ":cabove", ":cbelow", ":labove", ":lbelow", ":cafter", ":cbefore",
/// ":lafter" and ":lbefore" commands
void ex_cbelow(exarg_T *eap)
{
 if (eap->addr_count > 0 && eap->line2 <= 0) {
   emsg(_(e_invrange));
   return;
 }

 // Check whether the current buffer has any quickfix entries
 int buf_has_flag = (eap->cmdidx == CMD_cabove
                     || eap->cmdidx == CMD_cbelow
                     || eap->cmdidx == CMD_cbefore
                     || eap->cmdidx == CMD_cafter) ? BUF_HAS_QF_ENTRY : BUF_HAS_LL_ENTRY;

 if (!(curbuf->b_has_qf_entry & buf_has_flag)) {
   emsg(_(e_no_errors));
   return;
 }

 qf_info_T *qi;
 if ((qi = qf_cmd_get_stack(eap, true)) == NULL) {
   return;
 }

 qf_list_T *qfl = qf_get_curlist(qi);
 // check if the list has valid errors
 if (!qf_list_has_valid_entries(qfl)) {
   emsg(_(e_no_errors));
   return;
 }

 // Forward motion commands
 int dir = (eap->cmdidx == CMD_cbelow
            || eap->cmdidx == CMD_lbelow
            || eap->cmdidx == CMD_cafter
            || eap->cmdidx == CMD_lafter) ? FORWARD : BACKWARD;

 pos_T pos = curwin->w_cursor;
 // A quickfix entry column number is 1 based whereas cursor column
 // number is 0 based. Adjust the column number.
 pos.col++;
 const int errornr = qf_find_nth_adj_entry(qfl,
                                           curbuf->b_fnum,
                                           &pos,
                                           eap->addr_count > 0 ? eap->line2 : 0,
                                           dir,
                                           eap->cmdidx == CMD_cbelow
                                           || eap->cmdidx == CMD_lbelow
                                           || eap->cmdidx == CMD_cabove
                                           || eap->cmdidx == CMD_labove);

 if (errornr > 0) {
   qf_jump(qi, 0, errornr, false);
 } else {
   emsg(_(e_no_more_items));
 }
}

/// Return the autocmd name for the :cfile Ex commands
static char *cfile_get_auname(cmdidx_T cmdidx)
{
 switch (cmdidx) {
 case CMD_cfile:
   return "cfile";
 case CMD_cgetfile:
   return "cgetfile";
 case CMD_caddfile:
   return "caddfile";
 case CMD_lfile:
   return "lfile";
 case CMD_lgetfile:
   return "lgetfile";
 case CMD_laddfile:
   return "laddfile";
 default:
   return NULL;
 }
}

// ":cfile"/":cgetfile"/":caddfile" commands.
// ":lfile"/":lgetfile"/":laddfile" commands.
void ex_cfile(exarg_T *eap)
{
 win_T *wp = NULL;
 qf_info_T *qi = ql_info;
 assert(qi != NULL);
 char *au_name = NULL;

 au_name = cfile_get_auname(eap->cmdidx);
 if (au_name != NULL
     && apply_autocmds(EVENT_QUICKFIXCMDPRE, au_name, NULL, false, curbuf)) {
   if (aborting()) {
     return;
   }
 }
 if (*eap->arg != NUL) {
   set_option_direct(kOptErrorfile, CSTR_AS_OPTVAL(eap->arg), 0, 0);
 }

 char *enc = (*curbuf->b_p_menc != NUL) ? curbuf->b_p_menc : p_menc;

 if (is_loclist_cmd(eap->cmdidx)) {
   wp = curwin;
 }

 incr_quickfix_busy();

 // This function is used by the :cfile, :cgetfile and :caddfile
 // commands.
 // :cfile always creates a new quickfix list and may jump to the
 // first error.
 // :cgetfile creates a new quickfix list but doesn't jump to the
 // first error.
 // :caddfile adds to an existing quickfix list. If there is no
 // quickfix list then a new list is created.
 int res = qf_init(wp, p_ef, p_efm, (eap->cmdidx != CMD_caddfile
                                     && eap->cmdidx != CMD_laddfile),
                   qf_cmdtitle(*eap->cmdlinep), enc);
 if (wp != NULL) {
   qi = GET_LOC_LIST(wp);
   if (qi == NULL) {
     decr_quickfix_busy();
     return;
   }
 }
 if (res >= 0) {
   qf_list_changed(qf_get_curlist(qi));
 }
 unsigned save_qfid = qf_get_curlist(qi)->qf_id;
 if (au_name != NULL) {
   apply_autocmds(EVENT_QUICKFIXCMDPOST, au_name, NULL, false, curbuf);
 }
 // Jump to the first error for a new list and if autocmds didn't free the
 // list.
 if (res > 0 && (eap->cmdidx == CMD_cfile || eap->cmdidx == CMD_lfile)
     && qflist_valid(wp, save_qfid)) {
   // display the first error
   qf_jump_first(qi, save_qfid, eap->forceit);
 }

 decr_quickfix_busy();
}

/// Return the vimgrep autocmd name.
static char *vgr_get_auname(cmdidx_T cmdidx)
{
 switch (cmdidx) {
 case CMD_vimgrep:
   return "vimgrep";
 case CMD_lvimgrep:
   return "lvimgrep";
 case CMD_vimgrepadd:
   return "vimgrepadd";
 case CMD_lvimgrepadd:
   return "lvimgrepadd";
 case CMD_grep:
   return "grep";
 case CMD_lgrep:
   return "lgrep";
 case CMD_grepadd:
   return "grepadd";
 case CMD_lgrepadd:
   return "lgrepadd";
 default:
   return NULL;
 }
}

/// Initialize the regmatch used by vimgrep for pattern "s".
static void vgr_init_regmatch(regmmatch_T *regmatch, char *s)
{
 // Get the search pattern: either white-separated or enclosed in //.
 regmatch->regprog = NULL;

 if (s == NULL || *s == NUL) {
   // Pattern is empty, use last search pattern.
   if (last_search_pat() == NULL) {
     emsg(_(e_noprevre));
     return;
   }
   regmatch->regprog = vim_regcomp(last_search_pat(), RE_MAGIC);
 } else {
   regmatch->regprog = vim_regcomp(s, RE_MAGIC);
 }

 regmatch->rmm_ic = p_ic;
 regmatch->rmm_maxcol = 0;
}

/// Display a file name when vimgrep is running.
static void vgr_display_fname(char *fname)
{
 msg_start();
 char *p = msg_strtrunc(fname, true);
 if (p == NULL) {
   msg_outtrans(fname, 0, false);
 } else {
   msg_outtrans(p, 0, false);
   xfree(p);
 }
 msg_clr_eos();
 msg_didout = false;  // overwrite this message
 msg_nowait = true;   // don't wait for this message
 msg_col = 0;
 ui_flush();
}

/// Load a dummy buffer to search for a pattern using vimgrep.
static buf_T *vgr_load_dummy_buf(char *fname, char *dirname_start, char *dirname_now)
{
 // Don't do Filetype autocommands to avoid loading syntax and
 // indent scripts, a great speed improvement.
 char *save_ei = au_event_disable(",Filetype");

 OptInt save_mls = p_mls;
 p_mls = 0;

 // Load file into a buffer, so that 'fileencoding' is detected,
 // autocommands applied, etc.
 buf_T *buf = load_dummy_buffer(fname, dirname_start, dirname_now);

 p_mls = save_mls;
 au_event_restore(save_ei);

 return buf;
}

/// Check whether a quickfix/location list is valid. Autocmds may remove or
/// change a quickfix list when vimgrep is running. If the list is not found,
/// create a new list.
static bool vgr_qflist_valid(win_T *wp, qf_info_T *qi, unsigned qfid, char *title)
{
 // Verify that the quickfix/location list was not freed by an autocmd
 if (!qflist_valid(wp, qfid)) {
   if (wp != NULL) {
     // An autocmd has freed the location list
     emsg(_(e_current_location_list_was_changed));
     return false;
   }
   // Quickfix list is not found, create a new one.
   qf_new_list(qi, title);
   return true;
 }
 if (qf_restore_list(qi, qfid) == FAIL) {
   return false;
 }

 return true;
}

/// Search for a pattern in all the lines in a buffer and add the matching lines
/// to a quickfix list.
static bool vgr_match_buflines(qf_list_T *qfl, char *fname, buf_T *buf, char *spat,
                              regmmatch_T *regmatch, int *tomatch, int duplicate_name, int flags)
 FUNC_ATTR_NONNULL_ARG(1, 3, 4, 5, 6)
{
 bool found_match = false;
 size_t pat_len = strlen(spat);
 pat_len = MIN(pat_len, FUZZY_MATCH_MAX_LEN);

 for (linenr_T lnum = 1; lnum <= buf->b_ml.ml_line_count && *tomatch > 0; lnum++) {
   colnr_T col = 0;
   if (!(flags & VGR_FUZZY)) {
     // Regular expression match
     while (vim_regexec_multi(regmatch, curwin, buf, lnum, col, NULL, NULL) > 0) {
       // Pass the buffer number so that it gets used even for a
       // dummy buffer, unless duplicate_name is set, then the
       // buffer will be wiped out below.
       if (qf_add_entry(qfl,
                        NULL,   // dir
                        fname,
                        NULL,
                        duplicate_name ? 0 : buf->b_fnum,
                        ml_get_buf(buf, regmatch->startpos[0].lnum + lnum),
                        regmatch->startpos[0].lnum + lnum,
                        regmatch->endpos[0].lnum + lnum,
                        regmatch->startpos[0].col + 1,
                        regmatch->endpos[0].col + 1,
                        false,  // vis_col
                        NULL,   // search pattern
                        0,      // nr
                        0,      // type
                        NULL,   // user_data
                        true)   // valid
           == QF_FAIL) {
         got_int = true;
         break;
       }
       found_match = true;
       if (--*tomatch == 0) {
         break;
       }
       if ((flags & VGR_GLOBAL) == 0 || regmatch->endpos[0].lnum > 0) {
         break;
       }
       col = regmatch->endpos[0].col + (col == regmatch->endpos[0].col);
       if (col > ml_get_buf_len(buf, lnum)) {
         break;
       }
     }
   } else {
     char *const str = ml_get_buf(buf, lnum);
     const colnr_T linelen = ml_get_buf_len(buf, lnum);
     int score;
     uint32_t matches[FUZZY_MATCH_MAX_LEN];
     const size_t sz = sizeof(matches) / sizeof(matches[0]);

     // Fuzzy string match
     CLEAR_FIELD(matches);
     while (fuzzy_match(str + col, spat, false, &score, matches, (int)sz) > 0) {
       // Pass the buffer number so that it gets used even for a
       // dummy buffer, unless duplicate_name is set, then the
       // buffer will be wiped out below.
       if (qf_add_entry(qfl,
                        NULL,   // dir
                        fname,
                        NULL,
                        duplicate_name ? 0 : buf->b_fnum,
                        str,
                        lnum,
                        0,
                        (colnr_T)matches[0] + col + 1,
                        0,
                        false,  // vis_col
                        NULL,   // search pattern
                        0,      // nr
                        0,      // type
                        NULL,   // user_data
                        true)   // valid
           == QF_FAIL) {
         got_int = true;
         break;
       }
       found_match = true;
       if (--*tomatch == 0) {
         break;
       }
       if ((flags & VGR_GLOBAL) == 0) {
         break;
       }
       col = (colnr_T)matches[pat_len - 1] + col + 1;
       if (col > linelen) {
         break;
       }
     }
   }
   line_breakcheck();
   if (got_int) {
     break;
   }
 }

 return found_match;
}

/// Jump to the first match and update the directory.
static void vgr_jump_to_match(qf_info_T *qi, int forceit, bool *redraw_for_dummy,
                             buf_T *first_match_buf, char *target_dir)  // NOLINT(readability-non-const-parameter)
{
 buf_T *buf = curbuf;
 qf_jump(qi, 0, 0, forceit);
 if (buf != curbuf) {
   // If we jumped to another buffer redrawing will already be
   // taken care of.
   *redraw_for_dummy = false;
 }

 // Jump to the directory used after loading the buffer.
 if (curbuf == first_match_buf && target_dir != NULL) {
   exarg_T ea = {
     .arg = target_dir,
     .cmdidx = CMD_lcd,
   };
   ex_cd(&ea);
 }
}

// Return true if "buf" had an existing swap file, the current swap file does
// not end in ".swp".
static bool existing_swapfile(const buf_T *buf)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 if (buf->b_ml.ml_mfp != NULL && buf->b_ml.ml_mfp->mf_fname != NULL) {
   const char *const fname = buf->b_ml.ml_mfp->mf_fname;
   const size_t len = strlen(fname);

   return fname[len - 1] != 'p' || fname[len - 2] != 'w';
 }
 return false;
}

/// Process :vimgrep command arguments. The command syntax is:
///
/// :{count}vimgrep /{pattern}/[g][j] {file} ...
static int vgr_process_args(exarg_T *eap, vgr_args_T *args)
{
 CLEAR_POINTER(args);

 args->regmatch.regprog = NULL;
 args->qf_title = xstrdup(qf_cmdtitle(*eap->cmdlinep));
 args->tomatch = eap->addr_count > 0 ? eap->line2 : MAXLNUM;

 // Get the search pattern: either white-separated or enclosed in //
 char *p = skip_vimgrep_pat(eap->arg, &args->spat, &args->flags);
 if (p == NULL) {
   emsg(_(e_invalpat));
   return FAIL;
 }

 vgr_init_regmatch(&args->regmatch, args->spat);
 if (args->regmatch.regprog == NULL) {
   return FAIL;
 }

 p = skipwhite(p);
 if (*p == NUL) {
   emsg(_("E683: File name missing or invalid pattern"));
   return FAIL;
 }

 // Parse the list of arguments, wildcards have already been expanded.
 if (get_arglist_exp(p, &args->fcount, &args->fnames, true) == FAIL
     || args->fcount == 0) {
   emsg(_(e_nomatch));
   return FAIL;
 }

 return OK;
}

/// Search for a pattern in a list of files and populate the quickfix list with
/// the matches.
static int vgr_process_files(win_T *wp, qf_info_T *qi, vgr_args_T *cmd_args, bool *redraw_for_dummy,
                            buf_T **first_match_buf, char **target_dir)
{
 int status = FAIL;
 unsigned save_qfid = qf_get_curlist(qi)->qf_id;
 bool duplicate_name = false;

 char *dirname_start = xmalloc(MAXPATHL);
 char *dirname_now = xmalloc(MAXPATHL);

 // Remember the current directory, because a BufRead autocommand that does
 // ":lcd %:p:h" changes the meaning of short path names.
 os_dirname(dirname_start, MAXPATHL);

 time_t seconds = 0;
 for (int fi = 0; fi < cmd_args->fcount && !got_int && cmd_args->tomatch > 0; fi++) {
   char *fname = path_try_shorten_fname(cmd_args->fnames[fi]);
   if (time(NULL) > seconds) {
     // Display the file name every second or so, show the user we are
     // working on it.
     seconds = time(NULL);
     vgr_display_fname(fname);
   }

   buf_T *buf = buflist_findname_exp(cmd_args->fnames[fi]);
   bool using_dummy;
   if (buf == NULL || buf->b_ml.ml_mfp == NULL) {
     // Remember that a buffer with this name already exists.
     duplicate_name = (buf != NULL);
     using_dummy = true;
     *redraw_for_dummy = true;
     buf = vgr_load_dummy_buf(fname, dirname_start, dirname_now);
   } else {
     // Use existing, loaded buffer.
     using_dummy = false;
   }

   // Check whether the quickfix list is still valid. When loading a
   // buffer above, autocommands might have changed the quickfix list.
   if (!vgr_qflist_valid(wp, qi, save_qfid, cmd_args->qf_title)) {
     goto theend;
   }

   save_qfid = qf_get_curlist(qi)->qf_id;

   if (buf == NULL) {
     if (!got_int) {
       smsg(0, _("Cannot open file \"%s\""), fname);
     }
   } else {
     // Try for a match in all lines of the buffer.
     // For ":1vimgrep" look for first match only.
     bool found_match = vgr_match_buflines(qf_get_curlist(qi),
                                           fname,
                                           buf,
                                           cmd_args->spat,
                                           &cmd_args->regmatch,
                                           &cmd_args->tomatch,
                                           duplicate_name,
                                           cmd_args->flags);

     if (using_dummy) {
       if (found_match && *first_match_buf == NULL) {
         *first_match_buf = buf;
       }
       if (duplicate_name) {
         // Never keep a dummy buffer if there is another buffer
         // with the same name.
         wipe_dummy_buffer(buf, dirname_start);
         buf = NULL;
       } else if ((cmdmod.cmod_flags & CMOD_HIDE) == 0
                  || buf->b_p_bh[0] == 'u'             // "unload"
                  || buf->b_p_bh[0] == 'w'             // "wipe"
                  || buf->b_p_bh[0] == 'd') {          // "delete"
         // When no match was found we don't need to remember the
         // buffer, wipe it out.  If there was a match and it
         // wasn't the first one or we won't jump there: only
         // unload the buffer.
         // Ignore 'hidden' here, because it may lead to having too
         // many swap files.
         if (!found_match) {
           wipe_dummy_buffer(buf, dirname_start);
           buf = NULL;
         } else if (buf != *first_match_buf
                    || (cmd_args->flags & VGR_NOJUMP)
                    || existing_swapfile(buf)) {
           unload_dummy_buffer(buf, dirname_start);
           // Keeping the buffer, remove the dummy flag.
           buf->b_flags &= ~BF_DUMMY;
           buf = NULL;
         }
       }

       if (buf != NULL) {
         // Keeping the buffer, remove the dummy flag.
         buf->b_flags &= ~BF_DUMMY;

         // If the buffer is still loaded we need to use the
         // directory we jumped to below.
         if (buf == *first_match_buf
             && *target_dir == NULL
             && strcmp(dirname_start, dirname_now) != 0) {
           *target_dir = xstrdup(dirname_now);
         }

         // The buffer is still loaded, the Filetype autocommands
         // need to be done now, in that buffer.  And the modelines
         // need to be done (again).  But not the window-local
         // options!
         aco_save_T aco;
         aucmd_prepbuf(&aco, buf);
         apply_autocmds(EVENT_FILETYPE, buf->b_p_ft, buf->b_fname, true, buf);
         do_modelines(OPT_NOWIN);
         aucmd_restbuf(&aco);
       }
     }
   }
 }

 status = OK;

theend:
 xfree(dirname_now);
 xfree(dirname_start);
 return status;
}

/// ":vimgrep {pattern} file(s)"
/// ":vimgrepadd {pattern} file(s)"
/// ":lvimgrep {pattern} file(s)"
/// ":lvimgrepadd {pattern} file(s)"
void ex_vimgrep(exarg_T *eap)
{
 if (!check_can_set_curbuf_forceit(eap->forceit)) {
   return;
 }

 char *au_name = vgr_get_auname(eap->cmdidx);
 if (au_name != NULL && apply_autocmds(EVENT_QUICKFIXCMDPRE, au_name,
                                       curbuf->b_fname, true, curbuf)) {
   if (aborting()) {
     return;
   }
 }

 win_T *wp = NULL;
 qf_info_T *qi = qf_cmd_get_or_alloc_stack(eap, &wp);
 char *target_dir = NULL;
 vgr_args_T args;
 if (vgr_process_args(eap, &args) == FAIL) {
   goto theend;
 }

 if ((eap->cmdidx != CMD_grepadd && eap->cmdidx != CMD_lgrepadd
      && eap->cmdidx != CMD_vimgrepadd && eap->cmdidx != CMD_lvimgrepadd)
     || qf_stack_empty(qi)) {
   // make place for a new list
   qf_new_list(qi, args.qf_title);
 }

 incr_quickfix_busy();

 bool redraw_for_dummy = false;
 buf_T *first_match_buf = NULL;
 int status = vgr_process_files(wp, qi, &args, &redraw_for_dummy, &first_match_buf, &target_dir);

 if (status != OK) {
   FreeWild(args.fcount, args.fnames);
   decr_quickfix_busy();
   goto theend;
 }

 FreeWild(args.fcount, args.fnames);

 qf_list_T *qfl = qf_get_curlist(qi);
 qfl->qf_nonevalid = false;
 qfl->qf_ptr = qfl->qf_start;
 qfl->qf_index = 1;
 qf_list_changed(qfl);

 qf_update_buffer(qi, NULL);

 // Remember the current quickfix list identifier, so that we can check for
 // autocommands changing the current quickfix list.
 unsigned save_qfid = qf_get_curlist(qi)->qf_id;

 if (au_name != NULL) {
   apply_autocmds(EVENT_QUICKFIXCMDPOST, au_name, curbuf->b_fname, true, curbuf);
 }

 // The QuickFixCmdPost autocmd may free the quickfix list. Check the list
 // is still valid.
 if (!qflist_valid(wp, save_qfid) || qf_restore_list(qi, save_qfid) == FAIL) {
   decr_quickfix_busy();
   goto theend;
 }

 // Jump to first match.
 if (!qf_list_empty(qf_get_curlist(qi))) {
   if ((args.flags & VGR_NOJUMP) == 0) {
     vgr_jump_to_match(qi, eap->forceit, &redraw_for_dummy, first_match_buf, target_dir);
   }
 } else {
   semsg(_(e_nomatch2), args.spat);
 }

 decr_quickfix_busy();

 // If we loaded a dummy buffer into the current window, the autocommands
 // may have messed up things, need to redraw and recompute folds.
 if (redraw_for_dummy) {
   foldUpdateAll(curwin);
 }

theend:
 xfree(args.qf_title);
 xfree(target_dir);
 vim_regfree(args.regmatch.regprog);
}

// Restore current working directory to "dirname_start" if they differ, taking
// into account whether it is set locally or globally.
static void restore_start_dir(char *dirname_start)
 FUNC_ATTR_NONNULL_ALL
{
 char *dirname_now = xmalloc(MAXPATHL);

 os_dirname(dirname_now, MAXPATHL);
 if (strcmp(dirname_start, dirname_now) != 0) {
   // If the directory has changed, change it back by building up an
   // appropriate ex command and executing it.
   exarg_T ea = {
     .arg = dirname_start,
     .cmdidx = (curwin->w_localdir == NULL) ? CMD_cd : CMD_lcd,
   };
   ex_cd(&ea);
 }
 xfree(dirname_now);
}

/// Load file "fname" into a dummy buffer and return the buffer pointer,
/// placing the directory resulting from the buffer load into the
/// "resulting_dir" pointer. "resulting_dir" must be allocated by the caller
/// prior to calling this function. Restores directory to "dirname_start" prior
/// to returning, if autocmds or the 'autochdir' option have changed it.
///
/// If creating the dummy buffer does not fail, must call unload_dummy_buffer()
/// or wipe_dummy_buffer() later!
///
/// @param dirname_start  in: old directory
/// @param resulting_dir  out: new directory
///
/// @return  NULL if it fails.
static buf_T *load_dummy_buffer(char *fname, char *dirname_start, char *resulting_dir)
{
 // Allocate a buffer without putting it in the buffer list.
 buf_T *newbuf = buflist_new(NULL, NULL, 1, BLN_DUMMY);
 if (newbuf == NULL) {
   return NULL;
 }

 bool failed = true;
 bufref_T newbufref;
 set_bufref(&newbufref, newbuf);

 // Init the options.
 buf_copy_options(newbuf, BCO_ENTER | BCO_NOHELP);

 // need to open the memfile before putting the buffer in a window
 if (ml_open(newbuf) == OK) {
   // Make sure this buffer isn't wiped out by autocommands.
   newbuf->b_locked++;
   // set curwin/curbuf to buf and save a few things
   aco_save_T aco;
   aucmd_prepbuf(&aco, newbuf);

   // Need to set the filename for autocommands.
   setfname(curbuf, fname, NULL, false);

   // Create swap file now to avoid the ATTENTION message.
   check_need_swap(true);

   // Remove the "dummy" flag, otherwise autocommands may not
   // work.
   curbuf->b_flags &= ~BF_DUMMY;

   bufref_T newbuf_to_wipe;
   newbuf_to_wipe.br_buf = NULL;
   int readfile_result = readfile(fname, NULL, 0, 0,
                                  (linenr_T)MAXLNUM, NULL,
                                  READ_NEW | READ_DUMMY, false);
   newbuf->b_locked--;
   if (readfile_result == OK
       && !got_int
       && !(curbuf->b_flags & BF_NEW)) {
     failed = false;
     if (curbuf != newbuf) {
       // Bloody autocommands changed the buffer!  Can happen when
       // using netrw and editing a remote file.  Use the current
       // buffer instead, delete the dummy one after restoring the
       // window stuff.
       set_bufref(&newbuf_to_wipe, newbuf);
       newbuf = curbuf;
     }
   }

   // Restore curwin/curbuf and a few other things.
   aucmd_restbuf(&aco);

   if (newbuf_to_wipe.br_buf != NULL && bufref_valid(&newbuf_to_wipe)) {
     block_autocmds();
     wipe_dummy_buffer(newbuf_to_wipe.br_buf, NULL);
     unblock_autocmds();
   }

   // Add back the "dummy" flag, otherwise buflist_findname_file_id()
   // won't skip it.
   newbuf->b_flags |= BF_DUMMY;
 }

 // When autocommands/'autochdir' option changed directory: go back.
 // Let the caller know what the resulting dir was first, in case it is
 // important.
 os_dirname(resulting_dir, MAXPATHL);
 restore_start_dir(dirname_start);

 if (!bufref_valid(&newbufref)) {
   return NULL;
 }
 if (failed) {
   wipe_dummy_buffer(newbuf, dirname_start);
   return NULL;
 }
 return newbuf;
}

/// Wipe out the dummy buffer that load_dummy_buffer() created. Restores
/// directory to "dirname_start" if not NULL prior to returning, if autocmds or
/// the 'autochdir' option have changed it.
static void wipe_dummy_buffer(buf_T *buf, char *dirname_start)
 FUNC_ATTR_NONNULL_ARG(1)
{
 // If any autocommand opened a window on the dummy buffer, close that
 // window.  If we can't close them all then give up.
 while (buf->b_nwindows > 0) {
   bool did_one = false;

   if (firstwin->w_next != NULL) {
     for (win_T *wp = firstwin; wp != NULL; wp = wp->w_next) {
       if (wp->w_buffer == buf) {
         if (win_close(wp, false, false) == OK) {
           did_one = true;
         }
         break;
       }
     }
   }
   if (!did_one) {
     goto fail;
   }
 }

 if (curbuf != buf && buf->b_nwindows == 0) {  // safety check
   cleanup_T cs;

   // Reset the error/interrupt/exception state here so that aborting()
   // returns false when wiping out the buffer.  Otherwise it doesn't
   // work when got_int is set.
   enter_cleanup(&cs);

   wipe_buffer(buf, true);

   // Restore the error/interrupt/exception state if not discarded by a
   // new aborting error, interrupt, or uncaught exception.
   leave_cleanup(&cs);

   if (dirname_start != NULL) {
     // When autocommands/'autochdir' option changed directory: go back.
     restore_start_dir(dirname_start);
   }

   return;
 }

fail:
 // Keeping the buffer, remove the dummy flag.
 buf->b_flags &= ~BF_DUMMY;
}

/// Unload the dummy buffer that load_dummy_buffer() created. Restores
/// directory to "dirname_start" prior to returning, if autocmds or the
/// 'autochdir' option have changed it.
static void unload_dummy_buffer(buf_T *buf, char *dirname_start)
{
 if (curbuf == buf) {          // safety check
   return;
 }

 close_buffer(NULL, buf, DOBUF_UNLOAD, false, true);

 // When autocommands/'autochdir' option changed directory: go back.
 restore_start_dir(dirname_start);
}

/// Copy the specified quickfix entry items into a new dict and append the dict
/// to 'list'.  Returns OK on success.
static int get_qfline_items(qfline_T *qfp, list_T *list)
{
 // Handle entries with a non-existing buffer number.
 int bufnum = qfp->qf_fnum;
 if (bufnum != 0 && (buflist_findnr(bufnum) == NULL)) {
   bufnum = 0;
 }

 dict_T *const dict = tv_dict_alloc();
 tv_list_append_dict(list, dict);

 char buf[2];
 buf[0] = qfp->qf_type;
 buf[1] = NUL;
 if (tv_dict_add_nr(dict, S_LEN("bufnr"), (varnumber_T)bufnum) == FAIL
     || (tv_dict_add_nr(dict, S_LEN("lnum"), (varnumber_T)qfp->qf_lnum) == FAIL)
     || (tv_dict_add_nr(dict, S_LEN("end_lnum"), (varnumber_T)qfp->qf_end_lnum) == FAIL)
     || (tv_dict_add_nr(dict, S_LEN("col"), (varnumber_T)qfp->qf_col) == FAIL)
     || (tv_dict_add_nr(dict, S_LEN("end_col"), (varnumber_T)qfp->qf_end_col) == FAIL)
     || (tv_dict_add_nr(dict, S_LEN("vcol"), (varnumber_T)qfp->qf_viscol) == FAIL)
     || (tv_dict_add_nr(dict, S_LEN("nr"), (varnumber_T)qfp->qf_nr) == FAIL)
     || (tv_dict_add_str(dict, S_LEN("module"), (qfp->qf_module == NULL ? "" : qfp->qf_module))
         == FAIL)
     || (tv_dict_add_str(dict, S_LEN("pattern"), (qfp->qf_pattern == NULL ? "" : qfp->qf_pattern))
         == FAIL)
     || (tv_dict_add_str(dict, S_LEN("text"), (qfp->qf_text == NULL ? "" : qfp->qf_text)) == FAIL)
     || (tv_dict_add_str(dict, S_LEN("type"), buf) == FAIL)
     || (qfp->qf_user_data.v_type != VAR_UNKNOWN
         && tv_dict_add_tv(dict, S_LEN("user_data"), &qfp->qf_user_data) == FAIL)
     || (tv_dict_add_nr(dict, S_LEN("valid"), (varnumber_T)qfp->qf_valid) == FAIL)) {
   // tv_dict_add* fail only if key already exist, but this is a newly
   // allocated dictionary which is thus guaranteed to have no existing keys.
   abort();
 }

 return OK;
}

/// Add each quickfix error to list "list" as a dictionary.
/// If qf_idx is -1, use the current list. Otherwise, use the specified list.
/// If eidx is not 0, then return only the specified entry. Otherwise return
/// all the entries.
static int get_errorlist(qf_info_T *qi_arg, win_T *wp, int qf_idx, int eidx, list_T *list)
{
 qf_info_T *qi = qi_arg;

 if (qi == NULL) {
   qi = ql_info;
   if (wp != NULL) {
     qi = GET_LOC_LIST(wp);
   }
   if (qi == NULL) {
     return FAIL;
   }
 }

 if (eidx < 0) {
   return OK;
 }

 if (qf_idx == INVALID_QFIDX) {
   qf_idx = qi->qf_curlist;
 }

 if (qf_idx >= qi->qf_listcount) {
   return FAIL;
 }

 qf_list_T *qfl = qf_get_list(qi, qf_idx);
 if (qf_list_empty(qfl)) {
   return FAIL;
 }

 qfline_T *qfp;
 int i;
 FOR_ALL_QFL_ITEMS(qfl, qfp, i) {
   if (eidx > 0) {
     if (eidx == i) {
       return get_qfline_items(qfp, list);
     }
   } else if (get_qfline_items(qfp, list) == FAIL) {
     return FAIL;
   }
 }

 return OK;
}

/// Flags used by getqflist()/getloclist() to determine which fields to return.
enum {
 QF_GETLIST_NONE = 0x0,
 QF_GETLIST_TITLE = 0x1,
 QF_GETLIST_ITEMS = 0x2,
 QF_GETLIST_NR = 0x4,
 QF_GETLIST_WINID = 0x8,
 QF_GETLIST_CONTEXT = 0x10,
 QF_GETLIST_ID = 0x20,
 QF_GETLIST_IDX = 0x40,
 QF_GETLIST_SIZE = 0x80,
 QF_GETLIST_TICK = 0x100,
 QF_GETLIST_FILEWINID = 0x200,
 QF_GETLIST_QFBUFNR = 0x400,
 QF_GETLIST_QFTF = 0x800,
 QF_GETLIST_ALL = 0xFFF,
};

/// Parse text from 'di' and return the quickfix list items.
/// Existing quickfix lists are not modified.
static int qf_get_list_from_lines(dict_T *what, dictitem_T *di, dict_T *retdict)
{
 int status = FAIL;

 // Only a List value is supported
 if (di->di_tv.v_type != VAR_LIST || di->di_tv.vval.v_list == NULL) {
   return FAIL;
 }

 char *errorformat = p_efm;
 dictitem_T *efm_di;
 // If errorformat is supplied then use it, otherwise use the 'efm'
 // option setting
 if ((efm_di = tv_dict_find(what, S_LEN("efm"))) != NULL) {
   if (efm_di->di_tv.v_type != VAR_STRING
       || efm_di->di_tv.vval.v_string == NULL) {
     return FAIL;
   }
   errorformat = efm_di->di_tv.vval.v_string;
 }

 list_T *l = tv_list_alloc(kListLenMayKnow);
 qf_info_T *const qi = qf_alloc_stack(QFLT_INTERNAL, 1);

 if (qf_init_ext(qi, 0, NULL, NULL, &di->di_tv, errorformat,
                 true, 0, 0, NULL, NULL) > 0) {
   get_errorlist(qi, NULL, 0, 0, l);
   qf_free(&qi->qf_lists[0]);
 }

 qf_free_lists(qi);

 tv_dict_add_list(retdict, S_LEN("items"), l);
 status = OK;

 return status;
}

/// Return the quickfix/location list window identifier in the current tabpage.
static int qf_winid(qf_info_T *qi)
{
 // The quickfix window can be opened even if the quickfix list is not set
 // using ":copen". This is not true for location lists.
 if (qi == NULL) {
   return 0;
 }
 win_T *win = qf_find_win(qi);
 if (win != NULL) {
   return win->handle;
 }
 return 0;
}

/// Returns the number of the buffer displayed in the quickfix/location list
/// window. If there is no buffer associated with the list or the buffer is
/// wiped out, then returns 0.
static int qf_getprop_qfbufnr(const qf_info_T *qi, dict_T *retdict)
 FUNC_ATTR_NONNULL_ARG(2)
{
 int bufnum = 0;

 if (qi != NULL && buflist_findnr(qi->qf_bufnr) != NULL) {
   bufnum = qi->qf_bufnr;
 }

 return tv_dict_add_nr(retdict, S_LEN("qfbufnr"), bufnum);
}

/// Convert the keys in 'what' to quickfix list property flags.
static int qf_getprop_keys2flags(const dict_T *what, bool loclist)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 int flags = QF_GETLIST_NONE;

 if (tv_dict_find(what, S_LEN("all")) != NULL) {
   flags |= QF_GETLIST_ALL;
   if (!loclist) {
     // File window ID is applicable only to location list windows
     flags &= ~QF_GETLIST_FILEWINID;
   }
 }
 if (tv_dict_find(what, S_LEN("title")) != NULL) {
   flags |= QF_GETLIST_TITLE;
 }
 if (tv_dict_find(what, S_LEN("nr")) != NULL) {
   flags |= QF_GETLIST_NR;
 }
 if (tv_dict_find(what, S_LEN("winid")) != NULL) {
   flags |= QF_GETLIST_WINID;
 }
 if (tv_dict_find(what, S_LEN("context")) != NULL) {
   flags |= QF_GETLIST_CONTEXT;
 }
 if (tv_dict_find(what, S_LEN("id")) != NULL) {
   flags |= QF_GETLIST_ID;
 }
 if (tv_dict_find(what, S_LEN("items")) != NULL) {
   flags |= QF_GETLIST_ITEMS;
 }
 if (tv_dict_find(what, S_LEN("idx")) != NULL) {
   flags |= QF_GETLIST_IDX;
 }
 if (tv_dict_find(what, S_LEN("size")) != NULL) {
   flags |= QF_GETLIST_SIZE;
 }
 if (tv_dict_find(what, S_LEN("changedtick")) != NULL) {
   flags |= QF_GETLIST_TICK;
 }
 if (loclist && tv_dict_find(what, S_LEN("filewinid")) != NULL) {
   flags |= QF_GETLIST_FILEWINID;
 }
 if (tv_dict_find(what, S_LEN("qfbufnr")) != NULL) {
   flags |= QF_GETLIST_QFBUFNR;
 }
 if (tv_dict_find(what, S_LEN("quickfixtextfunc")) != NULL) {
   flags |= QF_GETLIST_QFTF;
 }

 return flags;
}

/// Return the quickfix list index based on 'nr' or 'id' in 'what'.
///
/// If 'nr' and 'id' are not present in 'what' then return the current
/// quickfix list index.
/// If 'nr' is zero then return the current quickfix list index.
/// If 'nr' is '$' then return the last quickfix list index.
/// If 'id' is present then return the index of the quickfix list with that id.
/// If 'id' is zero then return the quickfix list index specified by 'nr'.
/// Return -1, if quickfix list is not present or if the stack is empty.
static int qf_getprop_qfidx(qf_info_T *qi, dict_T *what)
{
 dictitem_T *di = NULL;

 int qf_idx = qi->qf_curlist;  // default is the current list
 if ((di = tv_dict_find(what, S_LEN("nr"))) != NULL) {
   // Use the specified quickfix/location list
   if (di->di_tv.v_type == VAR_NUMBER) {
     // for zero use the current list
     if (di->di_tv.vval.v_number != 0) {
       qf_idx = (int)di->di_tv.vval.v_number - 1;
       if (qf_idx < 0 || qf_idx >= qi->qf_listcount) {
         qf_idx = INVALID_QFIDX;
       }
     }
   } else if (di->di_tv.v_type == VAR_STRING && strequal(di->di_tv.vval.v_string, "$")) {
     // Get the last quickfix list number
     qf_idx = qi->qf_listcount - 1;
   } else {
     qf_idx = INVALID_QFIDX;
   }
 }

 if ((di = tv_dict_find(what, S_LEN("id"))) != NULL) {
   // Look for a list with the specified id
   if (di->di_tv.v_type == VAR_NUMBER) {
     // For zero, use the current list or the list specified by 'nr'
     if (di->di_tv.vval.v_number != 0) {
       qf_idx = qf_id2nr(qi, (unsigned)di->di_tv.vval.v_number);
     }
   } else {
     qf_idx = INVALID_QFIDX;
   }
 }

 return qf_idx;
}

/// Return default values for quickfix list properties in retdict.
static int qf_getprop_defaults(qf_info_T *qi, int flags, int locstack, dict_T *retdict)
{
 int status = OK;

 if (flags & QF_GETLIST_TITLE) {
   status = tv_dict_add_str(retdict, S_LEN("title"), "");
 }
 if ((status == OK) && (flags & QF_GETLIST_ITEMS)) {
   list_T *l = tv_list_alloc(kListLenMayKnow);
   status = tv_dict_add_list(retdict, S_LEN("items"), l);
 }
 if ((status == OK) && (flags & QF_GETLIST_NR)) {
   status = tv_dict_add_nr(retdict, S_LEN("nr"), 0);
 }
 if ((status == OK) && (flags & QF_GETLIST_WINID)) {
   status = tv_dict_add_nr(retdict, S_LEN("winid"), qf_winid(qi));
 }
 if ((status == OK) && (flags & QF_GETLIST_CONTEXT)) {
   status = tv_dict_add_str(retdict, S_LEN("context"), "");
 }
 if ((status == OK) && (flags & QF_GETLIST_ID)) {
   status = tv_dict_add_nr(retdict, S_LEN("id"), 0);
 }
 if ((status == OK) && (flags & QF_GETLIST_IDX)) {
   status = tv_dict_add_nr(retdict, S_LEN("idx"), 0);
 }
 if ((status == OK) && (flags & QF_GETLIST_SIZE)) {
   status = tv_dict_add_nr(retdict, S_LEN("size"), 0);
 }
 if ((status == OK) && (flags & QF_GETLIST_TICK)) {
   status = tv_dict_add_nr(retdict, S_LEN("changedtick"), 0);
 }
 if ((status == OK) && locstack && (flags & QF_GETLIST_FILEWINID)) {
   status = tv_dict_add_nr(retdict, S_LEN("filewinid"), 0);
 }
 if ((status == OK) && (flags & QF_GETLIST_QFBUFNR)) {
   status = qf_getprop_qfbufnr(qi, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_QFTF)) {
   status = tv_dict_add_str(retdict, S_LEN("quickfixtextfunc"), "");
 }

 return status;
}

/// Return the quickfix list title as 'title' in retdict
static int qf_getprop_title(qf_list_T *qfl, dict_T *retdict)
{
 return tv_dict_add_str(retdict, S_LEN("title"), qfl->qf_title);
}

// Returns the identifier of the window used to display files from a location
// list.  If there is no associated window, then returns 0. Useful only when
// called from a location list window.
static int qf_getprop_filewinid(const win_T *wp, const qf_info_T *qi, dict_T *retdict)
 FUNC_ATTR_NONNULL_ARG(3)
{
 handle_T winid = 0;

 if (wp != NULL && IS_LL_WINDOW(wp)) {
   win_T *ll_wp = qf_find_win_with_loclist(qi);
   if (ll_wp != NULL) {
     winid = ll_wp->handle;
   }
 }

 return tv_dict_add_nr(retdict, S_LEN("filewinid"), winid);
}

/// Return the quickfix list items/entries as 'items' in retdict.
/// If eidx is not 0, then return the item at the specified index.
static int qf_getprop_items(qf_info_T *qi, int qf_idx, int eidx, dict_T *retdict)
{
 list_T *l = tv_list_alloc(kListLenMayKnow);
 get_errorlist(qi, NULL, qf_idx, eidx, l);
 tv_dict_add_list(retdict, S_LEN("items"), l);

 return OK;
}

/// Return the quickfix list context (if any) as 'context' in retdict.
static int qf_getprop_ctx(qf_list_T *qfl, dict_T *retdict)
{
 int status;

 if (qfl->qf_ctx != NULL) {
   dictitem_T *di = tv_dict_item_alloc_len(S_LEN("context"));
   tv_copy(qfl->qf_ctx, &di->di_tv);
   status = tv_dict_add(retdict, di);
   if (status == FAIL) {
     tv_dict_item_free(di);
   }
 } else {
   status = tv_dict_add_str(retdict, S_LEN("context"), "");
 }

 return status;
}

/// Return the current quickfix list index as 'idx' in retdict.
/// If a specific entry index (eidx) is supplied, then use that.
static int qf_getprop_idx(qf_list_T *qfl, int eidx, dict_T *retdict)
{
 if (eidx == 0) {
   eidx = qfl->qf_index;
   if (qf_list_empty(qfl)) {
     // For empty lists, current index is set to 0
     eidx = 0;
   }
 }
 return tv_dict_add_nr(retdict, S_LEN("idx"), eidx);
}

/// Return the 'quickfixtextfunc' function of a quickfix/location list
/// @return OK or FAIL
static int qf_getprop_qftf(qf_list_T *qfl, dict_T *retdict)
 FUNC_ATTR_NONNULL_ALL
{
 int status;

 if (qfl->qf_qftf_cb.type != kCallbackNone) {
   typval_T tv;

   callback_put(&qfl->qf_qftf_cb, &tv);
   status = tv_dict_add_tv(retdict, S_LEN("quickfixtextfunc"), &tv);
   tv_clear(&tv);
 } else {
   status = tv_dict_add_str(retdict, S_LEN("quickfixtextfunc"), "");
 }

 return status;
}

/// Return quickfix/location list details (title) as a dictionary.
/// 'what' contains the details to return. If 'list_idx' is -1,
/// then current list is used. Otherwise the specified list is used.
static int qf_get_properties(win_T *wp, dict_T *what, dict_T *retdict)
{
 qf_info_T *qi = ql_info;
 assert(qi != NULL);
 dictitem_T *di = NULL;
 int status = OK;
 int qf_idx = INVALID_QFIDX;

 if ((di = tv_dict_find(what, S_LEN("lines"))) != NULL) {
   return qf_get_list_from_lines(what, di, retdict);
 }

 if (wp != NULL) {
   qi = GET_LOC_LIST(wp);
 }

 const int flags = qf_getprop_keys2flags(what, wp != NULL);

 if (!qf_stack_empty(qi)) {
   qf_idx = qf_getprop_qfidx(qi, what);
 }

 // List is not present or is empty
 if (qf_stack_empty(qi) || qf_idx == INVALID_QFIDX) {
   return qf_getprop_defaults(qi, flags, wp != NULL, retdict);
 }

 qf_list_T *qfl = qf_get_list(qi, qf_idx);
 int eidx = 0;

 // If an entry index is specified, use that
 if ((di = tv_dict_find(what, S_LEN("idx"))) != NULL) {
   if (di->di_tv.v_type != VAR_NUMBER) {
     return FAIL;
   }
   eidx = (int)di->di_tv.vval.v_number;
 }

 if (flags & QF_GETLIST_TITLE) {
   status = qf_getprop_title(qfl, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_NR)) {
   status = tv_dict_add_nr(retdict, S_LEN("nr"), qf_idx + 1);
 }
 if ((status == OK) && (flags & QF_GETLIST_WINID)) {
   status = tv_dict_add_nr(retdict, S_LEN("winid"), qf_winid(qi));
 }
 if ((status == OK) && (flags & QF_GETLIST_ITEMS)) {
   status = qf_getprop_items(qi, qf_idx, eidx, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_CONTEXT)) {
   status = qf_getprop_ctx(qfl, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_ID)) {
   status = tv_dict_add_nr(retdict, S_LEN("id"), qfl->qf_id);
 }
 if ((status == OK) && (flags & QF_GETLIST_IDX)) {
   status = qf_getprop_idx(qfl, eidx, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_SIZE)) {
   status = tv_dict_add_nr(retdict, S_LEN("size"),
                           qfl->qf_count);
 }
 if ((status == OK) && (flags & QF_GETLIST_TICK)) {
   status = tv_dict_add_nr(retdict, S_LEN("changedtick"),
                           qfl->qf_changedtick);
 }
 if ((status == OK) && (wp != NULL) && (flags & QF_GETLIST_FILEWINID)) {
   status = qf_getprop_filewinid(wp, qi, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_QFBUFNR)) {
   status = qf_getprop_qfbufnr(qi, retdict);
 }
 if ((status == OK) && (flags & QF_GETLIST_QFTF)) {
   status = qf_getprop_qftf(qfl, retdict);
 }

 return status;
}

/// Set the current index in the specified quickfix list
/// @return OK
static int qf_setprop_qftf(qf_list_T *qfl, dictitem_T *di)
 FUNC_ATTR_NONNULL_ALL
{
 Callback cb;

 callback_free(&qfl->qf_qftf_cb);
 if (callback_from_typval(&cb, &di->di_tv)) {
   qfl->qf_qftf_cb = cb;
 }
 return OK;
}

/// Add a new quickfix entry to list at 'qf_idx' in the stack 'qi' from the
/// items in the dict 'd'. If it is a valid error entry, then set 'valid_entry'
/// to true.
static int qf_add_entry_from_dict(qf_list_T *qfl, dict_T *d, bool first_entry, bool *valid_entry)
 FUNC_ATTR_NONNULL_ALL
{
 static bool did_bufnr_emsg;

 if (first_entry) {
   did_bufnr_emsg = false;
 }

 char *const filename = tv_dict_get_string(d, "filename", true);
 char *const module = tv_dict_get_string(d, "module", true);
 int bufnum = (int)tv_dict_get_number(d, "bufnr");
 const linenr_T lnum = (linenr_T)tv_dict_get_number(d, "lnum");
 const linenr_T end_lnum = (linenr_T)tv_dict_get_number(d, "end_lnum");
 const int col = (int)tv_dict_get_number(d, "col");
 const int end_col = (int)tv_dict_get_number(d, "end_col");
 const char vcol = (char)tv_dict_get_number(d, "vcol");
 const int nr = (int)tv_dict_get_number(d, "nr");
 const char *const type = tv_dict_get_string(d, "type", false);
 char *const pattern = tv_dict_get_string(d, "pattern", true);
 char *text = tv_dict_get_string(d, "text", true);
 if (text == NULL) {
   text = xcalloc(1, 1);
 }
 typval_T user_data = { .v_type = VAR_UNKNOWN };
 tv_dict_get_tv(d, "user_data", &user_data);

 bool valid = true;
 if ((filename == NULL && bufnum == 0)
     || (lnum == 0 && pattern == NULL)) {
   valid = false;
 }

 // Mark entries with non-existing buffer number as not valid. Give the
 // error message only once.
 if (bufnum != 0 && (buflist_findnr(bufnum) == NULL)) {
   if (!did_bufnr_emsg) {
     did_bufnr_emsg = true;
     semsg(_("E92: Buffer %d not found"), bufnum);
   }
   valid = false;
   bufnum = 0;
 }

 // If the 'valid' field is present it overrules the detected value.
 if (tv_dict_find(d, "valid", -1) != NULL) {
   valid = tv_dict_get_bool(d, "valid", false);
 }

 const int status = qf_add_entry(qfl,
                                 NULL,      // dir
                                 filename,
                                 module,
                                 bufnum,
                                 text,
                                 lnum,
                                 end_lnum,
                                 col,
                                 end_col,
                                 vcol,      // vis_col
                                 pattern,   // search pattern
                                 nr,
                                 type == NULL ? NUL : *type,
                                 &user_data,
                                 valid);

 xfree(filename);
 xfree(module);
 xfree(pattern);
 xfree(text);
 tv_clear(&user_data);

 if (valid) {
   *valid_entry = true;
 }

 return status;
}

/// Check if `entry` is closer to the target than `other_entry`.
///
/// Only returns true if `entry` is definitively closer. If it's further
/// away, or there's not enough information to tell, return false.
static bool entry_is_closer_to_target(qfline_T *entry, qfline_T *other_entry, int target_fnum,
                                     int target_lnum, int target_col)
{
 // First, compare entries to target file.
 if (!target_fnum) {
   // Without a target file, we can't know which is closer.
   return false;
 }

 bool is_target_file = entry->qf_fnum && entry->qf_fnum == target_fnum;
 bool other_is_target_file = other_entry->qf_fnum && other_entry->qf_fnum == target_fnum;
 if (!is_target_file && other_is_target_file) {
   return false;
 } else if (is_target_file && !other_is_target_file) {
   return true;
 }

 // Both entries are pointing at the exact same file. Now compare line numbers.
 if (!target_lnum) {
   // Without a target line number, we can't know which is closer.
   return false;
 }

 int line_distance = entry->qf_lnum
                     ? abs(entry->qf_lnum - target_lnum) : INT_MAX;
 int other_line_distance = other_entry->qf_lnum
                           ? abs(other_entry->qf_lnum - target_lnum) : INT_MAX;
 if (line_distance > other_line_distance) {
   return false;
 } else if (line_distance < other_line_distance) {
   return true;
 }

 // Both entries are pointing at the exact same line number (or no line
 // number at all). Now compare columns.
 if (!target_col) {
   // Without a target column, we can't know which is closer.
   return false;
 }

 int column_distance = entry->qf_col
                       ? abs(entry->qf_col - target_col) : INT_MAX;
 int other_column_distance = other_entry->qf_col
                             ? abs(other_entry->qf_col - target_col) : INT_MAX;
 if (column_distance > other_column_distance) {
   return false;
 } else if (column_distance < other_column_distance) {
   return true;
 }

 // It's a complete tie! The exact same file, line, and column.
 return false;
}

/// Add list of entries to quickfix/location list. Each list entry is
/// a dictionary with item information.
static int qf_add_entries(qf_info_T *qi, int qf_idx, list_T *list, char *title, int action)
{
 qf_list_T *qfl = qf_get_list(qi, qf_idx);
 qfline_T *old_last = NULL;
 int retval = OK;
 bool valid_entry = false;

 // If there's an entry selected in the quickfix list, remember its location
 // (file, line, column), so we can select the nearest entry in the updated
 // quickfix list.
 int prev_fnum = 0;
 int prev_lnum = 0;
 int prev_col = 0;
 if (qfl->qf_ptr) {
   prev_fnum = qfl->qf_ptr->qf_fnum;
   prev_lnum = qfl->qf_ptr->qf_lnum;
   prev_col = qfl->qf_ptr->qf_col;
 }

 bool select_first_entry = false;
 bool select_nearest_entry = false;

 if (action == ' ' || qf_idx == qi->qf_listcount) {
   select_first_entry = true;
   // make place for a new list
   qf_new_list(qi, title);
   qf_idx = qi->qf_curlist;
   qfl = qf_get_list(qi, qf_idx);
 } else if (action == 'a') {
   if (qf_list_empty(qfl)) {
     // Appending to empty list, select first entry.
     select_first_entry = true;
   } else {
     // Adding to existing list, use last entry.
     old_last = qfl->qf_last;
   }
 } else if (action == 'r') {
   select_first_entry = true;
   qf_free_items(qfl);
   qf_store_title(qfl, title);
 } else if (action == 'u') {
   select_nearest_entry = true;
   qf_free_items(qfl);
   qf_store_title(qfl, title);
 }

 qfline_T *entry_to_select = NULL;
 int entry_to_select_index = 0;

 TV_LIST_ITER_CONST(list, li, {
   if (TV_LIST_ITEM_TV(li)->v_type != VAR_DICT) {
     continue;  // Skip non-dict items.
   }

   dict_T *const d = TV_LIST_ITEM_TV(li)->vval.v_dict;
   if (d == NULL) {
     continue;
   }

   retval = qf_add_entry_from_dict(qfl, d, li == tv_list_first(list), &valid_entry);
   if (retval == QF_FAIL) {
     break;
   }

   qfline_T *entry = qfl->qf_last;
   if ((select_first_entry && entry_to_select == NULL)
       || (select_nearest_entry
           && (entry_to_select == NULL
               || entry_is_closer_to_target(entry, entry_to_select, prev_fnum,
                                            prev_lnum, prev_col)))) {
     entry_to_select = entry;
     entry_to_select_index = qfl->qf_count;
   }
 });

 // Check if any valid error entries are added to the list.
 if (valid_entry) {
   qfl->qf_nonevalid = false;
 } else if (qfl->qf_index == 0) {
   qfl->qf_nonevalid = true;
 }

 // Set the current error.
 if (entry_to_select) {
   qfl->qf_ptr = entry_to_select;
   qfl->qf_index = entry_to_select_index;
 }

 // Don't update the cursor in quickfix window when appending entries
 qf_update_buffer(qi, old_last);

 return retval;
}

/// Get the quickfix list index from 'nr' or 'id'
static int qf_setprop_get_qfidx(const qf_info_T *qi, const dict_T *what, int action, bool *newlist)
 FUNC_ATTR_NONNULL_ALL
{
 dictitem_T *di;
 int qf_idx = qi->qf_curlist;  // default is the current list

 if ((di = tv_dict_find(what, S_LEN("nr"))) != NULL) {
   // Use the specified quickfix/location list
   if (di->di_tv.v_type == VAR_NUMBER) {
     // for zero use the current list
     if (di->di_tv.vval.v_number != 0) {
       qf_idx = (int)di->di_tv.vval.v_number - 1;
     }

     if ((action == ' ' || action == 'a') && qf_idx == qi->qf_listcount) {
       // When creating a new list, accept qf_idx pointing to the next
       // non-available list and add the new list at the end of the
       // stack.
       *newlist = true;
       qf_idx = qf_stack_empty(qi) ? 0 : qi->qf_listcount - 1;
     } else if (qf_idx < 0 || qf_idx >= qi->qf_listcount) {
       return INVALID_QFIDX;
     } else if (action != ' ') {
       *newlist = false;  // use the specified list
     }
   } else if (di->di_tv.v_type == VAR_STRING && strequal(di->di_tv.vval.v_string, "$")) {
     if (!qf_stack_empty(qi)) {
       qf_idx = qi->qf_listcount - 1;
     } else if (*newlist) {
       qf_idx = 0;
     } else {
       return INVALID_QFIDX;
     }
   } else {
     return INVALID_QFIDX;
   }
 }

 if (!*newlist && (di = tv_dict_find(what, S_LEN("id"))) != NULL) {
   // Use the quickfix/location list with the specified id
   if (di->di_tv.v_type != VAR_NUMBER) {
     return INVALID_QFIDX;
   }
   return qf_id2nr(qi, (unsigned)di->di_tv.vval.v_number);
 }

 return qf_idx;
}

// Set the quickfix list title.
static int qf_setprop_title(qf_info_T *qi, int qf_idx, const dict_T *what, const dictitem_T *di)
 FUNC_ATTR_NONNULL_ALL
{
 qf_list_T *qfl = qf_get_list(qi, qf_idx);
 if (di->di_tv.v_type != VAR_STRING) {
   return FAIL;
 }

 xfree(qfl->qf_title);
 qfl->qf_title = tv_dict_get_string(what, "title", true);
 if (qf_idx == qi->qf_curlist) {
   qf_update_win_titlevar(qi);
 }

 return OK;
}

// Set quickfix list items/entries.
static int qf_setprop_items(qf_info_T *qi, int qf_idx, dictitem_T *di, int action)
 FUNC_ATTR_NONNULL_ALL
{
 if (di->di_tv.v_type != VAR_LIST) {
   return FAIL;
 }

 char *title_save = xstrdup(qi->qf_lists[qf_idx].qf_title);
 const int retval = qf_add_entries(qi, qf_idx, di->di_tv.vval.v_list, title_save,
                                   action == ' ' ? 'a' : action);
 xfree(title_save);

 return retval;
}

// Set quickfix list items/entries from a list of lines.
static int qf_setprop_items_from_lines(qf_info_T *qi, int qf_idx, const dict_T *what,
                                      dictitem_T *di, int action)
 FUNC_ATTR_NONNULL_ALL
{
 char *errorformat = p_efm;
 dictitem_T *efm_di;
 int retval = FAIL;

 // Use the user supplied errorformat settings (if present)
 if ((efm_di = tv_dict_find(what, S_LEN("efm"))) != NULL) {
   if (efm_di->di_tv.v_type != VAR_STRING
       || efm_di->di_tv.vval.v_string == NULL) {
     return FAIL;
   }
   errorformat = efm_di->di_tv.vval.v_string;
 }

 // Only a List value is supported
 if (di->di_tv.v_type != VAR_LIST || di->di_tv.vval.v_list == NULL) {
   return FAIL;
 }

 if (action == 'r' || action == 'u') {
   qf_free_items(&qi->qf_lists[qf_idx]);
 }
 if (qf_init_ext(qi, qf_idx, NULL, NULL, &di->di_tv, errorformat,
                 false, 0, 0, NULL, NULL) >= 0) {
   retval = OK;
 }

 return retval;
}

// Set quickfix list context.
static int qf_setprop_context(qf_list_T *qfl, dictitem_T *di)
 FUNC_ATTR_NONNULL_ALL
{
 tv_free(qfl->qf_ctx);
 typval_T *ctx = xcalloc(1, sizeof(typval_T));
 tv_copy(&di->di_tv, ctx);
 qfl->qf_ctx = ctx;

 return OK;
}

// Set the current index in the specified quickfix list
static int qf_setprop_curidx(qf_info_T *qi, qf_list_T *qfl, const dictitem_T *di)
 FUNC_ATTR_NONNULL_ALL
{
 int newidx;

 // If the specified index is '$', then use the last entry
 if (di->di_tv.v_type == VAR_STRING
     && di->di_tv.vval.v_string != NULL
     && strcmp(di->di_tv.vval.v_string, "$") == 0) {
   newidx = qfl->qf_count;
 } else {
   // Otherwise use the specified index
   bool denote = false;
   newidx = (int)tv_get_number_chk(&di->di_tv, &denote);
   if (denote) {
     return FAIL;
   }
 }

 if (newidx < 1) {  // sanity check
   return FAIL;
 }
 newidx = MIN(newidx, qfl->qf_count);
 const int old_qfidx = qfl->qf_index;
 qfline_T *const qf_ptr = get_nth_entry(qfl, newidx, &newidx);
 if (qf_ptr == NULL) {
   return FAIL;
 }
 qfl->qf_ptr = qf_ptr;
 qfl->qf_index = newidx;

 // If the current list is modified and it is displayed in the quickfix
 // window, then Update it.
 if (qi->qf_lists[qi->qf_curlist].qf_id == qfl->qf_id) {
   qf_win_pos_update(qi, old_qfidx);
 }
 return OK;
}

/// Set quickfix/location list properties (title, items, context).
/// Also used to add items from parsing a list of lines.
/// Used by the setqflist() and setloclist() Vim script functions.
static int qf_set_properties(qf_info_T *qi, const dict_T *what, int action, char *title)
 FUNC_ATTR_NONNULL_ALL
{
 bool newlist = action == ' ' || qf_stack_empty(qi);
 int qf_idx = qf_setprop_get_qfidx(qi, what, action, &newlist);
 if (qf_idx == INVALID_QFIDX) {  // List not found
   return FAIL;
 }

 if (newlist) {
   qi->qf_curlist = qf_idx;
   qf_new_list(qi, title);
   qf_idx = qi->qf_curlist;
 }

 qf_list_T *qfl = qf_get_list(qi, qf_idx);
 dictitem_T *di;
 int retval = FAIL;
 if ((di = tv_dict_find(what, S_LEN("title"))) != NULL) {
   retval = qf_setprop_title(qi, qf_idx, what, di);
 }
 if ((di = tv_dict_find(what, S_LEN("items"))) != NULL) {
   retval = qf_setprop_items(qi, qf_idx, di, action);
 }
 if ((di = tv_dict_find(what, S_LEN("lines"))) != NULL) {
   retval = qf_setprop_items_from_lines(qi, qf_idx, what, di, action);
 }
 if ((di = tv_dict_find(what, S_LEN("context"))) != NULL) {
   retval = qf_setprop_context(qfl, di);
 }
 if ((di = tv_dict_find(what, S_LEN("idx"))) != NULL) {
   retval = qf_setprop_curidx(qi, qfl, di);
 }
 if ((di = tv_dict_find(what, S_LEN("quickfixtextfunc"))) != NULL) {
   retval = qf_setprop_qftf(qfl, di);
 }

 if (newlist || retval == OK) {
   qf_list_changed(qfl);
 }
 if (newlist) {
   qf_update_buffer(qi, NULL);
 }

 return retval;
}

// Free the entire quickfix/location list stack.
// If the quickfix/location list window is open, then clear it.
static void qf_free_stack(win_T *wp, qf_info_T *qi)
{
 win_T *qfwin = qf_find_win(qi);

 if (qfwin != NULL) {
   // If the quickfix/location list window is open, then clear it
   if (qi->qf_curlist < qi->qf_listcount) {
     qf_free(qf_get_curlist(qi));
   }
   qf_update_buffer(qi, NULL);
 }

 if (wp != NULL && IS_LL_WINDOW(wp)) {
   // If in the location list window, then use the non-location list
   // window with this location list (if present)
   win_T *const llwin = qf_find_win_with_loclist(qi);
   if (llwin != NULL) {
     wp = llwin;
   }
 }

 qf_free_all(wp);
 if (wp == NULL) {
   // quickfix list
   qi->qf_curlist = 0;
   qi->qf_listcount = 0;
 } else if (qfwin != NULL) {
   // If the location list window is open, then create a new empty location
   // list
   qf_info_T *new_ll = qf_alloc_stack(QFLT_LOCATION, (int)wp->w_p_lhi);
   new_ll->qf_bufnr = qfwin->w_buffer->b_fnum;

   // first free the list reference in the location list window
   ll_free_all(&qfwin->w_llist_ref);

   qfwin->w_llist_ref = new_ll;
   if (wp != qfwin) {
     win_set_loclist(wp, new_ll);
   }
 }
}

/// Populate the quickfix list with the items supplied in the list
/// of dictionaries. "title" will be copied to w:quickfix_title
/// "action" is 'a' for add, 'r' for replace, 'u' for update.  Otherwise
/// create a new list.
/// When "what" is not NULL then only set some properties.
int set_errorlist(win_T *wp, list_T *list, int action, char *title, dict_T *what)
{
 qf_info_T *qi;
 if (wp != NULL) {
   qi = ll_get_or_alloc_list(wp);
 } else {
   qi = ql_info;
 }
 assert(qi != NULL);

 if (action == 'f') {
   // Free the entire quickfix or location list stack
   qf_free_stack(wp, qi);
   return OK;
 }

 // A dict argument cannot be specified with a non-empty list argument
 if (list != NULL && tv_list_len(list) != 0 && what != NULL) {
   semsg(_(e_invarg2), _("cannot have both a list and a \"what\" argument"));
   return FAIL;
 }

 incr_quickfix_busy();

 int retval = OK;
 if (what != NULL) {
   retval = qf_set_properties(qi, what, action, title);
 } else {
   retval = qf_add_entries(qi, qi->qf_curlist, list, title, action);
   if (retval == OK) {
     qf_list_changed(qf_get_curlist(qi));
   }
 }

 decr_quickfix_busy();

 return retval;
}

static bool mark_quickfix_user_data(qf_info_T *qi, int copyID)
{
 bool abort = false;
 for (int i = 0; i < qi->qf_maxcount && !abort; i++) {
   qf_list_T *qfl = &qi->qf_lists[i];
   if (!qfl->qf_has_user_data) {
     continue;
   }
   qfline_T *qfp;
   int j;
   FOR_ALL_QFL_ITEMS(qfl, qfp, j) {
     typval_T *user_data = &qfp->qf_user_data;
     if (user_data != NULL && user_data->v_type != VAR_NUMBER
         && user_data->v_type != VAR_STRING && user_data->v_type != VAR_FLOAT) {
       abort = abort || set_ref_in_item(user_data, copyID, NULL, NULL);
     }
   }
 }
 return abort;
}

/// Mark the quickfix context and callback function as in use for all the lists
/// in a quickfix stack.
static bool mark_quickfix_ctx(qf_info_T *qi, int copyID)
{
 bool abort = false;

 for (int i = 0; i < qi->qf_maxcount && !abort; i++) {
   typval_T *ctx = qi->qf_lists[i].qf_ctx;
   if (ctx != NULL && ctx->v_type != VAR_NUMBER
       && ctx->v_type != VAR_STRING && ctx->v_type != VAR_FLOAT) {
     abort = set_ref_in_item(ctx, copyID, NULL, NULL);
   }

   Callback *cb = &qi->qf_lists[i].qf_qftf_cb;
   abort = abort || set_ref_in_callback(cb, copyID, NULL, NULL);
 }

 return abort;
}

/// Mark the context of the quickfix list and the location lists (if present) as
/// "in use". So that garbage collection doesn't free the context.
bool set_ref_in_quickfix(int copyID)
{
 assert(ql_info != NULL);
 if (mark_quickfix_ctx(ql_info, copyID)
     || mark_quickfix_user_data(ql_info, copyID)
     || set_ref_in_callback(&qftf_cb, copyID, NULL, NULL)) {
   return true;
 }

 FOR_ALL_TAB_WINDOWS(tp, win) {
   if (win->w_llist != NULL) {
     if (mark_quickfix_ctx(win->w_llist, copyID)
         || mark_quickfix_user_data(win->w_llist, copyID)) {
       return true;
     }
   }

   if (IS_LL_WINDOW(win) && (win->w_llist_ref->qf_refcount == 1)) {
     // In a location list window and none of the other windows is
     // referring to this location list. Mark the location list
     // context as still in use.
     if (mark_quickfix_ctx(win->w_llist_ref, copyID)
         || mark_quickfix_user_data(win->w_llist_ref, copyID)) {
       return true;
     }
   }
 }

 return false;
}

/// Return the autocmd name for the :cbuffer Ex commands
static char *cbuffer_get_auname(cmdidx_T cmdidx)
{
 switch (cmdidx) {
 case CMD_cbuffer:
   return "cbuffer";
 case CMD_cgetbuffer:
   return "cgetbuffer";
 case CMD_caddbuffer:
   return "caddbuffer";
 case CMD_lbuffer:
   return "lbuffer";
 case CMD_lgetbuffer:
   return "lgetbuffer";
 case CMD_laddbuffer:
   return "laddbuffer";
 default:
   return NULL;
 }
}

/// Process and validate the arguments passed to the :cbuffer, :caddbuffer,
/// :cgetbuffer, :lbuffer, :laddbuffer, :lgetbuffer Ex commands.
static int cbuffer_process_args(exarg_T *eap, buf_T **bufp, linenr_T *line1, linenr_T *line2)
{
 buf_T *buf = NULL;

 if (*eap->arg == NUL) {
   buf = curbuf;
 } else if (*skipwhite(skipdigits(eap->arg)) == NUL) {
   buf = buflist_findnr(atoi(eap->arg));
 }

 if (buf == NULL) {
   emsg(_(e_invarg));
   return FAIL;
 }

 if (buf->b_ml.ml_mfp == NULL) {
   emsg(_(e_buffer_is_not_loaded));
   return FAIL;
 }

 if (eap->addr_count == 0) {
   eap->line1 = 1;
   eap->line2 = buf->b_ml.ml_line_count;
 }

 if (eap->line1 < 1 || eap->line1 > buf->b_ml.ml_line_count
     || eap->line2 < 1 || eap->line2 > buf->b_ml.ml_line_count) {
   emsg(_(e_invrange));
   return FAIL;
 }

 *line1 = eap->line1;
 *line2 = eap->line2;
 *bufp = buf;

 return OK;
}

// ":[range]cbuffer [bufnr]" command.
// ":[range]caddbuffer [bufnr]" command.
// ":[range]cgetbuffer [bufnr]" command.
// ":[range]lbuffer [bufnr]" command.
// ":[range]laddbuffer [bufnr]" command.
// ":[range]lgetbuffer [bufnr]" command.
void ex_cbuffer(exarg_T *eap)
{
 char *au_name = cbuffer_get_auname(eap->cmdidx);
 if (au_name != NULL && apply_autocmds(EVENT_QUICKFIXCMDPRE, au_name,
                                       curbuf->b_fname, true, curbuf)) {
   if (aborting()) {
     return;
   }
 }

 // Must come after autocommands.
 win_T *wp = NULL;
 qf_info_T *qi = qf_cmd_get_or_alloc_stack(eap, &wp);

 buf_T *buf = NULL;
 linenr_T line1;
 linenr_T line2;
 if (cbuffer_process_args(eap, &buf, &line1, &line2) == FAIL) {
   return;
 }

 char *qf_title = qf_cmdtitle(*eap->cmdlinep);

 if (buf->b_sfname) {
   vim_snprintf(IObuff, IOSIZE, "%s (%s)", qf_title, buf->b_sfname);
   qf_title = IObuff;
 }

 incr_quickfix_busy();

 int res = qf_init_ext(qi, qi->qf_curlist, NULL, buf, NULL, p_efm,
                       (eap->cmdidx != CMD_caddbuffer
                        && eap->cmdidx != CMD_laddbuffer),
                       eap->line1, eap->line2, qf_title, NULL);
 if (qf_stack_empty(qi)) {
   decr_quickfix_busy();
   return;
 }
 if (res >= 0) {
   qf_list_changed(qf_get_curlist(qi));
 }
 // Remember the current quickfix list identifier, so that we can
 // check for autocommands changing the current quickfix list.
 unsigned save_qfid = qf_get_curlist(qi)->qf_id;
 if (au_name != NULL) {
   const buf_T *const curbuf_old = curbuf;
   apply_autocmds(EVENT_QUICKFIXCMDPOST, au_name, curbuf->b_fname, true, curbuf);
   if (curbuf != curbuf_old) {
     // Autocommands changed buffer, don't jump now, "qi" may
     // be invalid.
     res = 0;
   }
 }
 // Jump to the first error for new list and if autocmds didn't
 // free the list.
 if (res > 0 && (eap->cmdidx == CMD_cbuffer || eap->cmdidx == CMD_lbuffer)
     && qflist_valid(wp, save_qfid)) {
   // display the first error
   qf_jump_first(qi, save_qfid, eap->forceit);
 }

 decr_quickfix_busy();
}

/// Return the autocmd name for the :cexpr Ex commands.
static char *cexpr_get_auname(cmdidx_T cmdidx)
{
 switch (cmdidx) {
 case CMD_cexpr:
   return "cexpr";
 case CMD_cgetexpr:
   return "cgetexpr";
 case CMD_caddexpr:
   return "caddexpr";
 case CMD_lexpr:
   return "lexpr";
 case CMD_lgetexpr:
   return "lgetexpr";
 case CMD_laddexpr:
   return "laddexpr";
 default:
   return NULL;
 }
}

static int trigger_cexpr_autocmd(int cmdidx)
{
 char *au_name = cexpr_get_auname(cmdidx);
 if (au_name != NULL && apply_autocmds(EVENT_QUICKFIXCMDPRE, au_name,
                                       curbuf->b_fname, true, curbuf)) {
   if (aborting()) {
     return FAIL;
   }
 }
 return OK;
}

int cexpr_core(const exarg_T *eap, typval_T *tv)
 FUNC_ATTR_NONNULL_ALL
{
 win_T *wp = NULL;
 qf_info_T *qi = qf_cmd_get_or_alloc_stack(eap, &wp);

 if ((tv->v_type == VAR_STRING && tv->vval.v_string != NULL)
     || tv->v_type == VAR_LIST) {
   char *au_name = cexpr_get_auname(eap->cmdidx);
   incr_quickfix_busy();
   int res = qf_init_ext(qi, qi->qf_curlist, NULL, NULL, tv, p_efm,
                         (eap->cmdidx != CMD_caddexpr
                          && eap->cmdidx != CMD_laddexpr),
                         0, 0,
                         qf_cmdtitle(*eap->cmdlinep), NULL);
   if (qf_stack_empty(qi)) {
     decr_quickfix_busy();
     return FAIL;
   }
   if (res >= 0) {
     qf_list_changed(qf_get_curlist(qi));
   }
   // Remember the current quickfix list identifier, so that we can
   // check for autocommands changing the current quickfix list.
   unsigned save_qfid = qf_get_curlist(qi)->qf_id;
   if (au_name != NULL) {
     apply_autocmds(EVENT_QUICKFIXCMDPOST, au_name, curbuf->b_fname, true, curbuf);
   }
   // Jump to the first error for a new list and if autocmds didn't
   // free the list.
   if (res > 0
       && (eap->cmdidx == CMD_cexpr || eap->cmdidx == CMD_lexpr)
       && qflist_valid(wp, save_qfid)) {
     // display the first error
     qf_jump_first(qi, save_qfid, eap->forceit);
   }
   decr_quickfix_busy();
   return OK;
 } else {
   emsg(_("E777: String or List expected"));
 }
 return FAIL;
}

/// ":cexpr {expr}", ":cgetexpr {expr}", ":caddexpr {expr}" command.
/// ":lexpr {expr}", ":lgetexpr {expr}", ":laddexpr {expr}" command.
/// Also: ":caddexpr", ":cgetexpr", "laddexpr" and "laddexpr".
void ex_cexpr(exarg_T *eap)
{
 if (trigger_cexpr_autocmd(eap->cmdidx) == FAIL) {
   return;
 }

 // Evaluate the expression.  When the result is a string or a list we can
 // use it to fill the errorlist.
 typval_T *tv = eval_expr(eap->arg, eap);
 if (tv == NULL) {
   return;
 }

 (void)cexpr_core(eap, tv);
 tv_free(tv);
}

// Get the location list for ":lhelpgrep"
static qf_info_T *hgr_get_ll(bool *new_ll)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
{
 // If the current window is a help window, then use it, else find an existing help window
 win_T *wp = bt_help(curwin->w_buffer) ? curwin : qf_find_help_win();

 qf_info_T *qi = wp == NULL ? NULL : wp->w_llist;
 if (qi == NULL) {
   // Allocate a new location list for help text matches
   qi = qf_alloc_stack(QFLT_LOCATION, 1);
   *new_ll = true;
 }

 return qi;
}

// Search for a pattern in a help file.
static void hgr_search_file(qf_list_T *qfl, char *fname, regmatch_T *p_regmatch)
 FUNC_ATTR_NONNULL_ARG(1, 3)
{
 FILE *const fd = os_fopen(fname, "r");
 if (fd == NULL) {
   return;
 }

 linenr_T lnum = 1;
 while (!vim_fgets(IObuff, IOSIZE, fd) && !got_int) {
   char *line = IObuff;

   if (vim_regexec(p_regmatch, line, 0)) {
     int l = (int)strlen(line);

     // remove trailing CR, LF, spaces, etc.
     while (l > 0 && line[l - 1] <= ' ') {
       line[--l] = NUL;
     }

     if (qf_add_entry(qfl,
                      NULL,   // dir
                      fname,
                      NULL,
                      0,
                      line,
                      lnum,
                      0,
                      (int)(p_regmatch->startp[0] - line) + 1,  // col
                      (int)(p_regmatch->endp[0] - line)
                      + 1,    // end_col
                      false,  // vis_col
                      NULL,   // search pattern
                      0,      // nr
                      1,      // type
                      NULL,   // user_data
                      true)   // valid
         == QF_FAIL) {
       got_int = true;
       if (line != IObuff) {
         xfree(line);
       }
       break;
     }
   }
   if (line != IObuff) {
     xfree(line);
   }
   lnum++;
   line_breakcheck();
 }
 fclose(fd);
}

// Search for a pattern in all the help files in the doc directory under
// the given directory.
static void hgr_search_files_in_dir(qf_list_T *qfl, char *dirname, regmatch_T *p_regmatch,
                                   const char *lang)
 FUNC_ATTR_NONNULL_ARG(1, 2, 3)
{
 int fcount;
 char **fnames;

 // Find all "*.txt" and "*.??x" files in the "doc" directory.
 add_pathsep(dirname);
 strcat(dirname, "doc/*.\\(txt\\|??x\\)");  // NOLINT
 if (gen_expand_wildcards(1, &dirname, &fcount, &fnames, EW_FILE|EW_SILENT) == OK
     && fcount > 0) {
   for (int fi = 0; fi < fcount && !got_int; fi++) {
     // Skip files for a different language.
     if (lang != NULL
         && STRNICMP(lang, fnames[fi] + strlen(fnames[fi]) - 3, 2) != 0
         && !(STRNICMP(lang, "en", 2) == 0
              && STRNICMP("txt", fnames[fi] + strlen(fnames[fi]) - 3, 3)
              == 0)) {
       continue;
     }

     hgr_search_file(qfl, fnames[fi], p_regmatch);
   }
   FreeWild(fcount, fnames);
 }
}

// Search for a pattern in all the help files in the 'runtimepath'
// and add the matches to a quickfix list.
// 'lang' is the language specifier.  If supplied, then only matches in the
// specified language are found.
static void hgr_search_in_rtp(qf_list_T *qfl, regmatch_T *p_regmatch, const char *lang)
 FUNC_ATTR_NONNULL_ARG(1, 2)
{
 // Go through all directories in 'runtimepath'
 char *p = p_rtp;
 while (*p != NUL && !got_int) {
   copy_option_part(&p, NameBuff, MAXPATHL, ",");

   hgr_search_files_in_dir(qfl, NameBuff, p_regmatch, lang);
 }
}

// ":helpgrep {pattern}"
void ex_helpgrep(exarg_T *eap)
{
 qf_info_T *qi = ql_info;
 assert(qi != NULL);
 char *au_name = NULL;

 switch (eap->cmdidx) {
 case CMD_helpgrep:
   au_name = "helpgrep"; break;
 case CMD_lhelpgrep:
   au_name = "lhelpgrep"; break;
 default:
   break;
 }
 if (au_name != NULL && apply_autocmds(EVENT_QUICKFIXCMDPRE, au_name,
                                       curbuf->b_fname, true, curbuf)) {
   if (aborting()) {
     return;
   }
 }

 bool updated = false;
 // Make 'cpoptions' empty, the 'l' flag should not be used here.
 char *const save_cpo = p_cpo;
 p_cpo = empty_string_option;

 bool new_qi = false;
 if (is_loclist_cmd(eap->cmdidx)) {
   qi = hgr_get_ll(&new_qi);
 }

 incr_quickfix_busy();

 // Check for a specified language
 char *const lang = check_help_lang(eap->arg);
 regmatch_T regmatch = {
   .regprog = vim_regcomp(eap->arg, RE_MAGIC + RE_STRING),
   .rm_ic = false,
 };
 if (regmatch.regprog != NULL) {
   // Create a new quickfix list.
   qf_new_list(qi, qf_cmdtitle(*eap->cmdlinep));
   qf_list_T *const qfl = qf_get_curlist(qi);

   hgr_search_in_rtp(qfl, &regmatch, lang);

   vim_regfree(regmatch.regprog);

   qfl->qf_nonevalid = false;
   qfl->qf_ptr = qfl->qf_start;
   qfl->qf_index = 1;
   qf_list_changed(qfl);
   updated = true;
 }

 if (p_cpo == empty_string_option) {
   p_cpo = save_cpo;
 } else {
   // Darn, some plugin changed the value.  If it's still empty it was
   // changed and restored, need to restore in the complicated way.
   if (*p_cpo == NUL) {
     set_option_value_give_err(kOptCpoptions, CSTR_AS_OPTVAL(save_cpo), 0);
   }
   free_string_option(save_cpo);
 }

 if (updated) {
   // This may open a window and source scripts, do this after 'cpo' was
   // restored.
   qf_update_buffer(qi, NULL);
 }

 if (au_name != NULL) {
   apply_autocmds(EVENT_QUICKFIXCMDPOST, au_name, curbuf->b_fname, true, curbuf);
   // When adding a location list to an existing location list stack,
   // if the autocmd made the stack invalid, then just return.
   if (!new_qi && IS_LL_STACK(qi) && qf_find_win_with_loclist(qi) == NULL) {
     decr_quickfix_busy();
     return;
   }
 }

 // Jump to first match.
 if (!qf_list_empty(qf_get_curlist(qi))) {
   qf_jump(qi, 0, 0, false);
 } else {
   semsg(_(e_nomatch2), eap->arg);
 }

 decr_quickfix_busy();

 if (eap->cmdidx == CMD_lhelpgrep) {
   // If the help window is not opened or if it already points to the
   // correct location list, then free the new location list.
   if (!bt_help(curwin->w_buffer) || curwin->w_llist == qi) {
     if (new_qi) {
       ll_free_all(&qi);
     }
   } else if (curwin->w_llist == NULL && new_qi) {
     // current window didn't have a location list associated with it
     // before. Associate the new location list now.
     curwin->w_llist = qi;
   }
 }
}

#if defined(EXITFREE)
void free_quickfix(void)
{
 qf_free_all(NULL);
 // Free all location lists
 FOR_ALL_TAB_WINDOWS(tab, win) {
   qf_free_all(win);
 }

 ga_clear(&qfga);
}
#endif

static void get_qf_loc_list(bool is_qf, win_T *wp, typval_T *what_arg, typval_T *rettv)
{
 if (what_arg->v_type == VAR_UNKNOWN) {
   tv_list_alloc_ret(rettv, kListLenMayKnow);
   if (is_qf || wp != NULL) {
     get_errorlist(NULL, wp, -1, 0, rettv->vval.v_list);
   }
 } else {
   tv_dict_alloc_ret(rettv);
   if (is_qf || wp != NULL) {
     if (what_arg->v_type == VAR_DICT) {
       dict_T *d = what_arg->vval.v_dict;

       if (d != NULL) {
         qf_get_properties(wp, d, rettv->vval.v_dict);
       }
     } else {
       emsg(_(e_dictreq));
     }
   }
 }
}

/// "getloclist()" function
void f_getloclist(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 win_T *wp = find_win_by_nr_or_id(&argvars[0]);
 get_qf_loc_list(false, wp, &argvars[1], rettv);
}

/// "getqflist()" functions
void f_getqflist(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 get_qf_loc_list(true, NULL, &argvars[0], rettv);
}

/// Create quickfix/location list from Vimscript values
///
/// Used by `setqflist()` and `setloclist()` functions. Accepts invalid
/// args argument in which case errors out, including VAR_UNKNOWN parameters.
///
/// @param[in,out]  wp  Window to create location list for. May be NULL in
///                     which case quickfix list will be created.
/// @param[in]  args  [list, action, what]
/// @param[in]  args[0]  Quickfix list contents.
/// @param[in]  args[1]  Optional. Action to perform:
///                      append to an existing list, replace its content,
///                      or create a new one.
/// @param[in]  args[2]  Optional. Quickfix list properties or title.
///                      Defaults to caller function name.
/// @param[out]  rettv  Return value: 0 in case of success, -1 otherwise.
static void set_qf_ll_list(win_T *wp, typval_T *args, typval_T *rettv)
 FUNC_ATTR_NONNULL_ARG(2, 3)
{
 static const char *e_invact = N_("E927: Invalid action: '%s'");
 const char *title = NULL;
 char action = ' ';
 static int recursive = 0;
 rettv->vval.v_number = -1;
 dict_T *what = NULL;

 typval_T *list_arg = &args[0];
 if (list_arg->v_type != VAR_LIST) {
   emsg(_(e_listreq));
   return;
 } else if (recursive != 0) {
   emsg(_(e_au_recursive));
   return;
 }

 typval_T *action_arg = &args[1];
 if (action_arg->v_type == VAR_UNKNOWN) {
   // Option argument was not given.
   goto skip_args;
 } else if (action_arg->v_type != VAR_STRING) {
   emsg(_(e_string_required));
   return;
 }
 const char *const act = tv_get_string_chk(action_arg);
 if ((*act == 'a' || *act == 'r' || *act == 'u' || *act == ' ' || *act == 'f')
     && act[1] == NUL) {
   action = *act;
 } else {
   semsg(_(e_invact), act);
   return;
 }

 typval_T *const what_arg = &args[2];
 if (what_arg->v_type == VAR_UNKNOWN) {
   // Option argument was not given.
   goto skip_args;
 } else if (what_arg->v_type == VAR_STRING) {
   title = tv_get_string_chk(what_arg);
   if (!title) {
     // Type error. Error already printed by tv_get_string_chk().
     return;
   }
 } else if (what_arg->v_type == VAR_DICT && what_arg->vval.v_dict != NULL) {
   what = what_arg->vval.v_dict;
 } else {
   emsg(_(e_dictreq));
   return;
 }

skip_args:
 if (!title) {
   title = (wp ? ":setloclist()" : ":setqflist()");
 }

 recursive++;
 list_T *const l = list_arg->vval.v_list;
 if (set_errorlist(wp, l, action, (char *)title, what) == OK) {
   rettv->vval.v_number = 0;
 }
 recursive--;
}

/// "setloclist()" function
void f_setloclist(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 rettv->vval.v_number = -1;

 win_T *win = find_win_by_nr_or_id(&argvars[0]);
 if (win != NULL) {
   set_qf_ll_list(win, &argvars[1], rettv);
 }
}

/// "setqflist()" function
void f_setqflist(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 set_qf_ll_list(NULL, argvars, rettv);
}