neovim

eval.c (192807B)

---

// eval.c: Expression evaluation.

#include <assert.h>
#include <ctype.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <uv.h>

#include "auto/config.h"
#include "nvim/api/private/converter.h"
#include "nvim/api/private/defs.h"
#include "nvim/api/private/helpers.h"
#include "nvim/ascii_defs.h"
#include "nvim/autocmd.h"
#include "nvim/buffer.h"
#include "nvim/buffer_defs.h"
#include "nvim/change.h"
#include "nvim/channel.h"
#include "nvim/charset.h"
#include "nvim/cmdexpand_defs.h"
#include "nvim/cursor.h"
#include "nvim/edit.h"
#include "nvim/errors.h"
#include "nvim/eval.h"
#include "nvim/eval/encode.h"
#include "nvim/eval/executor.h"
#include "nvim/eval/gc.h"
#include "nvim/eval/typval.h"
#include "nvim/eval/userfunc.h"
#include "nvim/eval/vars.h"
#include "nvim/event/loop.h"
#include "nvim/event/multiqueue.h"
#include "nvim/event/proc.h"
#include "nvim/event/time.h"
#include "nvim/ex_cmds.h"
#include "nvim/ex_docmd.h"
#include "nvim/ex_eval.h"
#include "nvim/garray.h"
#include "nvim/garray_defs.h"
#include "nvim/gettext_defs.h"
#include "nvim/globals.h"
#include "nvim/hashtab.h"
#include "nvim/highlight_group.h"
#include "nvim/insexpand.h"
#include "nvim/keycodes.h"
#include "nvim/lib/queue_defs.h"
#include "nvim/lua/executor.h"
#include "nvim/macros_defs.h"
#include "nvim/main.h"
#include "nvim/map_defs.h"
#include "nvim/mark.h"
#include "nvim/mark_defs.h"
#include "nvim/mbyte.h"
#include "nvim/memline.h"
#include "nvim/memory.h"
#include "nvim/message.h"
#include "nvim/move.h"
#include "nvim/msgpack_rpc/channel_defs.h"
#include "nvim/ops.h"
#include "nvim/option.h"
#include "nvim/option_vars.h"
#include "nvim/optionstr.h"
#include "nvim/os/fs.h"
#include "nvim/os/lang.h"
#include "nvim/os/os.h"
#include "nvim/os/os_defs.h"
#include "nvim/os/shell.h"
#include "nvim/path.h"
#include "nvim/pos_defs.h"
#include "nvim/profile.h"
#include "nvim/quickfix.h"
#include "nvim/regexp.h"
#include "nvim/regexp_defs.h"
#include "nvim/register.h"
#include "nvim/runtime.h"
#include "nvim/runtime_defs.h"
#include "nvim/strings.h"
#include "nvim/tag.h"
#include "nvim/types_defs.h"
#include "nvim/undo.h"
#include "nvim/vim_defs.h"
#include "nvim/window.h"

// TODO(ZyX-I): Remove DICT_MAXNEST, make users be non-recursive instead

#define DICT_MAXNEST 100        // maximum nesting of lists and dicts

static const char *e_missbrac = N_("E111: Missing ']'");
static const char *e_list_end = N_("E697: Missing end of List ']': %s");
static const char e_cannot_slice_dictionary[]
 = N_("E719: Cannot slice a Dictionary");
static const char e_cannot_index_special_variable[]
 = N_("E909: Cannot index a special variable");
static const char *e_nowhitespace
 = N_("E274: No white space allowed before parenthesis");
static const char e_cannot_index_a_funcref[]
 = N_("E695: Cannot index a Funcref");
static const char e_variable_nested_too_deep_for_making_copy[]
 = N_("E698: Variable nested too deep for making a copy");
static const char e_string_list_or_blob_required[]
 = N_("E1098: String, List or Blob required");
static const char e_expression_too_recursive_str[]
 = N_("E1169: Expression too recursive: %s");
static const char e_dot_can_only_be_used_on_dictionary_str[]
 = N_("E1203: Dot can only be used on a dictionary: %s");
static const char e_empty_function_name[]
 = N_("E1192: Empty function name");
static const char e_cannot_use_partial_here[]
 = N_("E1265: Cannot use a partial here");

static char * const namespace_char = "abglstvw";

/// Used for checking if local variables or arguments used in a lambda.
bool *eval_lavars_used = NULL;

static int echo_hl_id = 0;   // highlight id used for ":echo"

/// Info used by a ":for" loop.
typedef struct {
 int fi_semicolon;             // true if ending in '; var]'
 int fi_varcount;              // nr of variables in the list
 listwatch_T fi_lw;            // keep an eye on the item used.
 list_T *fi_list;              // list being used
 int fi_bi;                    // index of blob
 blob_T *fi_blob;              // blob being used
 char *fi_string;            // copy of string being used
 int fi_byte_idx;              // byte index in fi_string
} forinfo_T;

typedef enum {
 GLV_FAIL,
 GLV_OK,
 GLV_STOP,
} glv_status_T;

#include "eval.c.generated.h"

static uint64_t last_timer_id = 1;
static PMap(uint64_t) timers = MAP_INIT;

dict_T *get_v_event(save_v_event_T *sve)
{
 dict_T *v_event = get_vim_var_dict(VV_EVENT);

 if (v_event->dv_hashtab.ht_used > 0) {
   // recursive use of v:event, save, make empty and restore later
   sve->sve_did_save = true;
   sve->sve_hashtab = v_event->dv_hashtab;
   hash_init(&v_event->dv_hashtab);
 } else {
   sve->sve_did_save = false;
 }
 return v_event;
}

void restore_v_event(dict_T *v_event, save_v_event_T *sve)
{
 tv_dict_free_contents(v_event);
 if (sve->sve_did_save) {
   v_event->dv_hashtab = sve->sve_hashtab;
 } else {
   hash_init(&v_event->dv_hashtab);
 }
}

/// @return  "n1" divided by "n2", taking care of dividing by zero.
varnumber_T num_divide(varnumber_T n1, varnumber_T n2)
 FUNC_ATTR_CONST FUNC_ATTR_WARN_UNUSED_RESULT
{
 varnumber_T result;

 if (n2 == 0) {  // give an error message?
   if (n1 == 0) {
     result = VARNUMBER_MIN;  // similar to NaN
   } else if (n1 < 0) {
     result = -VARNUMBER_MAX;
   } else {
     result = VARNUMBER_MAX;
   }
 } else if (n1 == VARNUMBER_MIN && n2 == -1) {
   // specific case: trying to do VARNUMBAR_MIN / -1 results in a positive
   // number that doesn't fit in varnumber_T and causes an FPE
   result = VARNUMBER_MAX;
 } else {
   result = n1 / n2;
 }

 return result;
}

/// @return  "n1" modulus "n2", taking care of dividing by zero.
varnumber_T num_modulus(varnumber_T n1, varnumber_T n2)
 FUNC_ATTR_CONST FUNC_ATTR_WARN_UNUSED_RESULT
{
 // Give an error when n2 is 0?
 return (n2 == 0) ? 0 : (n1 % n2);
}

/// Initialize the global and v: variables.
void eval_init(void)
{
 evalvars_init();
 func_init();
}

#if defined(EXITFREE)
void eval_clear(void)
{
 evalvars_clear();
 free_scriptnames();  // must come after evalvars_clear().
# ifdef HAVE_WORKING_LIBINTL
 free_locales();
# endif

 // autoloaded script names
 free_autoload_scriptnames();

 // unreferenced lists and dicts
 garbage_collect(false);

 // functions not garbage collected
 free_all_functions();
}

#endif

void fill_evalarg_from_eap(evalarg_T *evalarg, exarg_T *eap, bool skip)
{
 *evalarg = (evalarg_T){ .eval_flags = skip ? 0 : EVAL_EVALUATE };

 if (eap == NULL) {
   return;
 }

 if (sourcing_a_script(eap)) {
   evalarg->eval_getline = eap->ea_getline;
   evalarg->eval_cookie = eap->cookie;
 }
}

/// Top level evaluation function, returning a boolean.
/// Sets "error" to true if there was an error.
///
/// @param skip  only parse, don't execute
///
/// @return  true or false.
bool eval_to_bool(char *arg, bool *error, exarg_T *eap, const bool skip,
                 const bool use_simple_function)
{
 typval_T tv;
 bool retval = false;
 evalarg_T evalarg;

 fill_evalarg_from_eap(&evalarg, eap, skip);

 if (skip) {
   emsg_skip++;
 }
 int r = use_simple_function ? eval0_simple_funccal(arg, &tv, eap, &evalarg)
                             : eval0(arg, &tv, eap, &evalarg);
 if (r == FAIL) {
   *error = true;
 } else {
   *error = false;
   if (!skip) {
     retval = (tv_get_number_chk(&tv, error) != 0);
     tv_clear(&tv);
   }
 }
 if (skip) {
   emsg_skip--;
 }
 clear_evalarg(&evalarg, eap);

 return retval;
}

/// Call eval1() and give an error message if not done at a lower level.
static int eval1_emsg(char **arg, typval_T *rettv, exarg_T *eap)
 FUNC_ATTR_NONNULL_ARG(1, 2)
{
 const char *const start = *arg;
 const int did_emsg_before = did_emsg;
 const int called_emsg_before = called_emsg;
 evalarg_T evalarg;

 fill_evalarg_from_eap(&evalarg, eap, eap != NULL && eap->skip);

 const int ret = eval1(arg, rettv, &evalarg);
 if (ret == FAIL) {
   // Report the invalid expression unless the expression evaluation has
   // been cancelled due to an aborting error, an interrupt, or an
   // exception, or we already gave a more specific error.
   // Also check called_emsg for when using assert_fails().
   if (!aborting()
       && did_emsg == did_emsg_before
       && called_emsg == called_emsg_before) {
     semsg(_(e_invexpr2), start);
   }
 }
 clear_evalarg(&evalarg, eap);
 return ret;
}

/// @return  whether a typval is a valid expression to pass to eval_expr_typval()
///          or eval_expr_to_bool().  An empty string returns false;
bool eval_expr_valid_arg(const typval_T *const tv)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_CONST
{
 return tv->v_type != VAR_UNKNOWN
        && (tv->v_type != VAR_STRING || (tv->vval.v_string != NULL && *tv->vval.v_string != NUL));
}

/// Evaluate a partial.
/// Pass arguments "argv[argc]".
/// Return the result in "rettv" and OK or FAIL.
static int eval_expr_partial(const typval_T *expr, typval_T *argv, int argc, typval_T *rettv)
 FUNC_ATTR_NONNULL_ALL
{
 partial_T *const partial = expr->vval.v_partial;
 if (partial == NULL) {
   return FAIL;
 }

 const char *const s = partial_name(partial);
 if (s == NULL || *s == NUL) {
   return FAIL;
 }

 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_evaluate = true;
 funcexe.fe_partial = partial;
 if (call_func(s, -1, rettv, argc, argv, &funcexe) == FAIL) {
   return FAIL;
 }

 return OK;
}

/// Evaluate an expression which is a function.
/// Pass arguments "argv[argc]".
/// Return the result in "rettv" and OK or FAIL.
static int eval_expr_func(const typval_T *expr, typval_T *argv, int argc, typval_T *rettv)
 FUNC_ATTR_NONNULL_ALL
{
 char buf[NUMBUFLEN];
 const char *const s = (expr->v_type == VAR_FUNC
                        ? expr->vval.v_string
                        : tv_get_string_buf_chk(expr, buf));
 if (s == NULL || *s == NUL) {
   return FAIL;
 }

 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_evaluate = true;
 if (call_func(s, -1, rettv, argc, argv, &funcexe) == FAIL) {
   return FAIL;
 }

 return OK;
}

/// Evaluate an expression, which is a string.
/// Return the result in "rettv" and OK or FAIL.
static int eval_expr_string(const typval_T *expr, typval_T *rettv)
 FUNC_ATTR_NONNULL_ALL
{
 char buf[NUMBUFLEN];
 char *s = (char *)tv_get_string_buf_chk(expr, buf);
 if (s == NULL) {
   return FAIL;
 }

 s = skipwhite(s);
 if (eval1_emsg(&s, rettv, NULL) == FAIL) {
   return FAIL;
 }

 if (*skipwhite(s) != NUL) {  // check for trailing chars after expr
   tv_clear(rettv);
   semsg(_(e_invexpr2), s);
   return FAIL;
 }

 return OK;
}

/// Evaluate an expression, which can be a function, partial or string.
/// Pass arguments "argv[argc]".
/// Return the result in "rettv" and OK or FAIL.
///
/// @param want_func  if true, treat a string as a function name, not an expression
int eval_expr_typval(const typval_T *expr, bool want_func, typval_T *argv, int argc,
                    typval_T *rettv)
 FUNC_ATTR_NONNULL_ALL
{
 if (expr->v_type == VAR_PARTIAL) {
   return eval_expr_partial(expr, argv, argc, rettv);
 }
 if (expr->v_type == VAR_FUNC || want_func) {
   return eval_expr_func(expr, argv, argc, rettv);
 }

 return eval_expr_string(expr, rettv);
}

/// Like eval_to_bool() but using a typval_T instead of a string.
/// Works for string, funcref and partial.
bool eval_expr_to_bool(const typval_T *expr, bool *error)
 FUNC_ATTR_NONNULL_ARG(1, 2)
{
 typval_T argv, rettv;

 if (eval_expr_typval(expr, false, &argv, 0, &rettv) == FAIL) {
   *error = true;
   return false;
 }
 const bool res = (tv_get_number_chk(&rettv, error) != 0);
 tv_clear(&rettv);
 return res;
}

/// Top level evaluation function, returning a string
///
/// @param[in]  arg  String to evaluate.
/// @param[in]  skip  If true, only do parsing to nextcmd without reporting
///                   errors or actually evaluating anything.
///
/// @return [allocated] string result of evaluation or NULL in case of error or
///                     when skipping.
char *eval_to_string_skip(char *arg, exarg_T *eap, const bool skip)
 FUNC_ATTR_MALLOC FUNC_ATTR_NONNULL_ARG(1) FUNC_ATTR_WARN_UNUSED_RESULT
{
 typval_T tv;
 char *retval;
 evalarg_T evalarg;

 fill_evalarg_from_eap(&evalarg, eap, skip);
 if (skip) {
   emsg_skip++;
 }
 if (eval0(arg, &tv, eap, &evalarg) == FAIL || skip) {
   retval = NULL;
 } else {
   retval = xstrdup(tv_get_string(&tv));
   tv_clear(&tv);
 }
 if (skip) {
   emsg_skip--;
 }
 clear_evalarg(&evalarg, eap);

 return retval;
}

/// Skip over an expression at "*pp".
///
/// @return  FAIL for an error, OK otherwise.
int skip_expr(char **pp, evalarg_T *const evalarg)
{
 const int save_flags = evalarg == NULL ? 0 : evalarg->eval_flags;

 // Don't evaluate the expression.
 if (evalarg != NULL) {
   evalarg->eval_flags &= ~EVAL_EVALUATE;
 }

 *pp = skipwhite(*pp);
 typval_T rettv;
 int res = eval1(pp, &rettv, NULL);

 if (evalarg != NULL) {
   evalarg->eval_flags = save_flags;
 }

 return res;
}

/// Convert "tv" to a string.
///
/// @param join_list  when true convert a List into a sequence of lines.
///
/// @return  an allocated string.
static char *typval2string(typval_T *tv, bool join_list)
{
 if (join_list && tv->v_type == VAR_LIST) {
   garray_T ga;
   ga_init(&ga, (int)sizeof(char), 80);
   if (tv->vval.v_list != NULL) {
     tv_list_join(&ga, tv->vval.v_list, "\n");
     if (tv_list_len(tv->vval.v_list) > 0) {
       ga_append(&ga, NL);
     }
   }
   ga_append(&ga, NUL);
   return (char *)ga.ga_data;
 } else if (tv->v_type == VAR_LIST || tv->v_type == VAR_DICT) {
   return encode_tv2string(tv, NULL);
 }
 return xstrdup(tv_get_string(tv));
}

/// Top level evaluation function, returning a string.
///
/// @param join_list  when true convert a List into a sequence of lines.
///
/// @return  pointer to allocated memory, or NULL for failure.
char *eval_to_string_eap(char *arg, const bool join_list, exarg_T *eap,
                        const bool use_simple_function)
{
 typval_T tv;
 char *retval;

 evalarg_T evalarg;
 fill_evalarg_from_eap(&evalarg, eap, eap != NULL && eap->skip);
 int r = use_simple_function ? eval0_simple_funccal(arg, &tv, NULL, &evalarg)
                             : eval0(arg, &tv, NULL, &evalarg);
 if (r == FAIL) {
   retval = NULL;
 } else {
   retval = typval2string(&tv, join_list);
   tv_clear(&tv);
 }
 clear_evalarg(&evalarg, NULL);

 return retval;
}

char *eval_to_string(char *arg, const bool join_list, const bool use_simple_function)
{
 return eval_to_string_eap(arg, join_list, NULL, use_simple_function);
}

/// Call eval_to_string() without using current local variables and using
/// textlock.
///
/// @param use_sandbox  when true, use the sandbox.
char *eval_to_string_safe(char *arg, const bool use_sandbox, const bool use_simple_function)
{
 char *retval;
 funccal_entry_T funccal_entry;

 save_funccal(&funccal_entry);
 if (use_sandbox) {
   sandbox++;
 }
 textlock++;
 retval = eval_to_string(arg, false, use_simple_function);
 if (use_sandbox) {
   sandbox--;
 }
 textlock--;
 restore_funccal();
 return retval;
}

/// Top level evaluation function, returning a number.
/// Evaluates "expr" silently.
///
/// @return  -1 for an error.
varnumber_T eval_to_number(char *expr, const bool use_simple_function)
{
 typval_T rettv;
 varnumber_T retval;
 char *p = skipwhite(expr);
 int r = NOTDONE;

 emsg_off++;

 if (use_simple_function) {
   r = may_call_simple_func(expr, &rettv);
 }
 if (r == NOTDONE) {
   r = eval1(&p, &rettv, &EVALARG_EVALUATE);
 }
 if (r == FAIL) {
   retval = -1;
 } else {
   retval = tv_get_number_chk(&rettv, NULL);
   tv_clear(&rettv);
 }
 emsg_off--;

 return retval;
}

/// Top level evaluation function.
///
/// @return  an allocated typval_T with the result or
///          NULL when there is an error.
typval_T *eval_expr(char *arg, exarg_T *eap)
{
 return eval_expr_ext(arg, eap, false);
}

typval_T *eval_expr_ext(char *arg, exarg_T *eap, const bool use_simple_function)
{
 typval_T *tv = xmalloc(sizeof(*tv));
 evalarg_T evalarg;

 fill_evalarg_from_eap(&evalarg, eap, eap != NULL && eap->skip);

 int r = NOTDONE;

 if (use_simple_function) {
   r = eval0_simple_funccal(arg, tv, eap, &evalarg);
 }
 if (r == NOTDONE) {
   r = eval0(arg, tv, eap, &evalarg);
 }

 if (r == FAIL) {
   XFREE_CLEAR(tv);
 }

 clear_evalarg(&evalarg, eap);
 return tv;
}

/// Call some Vim script function and return the result in "*rettv".
/// Uses argv[0] to argv[argc - 1] for the function arguments. argv[argc]
/// should have type VAR_UNKNOWN.
///
/// @return  OK or FAIL.
int call_vim_function(const char *func, int argc, typval_T *argv, typval_T *rettv)
 FUNC_ATTR_NONNULL_ALL
{
 int ret;
 int len = (int)strlen(func);
 partial_T *pt = NULL;

 if (len >= 6 && !memcmp(func, "v:lua.", 6)) {
   func += 6;
   len = check_luafunc_name(func, false);
   if (len == 0) {
     ret = FAIL;
     goto fail;
   }
   pt = get_vim_var_partial(VV_LUA);
 }

 rettv->v_type = VAR_UNKNOWN;  // tv_clear() uses this.
 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_firstline = curwin->w_cursor.lnum;
 funcexe.fe_lastline = curwin->w_cursor.lnum;
 funcexe.fe_evaluate = true;
 funcexe.fe_partial = pt;
 ret = call_func(func, len, rettv, argc, argv, &funcexe);

fail:
 if (ret == FAIL) {
   tv_clear(rettv);
 }

 return ret;
}

/// Call Vim script function and return the result as a string.
/// Uses "argv[0]" to "argv[argc - 1]" for the function arguments. "argv[argc]"
/// should have type VAR_UNKNOWN.
///
/// @param[in]  func  Function name.
/// @param[in]  argc  Number of arguments.
/// @param[in]  argv  Array with typval_T arguments.
///
/// @return [allocated] NULL when calling function fails, allocated string
///                     otherwise.
void *call_func_retstr(const char *const func, int argc, typval_T *argv)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_MALLOC
{
 typval_T rettv;
 // All arguments are passed as strings, no conversion to number.
 if (call_vim_function(func, argc, argv, &rettv)
     == FAIL) {
   return NULL;
 }

 char *const retval = xstrdup(tv_get_string(&rettv));
 tv_clear(&rettv);
 return retval;
}

/// Call Vim script function and return the result as a List.
/// Uses "argv" and "argc" as call_func_retstr().
///
/// @param[in]  func  Function name.
/// @param[in]  argc  Number of arguments.
/// @param[in]  argv  Array with typval_T arguments.
///
/// @return [allocated] NULL when calling function fails or return tv is not a
///                     List, allocated List otherwise.
void *call_func_retlist(const char *func, int argc, typval_T *argv)
 FUNC_ATTR_NONNULL_ALL
{
 typval_T rettv;

 // All arguments are passed as strings, no conversion to number.
 if (call_vim_function(func, argc, argv, &rettv) == FAIL) {
   return NULL;
 }

 if (rettv.v_type != VAR_LIST) {
   tv_clear(&rettv);
   return NULL;
 }

 return rettv.vval.v_list;
}

/// Evaluate 'foldexpr'.  Returns the foldlevel, and any character preceding
/// it in "*cp".  Doesn't give error messages.
int eval_foldexpr(win_T *wp, int *cp)
{
 const sctx_T saved_sctx = current_sctx;
 const bool use_sandbox = was_set_insecurely(wp, kOptFoldexpr, OPT_LOCAL);

 char *arg = skipwhite(wp->w_p_fde);
 current_sctx = wp->w_p_script_ctx[kWinOptFoldexpr];

 emsg_off++;
 if (use_sandbox) {
   sandbox++;
 }
 textlock++;
 *cp = NUL;

 typval_T tv;
 varnumber_T retval;
 // Evaluate the expression.  If the expression is "FuncName()" call the
 // function directly.
 if (eval0_simple_funccal(arg, &tv, NULL, &EVALARG_EVALUATE) == FAIL) {
   retval = 0;
 } else {
   // If the result is a number, just return the number.
   if (tv.v_type == VAR_NUMBER) {
     retval = tv.vval.v_number;
   } else if (tv.v_type != VAR_STRING || tv.vval.v_string == NULL) {
     retval = 0;
   } else {
     // If the result is a string, check if there is a non-digit before
     // the number.
     char *s = tv.vval.v_string;
     if (*s != NUL && !ascii_isdigit(*s) && *s != '-') {
       *cp = (uint8_t)(*s++);
     }
     retval = atol(s);
   }
   tv_clear(&tv);
 }

 emsg_off--;
 if (use_sandbox) {
   sandbox--;
 }
 textlock--;
 clear_evalarg(&EVALARG_EVALUATE, NULL);
 current_sctx = saved_sctx;

 return (int)retval;
}

/// Evaluate 'foldtext', returning an Array or a String (NULL_STRING on failure).
Object eval_foldtext(win_T *wp)
{
 const bool use_sandbox = was_set_insecurely(wp, kOptFoldtext, OPT_LOCAL);
 char *arg = wp->w_p_fdt;
 funccal_entry_T funccal_entry;

 save_funccal(&funccal_entry);
 if (use_sandbox) {
   sandbox++;
 }
 textlock++;

 typval_T tv;
 Object retval;
 if (eval0_simple_funccal(arg, &tv, NULL, &EVALARG_EVALUATE) == FAIL) {
   retval = STRING_OBJ(NULL_STRING);
 } else {
   if (tv.v_type == VAR_LIST) {
     retval = vim_to_object(&tv, NULL, false);
   } else {
     retval = STRING_OBJ(cstr_to_string(tv_get_string(&tv)));
   }
   tv_clear(&tv);
 }
 clear_evalarg(&EVALARG_EVALUATE, NULL);

 if (use_sandbox) {
   sandbox--;
 }
 textlock--;
 restore_funccal();

 return retval;
}

/// Find the end of a variable or function name.  Unlike find_name_end() this
/// does not recognize magic braces.
/// When "use_namespace" is true recognize "b:", "s:", etc.
/// Return a pointer to just after the name.  Equal to "arg" if there is no
/// valid name.
static const char *to_name_end(const char *arg, bool use_namespace)
{
 // Quick check for valid starting character.
 if (!eval_isnamec1(*arg)) {
   return arg;
 }

 const char *p;
 for (p = arg + 1; *p != NUL && eval_isnamec(*p); MB_PTR_ADV(p)) {
   // Include a namespace such as "s:var" and "v:var".  But "n:" is not
   // and can be used in slice "[n:]".
   if (*p == ':' && (p != arg + 1
                     || !use_namespace
                     || vim_strchr("bgstvw", *arg) == NULL)) {
     break;
   }
 }
 return p;
}

/// Get an Dict lval variable that can be assigned a value to: "name",
/// "name[expr]", "name[expr][expr]", "name.key", "name.key[expr]" etc.
/// "name" points to the start of the name.
/// If "rettv" is not NULL it points to the value to be assigned.
/// "unlet" is true for ":unlet": slightly different behavior when something is
/// wrong; must end in space or cmd separator.
///
/// flags:
///  GLV_QUIET:       do not give error messages
///  GLV_READ_ONLY:   will not change the variable
///  GLV_NO_AUTOLOAD: do not use script autoloading
///
/// The Dict is returned in 'lp'.  Returns GLV_OK on success and GLV_FAIL on
/// failure.  Returns GLV_STOP to stop processing the characters following
/// 'key_end'.
static glv_status_T get_lval_dict_item(lval_T *lp, char *name, char *key, int len, char **key_end,
                                      typval_T *var1, int flags, bool unlet, typval_T *rettv)
{
 bool quiet = flags & GLV_QUIET;
 char *p = *key_end;

 if (len == -1) {
   // "[key]": get key from "var1"
   key = (char *)tv_get_string(var1);  // is number or string
 }
 lp->ll_list = NULL;

 // a NULL dict is equivalent with an empty dict
 if (lp->ll_tv->vval.v_dict == NULL) {
   lp->ll_tv->vval.v_dict = tv_dict_alloc();
   lp->ll_tv->vval.v_dict->dv_refcount++;
 }
 lp->ll_dict = lp->ll_tv->vval.v_dict;

 lp->ll_di = tv_dict_find(lp->ll_dict, key, len);

 // When assigning to a scope dictionary check that a function and
 // variable name is valid (only variable name unless it is l: or
 // g: dictionary). Disallow overwriting a builtin function.
 if (rettv != NULL && lp->ll_dict->dv_scope != 0) {
   char prevval;
   if (len != -1) {
     prevval = key[len];
     key[len] = NUL;
   } else {
     prevval = 0;  // Avoid compiler warning.
   }
   bool wrong = ((lp->ll_dict->dv_scope == VAR_DEF_SCOPE
                  && tv_is_func(*rettv)
                  && var_wrong_func_name(key, lp->ll_di == NULL))
                 || !valid_varname(key));
   if (len != -1) {
     key[len] = prevval;
   }
   if (wrong) {
     return GLV_FAIL;
   }
 }

 if (lp->ll_di != NULL && tv_is_luafunc(&lp->ll_di->di_tv)
     && len == -1 && rettv == NULL) {
   semsg(e_illvar, "v:['lua']");
   return GLV_FAIL;
 }

 if (lp->ll_di == NULL) {
   // Can't add "v:" or "a:" variable.
   if (lp->ll_dict == get_vimvar_dict()
       || &lp->ll_dict->dv_hashtab == get_funccal_args_ht()) {
     semsg(_(e_illvar), name);
     return GLV_FAIL;
   }

   // Key does not exist in dict: may need to add it.
   if (*p == '[' || *p == '.' || unlet) {
     if (!quiet) {
       semsg(_(e_dictkey), key);
     }
     return GLV_FAIL;
   }
   if (len == -1) {
     lp->ll_newkey = xstrdup(key);
   } else {
     lp->ll_newkey = xmemdupz(key, (size_t)len);
   }
   *key_end = p;
   return GLV_STOP;
   // existing variable, need to check if it can be changed
 } else if (!(flags & GLV_READ_ONLY)
            && (var_check_ro(lp->ll_di->di_flags, name, (size_t)(p - name))
                || var_check_lock(lp->ll_di->di_flags, name, (size_t)(p - name)))) {
   return GLV_FAIL;
 }

 lp->ll_tv = &lp->ll_di->di_tv;

 return GLV_OK;
}

/// Get an blob lval variable that can be assigned a value to: "name",
/// "na{me}", "name[expr]", "name[expr:expr]", "name[expr][expr]", etc.
///
/// 'var1' specifies the starting blob index and 'var2' specifies the ending
/// blob index.  If the first index is not specified in a range, then 'empty1'
/// is true.  If 'quiet' is true, then error messages are not displayed for
/// invalid indexes.
///
/// The blob is returned in 'lp'.  Returns OK on success and FAIL on failure.
static int get_lval_blob(lval_T *lp, typval_T *var1, typval_T *var2, bool empty1, bool quiet)
{
 const int bloblen = tv_blob_len(lp->ll_tv->vval.v_blob);

 // Get the number and item for the only or first index of the List.
 if (empty1) {
   lp->ll_n1 = 0;
 } else {
   // Is number or string.
   lp->ll_n1 = (int)tv_get_number(var1);
 }

 if (tv_blob_check_index(bloblen, lp->ll_n1, quiet) == FAIL) {
   return FAIL;
 }
 if (lp->ll_range && !lp->ll_empty2) {
   lp->ll_n2 = (int)tv_get_number(var2);
   if (tv_blob_check_range(bloblen, lp->ll_n1, lp->ll_n2, quiet) == FAIL) {
     return FAIL;
   }
 }

 lp->ll_blob = lp->ll_tv->vval.v_blob;
 lp->ll_tv = NULL;

 return OK;
}

/// Get a List lval variable that can be assigned a value to: "name",
/// "na{me}", "name[expr]", "name[expr:expr]", "name[expr][expr]", etc.
///
/// 'var1' specifies the starting List index and 'var2' specifies the ending
/// List index.  If the first index is not specified in a range, then 'empty1'
/// is true.  If 'quiet' is true, then error messages are not displayed for
/// invalid indexes.
///
/// The List is returned in 'lp'.  Returns OK on success and FAIL on failure.
static int get_lval_list(lval_T *lp, typval_T *var1, typval_T *var2, bool empty1, int flags,
                        bool quiet)
{
 // Get the number and item for the only or first index of the List.
 if (empty1) {
   lp->ll_n1 = 0;
 } else {
   // Is number or string.
   lp->ll_n1 = (int)tv_get_number(var1);
 }

 lp->ll_dict = NULL;
 lp->ll_list = lp->ll_tv->vval.v_list;
 lp->ll_li = tv_list_check_range_index_one(lp->ll_list, &lp->ll_n1, quiet);
 if (lp->ll_li == NULL) {
   return FAIL;
 }

 // May need to find the item or absolute index for the second
 // index of a range.
 // When no index given: "lp->ll_empty2" is true.
 // Otherwise "lp->ll_n2" is set to the second index.
 if (lp->ll_range && !lp->ll_empty2) {
   lp->ll_n2 = (int)tv_get_number(var2);  // Is number or string.
   if (tv_list_check_range_index_two(lp->ll_list,
                                     &lp->ll_n1, lp->ll_li,
                                     &lp->ll_n2, quiet) == FAIL) {
     return FAIL;
   }
 }

 lp->ll_tv = TV_LIST_ITEM_TV(lp->ll_li);

 return OK;
}

/// Get the lval of a list/dict/blob subitem starting at "p". Loop
/// until no more [idx] or .key is following.
///
/// If "rettv" is not NULL it points to the value to be assigned.
/// "unlet" is true for ":unlet".
///
/// @param[in]  flags  @see GetLvalFlags.
///
/// @return A pointer to the character after the subscript on success or NULL on
///         failure.
static char *get_lval_subscript(lval_T *lp, char *p, char *name, typval_T *rettv, hashtab_T *ht,
                               dictitem_T *v, bool unlet, int flags)
{
 bool quiet = flags & GLV_QUIET;
 typval_T var1;
 var1.v_type = VAR_UNKNOWN;
 typval_T var2;
 var2.v_type = VAR_UNKNOWN;
 bool empty1 = false;
 int rc = FAIL;

 // Loop until no more [idx] or .key is following.
 while (*p == '[' || (*p == '.' && p[1] != '=' && p[1] != '.')) {
   if (*p == '.' && lp->ll_tv->v_type != VAR_DICT) {
     if (!quiet) {
       semsg(_(e_dot_can_only_be_used_on_dictionary_str), name);
     }
     return NULL;
   }
   if (lp->ll_tv->v_type != VAR_LIST
       && lp->ll_tv->v_type != VAR_DICT
       && lp->ll_tv->v_type != VAR_BLOB) {
     if (!quiet) {
       emsg(_("E689: Can only index a List, Dictionary or Blob"));
     }
     return NULL;
   }

   // A NULL list/blob works like an empty list/blob, allocate one now.
   if (lp->ll_tv->v_type == VAR_LIST && lp->ll_tv->vval.v_list == NULL) {
     tv_list_alloc_ret(lp->ll_tv, kListLenUnknown);
   } else if (lp->ll_tv->v_type == VAR_BLOB && lp->ll_tv->vval.v_blob == NULL) {
     tv_blob_alloc_ret(lp->ll_tv);
   }

   if (lp->ll_range) {
     if (!quiet) {
       emsg(_("E708: [:] must come last"));
     }
     goto done;
   }

   int len = -1;
   char *key = NULL;
   if (*p == '.') {
     key = p + 1;

     for (len = 0; ASCII_ISALNUM(key[len]) || key[len] == '_'; len++) {}
     if (len == 0) {
       if (!quiet) {
         emsg(_("E713: Cannot use empty key after ."));
       }
       return NULL;
     }
     p = key + len;
   } else {
     // Get the index [expr] or the first index [expr: ].
     p = skipwhite(p + 1);
     if (*p == ':') {
       empty1 = true;
     } else {
       empty1 = false;
       if (eval1(&p, &var1, &EVALARG_EVALUATE) == FAIL) {  // Recursive!
         goto done;
       }
       if (!tv_check_str(&var1)) {
         // Not a number or string.
         goto done;
       }
       p = skipwhite(p);
     }

     // Optionally get the second index [ :expr].
     if (*p == ':') {
       if (lp->ll_tv->v_type == VAR_DICT) {
         if (!quiet) {
           emsg(_(e_cannot_slice_dictionary));
         }
         goto done;
       }
       if (rettv != NULL
           && !(rettv->v_type == VAR_LIST && rettv->vval.v_list != NULL)
           && !(rettv->v_type == VAR_BLOB && rettv->vval.v_blob != NULL)) {
         if (!quiet) {
           emsg(_("E709: [:] requires a List or Blob value"));
         }
         goto done;
       }
       p = skipwhite(p + 1);
       if (*p == ']') {
         lp->ll_empty2 = true;
       } else {
         lp->ll_empty2 = false;
         // Recursive!
         if (eval1(&p, &var2, &EVALARG_EVALUATE) == FAIL) {
           goto done;
         }
         if (!tv_check_str(&var2)) {
           // Not a number or string.
           goto done;
         }
       }
       lp->ll_range = true;
     } else {
       lp->ll_range = false;
     }

     if (*p != ']') {
       if (!quiet) {
         emsg(_(e_missbrac));
       }
       goto done;
     }

     // Skip to past ']'.
     p++;
   }

   if (lp->ll_tv->v_type == VAR_DICT) {
     glv_status_T glv_status = get_lval_dict_item(lp, name, key, len, &p, &var1,
                                                  flags, unlet, rettv);
     if (glv_status == GLV_FAIL) {
       goto done;
     }
     if (glv_status == GLV_STOP) {
       break;
     }
   } else if (lp->ll_tv->v_type == VAR_BLOB) {
     if (get_lval_blob(lp, &var1, &var2, empty1, quiet) == FAIL) {
       goto done;
     }
     break;
   } else {
     if (get_lval_list(lp, &var1, &var2, empty1, flags, quiet) == FAIL) {
       goto done;
     }
   }

   tv_clear(&var1);
   tv_clear(&var2);
   var1.v_type = VAR_UNKNOWN;
   var2.v_type = VAR_UNKNOWN;
 }

 rc = OK;

done:
 tv_clear(&var1);
 tv_clear(&var2);
 return rc == OK ? p : NULL;
}

/// Get an lvalue
///
/// Lvalue may be
/// - variable: "name", "na{me}"
/// - dictionary item: "dict.key", "dict['key']"
/// - list item: "list[expr]"
/// - list slice: "list[expr:expr]"
///
/// Indexing only works if trying to use it with an existing List or Dictionary.
///
/// @param[in]  name  Name to parse.
/// @param  rettv  Pointer to the value to be assigned or NULL.
/// @param[out]  lp  Lvalue definition. When evaluation errors occur `->ll_name`
///                  is NULL.
/// @param[in]  unlet  True if using `:unlet`. This results in slightly
///                    different behaviour when something is wrong; must end in
///                    space or cmd separator.
/// @param[in]  skip  True when skipping.
/// @param[in]  flags  @see GetLvalFlags.
/// @param[in]  fne_flags  Flags for find_name_end().
///
/// @return A pointer to just after the name, including indexes. Returns NULL
///         for a parsing error, but it is still needed to free items in lp.
char *get_lval(char *const name, typval_T *const rettv, lval_T *const lp, const bool unlet,
              const bool skip, const int flags, const int fne_flags)
 FUNC_ATTR_NONNULL_ARG(1, 3)
{
 int quiet = flags & GLV_QUIET;

 // Clear everything in "lp".
 CLEAR_POINTER(lp);

 if (skip) {
   // When skipping just find the end of the name.
   lp->ll_name = name;
   return (char *)find_name_end(name, NULL, NULL, FNE_INCL_BR | fne_flags);
 }

 // Find the end of the name.
 char *expr_start;
 char *expr_end;
 char *p = (char *)find_name_end(name, (const char **)&expr_start,
                                 (const char **)&expr_end,
                                 fne_flags);
 if (expr_start != NULL) {
   // Don't expand the name when we already know there is an error.
   if (unlet && !ascii_iswhite(*p) && !ends_excmd(*p)
       && *p != '[' && *p != '.') {
     semsg(_(e_trailing_arg), p);
     return NULL;
   }

   lp->ll_exp_name = make_expanded_name(name, expr_start, expr_end, p);
   lp->ll_name = lp->ll_exp_name;
   if (lp->ll_exp_name == NULL) {
     // Report an invalid expression in braces, unless the
     // expression evaluation has been cancelled due to an
     // aborting error, an interrupt, or an exception.
     if (!aborting() && !quiet) {
       emsg_severe = true;
       semsg(_(e_invarg2), name);
       return NULL;
     }
     lp->ll_name_len = 0;
   } else {
     lp->ll_name_len = strlen(lp->ll_name);
   }
 } else {
   lp->ll_name = name;
   lp->ll_name_len = (size_t)(p - lp->ll_name);
 }

 // Without [idx] or .key we are done.
 if ((*p != '[' && *p != '.') || lp->ll_name == NULL) {
   return p;
 }

 hashtab_T *ht = NULL;

 // Only pass &ht when we would write to the variable, it prevents autoload
 // as well.
 dictitem_T *v = find_var(lp->ll_name, lp->ll_name_len,
                          (flags & GLV_READ_ONLY) ? NULL : &ht,
                          flags & GLV_NO_AUTOLOAD);
 if (v == NULL && !quiet) {
   semsg(_("E121: Undefined variable: %.*s"),
         (int)lp->ll_name_len, lp->ll_name);
 }
 if (v == NULL) {
   return NULL;
 }

 lp->ll_tv = &v->di_tv;

 if (tv_is_luafunc(lp->ll_tv)) {
   // For v:lua just return a pointer to the "." after the "v:lua".
   // If the caller is trans_function_name() it will check for a Lua function name.
   return p;
 }

 // If the next character is a "." or a "[", then process the subitem.
 p = get_lval_subscript(lp, p, name, rettv, ht, v, unlet, flags);
 if (p == NULL) {
   return NULL;
 }

 lp->ll_name_len = (size_t)(p - lp->ll_name);
 return p;
}

/// Clear lval "lp" that was filled by get_lval().
void clear_lval(lval_T *lp)
{
 xfree(lp->ll_exp_name);
 xfree(lp->ll_newkey);
}

/// Set a variable that was parsed by get_lval() to "rettv".
///
/// @param endp  points to just after the parsed name.
/// @param op    NULL, "+" for "+=", "-" for "-=", "*" for "*=", "/" for "/=",
///              "%" for "%=", "." for ".=" or "=" for "=".
void set_var_lval(lval_T *lp, char *endp, typval_T *rettv, bool copy, const bool is_const,
                 const char *op)
{
 int cc;
 dictitem_T *di;

 if (lp->ll_tv == NULL) {
   cc = (uint8_t)(*endp);
   *endp = NUL;
   if (lp->ll_blob != NULL) {
     if (op != NULL && *op != '=') {
       semsg(_(e_letwrong), op);
       return;
     }
     if (value_check_lock(lp->ll_blob->bv_lock, lp->ll_name, TV_CSTRING)) {
       return;
     }

     if (lp->ll_range && rettv->v_type == VAR_BLOB) {
       if (lp->ll_empty2) {
         lp->ll_n2 = tv_blob_len(lp->ll_blob) - 1;
       }

       if (tv_blob_set_range(lp->ll_blob, lp->ll_n1, lp->ll_n2, rettv) == FAIL) {
         return;
       }
     } else {
       bool error = false;
       const varnumber_T val = tv_get_number_chk(rettv, &error);
       if (!error) {
         if (val < 0 || val > 255) {
           semsg(_(e_invalid_value_for_blob_nr), val);
         } else {
           tv_blob_set_append(lp->ll_blob, lp->ll_n1, (uint8_t)val);
         }
       }
     }
   } else if (op != NULL && *op != '=') {
     typval_T tv;

     if (is_const) {
       emsg(_(e_cannot_mod));
       *endp = (char)cc;
       return;
     }

     // handle +=, -=, *=, /=, %= and .=
     di = NULL;
     if (eval_variable(lp->ll_name, (int)lp->ll_name_len,
                       &tv, &di, true, false) == OK) {
       if ((di == NULL
            || (!var_check_ro(di->di_flags, lp->ll_name, TV_CSTRING)
                && !tv_check_lock(&di->di_tv, lp->ll_name, TV_CSTRING)))
           && eexe_mod_op(&tv, rettv, op) == OK) {
         set_var(lp->ll_name, lp->ll_name_len, &tv, false);
       }
       tv_clear(&tv);
     }
   } else {
     set_var_const(lp->ll_name, lp->ll_name_len, rettv, copy, is_const);
   }
   *endp = (char)cc;
 } else if (value_check_lock(lp->ll_newkey == NULL
                             ? lp->ll_tv->v_lock
                             : lp->ll_tv->vval.v_dict->dv_lock,
                             lp->ll_name, TV_CSTRING)) {
   // Skip
 } else if (lp->ll_range) {
   if (is_const) {
     emsg(_("E996: Cannot lock a range"));
     return;
   }

   tv_list_assign_range(lp->ll_list, rettv->vval.v_list,
                        lp->ll_n1, lp->ll_n2, lp->ll_empty2, op, lp->ll_name);
 } else {
   typval_T oldtv = TV_INITIAL_VALUE;
   dict_T *dict = lp->ll_dict;
   bool watched = tv_dict_is_watched(dict);

   if (is_const) {
     emsg(_("E996: Cannot lock a list or dict"));
     return;
   }

   // Assign to a List or Dictionary item.
   if (lp->ll_newkey != NULL) {
     if (op != NULL && *op != '=') {
       semsg(_(e_dictkey), lp->ll_newkey);
       return;
     }
     if (tv_dict_wrong_func_name(lp->ll_tv->vval.v_dict, rettv, lp->ll_newkey)) {
       return;
     }

     // Need to add an item to the Dictionary.
     di = tv_dict_item_alloc(lp->ll_newkey);
     if (tv_dict_add(lp->ll_tv->vval.v_dict, di) == FAIL) {
       xfree(di);
       return;
     }
     lp->ll_tv = &di->di_tv;
   } else {
     if (watched) {
       tv_copy(lp->ll_tv, &oldtv);
     }

     if (op != NULL && *op != '=') {
       eexe_mod_op(lp->ll_tv, rettv, op);
       goto notify;
     } else {
       tv_clear(lp->ll_tv);
     }
   }

   // Assign the value to the variable or list item.
   if (copy) {
     tv_copy(rettv, lp->ll_tv);
   } else {
     *lp->ll_tv = *rettv;
     lp->ll_tv->v_lock = VAR_UNLOCKED;
     tv_init(rettv);
   }

notify:
   if (watched) {
     if (oldtv.v_type == VAR_UNKNOWN) {
       assert(lp->ll_newkey != NULL);
       tv_dict_watcher_notify(dict, lp->ll_newkey, lp->ll_tv, NULL);
     } else {
       dictitem_T *di_ = lp->ll_di;
       assert(di_->di_key != NULL);
       tv_dict_watcher_notify(dict, di_->di_key, lp->ll_tv, &oldtv);
       tv_clear(&oldtv);
     }
   }
 }
}

/// Evaluate the expression used in a ":for var in expr" command.
/// "arg" points to "var".
///
/// @param[out] *errp  set to true for an error, false otherwise;
///
/// @return  a pointer that holds the info.  Null when there is an error.
void *eval_for_line(const char *arg, bool *errp, exarg_T *eap, evalarg_T *const evalarg)
{
 forinfo_T *fi = xcalloc(1, sizeof(forinfo_T));
 typval_T tv;
 list_T *l;
 const bool skip = !(evalarg->eval_flags & EVAL_EVALUATE);

 *errp = true;  // Default: there is an error.

 const char *expr = skip_var_list(arg, &fi->fi_varcount, &fi->fi_semicolon, false);
 if (expr == NULL) {
   return fi;
 }

 expr = skipwhite(expr);
 if (expr[0] != 'i' || expr[1] != 'n'
     || !(expr[2] == NUL || ascii_iswhite(expr[2]))) {
   emsg(_("E690: Missing \"in\" after :for"));
   return fi;
 }

 if (skip) {
   emsg_skip++;
 }
 expr = skipwhite(expr + 2);
 if (eval0((char *)expr, &tv, eap, evalarg) == OK) {
   *errp = false;
   if (!skip) {
     if (tv.v_type == VAR_LIST) {
       l = tv.vval.v_list;
       if (l == NULL) {
         // a null list is like an empty list: do nothing
         tv_clear(&tv);
       } else {
         // No need to increment the refcount, it's already set for
         // the list being used in "tv".
         fi->fi_list = l;
         tv_list_watch_add(l, &fi->fi_lw);
         fi->fi_lw.lw_item = tv_list_first(l);
       }
     } else if (tv.v_type == VAR_BLOB) {
       fi->fi_bi = 0;
       if (tv.vval.v_blob != NULL) {
         typval_T btv;

         // Make a copy, so that the iteration still works when the
         // blob is changed.
         tv_blob_copy(tv.vval.v_blob, &btv);
         fi->fi_blob = btv.vval.v_blob;
       }
       tv_clear(&tv);
     } else if (tv.v_type == VAR_STRING) {
       fi->fi_byte_idx = 0;
       fi->fi_string = tv.vval.v_string;
       tv.vval.v_string = NULL;
       if (fi->fi_string == NULL) {
         fi->fi_string = xstrdup("");
       }
     } else {
       emsg(_(e_string_list_or_blob_required));
       tv_clear(&tv);
     }
   }
 }
 if (skip) {
   emsg_skip--;
 }

 return fi;
}

/// Use the first item in a ":for" list.  Advance to the next.
/// Assign the values to the variable (list).  "arg" points to the first one.
///
/// @return  true when a valid item was found, false when at end of list or
///          something wrong.
bool next_for_item(void *fi_void, char *arg)
{
 forinfo_T *fi = (forinfo_T *)fi_void;

 if (fi->fi_blob != NULL) {
   if (fi->fi_bi >= tv_blob_len(fi->fi_blob)) {
     return false;
   }
   typval_T tv;
   tv.v_type = VAR_NUMBER;
   tv.v_lock = VAR_FIXED;
   tv.vval.v_number = tv_blob_get(fi->fi_blob, fi->fi_bi);
   fi->fi_bi++;
   return ex_let_vars(arg, &tv, true, fi->fi_semicolon, fi->fi_varcount, false, NULL) == OK;
 }

 if (fi->fi_string != NULL) {
   const int len = utfc_ptr2len(fi->fi_string + fi->fi_byte_idx);
   if (len == 0) {
     return false;
   }
   typval_T tv;
   tv.v_type = VAR_STRING;
   tv.v_lock = VAR_FIXED;
   tv.vval.v_string = xmemdupz(fi->fi_string + fi->fi_byte_idx, (size_t)len);
   fi->fi_byte_idx += len;
   const int result
     = ex_let_vars(arg, &tv, true, fi->fi_semicolon, fi->fi_varcount, false, NULL) == OK;
   xfree(tv.vval.v_string);
   return result;
 }

 listitem_T *item = fi->fi_lw.lw_item;
 if (item == NULL) {
   return false;
 }
 fi->fi_lw.lw_item = TV_LIST_ITEM_NEXT(fi->fi_list, item);
 return (ex_let_vars(arg, TV_LIST_ITEM_TV(item), true,
                     fi->fi_semicolon, fi->fi_varcount, false, NULL) == OK);
}

/// Free the structure used to store info used by ":for".
void free_for_info(void *fi_void)
{
 forinfo_T *fi = (forinfo_T *)fi_void;

 if (fi == NULL) {
   return;
 }
 if (fi->fi_list != NULL) {
   tv_list_watch_remove(fi->fi_list, &fi->fi_lw);
   tv_list_unref(fi->fi_list);
 } else if (fi->fi_blob != NULL) {
   tv_blob_unref(fi->fi_blob);
 } else {
   xfree(fi->fi_string);
 }
 xfree(fi);
}

void set_context_for_expression(expand_T *xp, char *arg, cmdidx_T cmdidx)
 FUNC_ATTR_NONNULL_ALL
{
 bool got_eq = false;

 if (cmdidx == CMD_let || cmdidx == CMD_const) {
   xp->xp_context = EXPAND_USER_VARS;
   if (strpbrk(arg, "\"'+-*/%.=!?~|&$([<>,#") == NULL) {
     // ":let var1 var2 ...": find last space.
     for (char *p = arg + strlen(arg); p >= arg;) {
       xp->xp_pattern = p;
       MB_PTR_BACK(arg, p);
       if (ascii_iswhite(*p)) {
         break;
       }
     }
     return;
   }
 } else {
   xp->xp_context = cmdidx == CMD_call ? EXPAND_FUNCTIONS
                                       : EXPAND_EXPRESSION;
 }
 while ((xp->xp_pattern = strpbrk(arg, "\"'+-*/%.=!?~|&$([<>,#")) != NULL) {
   int c = (uint8_t)(*xp->xp_pattern);
   if (c == '&') {
     c = (uint8_t)xp->xp_pattern[1];
     if (c == '&') {
       xp->xp_pattern++;
       xp->xp_context = cmdidx != CMD_let || got_eq
                        ? EXPAND_EXPRESSION : EXPAND_NOTHING;
     } else if (c != ' ') {
       xp->xp_context = EXPAND_SETTINGS;
       if ((c == 'l' || c == 'g') && xp->xp_pattern[2] == ':') {
         xp->xp_pattern += 2;
       }
     }
   } else if (c == '$') {
     // environment variable
     xp->xp_context = EXPAND_ENV_VARS;
   } else if (c == '=') {
     got_eq = true;
     xp->xp_context = EXPAND_EXPRESSION;
   } else if (c == '#'
              && xp->xp_context == EXPAND_EXPRESSION) {
     // Autoload function/variable contains '#'
     break;
   } else if ((c == '<' || c == '#')
              && xp->xp_context == EXPAND_FUNCTIONS
              && vim_strchr(xp->xp_pattern, '(') == NULL) {
     // Function name can start with "<SNR>" and contain '#'.
     break;
   } else if (cmdidx != CMD_let || got_eq) {
     if (c == '"') {               // string
       while ((c = (uint8_t)(*++xp->xp_pattern)) != NUL && c != '"') {
         if (c == '\\' && xp->xp_pattern[1] != NUL) {
           xp->xp_pattern++;
         }
       }
       xp->xp_context = EXPAND_NOTHING;
     } else if (c == '\'') {     // literal string
       // Trick: '' is like stopping and starting a literal string.
       while ((c = (uint8_t)(*++xp->xp_pattern)) != NUL && c != '\'') {}
       xp->xp_context = EXPAND_NOTHING;
     } else if (c == '|') {
       if (xp->xp_pattern[1] == '|') {
         xp->xp_pattern++;
         xp->xp_context = EXPAND_EXPRESSION;
       } else {
         xp->xp_context = EXPAND_COMMANDS;
       }
     } else {
       xp->xp_context = EXPAND_EXPRESSION;
     }
   } else {
     // Doesn't look like something valid, expand as an expression
     // anyway.
     xp->xp_context = EXPAND_EXPRESSION;
   }
   arg = xp->xp_pattern;
   if (*arg != NUL) {
     while ((c = (uint8_t)(*++arg)) != NUL && (c == ' ' || c == '\t')) {}
   }
 }

 // ":exe one two" completes "two"
 if (cmd_has_expr_args(cmdidx) && xp->xp_context == EXPAND_EXPRESSION) {
   while (true) {
     char *const n = skiptowhite(arg);

     if (n == arg || ascii_iswhite_or_nul(*skipwhite(n))) {
       break;
     }
     arg = skipwhite(n);
   }
 }

 xp->xp_pattern = arg;
}

/// Does not use 'cpo' and always uses 'magic'.
///
/// @return  true if "pat" matches "text".
int pattern_match(const char *pat, const char *text, bool ic)
{
 int matches = 0;
 regmatch_T regmatch;

 // avoid 'l' flag in 'cpoptions'
 char *save_cpo = p_cpo;
 p_cpo = empty_string_option;
 regmatch.regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING);
 if (regmatch.regprog != NULL) {
   regmatch.rm_ic = ic;
   matches = vim_regexec_nl(&regmatch, text, 0);
   vim_regfree(regmatch.regprog);
 }
 p_cpo = save_cpo;
 return matches;
}

/// Handle a name followed by "(".  Both for just "name(arg)" and for
/// "expr->name(arg)".
///
/// @param arg  Points to "(", will be advanced
/// @param basetv  "expr" for "expr->name(arg)"
///
/// @return OK or FAIL.
static int eval_func(char **const arg, evalarg_T *const evalarg, char *const name,
                    const int name_len, typval_T *const rettv, const int flags,
                    typval_T *const basetv)
 FUNC_ATTR_NONNULL_ARG(1, 3, 5)
{
 const bool evaluate = flags & EVAL_EVALUATE;
 char *s = name;
 int len = name_len;
 bool found_var = false;

 if (!evaluate) {
   check_vars(s, (size_t)len);
 }

 // If "s" is the name of a variable of type VAR_FUNC
 // use its contents.
 partial_T *partial;
 s = deref_func_name(s, &len, &partial, !evaluate, &found_var);

 // Need to make a copy, in case evaluating the arguments makes
 // the name invalid.
 s = xmemdupz(s, (size_t)len);

 // Invoke the function.
 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_firstline = curwin->w_cursor.lnum;
 funcexe.fe_lastline = curwin->w_cursor.lnum;
 funcexe.fe_evaluate = evaluate;
 funcexe.fe_partial = partial;
 funcexe.fe_basetv = basetv;
 funcexe.fe_found_var = found_var;
 int ret = get_func_tv(s, len, rettv, arg, evalarg, &funcexe);

 xfree(s);

 // If evaluate is false rettv->v_type was not set in
 // get_func_tv, but it's needed in handle_subscript() to parse
 // what follows. So set it here.
 if (rettv->v_type == VAR_UNKNOWN && !evaluate && **arg == '(') {
   rettv->vval.v_string = (char *)tv_empty_string;
   rettv->v_type = VAR_FUNC;
 }

 // Stop the expression evaluation when immediately
 // aborting on error, or when an interrupt occurred or
 // an exception was thrown but not caught.
 if (evaluate && aborting()) {
   if (ret == OK) {
     tv_clear(rettv);
   }
   ret = FAIL;
 }
 return ret;
}

/// After using "evalarg" filled from "eap": free the memory.
void clear_evalarg(evalarg_T *evalarg, exarg_T *eap)
{
 if (evalarg == NULL) {
   return;
 }

 if (evalarg->eval_tofree != NULL) {
   if (eap != NULL) {
     // We may need to keep the original command line, e.g. for
     // ":let" it has the variable names.  But we may also need the
     // new one, "nextcmd" points into it.  Keep both.
     xfree(eap->cmdline_tofree);
     eap->cmdline_tofree = *eap->cmdlinep;
     *eap->cmdlinep = evalarg->eval_tofree;
   } else {
     xfree(evalarg->eval_tofree);
   }
   evalarg->eval_tofree = NULL;
 }
}

/// The "eval" functions have an "evalarg" argument: When NULL or
/// "evalarg->eval_flags" does not have EVAL_EVALUATE, then the argument is only
/// parsed but not executed.  The functions may return OK, but the rettv will be
/// of type VAR_UNKNOWN.  The functions still returns FAIL for a syntax error.

/// Handle zero level expression.
/// This calls eval1() and handles error message and nextcmd.
/// Put the result in "rettv" when returning OK and "evaluate" is true.
///
/// @param evalarg  can be NULL, &EVALARG_EVALUATE or a pointer.
///
/// @return OK or FAIL.
int eval0(char *arg, typval_T *rettv, exarg_T *eap, evalarg_T *const evalarg)
{
 const int did_emsg_before = did_emsg;
 const int called_emsg_before = called_emsg;
 bool end_error = false;

 char *p = skipwhite(arg);
 int ret = eval1(&p, rettv, evalarg);

 if (ret != FAIL) {
   end_error = !ends_excmd(*p);
 }
 if (ret == FAIL || end_error) {
   if (ret != FAIL) {
     tv_clear(rettv);
   }
   // Report the invalid expression unless the expression evaluation has
   // been cancelled due to an aborting error, an interrupt, or an
   // exception, or we already gave a more specific error.
   // Also check called_emsg for when using assert_fails().
   if (!aborting()
       && did_emsg == did_emsg_before
       && called_emsg == called_emsg_before) {
     if (end_error) {
       semsg(_(e_trailing_arg), p);
     } else {
       semsg(_(e_invexpr2), arg);
     }
   }

   if (eap != NULL && p != NULL) {
     // Some of the expression may not have been consumed.
     // Only execute a next command if it cannot be a "||" operator.
     // The next command may be "catch".
     char *nextcmd = check_nextcmd(p);
     if (nextcmd != NULL && *nextcmd != '|') {
       eap->nextcmd = nextcmd;
     }
   }
   return FAIL;
 }

 if (eap != NULL) {
   eap->nextcmd = check_nextcmd(p);
 }

 return ret;
}

/// If "arg" is a simple function call without arguments then call it and return
/// the result.  Otherwise return NOTDONE.
int may_call_simple_func(const char *arg, typval_T *rettv)
{
 const char *parens = strstr(arg, "()");
 int r = NOTDONE;

 // If the expression is "FuncName()" then we can skip a lot of overhead.
 if (parens != NULL && *skipwhite(parens + 2) == NUL) {
   if (strnequal(arg, "v:lua.", 6)) {
     const char *p = arg + 6;
     if (p != parens && skip_luafunc_name(p) == parens) {
       r = call_simple_luafunc(p, (size_t)(parens - p), rettv);
     }
   } else {
     const char *p = strncmp(arg, "<SNR>", 5) == 0 ? skipdigits(arg + 5) : arg;
     if (to_name_end(p, true) == parens) {
       r = call_simple_func(arg, (size_t)(parens - arg), rettv);
     }
   }
 }
 return r;
}

/// Handle zero level expression with optimization for a simple function call.
/// Same arguments and return value as eval0().
static int eval0_simple_funccal(char *arg, typval_T *rettv, exarg_T *eap, evalarg_T *const evalarg)
{
 int r = may_call_simple_func(arg, rettv);

 if (r == NOTDONE) {
   r = eval0(arg, rettv, eap, evalarg);
 }
 return r;
}

/// Handle top level expression:
///      expr2 ? expr1 : expr1
///      expr2 ?? expr1
///
/// "arg" must point to the first non-white of the expression.
/// "arg" is advanced to the next non-white after the recognized expression.
///
/// @return  OK or FAIL.
int eval1(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 CLEAR_POINTER(rettv);

 // Get the first variable.
 if (eval2(arg, rettv, evalarg) == FAIL) {
   return FAIL;
 }

 char *p = *arg;
 if (*p == '?') {
   const bool op_falsy = p[1] == '?';
   evalarg_T *evalarg_used = evalarg;
   evalarg_T local_evalarg;
   if (evalarg == NULL) {
     local_evalarg = (evalarg_T){ .eval_flags = 0 };
     evalarg_used = &local_evalarg;
   }
   const int orig_flags = evalarg_used->eval_flags;
   const bool evaluate = evalarg_used->eval_flags & EVAL_EVALUATE;

   bool result = false;
   if (evaluate) {
     bool error = false;

     if (op_falsy) {
       result = tv2bool(rettv);
     } else if (tv_get_number_chk(rettv, &error) != 0) {
       result = true;
     }
     if (error || !op_falsy || !result) {
       tv_clear(rettv);
     }
     if (error) {
       return FAIL;
     }
   }

   // Get the second variable.  Recursive!
   if (op_falsy) {
     (*arg)++;
   }
   *arg = skipwhite(*arg + 1);
   evalarg_used->eval_flags = (op_falsy ? !result : result)
                              ? orig_flags : (orig_flags & ~EVAL_EVALUATE);
   typval_T var2;
   if (eval1(arg, &var2, evalarg_used) == FAIL) {
     evalarg_used->eval_flags = orig_flags;
     return FAIL;
   }
   if (!op_falsy || !result) {
     *rettv = var2;
   }

   if (!op_falsy) {
     // Check for the ":".
     p = *arg;
     if (*p != ':') {
       emsg(_("E109: Missing ':' after '?'"));
       if (evaluate && result) {
         tv_clear(rettv);
       }
       evalarg_used->eval_flags = orig_flags;
       return FAIL;
     }

     // Get the third variable.  Recursive!
     *arg = skipwhite(*arg + 1);
     evalarg_used->eval_flags = !result ? orig_flags : (orig_flags & ~EVAL_EVALUATE);
     if (eval1(arg, &var2, evalarg_used) == FAIL) {
       if (evaluate && result) {
         tv_clear(rettv);
       }
       evalarg_used->eval_flags = orig_flags;
       return FAIL;
     }
     if (evaluate && !result) {
       *rettv = var2;
     }
   }

   if (evalarg == NULL) {
     clear_evalarg(&local_evalarg, NULL);
   } else {
     evalarg->eval_flags = orig_flags;
   }
 }

 return OK;
}

/// Handle first level expression:
///      expr2 || expr2 || expr2     logical OR
///
/// "arg" must point to the first non-white of the expression.
/// "arg" is advanced to the next non-white after the recognized expression.
///
/// @return  OK or FAIL.
static int eval2(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 // Get the first variable.
 if (eval3(arg, rettv, evalarg) == FAIL) {
   return FAIL;
 }

 // Handle the  "||" operator.
 char *p = *arg;
 if (p[0] == '|' && p[1] == '|') {
   evalarg_T *evalarg_used = evalarg;
   evalarg_T local_evalarg;
   if (evalarg == NULL) {
     local_evalarg = (evalarg_T){ .eval_flags = 0 };
     evalarg_used = &local_evalarg;
   }
   const int orig_flags = evalarg_used->eval_flags;
   const bool evaluate = evalarg_used->eval_flags & EVAL_EVALUATE;

   bool result = false;

   if (evaluate) {
     bool error = false;
     if (tv_get_number_chk(rettv, &error) != 0) {
       result = true;
     }
     tv_clear(rettv);
     if (error) {
       return FAIL;
     }
   }

   // Repeat until there is no following "||".
   while (p[0] == '|' && p[1] == '|') {
     // Get the second variable.
     *arg = skipwhite(*arg + 2);
     evalarg_used->eval_flags = !result ? orig_flags : (orig_flags & ~EVAL_EVALUATE);
     typval_T var2;
     if (eval3(arg, &var2, evalarg_used) == FAIL) {
       return FAIL;
     }

     // Compute the result.
     if (evaluate && !result) {
       bool error = false;
       if (tv_get_number_chk(&var2, &error) != 0) {
         result = true;
       }
       tv_clear(&var2);
       if (error) {
         return FAIL;
       }
     }
     if (evaluate) {
       rettv->v_type = VAR_NUMBER;
       rettv->vval.v_number = result;
     }

     p = *arg;
   }

   if (evalarg == NULL) {
     clear_evalarg(&local_evalarg, NULL);
   } else {
     evalarg->eval_flags = orig_flags;
   }
 }

 return OK;
}

/// Handle second level expression:
///      expr3 && expr3 && expr3     logical AND
///
/// @param arg  must point to the first non-white of the expression.
///             `arg` is advanced to the next non-white after the recognized expression.
///
/// @return  OK or FAIL.
static int eval3(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 // Get the first variable.
 if (eval4(arg, rettv, evalarg) == FAIL) {
   return FAIL;
 }

 char *p = *arg;
 // Handle the "&&" operator.
 if (p[0] == '&' && p[1] == '&') {
   evalarg_T *evalarg_used = evalarg;
   evalarg_T local_evalarg;
   if (evalarg == NULL) {
     local_evalarg = (evalarg_T){ .eval_flags = 0 };
     evalarg_used = &local_evalarg;
   }
   const int orig_flags = evalarg_used->eval_flags;
   const bool evaluate = evalarg_used->eval_flags & EVAL_EVALUATE;

   bool result = true;

   if (evaluate) {
     bool error = false;
     if (tv_get_number_chk(rettv, &error) == 0) {
       result = false;
     }
     tv_clear(rettv);
     if (error) {
       return FAIL;
     }
   }

   // Repeat until there is no following "&&".
   while (p[0] == '&' && p[1] == '&') {
     // Get the second variable.
     *arg = skipwhite(*arg + 2);
     evalarg_used->eval_flags = result ? orig_flags : (orig_flags & ~EVAL_EVALUATE);
     typval_T var2;
     if (eval4(arg, &var2, evalarg_used) == FAIL) {
       return FAIL;
     }

     // Compute the result.
     if (evaluate && result) {
       bool error = false;
       if (tv_get_number_chk(&var2, &error) == 0) {
         result = false;
       }
       tv_clear(&var2);
       if (error) {
         return FAIL;
       }
     }
     if (evaluate) {
       rettv->v_type = VAR_NUMBER;
       rettv->vval.v_number = result;
     }

     p = *arg;
   }

   if (evalarg == NULL) {
     clear_evalarg(&local_evalarg, NULL);
   } else {
     evalarg->eval_flags = orig_flags;
   }
 }

 return OK;
}

/// Handle third level expression:
///      var1 == var2
///      var1 =~ var2
///      var1 != var2
///      var1 !~ var2
///      var1 > var2
///      var1 >= var2
///      var1 < var2
///      var1 <= var2
///      var1 is var2
///      var1 isnot var2
///
/// "arg" must point to the first non-white of the expression.
/// "arg" is advanced to the next non-white after the recognized expression.
///
/// @return  OK or FAIL.
static int eval4(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 typval_T var2;
 exprtype_T type = EXPR_UNKNOWN;
 int len = 2;

 // Get the first variable.
 if (eval5(arg, rettv, evalarg) == FAIL) {
   return FAIL;
 }

 char *p = *arg;
 switch (p[0]) {
 case '=':
   if (p[1] == '=') {
     type = EXPR_EQUAL;
   } else if (p[1] == '~') {
     type = EXPR_MATCH;
   }
   break;
 case '!':
   if (p[1] == '=') {
     type = EXPR_NEQUAL;
   } else if (p[1] == '~') {
     type = EXPR_NOMATCH;
   }
   break;
 case '>':
   if (p[1] != '=') {
     type = EXPR_GREATER;
     len = 1;
   } else {
     type = EXPR_GEQUAL;
   }
   break;
 case '<':
   if (p[1] != '=') {
     type = EXPR_SMALLER;
     len = 1;
   } else {
     type = EXPR_SEQUAL;
   }
   break;
 case 'i':
   if (p[1] == 's') {
     if (p[2] == 'n' && p[3] == 'o' && p[4] == 't') {
       len = 5;
     }
     if (!isalnum((uint8_t)p[len]) && p[len] != '_') {
       type = len == 2 ? EXPR_IS : EXPR_ISNOT;
     }
   }
   break;
 }

 // If there is a comparative operator, use it.
 if (type != EXPR_UNKNOWN) {
   bool ic;
   // extra question mark appended: ignore case
   if (p[len] == '?') {
     ic = true;
     len++;
   } else if (p[len] == '#') {  // extra '#' appended: match case
     ic = false;
     len++;
   } else {  // nothing appended: use 'ignorecase'
     ic = p_ic;
   }

   // Get the second variable.
   *arg = skipwhite(p + len);
   if (eval5(arg, &var2, evalarg) == FAIL) {
     tv_clear(rettv);
     return FAIL;
   }
   if (evalarg != NULL && (evalarg->eval_flags & EVAL_EVALUATE)) {
     const int ret = typval_compare(rettv, &var2, type, ic);

     tv_clear(&var2);
     return ret;
   }
 }

 return OK;
}

/// Make a copy of blob "tv1" and append blob "tv2".
static void eval_addblob(typval_T *tv1, typval_T *tv2)
{
 const blob_T *const b1 = tv1->vval.v_blob;
 const blob_T *const b2 = tv2->vval.v_blob;
 blob_T *const b = tv_blob_alloc();

 int64_t len1 = tv_blob_len(b1);
 int64_t len2 = tv_blob_len(b2);
 int64_t totallen = len1 + len2;

 if (totallen >= 0 && totallen <= INT_MAX) {
   ga_grow(&b->bv_ga, (int)totallen);
   if (len1 > 0) {
     memmove((char *)b->bv_ga.ga_data, b1->bv_ga.ga_data, (size_t)len1);
   }
   if (len2 > 0) {
     memmove((char *)b->bv_ga.ga_data + len1, b2->bv_ga.ga_data, (size_t)len2);
   }
   b->bv_ga.ga_len = (int)totallen;
 }

 tv_clear(tv1);
 tv_blob_set_ret(tv1, b);
}

/// Make a copy of list "tv1" and append list "tv2".
static int eval_addlist(typval_T *tv1, typval_T *tv2)
{
 typval_T var3;
 // Concatenate Lists.
 if (tv_list_concat(tv1->vval.v_list, tv2->vval.v_list, &var3) == FAIL) {
   tv_clear(tv1);
   tv_clear(tv2);
   return FAIL;
 }
 tv_clear(tv1);
 *tv1 = var3;
 return OK;
}

/// Concatenate strings "tv1" and "tv2" and store the result in "tv1".
static int eval_concat_str(typval_T *tv1, typval_T *tv2)
{
 char buf1[NUMBUFLEN];
 char buf2[NUMBUFLEN];
 // s1 already checked
 const char *const s1 = tv_get_string_buf(tv1, buf1);
 const char *const s2 = tv_get_string_buf_chk(tv2, buf2);
 if (s2 == NULL) {  // Type error?
   tv_clear(tv1);
   tv_clear(tv2);
   return FAIL;
 }

 char *p = concat_str(s1, s2);
 tv_clear(tv1);
 tv1->v_type = VAR_STRING;
 tv1->vval.v_string = p;

 return OK;
}

/// Add or subtract numbers "tv1" and "tv2" and store the result in "tv1".
/// The numbers can be whole numbers or floats.
static int eval_addsub_number(typval_T *tv1, typval_T *tv2, int op)
{
 bool error = false;
 varnumber_T n1, n2;
 float_T f1 = 0;
 float_T f2 = 0;

 if (tv1->v_type == VAR_FLOAT) {
   f1 = tv1->vval.v_float;
   n1 = 0;
 } else {
   n1 = tv_get_number_chk(tv1, &error);
   if (error) {
     // This can only happen for "list + non-list" or
     // "blob + non-blob".  For "non-list + ..." or
     // "something - ...", we returned before evaluating the
     // 2nd operand.
     tv_clear(tv1);
     tv_clear(tv2);
     return FAIL;
   }
   if (tv2->v_type == VAR_FLOAT) {
     f1 = (float_T)n1;
   }
 }
 if (tv2->v_type == VAR_FLOAT) {
   f2 = tv2->vval.v_float;
   n2 = 0;
 } else {
   n2 = tv_get_number_chk(tv2, &error);
   if (error) {
     tv_clear(tv1);
     tv_clear(tv2);
     return FAIL;
   }
   if (tv1->v_type == VAR_FLOAT) {
     f2 = (float_T)n2;
   }
 }
 tv_clear(tv1);

 // If there is a float on either side the result is a float.
 if (tv1->v_type == VAR_FLOAT || tv2->v_type == VAR_FLOAT) {
   if (op == '+') {
     f1 = f1 + f2;
   } else {
     f1 = f1 - f2;
   }
   tv1->v_type = VAR_FLOAT;
   tv1->vval.v_float = f1;
 } else {
   if (op == '+') {
     n1 = n1 + n2;
   } else {
     n1 = n1 - n2;
   }
   tv1->v_type = VAR_NUMBER;
   tv1->vval.v_number = n1;
 }

 return OK;
}

/// Handle fourth level expression:
///      +       number addition, concatenation of list or blob
///      -       number subtraction
///      .       string concatenation
///      ..      string concatenation
///
/// @param arg  must point to the first non-white of the expression.
///             `arg` is advanced to the next non-white after the recognized expression.
///
/// @return  OK or FAIL.
static int eval5(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 // Get the first variable.
 if (eval6(arg, rettv, evalarg, false) == FAIL) {
   return FAIL;
 }

 // Repeat computing, until no '+', '-' or '.' is following.
 while (true) {
   int op = (uint8_t)(**arg);
   bool concat = op == '.';
   if (op != '+' && op != '-' && !concat) {
     break;
   }

   const bool evaluate = evalarg == NULL ? 0 : (evalarg->eval_flags & EVAL_EVALUATE);
   if ((op != '+' || (rettv->v_type != VAR_LIST && rettv->v_type != VAR_BLOB))
       && (op == '.' || rettv->v_type != VAR_FLOAT) && evaluate) {
     // For "list + ...", an illegal use of the first operand as
     // a number cannot be determined before evaluating the 2nd
     // operand: if this is also a list, all is ok.
     // For "something . ...", "something - ..." or "non-list + ...",
     // we know that the first operand needs to be a string or number
     // without evaluating the 2nd operand.  So check before to avoid
     // side effects after an error.
     if ((op == '.' && !tv_check_str(rettv)) || (op != '.' && !tv_check_num(rettv))) {
       tv_clear(rettv);
       return FAIL;
     }
   }

   // Get the second variable.
   if (op == '.' && *(*arg + 1) == '.') {  // ..string concatenation
     (*arg)++;
   }
   *arg = skipwhite(*arg + 1);
   typval_T var2;
   if (eval6(arg, &var2, evalarg, op == '.') == FAIL) {
     tv_clear(rettv);
     return FAIL;
   }

   if (evaluate) {
     // Compute the result.
     if (op == '.') {
       if (eval_concat_str(rettv, &var2) == FAIL) {
         return FAIL;
       }
     } else if (op == '+' && rettv->v_type == VAR_BLOB && var2.v_type == VAR_BLOB) {
       eval_addblob(rettv, &var2);
     } else if (op == '+' && rettv->v_type == VAR_LIST && var2.v_type == VAR_LIST) {
       if (eval_addlist(rettv, &var2) == FAIL) {
         return FAIL;
       }
     } else {
       if (eval_addsub_number(rettv, &var2, op) == FAIL) {
         return FAIL;
       }
     }
     tv_clear(&var2);
   }
 }
 return OK;
}

/// Multiply or divide or compute the modulo of numbers "tv1" and "tv2" and
/// store the result in "tv1".  The numbers can be whole numbers or floats.
static int eval_multdiv_number(typval_T *tv1, typval_T *tv2, int op)
 FUNC_ATTR_NO_SANITIZE_UNDEFINED
{
 varnumber_T n1, n2;
 bool use_float = false;

 float_T f1 = 0;
 float_T f2 = 0;
 bool error = false;
 if (tv1->v_type == VAR_FLOAT) {
   f1 = tv1->vval.v_float;
   use_float = true;
   n1 = 0;
 } else {
   n1 = tv_get_number_chk(tv1, &error);
 }
 tv_clear(tv1);
 if (error) {
   tv_clear(tv2);
   return FAIL;
 }

 if (tv2->v_type == VAR_FLOAT) {
   if (!use_float) {
     f1 = (float_T)n1;
     use_float = true;
   }
   f2 = tv2->vval.v_float;
   n2 = 0;
 } else {
   n2 = tv_get_number_chk(tv2, &error);
   tv_clear(tv2);
   if (error) {
     return FAIL;
   }
   if (use_float) {
     f2 = (float_T)n2;
   }
 }

 // Compute the result.
 // When either side is a float the result is a float.
 if (use_float) {
   if (op == '*') {
     f1 = f1 * f2;
   } else if (op == '/') {
     // uncrustify:off

     // Division by zero triggers error from AddressSanitizer
     f1 = (f2 == 0 ? (
#ifdef NAN
         f1 == 0 ? (float_T)NAN :
#endif
         (f1 > 0 ? (float_T)INFINITY : (float_T)-INFINITY)) : f1 / f2);

     // uncrustify:on
   } else {
     emsg(_("E804: Cannot use '%' with Float"));
     return FAIL;
   }
   tv1->v_type = VAR_FLOAT;
   tv1->vval.v_float = f1;
 } else {
   if (op == '*') {
     n1 = n1 * n2;
   } else if (op == '/') {
     n1 = num_divide(n1, n2);
   } else {
     n1 = num_modulus(n1, n2);
   }
   tv1->v_type = VAR_NUMBER;
   tv1->vval.v_number = n1;
 }

 return OK;
}

/// Handle fifth level expression:
///  - *  number multiplication
///  - /  number division
///  - %  number modulo
///
/// @param[in,out]  arg  Points to the first non-whitespace character of the
///                      expression.  Is advanced to the next non-whitespace
///                      character after the recognized expression.
/// @param[out]  rettv  Location where result is saved.
/// @param[in]  want_string  True if "." is string_concatenation, otherwise
///                          float
/// @return  OK or FAIL.
static int eval6(char **arg, typval_T *rettv, evalarg_T *const evalarg, bool want_string)
{
 // Get the first variable.
 if (eval7(arg, rettv, evalarg, want_string) == FAIL) {
   return FAIL;
 }

 // Repeat computing, until no '*', '/' or '%' is following.
 while (true) {
   int op = (uint8_t)(**arg);
   if (op != '*' && op != '/' && op != '%') {
     break;
   }

   const bool evaluate = evalarg == NULL ? 0 : (evalarg->eval_flags & EVAL_EVALUATE);

   // Get the second variable.
   *arg = skipwhite(*arg + 1);
   typval_T var2;
   if (eval7(arg, &var2, evalarg, false) == FAIL) {
     return FAIL;
   }

   if (evaluate) {
     // Compute the result.
     if (eval_multdiv_number(rettv, &var2, op) == FAIL) {
       return FAIL;
     }
   }
 }

 return OK;
}

/// Handle sixth level expression:
///  number  number constant
///  0zFFFFFFFF  Blob constant
///  "string"  string constant
///  'string'  literal string constant
///  &option-name option value
///  @r   register contents
///  identifier  variable value
///  function()  function call
///  $VAR  environment variable
///  (expression) nested expression
///  [expr, expr] List
///  {key: val, key: val}  Dictionary
///  #{key: val, key: val}  Dictionary with literal keys
///
///  Also handle:
///  ! in front  logical NOT
///  - in front  unary minus
///  + in front  unary plus (ignored)
///  trailing []  subscript in String or List
///  trailing .name entry in Dictionary
///  trailing ->name()  method call
///
/// "arg" must point to the first non-white of the expression.
/// "arg" is advanced to the next non-white after the recognized expression.
///
/// @param want_string  after "." operator
///
/// @return  OK or FAIL.
static int eval7(char **arg, typval_T *rettv, evalarg_T *const evalarg, bool want_string)
{
 const bool evaluate = evalarg != NULL && (evalarg->eval_flags & EVAL_EVALUATE);
 int ret = OK;
 static int recurse = 0;

 // Initialise variable so that tv_clear() can't mistake this for a
 // string and free a string that isn't there.
 rettv->v_type = VAR_UNKNOWN;

 // Skip '!', '-' and '+' characters.  They are handled later.
 const char *start_leader = *arg;
 while (**arg == '!' || **arg == '-' || **arg == '+') {
   *arg = skipwhite(*arg + 1);
 }
 const char *end_leader = *arg;

 // Limit recursion to 1000 levels.  At least at 10000 we run out of stack
 // and crash.  With MSVC the stack is smaller.
 if (recurse ==
#ifdef _MSC_VER
     300
#else
     1000
#endif
     ) {
   semsg(_(e_expression_too_recursive_str), *arg);
   return FAIL;
 }
 recurse++;

 switch (**arg) {
 // Number constant.
 case '0':
 case '1':
 case '2':
 case '3':
 case '4':
 case '5':
 case '6':
 case '7':
 case '8':
 case '9':
   ret = eval_number(arg, rettv, evaluate, want_string);

   // Apply prefixed "-" and "+" now.  Matters especially when
   // "->" follows.
   if (ret == OK && evaluate && end_leader > start_leader) {
     ret = eval7_leader(rettv, true, start_leader, &end_leader);
   }
   break;

 // String constant: "string".
 case '"':
   ret = eval_string(arg, rettv, evaluate, false);
   break;

 // Literal string constant: 'str''ing'.
 case '\'':
   ret = eval_lit_string(arg, rettv, evaluate, false);
   break;

 // List: [expr, expr]
 case '[':
   ret = eval_list(arg, rettv, evalarg);
   break;

 // Literal Dictionary: #{key: val, key: val}
 case '#':
   ret = eval_lit_dict(arg, rettv, evalarg);
   break;

 // Lambda: {arg, arg -> expr}
 // Dictionary: {'key': val, 'key': val}
 case '{':
   ret = get_lambda_tv(arg, rettv, evalarg);
   if (ret == NOTDONE) {
     ret = eval_dict(arg, rettv, evalarg, false);
   }
   break;

 // Option value: &name
 case '&':
   ret = eval_option((const char **)arg, rettv, evaluate);
   break;
 // Environment variable: $VAR.
 // Interpolated string: $"string" or $'string'.
 case '$':
   if ((*arg)[1] == '"' || (*arg)[1] == '\'') {
     ret = eval_interp_string(arg, rettv, evaluate);
   } else {
     ret = eval_env_var(arg, rettv, evaluate);
   }
   break;

 // Register contents: @r.
 case '@':
   (*arg)++;
   if (evaluate) {
     rettv->v_type = VAR_STRING;
     rettv->vval.v_string = get_reg_contents(**arg, kGRegExprSrc);
   }
   if (**arg != NUL) {
     (*arg)++;
   }
   break;

 // nested expression: (expression).
 case '(':
   *arg = skipwhite(*arg + 1);

   ret = eval1(arg, rettv, evalarg);  // recursive!
   if (**arg == ')') {
     (*arg)++;
   } else if (ret == OK) {
     emsg(_("E110: Missing ')'"));
     tv_clear(rettv);
     ret = FAIL;
   }
   break;

 default:
   ret = NOTDONE;
   break;
 }

 if (ret == NOTDONE) {
   // Must be a variable or function name.
   // Can also be a curly-braces kind of name: {expr}.
   char *s = *arg;
   char *alias;
   int len = get_name_len((const char **)arg, &alias, evaluate, true);
   if (alias != NULL) {
     s = alias;
   }

   if (len <= 0) {
     ret = FAIL;
   } else {
     const int flags = evalarg == NULL ? 0 : evalarg->eval_flags;
     if (*skipwhite(*arg) == '(') {
       // "name(..."  recursive!
       *arg = skipwhite(*arg);
       ret = eval_func(arg, evalarg, s, len, rettv, flags, NULL);
     } else if (evaluate) {
       // get value of variable
       ret = eval_variable(s, len, rettv, NULL, true, false);
     } else {
       // skip the name
       check_vars(s, (size_t)len);
       // If evaluate is false rettv->v_type was not set, but it's needed
       // in handle_subscript() to parse v:lua, so set it here.
       if (rettv->v_type == VAR_UNKNOWN && !evaluate && strnequal(s, "v:lua.", 6)) {
         rettv->v_type = VAR_PARTIAL;
         rettv->vval.v_partial = get_vim_var_partial(VV_LUA);
         rettv->vval.v_partial->pt_refcount++;
       }
       ret = OK;
     }
   }
   xfree(alias);
 }

 *arg = skipwhite(*arg);

 // Handle following '[', '(' and '.' for expr[expr], expr.name,
 // expr(expr), expr->name(expr)
 if (ret == OK) {
   ret = handle_subscript((const char **)arg, rettv, evalarg, true);
 }

 // Apply logical NOT and unary '-', from right to left, ignore '+'.
 if (ret == OK && evaluate && end_leader > start_leader) {
   ret = eval7_leader(rettv, false, start_leader, &end_leader);
 }

 recurse--;
 return ret;
}

/// Apply the leading "!" and "-" before an eval7 expression to "rettv".
/// Adjusts "end_leaderp" until it is at "start_leader".
///
/// @param numeric_only  if true only handle "+" and "-".
///
/// @return  OK on success, FAIL on failure.
static int eval7_leader(typval_T *const rettv, const bool numeric_only,
                       const char *const start_leader, const char **const end_leaderp)
 FUNC_ATTR_NONNULL_ALL
{
 const char *end_leader = *end_leaderp;
 int ret = OK;
 bool error = false;
 varnumber_T val = 0;
 float_T f = 0.0;

 if (rettv->v_type == VAR_FLOAT) {
   f = rettv->vval.v_float;
 } else {
   val = tv_get_number_chk(rettv, &error);
 }
 if (error) {
   tv_clear(rettv);
   ret = FAIL;
 } else {
   while (end_leader > start_leader) {
     end_leader--;
     if (*end_leader == '!') {
       if (numeric_only) {
         end_leader++;
         break;
       }
       if (rettv->v_type == VAR_FLOAT) {
         rettv->v_type = VAR_BOOL;
         val = f == 0.0 ? kBoolVarTrue : kBoolVarFalse;
       } else {
         val = !val;
       }
     } else if (*end_leader == '-') {
       if (rettv->v_type == VAR_FLOAT) {
         f = -f;
       } else {
         val = -val;
       }
     }
   }
   if (rettv->v_type == VAR_FLOAT) {
     tv_clear(rettv);
     rettv->vval.v_float = f;
   } else {
     tv_clear(rettv);
     rettv->v_type = VAR_NUMBER;
     rettv->vval.v_number = val;
   }
 }

 *end_leaderp = end_leader;
 return ret;
}

/// Call the function referred to in "rettv".
/// @param lua_funcname  If `rettv` refers to a v:lua function, this must point
///                      to the name of the Lua function to call (after the
///                      "v:lua." prefix).
/// @return  OK on success, FAIL on failure.
static int call_func_rettv(char **const arg, evalarg_T *const evalarg, typval_T *const rettv,
                          const bool evaluate, dict_T *const selfdict, typval_T *const basetv,
                          const char *const lua_funcname)
 FUNC_ATTR_NONNULL_ARG(1, 3)
{
 partial_T *pt = NULL;
 typval_T functv;
 const char *funcname;
 bool is_lua = false;
 int ret;

 // need to copy the funcref so that we can clear rettv
 if (evaluate) {
   functv = *rettv;
   rettv->v_type = VAR_UNKNOWN;

   // Invoke the function.  Recursive!
   if (functv.v_type == VAR_PARTIAL) {
     pt = functv.vval.v_partial;
     is_lua = is_luafunc(pt);
     funcname = is_lua ? lua_funcname : partial_name(pt);
   } else {
     funcname = functv.vval.v_string;
     if (funcname == NULL || *funcname == NUL) {
       emsg(_(e_empty_function_name));
       ret = FAIL;
       goto theend;
     }
   }
 } else {
   funcname = "";
 }

 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_firstline = curwin->w_cursor.lnum;
 funcexe.fe_lastline = curwin->w_cursor.lnum;
 funcexe.fe_evaluate = evaluate;
 funcexe.fe_partial = pt;
 funcexe.fe_selfdict = selfdict;
 funcexe.fe_basetv = basetv;
 ret = get_func_tv(funcname, is_lua ? (int)(*arg - funcname) : -1, rettv,
                   arg, evalarg, &funcexe);

theend:
 // Clear the funcref afterwards, so that deleting it while
 // evaluating the arguments is possible (see test55).
 if (evaluate) {
   tv_clear(&functv);
 }

 return ret;
}

/// Evaluate "->method()".
///
/// @param verbose  if true, give error messages.
/// @param *arg     points to the '-'.
///
/// @return  FAIL or OK.
///
/// @note "*arg" is advanced to after the ')'.
static int eval_lambda(char **const arg, typval_T *const rettv, evalarg_T *const evalarg,
                      const bool verbose)
 FUNC_ATTR_NONNULL_ARG(1, 2)
{
 const bool evaluate = evalarg != NULL && (evalarg->eval_flags & EVAL_EVALUATE);
 // Skip over the ->.
 *arg += 2;
 typval_T base = *rettv;
 rettv->v_type = VAR_UNKNOWN;

 int ret = get_lambda_tv(arg, rettv, evalarg);
 if (ret != OK) {
   return FAIL;
 } else if (**arg != '(') {
   if (verbose) {
     if (*skipwhite(*arg) == '(') {
       emsg(_(e_nowhitespace));
     } else {
       semsg(_(e_missingparen), "lambda");
     }
   }
   tv_clear(rettv);
   ret = FAIL;
 } else {
   ret = call_func_rettv(arg, evalarg, rettv, evaluate, NULL, &base, NULL);
 }

 // Clear the funcref afterwards, so that deleting it while
 // evaluating the arguments is possible (see test55).
 if (evaluate) {
   tv_clear(&base);
 }

 return ret;
}

/// Evaluate "->method()" or "->v:lua.method()".
///
/// @param *arg  points to the '-'.
///
/// @return  FAIL or OK. "*arg" is advanced to after the ')'.
static int eval_method(char **const arg, typval_T *const rettv, evalarg_T *const evalarg,
                      const bool verbose)
 FUNC_ATTR_NONNULL_ARG(1, 2)
{
 const bool evaluate = evalarg != NULL && (evalarg->eval_flags & EVAL_EVALUATE);

 // Skip over the ->.
 *arg += 2;
 typval_T base = *rettv;
 rettv->v_type = VAR_UNKNOWN;

 // Locate the method name.
 int len;
 char *name = *arg;
 char *lua_funcname = NULL;
 char *alias = NULL;
 if (strnequal(name, "v:lua.", 6)) {
   lua_funcname = name + 6;
   *arg = (char *)skip_luafunc_name(lua_funcname);
   *arg = skipwhite(*arg);  // to detect trailing whitespace later
   len = (int)(*arg - lua_funcname);
 } else {
   len = get_name_len((const char **)arg, &alias, evaluate, true);
   if (alias != NULL) {
     name = alias;
   }
 }

 char *tofree = NULL;
 int ret = OK;

 if (len <= 0) {
   if (verbose) {
     if (lua_funcname == NULL) {
       emsg(_("E260: Missing name after ->"));
     } else {
       semsg(_(e_invexpr2), name);
     }
   }
   ret = FAIL;
 } else {
   *arg = skipwhite(*arg);

   // If there is no "(" immediately following, but there is further on,
   // it can be "dict.Func()", "list[nr]", etc.
   // Does not handle anything where "(" is part of the expression.
   char *paren;
   if (**arg != '(' && lua_funcname == NULL && alias == NULL
       && (paren = vim_strchr(*arg, '(')) != NULL) {
     *arg = name;
     *paren = NUL;
     typval_T ref;
     ref.v_type = VAR_UNKNOWN;
     if (eval7(arg, &ref, evalarg, false) == FAIL) {
       *arg = name + len;
       ret = FAIL;
     } else if (*skipwhite(*arg) != NUL) {
       if (verbose) {
         semsg(_(e_trailing_arg), *arg);
       }
       ret = FAIL;
     } else if (ref.v_type == VAR_FUNC && ref.vval.v_string != NULL) {
       name = ref.vval.v_string;
       ref.vval.v_string = NULL;
       tofree = name;
       len = (int)strlen(name);
     } else if (ref.v_type == VAR_PARTIAL && ref.vval.v_partial != NULL) {
       if (ref.vval.v_partial->pt_argc > 0 || ref.vval.v_partial->pt_dict != NULL) {
         if (verbose) {
           emsg(_(e_cannot_use_partial_here));
         }
         ret = FAIL;
       } else {
         name = xstrdup(partial_name(ref.vval.v_partial));
         tofree = name;
         if (name == NULL) {
           ret = FAIL;
           name = *arg;
         } else {
           len = (int)strlen(name);
         }
       }
     } else {
       if (verbose) {
         semsg(_(e_not_callable_type_str), name);
       }
       ret = FAIL;
     }
     tv_clear(&ref);
     *paren = '(';
   }

   if (ret == OK) {
     if (**arg != '(') {
       if (verbose) {
         semsg(_(e_missingparen), name);
       }
       ret = FAIL;
     } else if (ascii_iswhite((*arg)[-1])) {
       if (verbose) {
         emsg(_(e_nowhitespace));
       }
       ret = FAIL;
     } else if (lua_funcname != NULL) {
       if (evaluate) {
         rettv->v_type = VAR_PARTIAL;
         rettv->vval.v_partial = get_vim_var_partial(VV_LUA);
         rettv->vval.v_partial->pt_refcount++;
       }
       ret = call_func_rettv(arg, evalarg, rettv, evaluate, NULL, &base, lua_funcname);
     } else {
       ret = eval_func(arg, evalarg, name, len, rettv,
                       evaluate ? EVAL_EVALUATE : 0, &base);
     }
   }
 }

 // Clear the funcref afterwards, so that deleting it while
 // evaluating the arguments is possible (see test55).
 if (evaluate) {
   tv_clear(&base);
 }
 xfree(tofree);

 if (alias != NULL) {
   xfree(alias);
 }

 return ret;
}

/// Evaluate an "[expr]" or "[expr:expr]" index.  Also "dict.key".
/// "*arg" points to the '[' or '.'.
///
/// @param verbose  give error messages
///
/// @returns FAIL or OK. "*arg" is advanced to after the ']'.
static int eval_index(char **arg, typval_T *rettv, evalarg_T *const evalarg, bool verbose)
{
 const bool evaluate = evalarg != NULL && (evalarg->eval_flags & EVAL_EVALUATE);
 bool empty1 = false;
 bool empty2 = false;
 bool range = false;
 const char *key = NULL;
 ptrdiff_t keylen = -1;

 if (check_can_index(rettv, evaluate, verbose) == FAIL) {
   return FAIL;
 }

 typval_T var1 = TV_INITIAL_VALUE;
 typval_T var2 = TV_INITIAL_VALUE;
 if (**arg == '.') {
   // dict.name
   key = *arg + 1;
   for (keylen = 0; eval_isdictc(key[keylen]); keylen++) {}
   if (keylen == 0) {
     return FAIL;
   }
   *arg = skipwhite(key + keylen);
 } else {
   // something[idx]
   //
   // Get the (first) variable from inside the [].
   *arg = skipwhite(*arg + 1);
   if (**arg == ':') {
     empty1 = true;
   } else if (eval1(arg, &var1, evalarg) == FAIL) {  // Recursive!
     return FAIL;
   } else if (evaluate && !tv_check_str(&var1)) {
     // Not a number or string.
     tv_clear(&var1);
     return FAIL;
   }

   // Get the second variable from inside the [:].
   if (**arg == ':') {
     range = true;
     *arg = skipwhite(*arg + 1);
     if (**arg == ']') {
       empty2 = true;
     } else if (eval1(arg, &var2, evalarg) == FAIL) {  // Recursive!
       if (!empty1) {
         tv_clear(&var1);
       }
       return FAIL;
     } else if (evaluate && !tv_check_str(&var2)) {
       // Not a number or string.
       if (!empty1) {
         tv_clear(&var1);
       }
       tv_clear(&var2);
       return FAIL;
     }
   }

   // Check for the ']'.
   if (**arg != ']') {
     if (verbose) {
       emsg(_(e_missbrac));
     }
     tv_clear(&var1);
     if (range) {
       tv_clear(&var2);
     }
     return FAIL;
   }
   *arg = skipwhite(*arg + 1);         // skip the ']'
 }

 if (evaluate) {
   int res = eval_index_inner(rettv, range,
                              empty1 ? NULL : &var1, empty2 ? NULL : &var2, false,
                              key, keylen, verbose);
   if (!empty1) {
     tv_clear(&var1);
   }
   if (range) {
     tv_clear(&var2);
   }
   return res;
 }
 return OK;
}

/// Check if "rettv" can have an [index] or [sli:ce]
static int check_can_index(typval_T *rettv, bool evaluate, bool verbose)
{
 switch (rettv->v_type) {
 case VAR_FUNC:
 case VAR_PARTIAL:
   if (verbose) {
     emsg(_(e_cannot_index_a_funcref));
   }
   return FAIL;
 case VAR_FLOAT:
   if (verbose) {
     emsg(_(e_using_float_as_string));
   }
   return FAIL;
 case VAR_BOOL:
 case VAR_SPECIAL:
   if (verbose) {
     emsg(_(e_cannot_index_special_variable));
   }
   return FAIL;
 case VAR_UNKNOWN:
   if (evaluate) {
     emsg(_(e_cannot_index_special_variable));
     return FAIL;
   }
   FALLTHROUGH;
 case VAR_STRING:
 case VAR_NUMBER:
 case VAR_LIST:
 case VAR_DICT:
 case VAR_BLOB:
   break;
 }
 return OK;
}

/// slice() function
void f_slice(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 if (check_can_index(&argvars[0], true, false) != OK) {
   return;
 }

 tv_copy(argvars, rettv);
 eval_index_inner(rettv, true, argvars + 1,
                  argvars[2].v_type == VAR_UNKNOWN ? NULL : argvars + 2,
                  true, NULL, 0, false);
}

/// Apply index or range to "rettv".
///
/// @param var1  the first index, NULL for [:expr].
/// @param var2  the second index, NULL for [expr] and [expr: ]
/// @param exclusive  true for slice(): second index is exclusive, use character
///                                     index for string.
/// Alternatively, "key" is not NULL, then key[keylen] is the dict index.
static int eval_index_inner(typval_T *rettv, bool is_range, typval_T *var1, typval_T *var2,
                           bool exclusive, const char *key, ptrdiff_t keylen, bool verbose)
{
 varnumber_T n1 = 0;
 varnumber_T n2 = 0;
 if (var1 != NULL && rettv->v_type != VAR_DICT) {
   n1 = tv_get_number(var1);
 }

 if (is_range) {
   if (rettv->v_type == VAR_DICT) {
     if (verbose) {
       emsg(_(e_cannot_slice_dictionary));
     }
     return FAIL;
   }
   if (var2 != NULL) {
     n2 = tv_get_number(var2);
   } else {
     n2 = VARNUMBER_MAX;
   }
 }

 switch (rettv->v_type) {
 case VAR_BOOL:
 case VAR_SPECIAL:
 case VAR_FUNC:
 case VAR_FLOAT:
 case VAR_PARTIAL:
 case VAR_UNKNOWN:
   break;  // Not evaluating, skipping over subscript

 case VAR_NUMBER:
 case VAR_STRING: {
   const char *const s = tv_get_string(rettv);
   char *v;
   int len = (int)strlen(s);
   if (exclusive) {
     if (is_range) {
       v = string_slice(s, n1, n2, exclusive);
     } else {
       v = char_from_string(s, n1);
     }
   } else if (is_range) {
     // The resulting variable is a substring.  If the indexes
     // are out of range the result is empty.
     if (n1 < 0) {
       n1 = len + n1;
       if (n1 < 0) {
         n1 = 0;
       }
     }
     if (n2 < 0) {
       n2 = len + n2;
     } else if (n2 >= len) {
       n2 = len;
     }
     if (n1 >= len || n2 < 0 || n1 > n2) {
       v = NULL;
     } else {
       v = xmemdupz(s + n1, (size_t)n2 - (size_t)n1 + 1);
     }
   } else {
     // The resulting variable is a string of a single
     // character.  If the index is too big or negative the
     // result is empty.
     if (n1 >= len || n1 < 0) {
       v = NULL;
     } else {
       v = xmemdupz(s + n1, 1);
     }
   }
   tv_clear(rettv);
   rettv->v_type = VAR_STRING;
   rettv->vval.v_string = v;
   break;
 }

 case VAR_BLOB:
   tv_blob_slice_or_index(rettv->vval.v_blob, is_range, n1, n2, exclusive, rettv);
   break;

 case VAR_LIST:
   if (var1 == NULL) {
     n1 = 0;
   }
   if (var2 == NULL) {
     n2 = VARNUMBER_MAX;
   }
   if (tv_list_slice_or_index(rettv->vval.v_list,
                              is_range, n1, n2, exclusive, rettv, verbose) == FAIL) {
     return FAIL;
   }
   break;

 case VAR_DICT: {
   if (key == NULL) {
     key = tv_get_string_chk(var1);
     if (key == NULL) {
       return FAIL;
     }
   }

   dictitem_T *const item = tv_dict_find(rettv->vval.v_dict, key, keylen);

   if (item == NULL && verbose) {
     if (keylen > 0) {
       semsg(_(e_dictkey_len), keylen, key);
     } else {
       semsg(_(e_dictkey), key);
     }
   }
   if (item == NULL || tv_is_luafunc(&item->di_tv)) {
     return FAIL;
   }

   typval_T tmp;
   tv_copy(&item->di_tv, &tmp);
   tv_clear(rettv);
   *rettv = tmp;
   break;
 }
 }
 return OK;
}

/// Get an option value
///
/// @param[in,out] arg  Points to the '&' or '+' before the option name. Is
///                      advanced to the character after the option name.
/// @param[out] rettv  Location where result is saved.
/// @param[in] evaluate  If not true, rettv is not populated.
///
/// @return  OK or FAIL.
int eval_option(const char **const arg, typval_T *const rettv, const bool evaluate)
 FUNC_ATTR_NONNULL_ARG(1)
{
 const bool working = (**arg == '+');  // has("+option")
 OptIndex opt_idx;
 int opt_flags;

 // Isolate the option name and find its value.
 char *const option_end = (char *)find_option_var_end(arg, &opt_idx, &opt_flags);

 if (option_end == NULL) {
   if (rettv != NULL) {
     semsg(_("E112: Option name missing: %s"), *arg);
   }
   return FAIL;
 }

 if (!evaluate) {
   *arg = option_end;
   return OK;
 }

 char c = *option_end;
 *option_end = NUL;

 int ret = OK;
 bool is_tty_opt = is_tty_option(*arg);

 if (opt_idx == kOptInvalid && !is_tty_opt) {
   // Only give error if result is going to be used.
   if (rettv != NULL) {
     semsg(_("E113: Unknown option: %s"), *arg);
   }

   ret = FAIL;
 } else if (rettv != NULL) {
   OptVal value = is_tty_opt ? get_tty_option(*arg) : get_option_value(opt_idx, opt_flags);
   assert(value.type != kOptValTypeNil);

   *rettv = optval_as_tv(value, true);
 } else if (working && !is_tty_opt && is_option_hidden(opt_idx)) {
   ret = FAIL;
 }

 *option_end = c;                  // put back for error messages
 *arg = option_end;

 return ret;
}

/// Allocate a variable for a number constant.  Also deals with "0z" for blob.
///
/// @return  OK or FAIL.
static int eval_number(char **arg, typval_T *rettv, bool evaluate, bool want_string)
{
 char *p = skipdigits(*arg + 1);
 bool get_float = false;

 // We accept a float when the format matches
 // "[0-9]\+\.[0-9]\+\([eE][+-]\?[0-9]\+\)\?".  This is very
 // strict to avoid backwards compatibility problems.
 // Don't look for a float after the "." operator, so that
 // ":let vers = 1.2.3" doesn't fail.
 if (!want_string && p[0] == '.' && ascii_isdigit(p[1])) {
   get_float = true;
   p = skipdigits(p + 2);
   if (*p == 'e' || *p == 'E') {
     p++;
     if (*p == '-' || *p == '+') {
       p++;
     }
     if (!ascii_isdigit(*p)) {
       get_float = false;
     } else {
       p = skipdigits(p + 1);
     }
   }
   if (ASCII_ISALPHA(*p) || *p == '.') {
     get_float = false;
   }
 }
 if (get_float) {
   float_T f;
   *arg += string2float(*arg, &f);
   if (evaluate) {
     rettv->v_type = VAR_FLOAT;
     rettv->vval.v_float = f;
   }
 } else if (**arg == '0' && ((*arg)[1] == 'z' || (*arg)[1] == 'Z')) {
   // Blob constant: 0z0123456789abcdef
   blob_T *blob = NULL;
   if (evaluate) {
     blob = tv_blob_alloc();
   }
   char *bp;
   for (bp = *arg + 2; ascii_isxdigit(bp[0]); bp += 2) {
     if (!ascii_isxdigit(bp[1])) {
       if (blob != NULL) {
         emsg(_("E973: Blob literal should have an even number of hex characters"));
         ga_clear(&blob->bv_ga);
         XFREE_CLEAR(blob);
       }
       return FAIL;
     }
     if (blob != NULL) {
       ga_append(&blob->bv_ga, (uint8_t)((hex2nr(*bp) << 4) + hex2nr(*(bp + 1))));
     }
     if (bp[2] == '.' && ascii_isxdigit(bp[3])) {
       bp++;
     }
   }
   if (blob != NULL) {
     tv_blob_set_ret(rettv, blob);
   }
   *arg = bp;
 } else {
   // decimal, hex or octal number
   int len;
   varnumber_T n;
   vim_str2nr(*arg, NULL, &len, STR2NR_ALL, &n, NULL, 0, true, NULL);
   if (len == 0) {
     if (evaluate) {
       semsg(_(e_invexpr2), *arg);
     }
     return FAIL;
   }
   *arg += len;
   if (evaluate) {
     rettv->v_type = VAR_NUMBER;
     rettv->vval.v_number = n;
   }
 }
 return OK;
}

/// Evaluate a string constant and put the result in "rettv".
/// "*arg" points to the double quote or to after it when "interpolate" is true.
/// When "interpolate" is true reduce "{{" to "{", reduce "}}" to "}" and stop
/// at a single "{".
///
/// @return  OK or FAIL.
static int eval_string(char **arg, typval_T *rettv, bool evaluate, bool interpolate)
{
 char *p;
 const char *const arg_end = *arg + strlen(*arg);
 unsigned extra = interpolate ? 1 : 0;
 const int off = interpolate ? 0 : 1;

 // Find the end of the string, skipping backslashed characters.
 for (p = *arg + off; *p != NUL && *p != '"'; MB_PTR_ADV(p)) {
   if (*p == '\\' && p[1] != NUL) {
     p++;
     // A "\<x>" form occupies at least 4 characters, and produces up
     // to 9 characters (6 for the char and 3 for a modifier):
     // reserve space for 5 extra.
     if (*p == '<') {
       int modifiers = 0;
       int flags = FSK_KEYCODE | FSK_IN_STRING;

       extra += 5;

       // Skip to the '>' to avoid using '{' inside for string
       // interpolation.
       if (p[1] != '*') {
         flags |= FSK_SIMPLIFY;
       }
       if (find_special_key((const char **)&p, (size_t)(arg_end - p),
                            &modifiers, flags, NULL) != 0) {
         p--;  // leave "p" on the ">"
       }
     }
   } else if (interpolate && (*p == '{' || *p == '}')) {
     if (*p == '{' && p[1] != '{') {  // start of expression
       break;
     }
     p++;
     if (p[-1] == '}' && *p != '}') {  // single '}' is an error
       semsg(_(e_stray_closing_curly_str), *arg);
       return FAIL;
     }
     extra--;  // "{{" becomes "{", "}}" becomes "}"
   }
 }

 if (*p != '"' && !(interpolate && *p == '{')) {
   semsg(_("E114: Missing quote: %s"), *arg);
   return FAIL;
 }

 // If only parsing, set *arg and return here
 if (!evaluate) {
   *arg = p + off;
   return OK;
 }

 // Copy the string into allocated memory, handling backslashed
 // characters.
 rettv->v_type = VAR_STRING;
 const int len = (int)(p - *arg + extra);
 rettv->vval.v_string = xmalloc((size_t)len);
 char *end = rettv->vval.v_string;

 for (p = *arg + off; *p != NUL && *p != '"';) {
   if (*p == '\\') {
     switch (*++p) {
     case 'b':
       *end++ = BS; ++p; break;
     case 'e':
       *end++ = ESC; ++p; break;
     case 'f':
       *end++ = FF; ++p; break;
     case 'n':
       *end++ = NL; ++p; break;
     case 'r':
       *end++ = CAR; ++p; break;
     case 't':
       *end++ = TAB; ++p; break;

     case 'X':           // hex: "\x1", "\x12"
     case 'x':
     case 'u':           // Unicode: "\u0023"
     case 'U':
       if (ascii_isxdigit(p[1])) {
         int n, nr;
         int c = toupper((uint8_t)(*p));

         if (c == 'X') {
           n = 2;
         } else if (*p == 'u') {
           n = 4;
         } else {
           n = 8;
         }
         nr = 0;
         while (--n >= 0 && ascii_isxdigit(p[1])) {
           p++;
           nr = (nr << 4) + hex2nr(*p);
         }
         p++;
         // For "\u" store the number according to
         // 'encoding'.
         if (c != 'X') {
           end += utf_char2bytes(nr, end);
         } else {
           *end++ = (char)nr;
         }
       }
       break;

     // octal: "\1", "\12", "\123"
     case '0':
     case '1':
     case '2':
     case '3':
     case '4':
     case '5':
     case '6':
     case '7':
       *end = (char)(*p++ - '0');
       if (*p >= '0' && *p <= '7') {
         *end = (char)((*end << 3) + *p++ - '0');
         if (*p >= '0' && *p <= '7') {
           *end = (char)((*end << 3) + *p++ - '0');
         }
       }
       end++;
       break;

     // Special key, e.g.: "\<C-W>"
     case '<': {
       int flags = FSK_KEYCODE | FSK_IN_STRING;

       if (p[1] != '*') {
         flags |= FSK_SIMPLIFY;
       }
       extra = trans_special((const char **)&p, (size_t)(arg_end - p),
                             end, flags, false, NULL);
       if (extra != 0) {
         end += extra;
         if (end >= rettv->vval.v_string + len) {
           iemsg("eval_string() used more space than allocated");
         }
         break;
       }
     }
       FALLTHROUGH;

     default:
       mb_copy_char((const char **)&p, &end);
       break;
     }
   } else {
     if (interpolate && (*p == '{' || *p == '}')) {
       if (*p == '{' && p[1] != '{') {  // start of expression
         break;
       }
       p++;  // reduce "{{" to "{" and "}}" to "}"
     }
     mb_copy_char((const char **)&p, &end);
   }
 }
 *end = NUL;
 if (*p == '"' && !interpolate) {
   p++;
 }
 *arg = p;

 return OK;
}

/// Allocate a variable for a 'str''ing' constant.
/// When "interpolate" is true reduce "{{" to "{" and stop at a single "{".
///
/// @return  OK when a "rettv" was set to the string.
///          FAIL on error, "rettv" is not set.
static int eval_lit_string(char **arg, typval_T *rettv, bool evaluate, bool interpolate)
{
 char *p;
 int reduce = interpolate ? -1 : 0;
 const int off = interpolate ? 0 : 1;

 // Find the end of the string, skipping ''.
 for (p = *arg + off; *p != NUL; MB_PTR_ADV(p)) {
   if (*p == '\'') {
     if (p[1] != '\'') {
       break;
     }
     reduce++;
     p++;
   } else if (interpolate) {
     if (*p == '{') {
       if (p[1] != '{') {
         break;
       }
       p++;
       reduce++;
     } else if (*p == '}') {
       p++;
       if (*p != '}') {
         semsg(_(e_stray_closing_curly_str), *arg);
         return FAIL;
       }
       reduce++;
     }
   }
 }

 if (*p != '\'' && !(interpolate && *p == '{')) {
   semsg(_("E115: Missing quote: %s"), *arg);
   return FAIL;
 }

 // If only parsing return after setting "*arg"
 if (!evaluate) {
   *arg = p + off;
   return OK;
 }

 // Copy the string into allocated memory, handling '' to ' reduction and
 // any expressions.
 char *str = xmalloc((size_t)((p - *arg) - reduce));
 rettv->v_type = VAR_STRING;
 rettv->vval.v_string = str;

 for (p = *arg + off; *p != NUL;) {
   if (*p == '\'') {
     if (p[1] != '\'') {
       break;
     }
     p++;
   } else if (interpolate && (*p == '{' || *p == '}')) {
     if (*p == '{' && p[1] != '{') {
       break;
     }
     p++;
   }
   mb_copy_char((const char **)&p, &str);
 }
 *str = NUL;
 *arg = p + off;

 return OK;
}

/// Evaluate a single or double quoted string possibly containing expressions.
/// "arg" points to the '$'.  The result is put in "rettv".
///
/// @return  OK or FAIL.
int eval_interp_string(char **arg, typval_T *rettv, bool evaluate)
{
 int ret = OK;

 garray_T ga;
 ga_init(&ga, 1, 80);

 // *arg is on the '$' character, move it to the first string character.
 (*arg)++;
 const int quote = (uint8_t)(**arg);
 (*arg)++;

 while (true) {
   typval_T tv;
   // Get the string up to the matching quote or to a single '{'.
   // "arg" is advanced to either the quote or the '{'.
   if (quote == '"') {
     ret = eval_string(arg, &tv, evaluate, true);
   } else {
     ret = eval_lit_string(arg, &tv, evaluate, true);
   }
   if (ret == FAIL) {
     break;
   }
   if (evaluate) {
     ga_concat(&ga, tv.vval.v_string);
     tv_clear(&tv);
   }

   if (**arg != '{') {
     // found terminating quote
     (*arg)++;
     break;
   }
   char *p = eval_one_expr_in_str(*arg, &ga, evaluate);
   if (p == NULL) {
     ret = FAIL;
     break;
   }
   *arg = p;
 }

 rettv->v_type = VAR_STRING;
 if (ret != FAIL && evaluate) {
   ga_append(&ga, NUL);
 }
 rettv->vval.v_string = ga.ga_data;
 return OK;
}

/// @return  the function name of the partial.
char *partial_name(partial_T *pt)
 FUNC_ATTR_PURE
{
 if (pt != NULL) {
   if (pt->pt_name != NULL) {
     return pt->pt_name;
   }
   if (pt->pt_func != NULL) {
     return pt->pt_func->uf_name;
   }
 }
 return "";
}

static void partial_free(partial_T *pt)
{
 for (int i = 0; i < pt->pt_argc; i++) {
   tv_clear(&pt->pt_argv[i]);
 }
 xfree(pt->pt_argv);
 tv_dict_unref(pt->pt_dict);
 if (pt->pt_name != NULL) {
   func_unref(pt->pt_name);
   xfree(pt->pt_name);
 } else {
   func_ptr_unref(pt->pt_func);
 }
 xfree(pt);
}

/// Unreference a closure: decrement the reference count and free it when it
/// becomes zero.
void partial_unref(partial_T *pt)
{
 if (pt == NULL) {
   return;
 }

 if (--pt->pt_refcount <= 0) {
   partial_free(pt);
 }
}

/// Allocate a variable for a List and fill it from "*arg".
///
/// @param arg  "*arg" points to the "[".
/// @return  OK or FAIL.
static int eval_list(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 const bool evaluate = evalarg == NULL ? false : evalarg->eval_flags & EVAL_EVALUATE;
 list_T *l = NULL;

 if (evaluate) {
   l = tv_list_alloc(kListLenShouldKnow);
 }

 *arg = skipwhite(*arg + 1);
 while (**arg != ']' && **arg != NUL) {
   typval_T tv;
   if (eval1(arg, &tv, evalarg) == FAIL) {  // Recursive!
     goto failret;
   }
   if (evaluate) {
     tv.v_lock = VAR_UNLOCKED;
     tv_list_append_owned_tv(l, tv);
   }

   // the comma must come after the value
   bool had_comma = **arg == ',';
   if (had_comma) {
     *arg = skipwhite(*arg + 1);
   }

   if (**arg == ']') {
     break;
   }

   if (!had_comma) {
     semsg(_("E696: Missing comma in List: %s"), *arg);
     goto failret;
   }
 }

 if (**arg != ']') {
   semsg(_(e_list_end), *arg);
failret:
   if (evaluate) {
     tv_list_free(l);
   }
   return FAIL;
 }

 *arg = skipwhite(*arg + 1);
 if (evaluate) {
   tv_list_set_ret(rettv, l);
 }

 return OK;
}

/// @param ic  ignore case
bool func_equal(typval_T *tv1, typval_T *tv2, bool ic)
{
 // empty and NULL function name considered the same
 char *s1 = tv1->v_type == VAR_FUNC ? tv1->vval.v_string : partial_name(tv1->vval.v_partial);
 if (s1 != NULL && *s1 == NUL) {
   s1 = NULL;
 }
 char *s2 = tv2->v_type == VAR_FUNC ? tv2->vval.v_string : partial_name(tv2->vval.v_partial);
 if (s2 != NULL && *s2 == NUL) {
   s2 = NULL;
 }
 if (s1 == NULL || s2 == NULL) {
   if (s1 != s2) {
     return false;
   }
 } else if (strcmp(s1, s2) != 0) {
   return false;
 }

 // empty dict and NULL dict is different
 dict_T *d1 = tv1->v_type == VAR_FUNC ? NULL : tv1->vval.v_partial->pt_dict;
 dict_T *d2 = tv2->v_type == VAR_FUNC ? NULL : tv2->vval.v_partial->pt_dict;
 if (d1 == NULL || d2 == NULL) {
   if (d1 != d2) {
     return false;
   }
 } else if (!tv_dict_equal(d1, d2, ic)) {
   return false;
 }

 // empty list and no list considered the same
 int a1 = tv1->v_type == VAR_FUNC ? 0 : tv1->vval.v_partial->pt_argc;
 int a2 = tv2->v_type == VAR_FUNC ? 0 : tv2->vval.v_partial->pt_argc;
 if (a1 != a2) {
   return false;
 }
 for (int i = 0; i < a1; i++) {
   if (!tv_equal(tv1->vval.v_partial->pt_argv + i,
                 tv2->vval.v_partial->pt_argv + i, ic)) {
     return false;
   }
 }
 return true;
}

/// Get next (unique) copy ID
///
/// Used for traversing nested structures e.g. when serializing them or garbage
/// collecting.
int get_copyID(void)
 FUNC_ATTR_WARN_UNUSED_RESULT
{
 // CopyID for recursively traversing lists and dicts
 //
 // This value is needed to avoid endless recursiveness. Last bit is used for
 // previous_funccal and normally ignored when comparing.
 static int current_copyID = 0;
 current_copyID += COPYID_INC;
 return current_copyID;
}

/// Garbage collection for lists and dictionaries.
///
/// We use reference counts to be able to free most items right away when they
/// are no longer used.  But for composite items it's possible that it becomes
/// unused while the reference count is > 0: When there is a recursive
/// reference.  Example:
///      :let l = [1, 2, 3]
///      :let d = {9: l}
///      :let l[1] = d
///
/// Since this is quite unusual we handle this with garbage collection: every
/// once in a while find out which lists and dicts are not referenced from any
/// variable.
///
/// Here is a good reference text about garbage collection (refers to Python
/// but it applies to all reference-counting mechanisms):
///      http://python.ca/nas/python/gc/

/// Do garbage collection for lists and dicts.
///
/// @param testing  true if called from test_garbagecollect_now().
///
/// @return  true if some memory was freed.
bool garbage_collect(bool testing)
{
 bool abort = false;
#define ABORTING(func) abort = abort || func

 if (!testing) {
   // Only do this once.
   want_garbage_collect = false;
   may_garbage_collect = false;
   garbage_collect_at_exit = false;
 }

 // The execution stack can grow big, limit the size.
 if (exestack.ga_maxlen - exestack.ga_len > 500) {
   // Keep 150% of the current size, with a minimum of the growth size.
   int n = exestack.ga_len / 2;
   if (n < exestack.ga_growsize) {
     n = exestack.ga_growsize;
   }

   // Don't make it bigger though.
   if (exestack.ga_len + n < exestack.ga_maxlen) {
     size_t new_len = (size_t)exestack.ga_itemsize * (size_t)(exestack.ga_len + n);
     char *pp = xrealloc(exestack.ga_data, new_len);
     exestack.ga_maxlen = exestack.ga_len + n;
     exestack.ga_data = pp;
   }
 }

 // We advance by two (COPYID_INC) because we add one for items referenced
 // through previous_funccal.
 const int copyID = get_copyID();

 // 1. Go through all accessible variables and mark all lists and dicts
 // with copyID.

 // Don't free variables in the previous_funccal list unless they are only
 // referenced through previous_funccal.  This must be first, because if
 // the item is referenced elsewhere the funccal must not be freed.
 ABORTING(set_ref_in_previous_funccal)(copyID);

 // script-local variables
 ABORTING(garbage_collect_scriptvars)(copyID);

 FOR_ALL_BUFFERS(buf) {
   // buffer-local variables
   ABORTING(set_ref_in_item)(&buf->b_bufvar.di_tv, copyID, NULL, NULL);

   // buffer callback functions
   ABORTING(set_ref_in_callback)(&buf->b_prompt_callback, copyID, NULL, NULL);
   ABORTING(set_ref_in_callback)(&buf->b_prompt_interrupt, copyID, NULL, NULL);
   ABORTING(set_ref_in_callback)(&buf->b_cfu_cb, copyID, NULL, NULL);
   ABORTING(set_ref_in_callback)(&buf->b_ofu_cb, copyID, NULL, NULL);
   ABORTING(set_ref_in_callback)(&buf->b_tsrfu_cb, copyID, NULL, NULL);
   ABORTING(set_ref_in_callback)(&buf->b_tfu_cb, copyID, NULL, NULL);
   ABORTING(set_ref_in_callback)(&buf->b_ffu_cb, copyID, NULL, NULL);
   if (!abort && buf->b_p_cpt_cb != NULL) {
     ABORTING(set_ref_in_cpt_callbacks)(buf->b_p_cpt_cb, buf->b_p_cpt_count, copyID);
   }
 }

 // 'completefunc', 'omnifunc' and 'thesaurusfunc' callbacks
 ABORTING(set_ref_in_insexpand_funcs)(copyID);

 // 'operatorfunc' callback
 ABORTING(set_ref_in_opfunc)(copyID);

 // 'tagfunc' callback
 ABORTING(set_ref_in_tagfunc)(copyID);

 // 'findfunc' callback
 ABORTING(set_ref_in_findfunc)(copyID);

 FOR_ALL_TAB_WINDOWS(tp, wp) {
   // window-local variables
   ABORTING(set_ref_in_item)(&wp->w_winvar.di_tv, copyID, NULL, NULL);
 }
 // window-local variables in autocmd windows
 for (int i = 0; i < AUCMD_WIN_COUNT; i++) {
   if (aucmd_win[i].auc_win != NULL) {
     ABORTING(set_ref_in_item)(&aucmd_win[i].auc_win->w_winvar.di_tv, copyID, NULL, NULL);
   }
 }

 // registers (ShaDa additional data)
 {
   const void *reg_iter = NULL;
   do {
     yankreg_T reg;
     char name = NUL;
     bool is_unnamed = false;
     reg_iter = op_global_reg_iter(reg_iter, &name, &reg, &is_unnamed);
   } while (reg_iter != NULL);
 }

 // global marks (ShaDa additional data)
 {
   const void *mark_iter = NULL;
   do {
     xfmark_T fm;
     char name = NUL;
     mark_iter = mark_global_iter(mark_iter, &name, &fm);
   } while (mark_iter != NULL);
 }

 // tabpage-local variables
 FOR_ALL_TABS(tp) {
   ABORTING(set_ref_in_item)(&tp->tp_winvar.di_tv, copyID, NULL, NULL);
 }

 // global variables
 ABORTING(garbage_collect_globvars)(copyID);

 // function-local variables
 ABORTING(set_ref_in_call_stack)(copyID);

 // named functions (matters for closures)
 ABORTING(set_ref_in_functions)(copyID);

 // Channels
 {
   Channel *data;
   map_foreach_value(&channels, data, {
     set_ref_in_callback_reader(&data->on_data, copyID, NULL, NULL);
     set_ref_in_callback_reader(&data->on_stderr, copyID, NULL, NULL);
     set_ref_in_callback(&data->on_exit, copyID, NULL, NULL);
   })
 }

 // Timers
 {
   timer_T *timer;
   map_foreach_value(&timers, timer, {
     set_ref_in_callback(&timer->callback, copyID, NULL, NULL);
   })
 }

 // function call arguments, if v:testing is set.
 ABORTING(set_ref_in_func_args)(copyID);

 // v: vars
 ABORTING(garbage_collect_vimvars)(copyID);

 ABORTING(set_ref_in_quickfix)(copyID);

 bool did_free = false;
 if (!abort) {
   // 2. Free lists and dictionaries that are not referenced.
   did_free = free_unref_items(copyID);

   // 3. Check if any funccal can be freed now.
   //    This may call us back recursively.
   did_free = free_unref_funccal(copyID, testing) || did_free;
 } else if (p_verbose > 0) {
   verb_msg(_("Not enough memory to set references, garbage collection aborted!"));
 }
#undef ABORTING
 return did_free;
}

/// Free lists and dictionaries that are no longer referenced.
///
/// @note  This function may only be called from garbage_collect().
///
/// @param copyID  Free lists/dictionaries that don't have this ID.
///
/// @return  true, if something was freed.
static int free_unref_items(int copyID)
{
 bool did_free = false;

 // Let all "free" functions know that we are here. This means no
 // dictionaries, lists, or jobs are to be freed, because we will
 // do that here.
 tv_in_free_unref_items = true;

 // PASS 1: free the contents of the items. We don't free the items
 // themselves yet, so that it is possible to decrement refcount counters.

 // Go through the list of dicts and free items without the copyID.
 // Don't free dicts that are referenced internally.
 for (dict_T *dd = gc_first_dict; dd != NULL; dd = dd->dv_used_next) {
   if ((dd->dv_copyID & COPYID_MASK) != (copyID & COPYID_MASK)) {
     // Free the Dictionary and ordinary items it contains, but don't
     // recurse into Lists and Dictionaries, they will be in the list
     // of dicts or list of lists.
     tv_dict_free_contents(dd);
     did_free = true;
   }
 }

 // Go through the list of lists and free items without the copyID.
 // But don't free a list that has a watcher (used in a for loop), these
 // are not referenced anywhere.
 for (list_T *ll = gc_first_list; ll != NULL; ll = ll->lv_used_next) {
   if ((tv_list_copyid(ll) & COPYID_MASK) != (copyID & COPYID_MASK)
       && !tv_list_has_watchers(ll)) {
     // Free the List and ordinary items it contains, but don't recurse
     // into Lists and Dictionaries, they will be in the list of dicts
     // or list of lists.
     tv_list_free_contents(ll);
     did_free = true;
   }
 }

 // PASS 2: free the items themselves.
 dict_T *dd_next;
 for (dict_T *dd = gc_first_dict; dd != NULL; dd = dd_next) {
   dd_next = dd->dv_used_next;
   if ((dd->dv_copyID & COPYID_MASK) != (copyID & COPYID_MASK)) {
     tv_dict_free_dict(dd);
   }
 }

 list_T *ll_next;
 for (list_T *ll = gc_first_list; ll != NULL; ll = ll_next) {
   ll_next = ll->lv_used_next;
   if ((ll->lv_copyID & COPYID_MASK) != (copyID & COPYID_MASK)
       && !tv_list_has_watchers(ll)) {
     // Free the List and ordinary items it contains, but don't recurse
     // into Lists and Dictionaries, they will be in the list of dicts
     // or list of lists.
     tv_list_free_list(ll);
   }
 }
 tv_in_free_unref_items = false;
 return did_free;
}

/// Mark all lists and dicts referenced through hashtab "ht" with "copyID".
///
/// @param ht            Hashtab content will be marked.
/// @param copyID        New mark for lists and dicts.
/// @param list_stack    Used to add lists to be marked. Can be NULL.
///
/// @returns             true if setting references failed somehow.
bool set_ref_in_ht(hashtab_T *ht, int copyID, list_stack_T **list_stack)
 FUNC_ATTR_WARN_UNUSED_RESULT
{
 bool abort = false;
 ht_stack_T *ht_stack = NULL;

 hashtab_T *cur_ht = ht;
 while (true) {
   if (!abort) {
     // Mark each item in the hashtab.  If the item contains a hashtab
     // it is added to ht_stack, if it contains a list it is added to
     // list_stack.
     HASHTAB_ITER(cur_ht, hi, {
       abort = abort || set_ref_in_item(&TV_DICT_HI2DI(hi)->di_tv, copyID, &ht_stack, list_stack);
     });
   }

   if (ht_stack == NULL) {
     break;
   }

   // take an item from the stack
   cur_ht = ht_stack->ht;
   ht_stack_T *tempitem = ht_stack;
   ht_stack = ht_stack->prev;
   xfree(tempitem);
 }

 return abort;
}

/// Mark all lists and dicts referenced through list "l" with "copyID".
///
/// @param l             List content will be marked.
/// @param copyID        New mark for lists and dicts.
/// @param ht_stack      Used to add hashtabs to be marked. Can be NULL.
///
/// @returns             true if setting references failed somehow.
bool set_ref_in_list_items(list_T *l, int copyID, ht_stack_T **ht_stack)
 FUNC_ATTR_WARN_UNUSED_RESULT
{
 bool abort = false;
 list_stack_T *list_stack = NULL;

 list_T *cur_l = l;
 while (true) {
   // Mark each item in the list.  If the item contains a hashtab
   // it is added to ht_stack, if it contains a list it is added to
   // list_stack.
   TV_LIST_ITER(cur_l, li, {
     if (abort) {
       break;
     }
     abort = set_ref_in_item(TV_LIST_ITEM_TV(li), copyID, ht_stack,
                             &list_stack);
   });

   if (list_stack == NULL) {
     break;
   }

   // take an item from the stack
   cur_l = list_stack->list;
   list_stack_T *tempitem = list_stack;
   list_stack = list_stack->prev;
   xfree(tempitem);
 }

 return abort;
}

/// Mark the dict "dd" with "copyID".
/// Also see set_ref_in_item().
static bool set_ref_in_item_dict(dict_T *dd, int copyID, ht_stack_T **ht_stack,
                                list_stack_T **list_stack)
{
 if (dd == NULL || dd->dv_copyID == copyID) {
   return false;
 }

 // Didn't see this dict yet.
 dd->dv_copyID = copyID;
 if (ht_stack == NULL) {
   return set_ref_in_ht(&dd->dv_hashtab, copyID, list_stack);
 }

 ht_stack_T *const newitem = xmalloc(sizeof(ht_stack_T));
 newitem->ht = &dd->dv_hashtab;
 newitem->prev = *ht_stack;
 *ht_stack = newitem;

 QUEUE *w = NULL;
 DictWatcher *watcher = NULL;
 QUEUE_FOREACH(w, &dd->watchers, {
   watcher = tv_dict_watcher_node_data(w);
   set_ref_in_callback(&watcher->callback, copyID, ht_stack, list_stack);
 })

 return false;
}

/// Mark the list "ll" with "copyID".
/// Also see set_ref_in_item().
static bool set_ref_in_item_list(list_T *ll, int copyID, ht_stack_T **ht_stack,
                                list_stack_T **list_stack)
{
 if (ll == NULL || ll->lv_copyID == copyID) {
   return false;
 }

 // Didn't see this list yet.
 ll->lv_copyID = copyID;
 if (list_stack == NULL) {
   return set_ref_in_list_items(ll, copyID, ht_stack);
 }

 list_stack_T *const newitem = xmalloc(sizeof(list_stack_T));
 newitem->list = ll;
 newitem->prev = *list_stack;
 *list_stack = newitem;

 return false;
}

/// Mark the partial "pt" with "copyID".
/// Also see set_ref_in_item().
static bool set_ref_in_item_partial(partial_T *pt, int copyID, ht_stack_T **ht_stack,
                                   list_stack_T **list_stack)
{
 if (pt == NULL || pt->pt_copyID == copyID) {
   return false;
 }

 // Didn't see this partial yet.
 pt->pt_copyID = copyID;

 bool abort = set_ref_in_func(pt->pt_name, pt->pt_func, copyID);

 if (pt->pt_dict != NULL) {
   typval_T dtv;

   dtv.v_type = VAR_DICT;
   dtv.vval.v_dict = pt->pt_dict;
   abort = abort || set_ref_in_item(&dtv, copyID, ht_stack, list_stack);
 }

 for (int i = 0; i < pt->pt_argc; i++) {
   abort = abort || set_ref_in_item(&pt->pt_argv[i], copyID, ht_stack, list_stack);
 }

 return abort;
}

/// Mark all lists and dicts referenced through typval "tv" with "copyID".
///
/// @param tv            Typval content will be marked.
/// @param copyID        New mark for lists and dicts.
/// @param ht_stack      Used to add hashtabs to be marked. Can be NULL.
/// @param list_stack    Used to add lists to be marked. Can be NULL.
///
/// @returns             true if setting references failed somehow.
bool set_ref_in_item(typval_T *tv, int copyID, ht_stack_T **ht_stack, list_stack_T **list_stack)
 FUNC_ATTR_WARN_UNUSED_RESULT
{
 bool abort = false;

 switch (tv->v_type) {
 case VAR_DICT:
   return set_ref_in_item_dict(tv->vval.v_dict, copyID, ht_stack, list_stack);
 case VAR_LIST:
   return set_ref_in_item_list(tv->vval.v_list, copyID, ht_stack, list_stack);
 case VAR_FUNC:
   abort = set_ref_in_func(tv->vval.v_string, NULL, copyID);
   break;
 case VAR_PARTIAL:
   return set_ref_in_item_partial(tv->vval.v_partial, copyID, ht_stack, list_stack);
 case VAR_UNKNOWN:
 case VAR_BOOL:
 case VAR_SPECIAL:
 case VAR_FLOAT:
 case VAR_NUMBER:
 case VAR_STRING:
 case VAR_BLOB:
   break;
 }
 return abort;
}

/// Get the key for #{key: val} into "tv" and advance "arg".
///
/// @return  FAIL when there is no valid key.
static int get_literal_key(char **arg, typval_T *tv)
 FUNC_ATTR_NONNULL_ALL
{
 char *p;

 if (!ASCII_ISALNUM(**arg) && **arg != '_' && **arg != '-') {
   return FAIL;
 }
 for (p = *arg; ASCII_ISALNUM(*p) || *p == '_' || *p == '-'; p++) {}
 tv->v_type = VAR_STRING;
 tv->vval.v_string = xmemdupz(*arg, (size_t)(p - *arg));

 *arg = skipwhite(p);
 return OK;
}

/// Allocate a variable for a Dictionary and fill it from "*arg".
///
/// @param arg  "*arg" points to the "{".
/// @param literal  true for #{key: val}
///
/// @return  OK or FAIL.  Returns NOTDONE for {expr}.
static int eval_dict(char **arg, typval_T *rettv, evalarg_T *const evalarg, bool literal)
{
 const bool evaluate = evalarg == NULL ? false : evalarg->eval_flags & EVAL_EVALUATE;
 typval_T tv;
 char *key = NULL;
 char *curly_expr = skipwhite(*arg + 1);
 char buf[NUMBUFLEN];

 // First check if it's not a curly-braces expression: {expr}.
 // Must do this without evaluating, otherwise a function may be called
 // twice.  Unfortunately this means we need to call eval1() twice for the
 // first item.
 // "{}" is an empty Dictionary.
 // "#{abc}" is never a curly-braces expression.
 if (*curly_expr != '}'
     && !literal
     && eval1(&curly_expr, &tv, NULL) == OK
     && *skipwhite(curly_expr) == '}') {
   return NOTDONE;
 }

 dict_T *d = NULL;
 if (evaluate) {
   d = tv_dict_alloc();
 }
 typval_T tvkey;
 tvkey.v_type = VAR_UNKNOWN;
 tv.v_type = VAR_UNKNOWN;

 *arg = skipwhite(*arg + 1);
 while (**arg != '}' && **arg != NUL) {
   if ((literal
        ? get_literal_key(arg, &tvkey)
        : eval1(arg, &tvkey, evalarg)) == FAIL) {  // recursive!
     goto failret;
   }
   if (**arg != ':') {
     semsg(_("E720: Missing colon in Dictionary: %s"), *arg);
     tv_clear(&tvkey);
     goto failret;
   }
   if (evaluate) {
     key = (char *)tv_get_string_buf_chk(&tvkey, buf);
     if (key == NULL) {
       // "key" is NULL when tv_get_string_buf_chk() gave an errmsg
       tv_clear(&tvkey);
       goto failret;
     }
   }

   *arg = skipwhite(*arg + 1);
   if (eval1(arg, &tv, evalarg) == FAIL) {  // Recursive!
     tv_clear(&tvkey);
     goto failret;
   }
   if (evaluate) {
     dictitem_T *item = tv_dict_find(d, key, -1);
     if (item != NULL) {
       semsg(_("E721: Duplicate key in Dictionary: \"%s\""), key);
       tv_clear(&tvkey);
       tv_clear(&tv);
       goto failret;
     }
     item = tv_dict_item_alloc(key);
     item->di_tv = tv;
     item->di_tv.v_lock = VAR_UNLOCKED;
     if (tv_dict_add(d, item) == FAIL) {
       tv_dict_item_free(item);
     }
   }
   tv_clear(&tvkey);

   // the comma must come after the value
   bool had_comma = **arg == ',';
   if (had_comma) {
     *arg = skipwhite(*arg + 1);
   }

   if (**arg == '}') {
     break;
   }
   if (!had_comma) {
     semsg(_("E722: Missing comma in Dictionary: %s"), *arg);
     goto failret;
   }
 }

 if (**arg != '}') {
   semsg(_("E723: Missing end of Dictionary '}': %s"), *arg);
failret:
   if (d != NULL) {
     tv_dict_free(d);
   }
   return FAIL;
 }

 *arg = skipwhite(*arg + 1);
 if (evaluate) {
   tv_dict_set_ret(rettv, d);
 }

 return OK;
}

/// Evaluate a literal dictionary: #{key: val, key: val}
/// "*arg" points to the "#".
/// On return, "*arg" points to the character after the Dict.
/// Return OK or FAIL.  Returns NOTDONE for {expr}.
static int eval_lit_dict(char **arg, typval_T *rettv, evalarg_T *const evalarg)
{
 int ret = OK;

 if ((*arg)[1] == '{') {
   (*arg)++;
   ret = eval_dict(arg, rettv, evalarg, true);
 } else {
   ret = NOTDONE;
 }

 return ret;
}

/// Convert the string to a floating point number
///
/// This uses strtod().  setlocale(LC_NUMERIC, "C") has been used earlier to
/// make sure this always uses a decimal point.
///
/// @param[in] text  String to convert.
/// @param[out] ret_value  Location where conversion result is saved.
///
/// @return  Length of the text that was consumed.
size_t string2float(const char *const text, float_T *const ret_value)
 FUNC_ATTR_NONNULL_ALL
{
 // MS-Windows does not deal with "inf" and "nan" properly
 if (STRNICMP(text, "inf", 3) == 0) {
   *ret_value = (float_T)INFINITY;
   return 3;
 }
 if (STRNICMP(text, "-inf", 4) == 0) {
   *ret_value = (float_T)(-INFINITY);
   return 4;
 }
 if (STRNICMP(text, "nan", 3) == 0) {
   *ret_value = (float_T)NAN;
   return 3;
 }
 char *s = NULL;
 *ret_value = strtod(text, &s);
 return (size_t)(s - text);
}

/// Get the value of an environment variable.
///
/// If the environment variable was not set, silently assume it is empty.
///
/// @param arg  Points to the '$'.  It is advanced to after the name.
///
/// @return  FAIL if the name is invalid.
static int eval_env_var(char **arg, typval_T *rettv, int evaluate)
{
 (*arg)++;
 char *name = *arg;
 int len = get_env_len((const char **)arg);

 if (evaluate) {
   if (len == 0) {
     return FAIL;  // Invalid empty name.
   }
   int cc = (int)name[len];
   name[len] = NUL;
   // First try vim_getenv(), fast for normal environment vars.
   char *string = vim_getenv(name);
   if (string == NULL || *string == NUL) {
     xfree(string);

     // Next try expanding things like $VIM and ${HOME}.
     string = expand_env_save(name - 1);
     if (string != NULL && *string == '$') {
       XFREE_CLEAR(string);
     }
   }
   name[len] = (char)cc;
   rettv->v_type = VAR_STRING;
   rettv->vval.v_string = string;
   rettv->v_lock = VAR_UNLOCKED;
 }

 return OK;
}

/// Builds a process argument vector from a Vimscript object (typval_T).
///
/// @param[in]  cmd_tv      Vimscript object
/// @param[out] cmd         Returns the command or executable name.
/// @param[out] executable  Returns `false` if argv[0] is not executable.
///
/// @return  Result of `shell_build_argv()` if `cmd_tv` is a String.
///          Else, string values of `cmd_tv` copied to a (char **) list with
///          argv[0] resolved to full path ($PATHEXT-resolved on Windows).
char **tv_to_argv(typval_T *cmd_tv, const char **cmd, bool *executable)
{
 if (cmd_tv->v_type == VAR_STRING) {  // String => "shell semantics".
   const char *cmd_str = tv_get_string(cmd_tv);
   if (cmd) {
     *cmd = cmd_str;
   }
   return shell_build_argv(cmd_str, NULL);
 }

 if (cmd_tv->v_type != VAR_LIST) {
   semsg(_(e_invarg2), "expected String or List");
   return NULL;
 }

 list_T *argl = cmd_tv->vval.v_list;
 int argc = tv_list_len(argl);
 if (!argc) {
   emsg(_(e_invarg));  // List must have at least one item.
   return NULL;
 }

 const char *arg0 = tv_get_string_chk(TV_LIST_ITEM_TV(tv_list_first(argl)));
 char *exe_resolved = NULL;
 if (!arg0 || !os_can_exe(arg0, &exe_resolved, true)) {
   if (arg0 && executable) {
     char buf[IOSIZE];
     snprintf(buf, sizeof(buf), "'%s' is not executable", arg0);
     semsg(_(e_invargNval), "cmd", buf);
     *executable = false;
   }
   return NULL;
 }

 if (cmd) {
   *cmd = exe_resolved;
 }

 // Build the argument vector
 int i = 0;
 char **argv = xcalloc((size_t)argc + 1, sizeof(char *));
 TV_LIST_ITER_CONST(argl, arg, {
   const char *a = tv_get_string_chk(TV_LIST_ITEM_TV(arg));
   if (!a) {
     // Did emsg in tv_get_string_chk; just deallocate argv.
     shell_free_argv(argv);
     xfree(exe_resolved);
     return NULL;
   }
   argv[i++] = xstrdup(a);
 });
 // Replace argv[0] with absolute path. The only reason for this is to make
 // $PATHEXT work on Windows with jobstart([…]). #9569
 xfree(argv[0]);
 argv[0] = exe_resolved;

 return argv;
}

static list_T *string_to_list(const char *str, size_t len, const bool keepempty)
{
 if (!keepempty && str[len - 1] == NL) {
   len--;
 }
 list_T *const list = tv_list_alloc(kListLenMayKnow);
 encode_list_write(list, str, len);
 return list;
}

/// os_system wrapper. Handles 'verbose', :profile, and v:shell_error.
static void get_system_output_as_rettv(typval_T *argvars, typval_T *rettv, bool retlist)
{
 proftime_T wait_time;
 bool profiling = do_profiling == PROF_YES;

 rettv->v_type = VAR_STRING;
 rettv->vval.v_string = NULL;

 if (check_secure()) {
   return;
 }

 // get input to the shell command (if any), and its length
 ptrdiff_t input_len;
 char *input = save_tv_as_string(&argvars[1], &input_len, false, false);
 if (input_len < 0) {
   assert(input == NULL);
   return;
 }

 // get shell command to execute
 bool executable = true;
 char **argv = tv_to_argv(&argvars[0], NULL, &executable);
 if (!argv) {
   if (!executable) {
     set_vim_var_nr(VV_SHELL_ERROR, -1);
   }
   xfree(input);
   return;  // Already did emsg.
 }

 if (p_verbose > 3) {
   char *cmdstr = shell_argv_to_str(argv);
   verbose_enter_scroll();
   smsg(0, _("Executing command: \"%s\""), cmdstr);
   msg_puts("\n\n");
   verbose_leave_scroll();
   xfree(cmdstr);
 }

 if (profiling) {
   prof_child_enter(&wait_time);
 }

 // execute the command
 size_t nread = 0;
 char *res = NULL;
 int status = os_system(argv, input, (size_t)input_len, &res, &nread);

 if (profiling) {
   prof_child_exit(&wait_time);
 }

 xfree(input);

 set_vim_var_nr(VV_SHELL_ERROR, status);

 if (res == NULL) {
   if (retlist) {
     // return an empty list when there's no output
     tv_list_alloc_ret(rettv, 0);
   } else {
     rettv->vval.v_string = xstrdup("");
   }
   return;
 }

 if (retlist) {
   int keepempty = 0;
   if (argvars[1].v_type != VAR_UNKNOWN && argvars[2].v_type != VAR_UNKNOWN) {
     keepempty = (int)tv_get_number(&argvars[2]);
   }
   rettv->vval.v_list = string_to_list(res, nread, (bool)keepempty);
   tv_list_ref(rettv->vval.v_list);
   rettv->v_type = VAR_LIST;

   xfree(res);
 } else {
   // res may contain several NULs before the final terminating one.
   // Replace them with SOH (1) like in get_cmd_output() to avoid truncation.
   memchrsub(res, NUL, 1, nread);
#ifdef USE_CRNL
   // translate <CR><NL> into <NL>
   char *d = res;
   for (char *s = res; *s; s++) {
     if (s[0] == CAR && s[1] == NL) {
       s++;
     }

     *d++ = *s;
   }

   *d = NUL;
#endif
   rettv->vval.v_string = res;
 }
}

/// f_system - the Vimscript system() function
void f_system(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 get_system_output_as_rettv(argvars, rettv, false);
}

void f_systemlist(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
{
 get_system_output_as_rettv(argvars, rettv, true);
}

/// Get a callback from "arg".  It can be a Funcref or a function name.
bool callback_from_typval(Callback *const callback, const typval_T *const arg)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
{
 int r = OK;

 if (arg->v_type == VAR_PARTIAL && arg->vval.v_partial != NULL) {
   callback->data.partial = arg->vval.v_partial;
   callback->data.partial->pt_refcount++;
   callback->type = kCallbackPartial;
 } else if (arg->v_type == VAR_STRING
            && arg->vval.v_string != NULL
            && ascii_isdigit(*arg->vval.v_string)) {
   r = FAIL;
 } else if (arg->v_type == VAR_FUNC || arg->v_type == VAR_STRING) {
   char *name = arg->vval.v_string;
   if (name == NULL) {
     r = FAIL;
   } else if (*name == NUL) {
     callback->type = kCallbackNone;
     callback->data.funcref = NULL;
   } else {
     callback->data.funcref = NULL;
     if (arg->v_type == VAR_STRING) {
       callback->data.funcref = get_scriptlocal_funcname(name);
     }
     if (callback->data.funcref == NULL) {
       callback->data.funcref = xstrdup(name);
     }
     func_ref(callback->data.funcref);
     callback->type = kCallbackFuncref;
   }
 } else if (nlua_is_table_from_lua(arg)) {
   // TODO(tjdvries): UnifiedCallback
   char *name = nlua_register_table_as_callable(arg);

   if (name != NULL) {
     callback->data.funcref = xstrdup(name);
     callback->type = kCallbackFuncref;
   } else {
     r = FAIL;
   }
 } else if (arg->v_type == VAR_SPECIAL
            || (arg->v_type == VAR_NUMBER && arg->vval.v_number == 0)) {
   callback->type = kCallbackNone;
   callback->data.funcref = NULL;
 } else {
   r = FAIL;
 }

 if (r == FAIL) {
   emsg(_("E921: Invalid callback argument"));
   return false;
 }
 return true;
}

static int callback_depth = 0;

int get_callback_depth(void)
{
 return callback_depth;
}

/// @return  whether the callback could be called.
bool callback_call(Callback *const callback, const int argcount_in, typval_T *const argvars_in,
                  typval_T *const rettv)
 FUNC_ATTR_NONNULL_ALL
{
 if (callback_depth > p_mfd) {
   emsg(_(e_command_too_recursive));
   return false;
 }

 partial_T *partial;
 char *name;
 Array args = ARRAY_DICT_INIT;
 Object rv;
 switch (callback->type) {
 case kCallbackFuncref:
   name = callback->data.funcref;
   int len = (int)strlen(name);
   if (len >= 6 && !memcmp(name, "v:lua.", 6)) {
     name += 6;
     len = check_luafunc_name(name, false);
     if (len == 0) {
       return false;
     }
     partial = get_vim_var_partial(VV_LUA);
   } else {
     partial = NULL;
   }
   break;

 case kCallbackPartial:
   partial = callback->data.partial;
   name = partial_name(partial);
   break;

 case kCallbackLua:
   rv = nlua_call_ref(callback->data.luaref, NULL, args, kRetNilBool, NULL, NULL);
   return LUARET_TRUTHY(rv);

 case kCallbackNone:
   return false;
   break;
 }

 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_firstline = curwin->w_cursor.lnum;
 funcexe.fe_lastline = curwin->w_cursor.lnum;
 funcexe.fe_evaluate = true;
 funcexe.fe_partial = partial;

 callback_depth++;
 int ret = call_func(name, -1, rettv, argcount_in, argvars_in, &funcexe);
 callback_depth--;
 return ret;
}

bool set_ref_in_callback(Callback *callback, int copyID, ht_stack_T **ht_stack,
                        list_stack_T **list_stack)
{
 typval_T tv;
 switch (callback->type) {
 case kCallbackFuncref:
 case kCallbackNone:
   break;

 case kCallbackPartial:
   tv.v_type = VAR_PARTIAL;
   tv.vval.v_partial = callback->data.partial;
   return set_ref_in_item(&tv, copyID, ht_stack, list_stack);
   break;

 case kCallbackLua:
   abort();
 }
 return false;
}

static bool set_ref_in_callback_reader(CallbackReader *reader, int copyID, ht_stack_T **ht_stack,
                                      list_stack_T **list_stack)
{
 if (set_ref_in_callback(&reader->cb, copyID, ht_stack, list_stack)) {
   return true;
 }

 if (reader->self) {
   typval_T tv;
   tv.v_type = VAR_DICT;
   tv.vval.v_dict = reader->self;
   return set_ref_in_item(&tv, copyID, ht_stack, list_stack);
 }
 return false;
}

timer_T *find_timer_by_nr(varnumber_T xx)
{
 return pmap_get(uint64_t)(&timers, (uint64_t)xx);
}

void add_timer_info(typval_T *rettv, timer_T *timer)
{
 list_T *list = rettv->vval.v_list;
 dict_T *dict = tv_dict_alloc();

 tv_list_append_dict(list, dict);
 tv_dict_add_nr(dict, S_LEN("id"), timer->timer_id);
 tv_dict_add_nr(dict, S_LEN("time"), timer->timeout);
 tv_dict_add_nr(dict, S_LEN("paused"), timer->paused);

 tv_dict_add_nr(dict, S_LEN("repeat"),
                (timer->repeat_count < 0 ? -1 : timer->repeat_count));

 dictitem_T *di = tv_dict_item_alloc("callback");
 if (tv_dict_add(dict, di) == FAIL) {
   xfree(di);
   return;
 }

 callback_put(&timer->callback, &di->di_tv);
}

void add_timer_info_all(typval_T *rettv)
{
 tv_list_alloc_ret(rettv, map_size(&timers));
 timer_T *timer;
 map_foreach_value(&timers, timer, {
   if (!timer->stopped || timer->refcount > 1) {
     add_timer_info(rettv, timer);
   }
 })
}

/// invoked on the main loop
void timer_due_cb(TimeWatcher *tw, void *data)
{
 timer_T *timer = (timer_T *)data;
 int save_did_emsg = did_emsg;
 const int called_emsg_before = called_emsg;
 const bool save_ex_pressedreturn = get_pressedreturn();

 if (timer->stopped || timer->paused) {
   return;
 }

 timer->refcount++;
 // if repeat was negative repeat forever
 if (timer->repeat_count >= 0 && --timer->repeat_count == 0) {
   timer_stop(timer);
 }

 typval_T argv[2] = { TV_INITIAL_VALUE, TV_INITIAL_VALUE };
 argv[0].v_type = VAR_NUMBER;
 argv[0].vval.v_number = timer->timer_id;
 typval_T rettv = TV_INITIAL_VALUE;

 callback_call(&timer->callback, 1, argv, &rettv);

 // Handle error message
 if (called_emsg > called_emsg_before && did_emsg) {
   timer->emsg_count++;
   if (did_throw) {
     discard_current_exception();
   }
 }
 did_emsg = save_did_emsg;
 set_pressedreturn(save_ex_pressedreturn);

 if (timer->emsg_count >= 3) {
   timer_stop(timer);
 }

 tv_clear(&rettv);

 if (!timer->stopped && timer->timeout == 0) {
   // special case: timeout=0 means the callback will be
   // invoked again on the next event loop tick.
   // we don't use uv_idle_t to not spin the event loop
   // when the main loop is blocked.
   time_watcher_start(&timer->tw, timer_due_cb, 0, 0);
 }
 timer_decref(timer);
}

uint64_t timer_start(const int64_t timeout, const int repeat_count, const Callback *const callback)
{
 timer_T *timer = xmalloc(sizeof *timer);
 timer->refcount = 1;
 timer->stopped = false;
 timer->paused = false;
 timer->emsg_count = 0;
 timer->repeat_count = repeat_count;
 timer->timeout = timeout;
 timer->timer_id = (int)last_timer_id++;
 timer->callback = *callback;

 time_watcher_init(&main_loop, &timer->tw, timer);
 timer->tw.events = multiqueue_new_child(main_loop.events);
 // if main loop is blocked, don't queue up multiple events
 timer->tw.blockable = true;
 time_watcher_start(&timer->tw, timer_due_cb, (uint64_t)timeout, (uint64_t)timeout);

 pmap_put(uint64_t)(&timers, (uint64_t)timer->timer_id, timer);
 return (uint64_t)timer->timer_id;
}

void timer_stop(timer_T *timer)
{
 if (timer->stopped) {
   // avoid double free
   return;
 }
 timer->stopped = true;
 time_watcher_stop(&timer->tw);
 time_watcher_close(&timer->tw, timer_close_cb);
}

/// This will be run on the main loop after the last timer_due_cb, so at this
/// point it is safe to free the callback.
static void timer_close_cb(TimeWatcher *tw, void *data)
{
 timer_T *timer = (timer_T *)data;
 multiqueue_free(timer->tw.events);
 callback_free(&timer->callback);
 pmap_del(uint64_t)(&timers, (uint64_t)timer->timer_id, NULL);
 timer_decref(timer);
}

static void timer_decref(timer_T *timer)
{
 if (--timer->refcount == 0) {
   xfree(timer);
 }
}

void timer_stop_all(void)
{
 timer_T *timer;
 map_foreach_value(&timers, timer, {
   timer_stop(timer);
 })
}

void timer_teardown(void)
{
 timer_stop_all();
}

/// Saves a typval_T as a string.
///
/// For lists or buffers, replaces NLs with NUL and separates items with NLs.
///
/// @param[in]  tv   Value to store as a string.
/// @param[out] len  Length of the resulting string or -1 on error.
/// @param[in]  endnl If true, the output will end in a newline (if a list).
/// @param[in]  crlf  If true, list items will be joined with CRLF (if a list).
/// @returns an allocated string if `tv` represents a Vimscript string, list, or
///          number; NULL otherwise.
char *save_tv_as_string(typval_T *tv, ptrdiff_t *const len, bool endnl, bool crlf)
 FUNC_ATTR_MALLOC FUNC_ATTR_NONNULL_ALL
{
 *len = 0;
 if (tv->v_type == VAR_UNKNOWN) {
   return NULL;
 }

 // For other types, let tv_get_string_buf_chk() get the value or
 // print an error.
 if (tv->v_type != VAR_LIST && tv->v_type != VAR_NUMBER) {
   const char *ret = tv_get_string_chk(tv);
   if (ret) {
     *len = (ptrdiff_t)strlen(ret);
     return xmemdupz(ret, (size_t)(*len));
   } else {
     *len = -1;
     return NULL;
   }
 }

 if (tv->v_type == VAR_NUMBER) {  // Treat number as a buffer-id.
   buf_T *buf = buflist_findnr((int)tv->vval.v_number);
   if (buf) {
     for (linenr_T lnum = 1; lnum <= buf->b_ml.ml_line_count; lnum++) {
       for (char *p = ml_get_buf(buf, lnum); *p != NUL; p++) {
         *len += 1;
       }
       *len += 1;
     }
   } else {
     semsg(_(e_nobufnr), tv->vval.v_number);
     *len = -1;
     return NULL;
   }

   if (*len == 0) {
     return NULL;
   }

   char *ret = xmalloc((size_t)(*len) + 1);
   char *end = ret;
   for (linenr_T lnum = 1; lnum <= buf->b_ml.ml_line_count; lnum++) {
     for (char *p = ml_get_buf(buf, lnum); *p != NUL; p++) {
       *end++ = (*p == '\n') ? NUL : *p;
     }
     *end++ = '\n';
   }
   *end = NUL;
   *len = end - ret;
   return ret;
 }

 assert(tv->v_type == VAR_LIST);
 // Pre-calculate the resulting length.
 list_T *list = tv->vval.v_list;
 TV_LIST_ITER_CONST(list, li, {
   *len += (ptrdiff_t)strlen(tv_get_string(TV_LIST_ITEM_TV(li))) + (crlf ? 2 : 1);
 });

 if (*len == 0) {
   return NULL;
 }

 char *ret = xmalloc((size_t)(*len) + (endnl ? (crlf ? 2 : 1) : 0));
 char *end = ret;
 TV_LIST_ITER_CONST(list, li, {
   for (const char *s = tv_get_string(TV_LIST_ITEM_TV(li)); *s != NUL; s++) {
     *end++ = (*s == '\n') ? NUL : *s;
   }
   if (endnl || TV_LIST_ITEM_NEXT(list, li) != NULL) {
     if (crlf) {
       *end++ = '\r';
     }
     *end++ = '\n';
   }
 });
 *end = NUL;
 *len = end - ret;
 return ret;
}

/// Convert the specified byte index of line 'lnum' in buffer 'buf' to a
/// character index.  Works only for loaded buffers. Returns -1 on failure.
/// The index of the first byte and the first character is zero.
int buf_byteidx_to_charidx(buf_T *buf, linenr_T lnum, int byteidx)
{
 if (buf == NULL || buf->b_ml.ml_mfp == NULL) {
   return -1;
 }

 if (lnum > buf->b_ml.ml_line_count) {
   lnum = buf->b_ml.ml_line_count;
 }

 char *str = ml_get_buf(buf, lnum);

 if (*str == NUL) {
   return 0;
 }

 // count the number of characters
 char *t = str;
 int count;
 for (count = 0; *t != NUL && t <= str + byteidx; count++) {
   t += utfc_ptr2len(t);
 }

 // In insert mode, when the cursor is at the end of a non-empty line,
 // byteidx points to the NUL character immediately past the end of the
 // string. In this case, add one to the character count.
 if (*t == NUL && byteidx != 0 && t == str + byteidx) {
   count++;
 }

 return count - 1;
}

/// Convert the specified character index of line 'lnum' in buffer 'buf' to a
/// byte index.  Works only for loaded buffers.
/// The index of the first byte and the first character is zero.
///
/// @return  -1 on failure.
int buf_charidx_to_byteidx(buf_T *buf, linenr_T lnum, int charidx)
{
 if (buf == NULL || buf->b_ml.ml_mfp == NULL) {
   return -1;
 }

 if (lnum > buf->b_ml.ml_line_count) {
   lnum = buf->b_ml.ml_line_count;
 }

 char *str = ml_get_buf(buf, lnum);

 // Convert the character offset to a byte offset
 char *t = str;
 while (*t != NUL && --charidx > 0) {
   t += utfc_ptr2len(t);
 }

 return (int)(t - str);
}

/// Translate a Vimscript object into a position
///
/// Accepts VAR_LIST and VAR_STRING objects. Does not give an error for invalid
/// type.
///
/// @param[in]  tv  Object to translate.
/// @param[in]  dollar_lnum  True when "$" is last line.
/// @param[out]  ret_fnum  Set to fnum for marks.
/// @param[in]  charcol  True to return character column.
/// @param[in]  wp  Window for which to get the position.
///
/// @return Pointer to position or NULL in case of error (e.g. invalid type).
pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret_fnum,
               const bool charcol, win_T *wp)
 FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
{
 static pos_T pos;

 buf_T *bp = wp->w_buffer;

 // Argument can be [lnum, col, coladd].
 if (tv->v_type == VAR_LIST) {
   bool error = false;

   list_T *l = tv->vval.v_list;
   if (l == NULL) {
     return NULL;
   }

   // Get the line number.
   pos.lnum = (linenr_T)tv_list_find_nr(l, 0, &error);
   if (error || pos.lnum <= 0 || pos.lnum > bp->b_ml.ml_line_count) {
     // Invalid line number.
     return NULL;
   }

   // Get the column number.
   pos.col = (colnr_T)tv_list_find_nr(l, 1, &error);
   if (error) {
     return NULL;
   }
   int len;
   if (charcol) {
     len = mb_charlen(ml_get_buf(bp, pos.lnum));
   } else {
     len = ml_get_buf_len(bp, pos.lnum);
   }

   // We accept "$" for the column number: last column.
   listitem_T *li = tv_list_find(l, 1);
   if (li != NULL && TV_LIST_ITEM_TV(li)->v_type == VAR_STRING
       && TV_LIST_ITEM_TV(li)->vval.v_string != NULL
       && strcmp(TV_LIST_ITEM_TV(li)->vval.v_string, "$") == 0) {
     pos.col = len + 1;
   }

   // Accept a position up to the NUL after the line.
   if (pos.col == 0 || (int)pos.col > len + 1) {
     // Invalid column number.
     return NULL;
   }
   pos.col--;

   // Get the virtual offset.  Defaults to zero.
   pos.coladd = (colnr_T)tv_list_find_nr(l, 2, &error);
   if (error) {
     pos.coladd = 0;
   }

   return &pos;
 }

 const char *const name = tv_get_string_chk(tv);
 if (name == NULL) {
   return NULL;
 }

 pos.lnum = 0;
 if (name[0] == '.') {
   // cursor
   pos = wp->w_cursor;
 } else if (name[0] == 'v' && name[1] == NUL) {
   // Visual start
   if (VIsual_active && wp == curwin) {
     pos = VIsual;
   } else {
     pos = wp->w_cursor;
   }
 } else if (name[0] == '\'') {
   // mark
   int mname = (uint8_t)name[1];
   const fmark_T *const fm = mark_get(bp, wp, NULL, kMarkAll, mname);
   if (fm == NULL || fm->mark.lnum <= 0) {
     return NULL;
   }
   pos = fm->mark;
   // Vimscript behavior, only provide fnum if mark is global.
   *ret_fnum = ASCII_ISUPPER(mname) || ascii_isdigit(mname) ? fm->fnum : *ret_fnum;
 }
 if (pos.lnum != 0) {
   if (charcol) {
     pos.col = buf_byteidx_to_charidx(bp, pos.lnum, pos.col);
   }
   return &pos;
 }

 pos.coladd = 0;

 if (name[0] == 'w' && dollar_lnum) {
   // the "w_valid" flags are not reset when moving the cursor, but they
   // do matter for update_topline() and validate_botline_win().
   check_cursor_moved(wp);

   pos.col = 0;
   if (name[1] == '0') {               // "w0": first visible line
     update_topline(wp);
     // In silent Ex mode topline is zero, but that's not a valid line
     // number; use one instead.
     pos.lnum = wp->w_topline > 0 ? wp->w_topline : 1;
     return &pos;
   } else if (name[1] == '$') {      // "w$": last visible line
     validate_botline_win(wp);
     // In silent Ex mode botline is zero, return zero then.
     pos.lnum = wp->w_botline > 0 ? wp->w_botline - 1 : 0;
     return &pos;
   }
 } else if (name[0] == '$') {        // last column or line
   if (dollar_lnum) {
     pos.lnum = bp->b_ml.ml_line_count;
     pos.col = 0;
   } else {
     pos.lnum = wp->w_cursor.lnum;
     if (charcol) {
       pos.col = (colnr_T)mb_charlen(ml_get_buf(bp, wp->w_cursor.lnum));
     } else {
       pos.col = ml_get_buf_len(bp, wp->w_cursor.lnum);
     }
   }
   return &pos;
 }
 return NULL;
}

/// Convert list in "arg" into position "posp" and optional file number "fnump".
/// When "fnump" is NULL there is no file number, only 3 items: [lnum, col, off]
/// Note that the column is passed on as-is, the caller may want to decrement
/// it to use 1 for the first column.
///
/// @param charcol  if true, use the column as the character index instead of the
///                 byte index.
///
/// @return  FAIL when conversion is not possible, doesn't check the position for
///          validity.
int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp, bool charcol)
{
 list_T *l;

 // List must be: [fnum, lnum, col, coladd, curswant], where "fnum" is only
 // there when "fnump" isn't NULL; "coladd" and "curswant" are optional.
 if (arg->v_type != VAR_LIST
     || (l = arg->vval.v_list) == NULL
     || tv_list_len(l) < (fnump == NULL ? 2 : 3)
     || tv_list_len(l) > (fnump == NULL ? 4 : 5)) {
   return FAIL;
 }

 int i = 0;
 int n;
 if (fnump != NULL) {
   n = (int)tv_list_find_nr(l, i++, NULL);  // fnum
   if (n < 0) {
     return FAIL;
   }
   if (n == 0) {
     n = curbuf->b_fnum;  // Current buffer.
   }
   *fnump = n;
 }

 n = (int)tv_list_find_nr(l, i++, NULL);  // lnum
 if (n < 0) {
   return FAIL;
 }
 posp->lnum = n;

 n = (int)tv_list_find_nr(l, i++, NULL);  // col
 if (n < 0) {
   return FAIL;
 }
 // If character position is specified, then convert to byte position
 // If the line number is zero use the cursor line.
 if (charcol) {
   // Get the text for the specified line in a loaded buffer
   buf_T *buf = buflist_findnr(fnump == NULL ? curbuf->b_fnum : *fnump);
   if (buf == NULL || buf->b_ml.ml_mfp == NULL) {
     return FAIL;
   }
   n = buf_charidx_to_byteidx(buf,
                              posp->lnum == 0 ? curwin->w_cursor.lnum : posp->lnum,
                              n) + 1;
 }
 posp->col = n;

 n = (int)tv_list_find_nr(l, i, NULL);  // off
 if (n < 0) {
   posp->coladd = 0;
 } else {
   posp->coladd = n;
 }

 if (curswantp != NULL) {
   *curswantp = (colnr_T)tv_list_find_nr(l, i + 1, NULL);  // curswant
 }

 return OK;
}

/// Get the length of an environment variable name.
/// Advance "arg" to the first character after the name.
///
/// @return  0 for error.
int get_env_len(const char **arg)
{
 const char *p;
 for (p = *arg; vim_isIDc((uint8_t)(*p)); p++) {}
 if (p == *arg) {  // No name found.
   return 0;
 }

 int len = (int)(p - *arg);
 *arg = p;
 return len;
}

/// Get the length of the name of a function or internal variable.
///
/// @param arg  is advanced to the first non-white character after the name.
///
/// @return  0 if something is wrong.
int get_id_len(const char **const arg)
{
 int len;

 // Find the end of the name.
 const char *p;
 for (p = *arg; eval_isnamec(*p); p++) {
   if (*p == ':') {
     // "s:" is start of "s:var", but "n:" is not and can be used in
     // slice "[n:]". Also "xx:" is not a namespace.
     len = (int)(p - *arg);
     if (len > 1
         || (len == 1 && vim_strchr(namespace_char, (uint8_t)(**arg)) == NULL)) {
       break;
     }
   }
 }
 if (p == *arg) {  // no name found
   return 0;
 }

 len = (int)(p - *arg);
 *arg = skipwhite(p);

 return len;
}

/// Get the length of the name of a variable or function.
/// Only the name is recognized, does not handle ".key" or "[idx]".
///
/// @param arg  is advanced to the first non-white character after the name.
///             If the name contains 'magic' {}'s, expand them and return the
///             expanded name in an allocated string via 'alias' - caller must free.
///
/// @return  -1 if curly braces expansion failed or
///           0 if something else is wrong.
int get_name_len(const char **const arg, char **alias, bool evaluate, bool verbose)
{
 *alias = NULL;    // default to no alias

 if ((*arg)[0] == (char)K_SPECIAL && (*arg)[1] == (char)KS_EXTRA
     && (*arg)[2] == (char)KE_SNR) {
   // Hard coded <SNR>, already translated.
   *arg += 3;
   return get_id_len(arg) + 3;
 }
 int len = eval_fname_script(*arg);
 if (len > 0) {
   // literal "<SID>", "s:" or "<SNR>"
   *arg += len;
 }

 // Find the end of the name; check for {} construction.
 char *expr_start;
 char *expr_end;
 const char *p = find_name_end((*arg), (const char **)&expr_start, (const char **)&expr_end,
                               len > 0 ? 0 : FNE_CHECK_START);
 if (expr_start != NULL) {
   if (!evaluate) {
     len += (int)(p - *arg);
     *arg = skipwhite(p);
     return len;
   }

   // Include any <SID> etc in the expanded string:
   // Thus the -len here.
   char *temp_string = make_expanded_name(*arg - len, expr_start, expr_end, (char *)p);
   if (temp_string == NULL) {
     return -1;
   }
   *alias = temp_string;
   *arg = skipwhite(p);
   return (int)strlen(temp_string);
 }

 len += get_id_len(arg);
 // Only give an error when there is something, otherwise it will be
 // reported at a higher level.
 if (len == 0 && verbose && **arg != NUL) {
   semsg(_(e_invexpr2), *arg);
 }

 return len;
}

/// Find the end of a variable or function name, taking care of magic braces.
///
/// @param expr_start  if not NULL, then `expr_start` and `expr_end` are set to the
///                    start and end of the first magic braces item.
///
/// @param flags  can have FNE_INCL_BR and FNE_CHECK_START.
///
/// @return  a pointer to just after the name.  Equal to "arg" if there is no
///          valid name.
const char *find_name_end(const char *arg, const char **expr_start, const char **expr_end,
                         int flags)
{
 if (expr_start != NULL) {
   *expr_start = NULL;
   *expr_end = NULL;
 }

 // Quick check for valid starting character.
 if ((flags & FNE_CHECK_START) && !eval_isnamec1(*arg) && *arg != '{') {
   return arg;
 }

 int mb_nest = 0;
 int br_nest = 0;
 int len;

 const char *p;
 for (p = arg; *p != NUL
      && (eval_isnamec(*p)
          || *p == '{'
          || ((flags & FNE_INCL_BR) && (*p == '['
                                        || (*p == '.' && eval_isdictc(p[1]))))
          || mb_nest != 0
          || br_nest != 0); MB_PTR_ADV(p)) {
   if (*p == '\'') {
     // skip over 'string' to avoid counting [ and ] inside it.
     for (p = p + 1; *p != NUL && *p != '\''; MB_PTR_ADV(p)) {}
     if (*p == NUL) {
       break;
     }
   } else if (*p == '"') {
     // skip over "str\"ing" to avoid counting [ and ] inside it.
     for (p = p + 1; *p != NUL && *p != '"'; MB_PTR_ADV(p)) {
       if (*p == '\\' && p[1] != NUL) {
         p++;
       }
     }
     if (*p == NUL) {
       break;
     }
   } else if (br_nest == 0 && mb_nest == 0 && *p == ':') {
     // "s:" is start of "s:var", but "n:" is not and can be used in
     // slice "[n:]".  Also "xx:" is not a namespace. But {ns}: is.
     len = (int)(p - arg);
     if ((len > 1 && p[-1] != '}')
         || (len == 1 && vim_strchr(namespace_char, (uint8_t)(*arg)) == NULL)) {
       break;
     }
   }

   if (mb_nest == 0) {
     if (*p == '[') {
       br_nest++;
     } else if (*p == ']') {
       br_nest--;
     }
   }

   if (br_nest == 0) {
     if (*p == '{') {
       mb_nest++;
       if (expr_start != NULL && *expr_start == NULL) {
         *expr_start = p;
       }
     } else if (*p == '}') {
       mb_nest--;
       if (expr_start != NULL && mb_nest == 0 && *expr_end == NULL) {
         *expr_end = p;
       }
     }
   }
 }

 return p;
}

/// Expands out the 'magic' {}'s in a variable/function name.
/// Note that this can call itself recursively, to deal with
/// constructs like foo{bar}{baz}{bam}
/// The four pointer arguments point to "foo{expre}ss{ion}bar"
///                      "in_start"      ^
///                      "expr_start"       ^
///                      "expr_end"               ^
///                      "in_end"                            ^
///
/// @return  a new allocated string, which the caller must free or
///          NULL for failure.
static char *make_expanded_name(const char *in_start, char *expr_start, char *expr_end,
                               char *in_end)
{
 if (expr_end == NULL || in_end == NULL) {
   return NULL;
 }

 char *retval = NULL;

 *expr_start = NUL;
 *expr_end = NUL;
 char c1 = *in_end;
 *in_end = NUL;

 char *temp_result = eval_to_string(expr_start + 1, false, false);
 if (temp_result != NULL) {
   size_t retvalsize = (size_t)(expr_start - in_start)
                       + strlen(temp_result)
                       + (size_t)(in_end - expr_end) + 1;
   retval = xmalloc(retvalsize);
   vim_snprintf(retval, retvalsize, "%s%s%s", in_start, temp_result, expr_end + 1);
 }
 xfree(temp_result);

 *in_end = c1;                 // put char back for error messages
 *expr_start = '{';
 *expr_end = '}';

 if (retval != NULL) {
   temp_result = (char *)find_name_end(retval,
                                       (const char **)&expr_start,
                                       (const char **)&expr_end, 0);
   if (expr_start != NULL) {
     // Further expansion!
     temp_result = make_expanded_name(retval, expr_start,
                                      expr_end, temp_result);
     xfree(retval);
     retval = temp_result;
   }
 }

 return retval;
}

/// @return  true if character "c" can be used in a variable or function name.
///          Does not include '{' or '}' for magic braces.
bool eval_isnamec(int c)
{
 return ASCII_ISALNUM(c) || c == '_' || c == ':' || c == AUTOLOAD_CHAR;
}

/// @return  true if character "c" can be used as the first character in a
///          variable or function name (excluding '{' and '}').
bool eval_isnamec1(int c)
{
 return ASCII_ISALPHA(c) || c == '_';
}

/// @return  true if character "c" can be used as the first character of a
///          dictionary key.
bool eval_isdictc(int c)
{
 return ASCII_ISALNUM(c) || c == '_';
}

/// Set the v:argv list.
void set_argv_var(char **argv, int argc)
{
 list_T *l = tv_list_alloc(argc);

 tv_list_set_lock(l, VAR_FIXED);
 for (int i = 0; i < argc; i++) {
   tv_list_append_string(l, (const char *const)argv[i], -1);
   TV_LIST_ITEM_TV(tv_list_last(l))->v_lock = VAR_FIXED;
 }
 set_vim_var_list(VV_ARGV, l);
}

/// check if special v:lua value for calling lua functions
bool is_luafunc(partial_T *partial)
 FUNC_ATTR_PURE
{
 return partial == get_vim_var_partial(VV_LUA);
}

/// check if special v:lua value for calling lua functions
static bool tv_is_luafunc(typval_T *tv)
{
 return tv->v_type == VAR_PARTIAL && is_luafunc(tv->vval.v_partial);
}

/// Skips one character past the end of the name of a v:lua function.
/// @param p  Pointer to the char AFTER the "v:lua." prefix.
/// @return Pointer to the char one past the end of the function's name.
const char *skip_luafunc_name(const char *p)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 while (ASCII_ISALNUM(*p) || *p == '_' || *p == '-' || *p == '.' || *p == '\'') {
   p++;
 }
 return p;
}

/// check the function name after "v:lua."
int check_luafunc_name(const char *const str, const bool paren)
 FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
{
 const char *const p = skip_luafunc_name(str);
 if (*p != (paren ? '(' : NUL)) {
   return 0;
 }
 return (int)(p - str);
}

/// Return the character "str[index]" where "index" is the character index,
/// including composing characters.
/// If "index" is out of range NULL is returned.
char *char_from_string(const char *str, varnumber_T index)
{
 varnumber_T nchar = index;

 if (str == NULL) {
   return NULL;
 }
 size_t slen = strlen(str);

 // do the same as for a list: a negative index counts from the end
 if (index < 0) {
   int clen = 0;

   for (size_t nbyte = 0; nbyte < slen; clen++) {
     nbyte += (size_t)utfc_ptr2len(str + nbyte);
   }
   nchar = clen + index;
   if (nchar < 0) {
     // unlike list: index out of range results in empty string
     return NULL;
   }
 }

 size_t nbyte = 0;
 for (; nchar > 0 && nbyte < slen; nchar--) {
   nbyte += (size_t)utfc_ptr2len(str + nbyte);
 }
 if (nbyte >= slen) {
   return NULL;
 }
 return xmemdupz(str + nbyte, (size_t)utfc_ptr2len(str + nbyte));
}

/// Get the byte index for character index "idx" in string "str" with length
/// "str_len".  Composing characters are included.
/// If going over the end return "str_len".
/// If "idx" is negative count from the end, -1 is the last character.
/// When going over the start return -1.
static ssize_t char_idx2byte(const char *str, size_t str_len, varnumber_T idx)
{
 varnumber_T nchar = idx;
 size_t nbyte = 0;

 if (nchar >= 0) {
   while (nchar > 0 && nbyte < str_len) {
     nbyte += (size_t)utfc_ptr2len(str + nbyte);
     nchar--;
   }
 } else {
   nbyte = str_len;
   while (nchar < 0 && nbyte > 0) {
     nbyte--;
     nbyte -= (size_t)utf_head_off(str, str + nbyte);
     nchar++;
   }
   if (nchar < 0) {
     return -1;
   }
 }
 return (ssize_t)nbyte;
}

/// Return the slice "str[first : last]" using character indexes.  Composing
/// characters are included.
///
/// @param exclusive  true for slice().
///
/// Return NULL when the result is empty.
char *string_slice(const char *str, varnumber_T first, varnumber_T last, bool exclusive)
{
 if (str == NULL) {
   return NULL;
 }
 size_t slen = strlen(str);
 ssize_t start_byte = char_idx2byte(str, slen, first);
 if (start_byte < 0) {
   start_byte = 0;  // first index very negative: use zero
 }
 ssize_t end_byte;
 if ((last == -1 && !exclusive) || last == VARNUMBER_MAX) {
   end_byte = (ssize_t)slen;
 } else {
   end_byte = char_idx2byte(str, slen, last);
   if (!exclusive && end_byte >= 0 && end_byte < (ssize_t)slen) {
     // end index is inclusive
     end_byte += utfc_ptr2len(str + end_byte);
   }
 }

 if (start_byte >= (ssize_t)slen || end_byte <= start_byte) {
   return NULL;
 }
 return xmemdupz(str + start_byte, (size_t)(end_byte - start_byte));
}

/// Handle:
/// - expr[expr], expr[expr:expr] subscript
/// - ".name" lookup
/// - function call with Funcref variable: func(expr)
/// - method call: var->method()
///
/// Can all be combined in any order: dict.func(expr)[idx]['func'](expr)->len()
///
/// @param verbose  give error messages
/// @param start_leader  start of '!' and '-' prefixes
/// @param end_leaderp  end of '!' and '-' prefixes
int handle_subscript(const char **const arg, typval_T *rettv, evalarg_T *const evalarg,
                    bool verbose)
{
 const bool evaluate = evalarg != NULL && (evalarg->eval_flags & EVAL_EVALUATE);
 int ret = OK;
 dict_T *selfdict = NULL;
 const char *lua_funcname = NULL;

 if (tv_is_luafunc(rettv)) {
   if (!evaluate) {
     tv_clear(rettv);
   }

   if (**arg != '.') {
     tv_clear(rettv);
     ret = FAIL;
   } else {
     (*arg)++;

     lua_funcname = *arg;
     const int len = check_luafunc_name(*arg, true);
     if (len == 0) {
       tv_clear(rettv);
       ret = FAIL;
     }
     (*arg) += len;
   }
 }

 // "." is ".name" lookup when we found a dict.
 while (ret == OK
        && (((**arg == '[' || (**arg == '.' && rettv->v_type == VAR_DICT)
              || (**arg == '(' && (!evaluate || tv_is_func(*rettv))))
             && !ascii_iswhite(*(*arg - 1)))
            || (**arg == '-' && (*arg)[1] == '>'))) {
   if (**arg == '(') {
     ret = call_func_rettv((char **)arg, evalarg, rettv, evaluate, selfdict, NULL, lua_funcname);

     // Stop the expression evaluation when immediately aborting on
     // error, or when an interrupt occurred or an exception was thrown
     // but not caught.
     if (aborting()) {
       if (ret == OK) {
         tv_clear(rettv);
       }
       ret = FAIL;
     }
     tv_dict_unref(selfdict);
     selfdict = NULL;
   } else if (**arg == '-') {
     if ((*arg)[2] == '{') {
       // expr->{lambda}()
       ret = eval_lambda((char **)arg, rettv, evalarg, verbose);
     } else {
       // expr->name()
       ret = eval_method((char **)arg, rettv, evalarg, verbose);
     }
   } else {  // **arg == '[' || **arg == '.'
     tv_dict_unref(selfdict);
     if (rettv->v_type == VAR_DICT) {
       selfdict = rettv->vval.v_dict;
       if (selfdict != NULL) {
         selfdict->dv_refcount++;
       }
     } else {
       selfdict = NULL;
     }
     if (eval_index((char **)arg, rettv, evalarg, verbose) == FAIL) {
       tv_clear(rettv);
       ret = FAIL;
     }
   }
 }

 // Turn "dict.Func" into a partial for "Func" bound to "dict".
 if (selfdict != NULL && tv_is_func(*rettv)) {
   set_selfdict(rettv, selfdict);
 }

 tv_dict_unref(selfdict);
 return ret;
}

void set_selfdict(typval_T *const rettv, dict_T *const selfdict)
{
 // Don't do this when "dict.Func" is already a partial that was bound
 // explicitly (pt_auto is false).
 if (rettv->v_type == VAR_PARTIAL && !rettv->vval.v_partial->pt_auto
     && rettv->vval.v_partial->pt_dict != NULL) {
   return;
 }
 make_partial(selfdict, rettv);
}

/// Make a copy of an item
///
/// Lists and Dictionaries are also copied.
///
/// @param[in]  conv  If not NULL, convert all copied strings.
/// @param[in]  from  Value to copy.
/// @param[out]  to  Location where to copy to.
/// @param[in]  deep  If true, use copy the container and all of the contained
///                   containers (nested).
/// @param[in]  copyID  If non-zero then when container is referenced more then
///                     once then copy of it that was already done is used. E.g.
///                     when copying list `list = [list2, list2]` (`list[0] is
///                     list[1]`) var_item_copy with zero copyID will emit
///                     a copy with (`copy[0] isnot copy[1]`), with non-zero it
///                     will emit a copy with (`copy[0] is copy[1]`) like in the
///                     original list. Not used when deep is false.
int var_item_copy(const vimconv_T *const conv, typval_T *const from, typval_T *const to,
                 const bool deep, const int copyID)
 FUNC_ATTR_NONNULL_ARG(2, 3)
{
 static int recurse = 0;
 int ret = OK;

 if (recurse >= DICT_MAXNEST) {
   emsg(_(e_variable_nested_too_deep_for_making_copy));
   return FAIL;
 }
 recurse++;

 switch (from->v_type) {
 case VAR_NUMBER:
 case VAR_FLOAT:
 case VAR_FUNC:
 case VAR_PARTIAL:
 case VAR_BOOL:
 case VAR_SPECIAL:
   tv_copy(from, to);
   break;
 case VAR_STRING:
   if (conv == NULL || conv->vc_type == CONV_NONE
       || from->vval.v_string == NULL) {
     tv_copy(from, to);
   } else {
     to->v_type = VAR_STRING;
     to->v_lock = VAR_UNLOCKED;
     if ((to->vval.v_string = string_convert((vimconv_T *)conv,
                                             from->vval.v_string,
                                             NULL))
         == NULL) {
       to->vval.v_string = xstrdup(from->vval.v_string);
     }
   }
   break;
 case VAR_LIST:
   to->v_type = VAR_LIST;
   to->v_lock = VAR_UNLOCKED;
   if (from->vval.v_list == NULL) {
     to->vval.v_list = NULL;
   } else if (copyID != 0 && tv_list_copyid(from->vval.v_list) == copyID) {
     // Use the copy made earlier.
     to->vval.v_list = tv_list_latest_copy(from->vval.v_list);
     tv_list_ref(to->vval.v_list);
   } else {
     to->vval.v_list = tv_list_copy(conv, from->vval.v_list, deep, copyID);
   }
   if (to->vval.v_list == NULL && from->vval.v_list != NULL) {
     ret = FAIL;
   }
   break;
 case VAR_BLOB:
   tv_blob_copy(from->vval.v_blob, to);
   break;
 case VAR_DICT:
   to->v_type = VAR_DICT;
   to->v_lock = VAR_UNLOCKED;
   if (from->vval.v_dict == NULL) {
     to->vval.v_dict = NULL;
   } else if (copyID != 0 && from->vval.v_dict->dv_copyID == copyID) {
     // use the copy made earlier
     to->vval.v_dict = from->vval.v_dict->dv_copydict;
     to->vval.v_dict->dv_refcount++;
   } else {
     to->vval.v_dict = tv_dict_copy(conv, from->vval.v_dict, deep, copyID);
   }
   if (to->vval.v_dict == NULL && from->vval.v_dict != NULL) {
     ret = FAIL;
   }
   break;
 case VAR_UNKNOWN:
   internal_error("var_item_copy(UNKNOWN)");
   ret = FAIL;
 }
 recurse--;
 return ret;
}

/// ":echo expr1 ..."    print each argument separated with a space, add a
///                      newline at the end.
/// ":echon expr1 ..."   print each argument plain.
void ex_echo(exarg_T *eap)
{
 char *arg = eap->arg;
 typval_T rettv;
 bool atstart = true;
 bool need_clear = true;
 const int did_emsg_before = did_emsg;
 const int called_emsg_before = called_emsg;
 evalarg_T evalarg;

 fill_evalarg_from_eap(&evalarg, eap, eap->skip);

 if (eap->skip) {
   emsg_skip++;
 }
 while (*arg != NUL && *arg != '|' && *arg != '\n' && !got_int) {
   // If eval1() causes an error message the text from the command may
   // still need to be cleared. E.g., "echo 22,44".
   need_clr_eos = true;

   {
     char *p = arg;
     if (eval1(&arg, &rettv, &evalarg) == FAIL) {
       // Report the invalid expression unless the expression evaluation
       // has been cancelled due to an aborting error, an interrupt, or an
       // exception.
       if (!aborting() && did_emsg == did_emsg_before
           && called_emsg == called_emsg_before) {
         semsg(_(e_invexpr2), p);
       }
       need_clr_eos = false;
       break;
     }
     need_clr_eos = false;
   }

   if (!eap->skip) {
     if (atstart) {
       atstart = false;
       msg_ext_set_kind("echo");
       // Call msg_start() after eval1(), evaluating the expression
       // may cause a message to appear.
       if (eap->cmdidx == CMD_echo) {
         if (!msg_didout) {
           // Mark the saved text as finishing the line, so that what
           // follows is displayed on a new line when scrolling back
           // at the more prompt.
           msg_sb_eol();
         }
         msg_start();
       }
     } else if (eap->cmdidx == CMD_echo) {
       msg_puts_hl(" ", echo_hl_id, false);
     }
     char *tofree = encode_tv2echo(&rettv, NULL);
     msg_ext_append = eap->cmdidx == CMD_echon;
     msg_multiline(cstr_as_string(tofree), echo_hl_id, true, false, &need_clear);
     xfree(tofree);
   }
   tv_clear(&rettv);
   arg = skipwhite(arg);
 }
 eap->nextcmd = check_nextcmd(arg);
 clear_evalarg(&evalarg, eap);

 if (eap->skip) {
   emsg_skip--;
 } else {
   // remove text that may still be there from the command
   if (need_clear) {
     msg_clr_eos();
   }
   if (eap->cmdidx == CMD_echo) {
     msg_end();
   }
 }
}

/// ":echohl {name}".
void ex_echohl(exarg_T *eap)
{
 echo_hl_id = syn_name2id(eap->arg);
}

/// Returns the :echo highlight id
int get_echo_hl_id(void)
{
 return echo_hl_id;
}

/// ":execute expr1 ..." execute the result of an expression.
/// ":echomsg expr1 ..." Print a message
/// ":echoerr expr1 ..." Print an error
/// Each gets spaces around each argument and a newline at the end for
/// echo commands
void ex_execute(exarg_T *eap)
{
 char *arg = eap->arg;
 typval_T rettv;
 int ret = OK;
 garray_T ga;

 ga_init(&ga, 1, 80);

 if (eap->skip) {
   emsg_skip++;
 }
 while (*arg != NUL && *arg != '|' && *arg != '\n') {
   ret = eval1_emsg(&arg, &rettv, eap);
   if (ret == FAIL) {
     break;
   }

   if (!eap->skip) {
     const char *const argstr = eap->cmdidx == CMD_execute
                                ? tv_get_string(&rettv)
                                : rettv.v_type == VAR_STRING
                                ? encode_tv2echo(&rettv, NULL)
                                : encode_tv2string(&rettv, NULL);
     const size_t len = strlen(argstr);
     ga_grow(&ga, (int)len + 2);
     if (!GA_EMPTY(&ga)) {
       ((char *)(ga.ga_data))[ga.ga_len++] = ' ';
     }
     memcpy((char *)(ga.ga_data) + ga.ga_len, argstr, len + 1);
     if (eap->cmdidx != CMD_execute) {
       xfree((void *)argstr);
     }
     ga.ga_len += (int)len;
   }

   tv_clear(&rettv);
   arg = skipwhite(arg);
 }

 if (ret != FAIL && ga.ga_data != NULL) {
   if (eap->cmdidx == CMD_echomsg) {
     msg_ext_set_kind("echomsg");
     msg(ga.ga_data, echo_hl_id);
   } else if (eap->cmdidx == CMD_echoerr) {
     // We don't want to abort following commands, restore did_emsg.
     int save_did_emsg = did_emsg;
     emsg_multiline(ga.ga_data, "echoerr", HLF_E, true);
     if (!force_abort) {
       did_emsg = save_did_emsg;
     }
   } else if (eap->cmdidx == CMD_execute) {
     do_cmdline(ga.ga_data, eap->ea_getline, eap->cookie, DOCMD_NOWAIT|DOCMD_VERBOSE);
   }
 }

 ga_clear(&ga);

 if (eap->skip) {
   emsg_skip--;
 }

 eap->nextcmd = check_nextcmd(arg);
}

/// Skip over the name of an option variable: "&option", "&g:option" or "&l:option".
///
/// @param[in,out]  arg        Points to the "&" or '+' when called, to "option" when returning.
/// @param[out]     opt_idxp   Set to option index in options[] table.
/// @param[out]     opt_flags  Option flags.
///
/// @return NULL when no option name found. Otherwise pointer to the char after the option name.
const char *find_option_var_end(const char **const arg, OptIndex *const opt_idxp,
                               int *const opt_flags)
{
 const char *p = *arg;

 p++;
 if (*p == 'g' && p[1] == ':') {
   *opt_flags = OPT_GLOBAL;
   p += 2;
 } else if (*p == 'l' && p[1] == ':') {
   *opt_flags = OPT_LOCAL;
   p += 2;
 } else {
   *opt_flags = 0;
 }

 const char *end = find_option_end(p, opt_idxp);
 *arg = end == NULL ? *arg : p;
 return end;
}

var_flavour_T var_flavour(char *varname)
 FUNC_ATTR_PURE
{
 char *p = varname;

 if (ASCII_ISUPPER(*p)) {
   while (*(++p)) {
     if (ASCII_ISLOWER(*p)) {
       return VAR_FLAVOUR_SESSION;
     }
   }
   return VAR_FLAVOUR_SHADA;
 }
 return VAR_FLAVOUR_DEFAULT;
}

void var_set_global(const char *const name, typval_T vartv)
{
 funccal_entry_T funccall_entry;

 save_funccal(&funccall_entry);
 set_var(name, strlen(name), &vartv, false);
 restore_funccal();
}

/// Display script name where an item was last set.
/// Should only be invoked when 'verbose' is non-zero.
void last_set_msg(sctx_T script_ctx)
{
 if (script_ctx.sc_sid == 0) {
   return;
 }

 bool should_free;
 char *p = get_scriptname(script_ctx, &should_free);
 msg_ext_skip_verbose = true;  // no verbose kind for last set messages: too noisy

 verbose_enter();
 msg_puts(_("\n\tLast set from "));
 msg_puts(p);
 if (script_ctx.sc_lnum > 0) {
   msg_puts(_(line_msg));
   msg_outnum(script_ctx.sc_lnum);
 } else if (script_is_lua(script_ctx.sc_sid)) {
   msg_puts(_(" (run Nvim with -V1 for more details)"));
 }
 if (should_free) {
   xfree(p);
 }
 verbose_leave();
}

/// Perform a substitution on "str" with pattern "pat" and substitute "sub".
/// When "sub" is NULL "expr" is used, must be a VAR_FUNC or VAR_PARTIAL.
/// "flags" can be "g" to do a global substitute.
///
/// @param ret_len  length of returned buffer
///
/// @return  an allocated string, NULL for error.
char *do_string_sub(char *str, size_t len, char *pat, char *sub, typval_T *expr, const char *flags,
                   size_t *ret_len)
{
 regmatch_T regmatch;
 garray_T ga;

 // Make 'cpoptions' empty, so that the 'l' flag doesn't work here
 char *save_cpo = p_cpo;
 p_cpo = empty_string_option;

 ga_init(&ga, 1, 200);

 regmatch.rm_ic = p_ic;
 regmatch.regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING);
 if (regmatch.regprog != NULL) {
   char *tail = str;
   char *end = str + len;
   bool do_all = (flags[0] == 'g');
   int sublen;
   char *zero_width = NULL;

   while (vim_regexec_nl(&regmatch, str, (colnr_T)(tail - str))) {
     // Skip empty match except for first match.
     if (regmatch.startp[0] == regmatch.endp[0]) {
       if (zero_width == regmatch.startp[0]) {
         // avoid getting stuck on a match with an empty string
         int i = utfc_ptr2len(tail);
         memmove((char *)ga.ga_data + ga.ga_len, tail, (size_t)i);
         ga.ga_len += i;
         tail += i;
         continue;
       }
       zero_width = regmatch.startp[0];
     }

     // Get some space for a temporary buffer to do the substitution
     // into.  It will contain:
     // - The text up to where the match is.
     // - The substituted text.
     // - The text after the match.
     sublen = vim_regsub(&regmatch, sub, expr, tail, 0, REGSUB_MAGIC);
     if (sublen <= 0) {
       ga_clear(&ga);
       break;
     }
     ga_grow(&ga, (int)((end - tail) + sublen -
                        (regmatch.endp[0] - regmatch.startp[0])));

     // copy the text up to where the match is
     int i = (int)(regmatch.startp[0] - tail);
     memmove((char *)ga.ga_data + ga.ga_len, tail, (size_t)i);
     // add the substituted text
     vim_regsub(&regmatch, sub, expr,
                (char *)ga.ga_data + ga.ga_len + i, sublen,
                REGSUB_COPY | REGSUB_MAGIC);
     ga.ga_len += i + sublen - 1;
     tail = regmatch.endp[0];
     if (*tail == NUL) {
       break;
     }
     if (!do_all) {
       break;
     }
   }

   if (ga.ga_data != NULL) {
     STRCPY((char *)ga.ga_data + ga.ga_len, tail);
     ga.ga_len += (int)(end - tail);
   }

   vim_regfree(regmatch.regprog);
 }

 if (ga.ga_data != NULL) {
   str = ga.ga_data;
   len = (size_t)ga.ga_len;
 }
 char *ret = xstrnsave(str, len);
 ga_clear(&ga);
 if (p_cpo == empty_string_option) {
   p_cpo = save_cpo;
 } else {
   // Darn, evaluating {sub} expression or {expr} 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 (ret_len != NULL) {
   *ret_len = len;
 }

 return ret;
}

/// Common code for getting job callbacks for `jobstart`.
///
/// @return true/false on success/failure.
bool common_job_callbacks(dict_T *vopts, CallbackReader *on_stdout, CallbackReader *on_stderr,
                         Callback *on_exit)
{
 if (tv_dict_get_callback(vopts, S_LEN("on_stdout"), &on_stdout->cb)
     && tv_dict_get_callback(vopts, S_LEN("on_stderr"), &on_stderr->cb)
     && tv_dict_get_callback(vopts, S_LEN("on_exit"), on_exit)) {
   on_stdout->buffered = tv_dict_get_number(vopts, "stdout_buffered");
   on_stderr->buffered = tv_dict_get_number(vopts, "stderr_buffered");
   if (on_stdout->buffered && on_stdout->cb.type == kCallbackNone) {
     on_stdout->self = vopts;
   }
   if (on_stderr->buffered && on_stderr->cb.type == kCallbackNone) {
     on_stderr->self = vopts;
   }
   vopts->dv_refcount++;
   return true;
 }

 callback_reader_free(on_stdout);
 callback_reader_free(on_stderr);
 callback_free(on_exit);
 return false;
}

Channel *find_job(uint64_t id, bool show_error)
{
 Channel *data = find_channel(id);
 if (!data || data->streamtype != kChannelStreamProc
     || proc_is_stopped(&data->stream.proc)) {
   if (show_error) {
     if (data && data->streamtype != kChannelStreamProc) {
       emsg(_(e_invchanjob));
     } else {
       emsg(_(e_invchan));
     }
   }
   return NULL;
 }
 return data;
}

void script_host_eval(char *name, typval_T *argvars, typval_T *rettv)
{
 if (check_secure()) {
   return;
 }

 if (argvars[0].v_type != VAR_STRING) {
   emsg(_(e_invarg));
   return;
 }

 list_T *args = tv_list_alloc(1);
 tv_list_append_string(args, argvars[0].vval.v_string, -1);
 *rettv = eval_call_provider(name, "eval", args, false);
}

/// @param discard  Clears the value returned by the provider and returns
///                 an empty typval_T.
typval_T eval_call_provider(char *provider, char *method, list_T *arguments, bool discard)
{
 if (!eval_has_provider(provider, false)) {
   semsg("E319: No \"%s\" provider found. Run \":checkhealth vim.provider\"",
         provider);
   return (typval_T){
     .v_type = VAR_NUMBER,
     .v_lock = VAR_UNLOCKED,
     .vval.v_number = 0
   };
 }

 char func[256];
 int name_len = snprintf(func, sizeof(func), "provider#%s#Call", provider);

 // Save caller scope information
 struct caller_scope saved_provider_caller_scope = provider_caller_scope;
 provider_caller_scope = (struct caller_scope) {
   .script_ctx = current_sctx,
   .es_entry = ((estack_T *)exestack.ga_data)[exestack.ga_len - 1],
   .autocmd_fname = autocmd_fname,
   .autocmd_match = autocmd_match,
   .autocmd_fname_full = autocmd_fname_full,
   .autocmd_bufnr = autocmd_bufnr,
   .funccalp = (void *)get_current_funccal()
 };
 funccal_entry_T funccal_entry;
 save_funccal(&funccal_entry);
 provider_call_nesting++;

 typval_T argvars[3] = {
   { .v_type = VAR_STRING, .vval.v_string = method,
     .v_lock = VAR_UNLOCKED },
   { .v_type = VAR_LIST, .vval.v_list = arguments, .v_lock = VAR_UNLOCKED },
   { .v_type = VAR_UNKNOWN }
 };
 typval_T rettv = { .v_type = VAR_UNKNOWN, .v_lock = VAR_UNLOCKED };
 tv_list_ref(arguments);

 funcexe_T funcexe = FUNCEXE_INIT;
 funcexe.fe_firstline = curwin->w_cursor.lnum;
 funcexe.fe_lastline = curwin->w_cursor.lnum;
 funcexe.fe_evaluate = true;
 call_func(func, name_len, &rettv, 2, argvars, &funcexe);

 tv_list_unref(arguments);
 // Restore caller scope information
 restore_funccal();
 provider_caller_scope = saved_provider_caller_scope;
 provider_call_nesting--;
 assert(provider_call_nesting >= 0);

 if (discard) {
   tv_clear(&rettv);
 }

 return rettv;
}

/// Checks if provider for feature `feat` is enabled.
bool eval_has_provider(const char *feat, bool throw_if_fast)
{
 if (!strequal(feat, "clipboard")
     && !strequal(feat, "python3")
     && !strequal(feat, "python3_compiled")
     && !strequal(feat, "python3_dynamic")
     && !strequal(feat, "perl")
     && !strequal(feat, "ruby")
     && !strequal(feat, "node")) {
   // Avoid autoload for non-provider has() features.
   return false;
 }

 if (throw_if_fast && !nlua_is_deferred_safe()) {
   semsg(e_fast_api_disabled, "Vimscript function");
   return false;
 }

 char name[32];  // Normalized: "python3_compiled" => "python3".
 snprintf(name, sizeof(name), "%s", feat);
 strchrsub(name, '_', NUL);  // Chop any "_xx" suffix.

 char buf[256];
 typval_T tv;
 // Get the g:loaded_xx_provider variable.
 int len = snprintf(buf, sizeof(buf), "g:loaded_%s_provider", name);
 if (eval_variable(buf, len, &tv, NULL, false, true) == FAIL) {
   // Trigger autoload once.
   len = snprintf(buf, sizeof(buf), "provider#%s#bogus", name);
   script_autoload(buf, (size_t)len, false);

   // Retry the (non-autoload-style) variable.
   len = snprintf(buf, sizeof(buf), "g:loaded_%s_provider", name);
   if (eval_variable(buf, len, &tv, NULL, false, true) == FAIL) {
     // Show a hint if Call() is defined but g:loaded_xx_provider is missing.
     snprintf(buf, sizeof(buf), "provider#%s#Call", name);
     if (!!find_func(buf) && p_lpl) {
       semsg("provider: %s: missing required variable g:loaded_%s_provider",
             name, name);
     }
     return false;
   }
 }

 bool ok = (tv.v_type == VAR_NUMBER)
           ? 2 == tv.vval.v_number  // Value of 2 means "loaded and working".
           : false;

 if (ok) {
   // Call() must be defined if provider claims to be working.
   snprintf(buf, sizeof(buf), "provider#%s#Call", name);
   if (!find_func(buf)) {
     semsg("provider: %s: g:loaded_%s_provider=2 but %s is not defined",
           name, name, buf);
     ok = false;
   }
 }

 return ok;
}

/// Writes "<sourcing_name>:<sourcing_lnum>" to `buf[bufsize]`.
void eval_fmt_source_name_line(char *buf, size_t bufsize)
{
 if (SOURCING_NAME) {
   snprintf(buf, bufsize, "%s:%" PRIdLINENR, SOURCING_NAME, SOURCING_LNUM);
 } else {
   snprintf(buf, bufsize, "?");
 }
}

/// Gets the current user-input in prompt buffer `buf`, or NULL if buffer is not a prompt buffer.
char *prompt_get_input(buf_T *buf)
{
 if (!bt_prompt(buf)) {
   return NULL;
 }
 linenr_T lnum_start = buf->b_prompt_start.mark.lnum;
 linenr_T lnum_last = buf->b_ml.ml_line_count;

 char *text = ml_get_buf(buf, lnum_start);
 if ((int)strlen(text) >= buf->b_prompt_start.mark.col) {
   text += buf->b_prompt_start.mark.col;
 }

 char *full_text = xstrdup(text);
 for (linenr_T i = lnum_start + 1; i <= lnum_last; i++) {
   char *half_text = concat_str(full_text, "\n");
   xfree(full_text);
   full_text = concat_str(half_text, ml_get_buf(buf, i));
   xfree(half_text);
 }
 return full_text;
}

/// Invokes the user-defined callback defined for the current prompt-buffer.
void prompt_invoke_callback(void)
{
 typval_T rettv;
 typval_T argv[2];
 linenr_T lnum = curbuf->b_ml.ml_line_count;

 char *user_input = prompt_get_input(curbuf);

 if (!user_input) {
   return;
 }

 // Add a new line for the prompt before invoking the callback, so that
 // text can always be inserted above the last line.
 ml_append(lnum, "", 0, false);
 appended_lines_mark(lnum, 1);
 curwin->w_cursor.lnum = lnum + 1;
 curwin->w_cursor.col = 0;
 curbuf->b_prompt_start.mark.lnum = lnum + 1;

 if (curbuf->b_prompt_callback.type == kCallbackNone) {
   xfree(user_input);
   goto theend;
 }

 argv[0].v_type = VAR_STRING;
 argv[0].vval.v_string = user_input;
 argv[1].v_type = VAR_UNKNOWN;

 callback_call(&curbuf->b_prompt_callback, 1, argv, &rettv);
 tv_clear(&argv[0]);
 tv_clear(&rettv);

theend:
 // clear undo history on submit
 u_clearallandblockfree(curbuf);

 curbuf->b_prompt_start.mark.lnum = curbuf->b_ml.ml_line_count;
}

/// @return  true when the interrupt callback was invoked.
bool invoke_prompt_interrupt(void)
{
 typval_T rettv;
 typval_T argv[1];

 if (curbuf->b_prompt_interrupt.type == kCallbackNone) {
   return false;
 }
 argv[0].v_type = VAR_UNKNOWN;

 got_int = false;  // don't skip executing commands
 int ret = callback_call(&curbuf->b_prompt_interrupt, 0, argv, &rettv);
 tv_clear(&rettv);
 return ret != FAIL;
}

/// Compare "typ1" and "typ2".  Put the result in "typ1".
///
/// @param typ1  first operand
/// @param typ2  second operand
/// @param type  operator
/// @param ic  ignore case
int typval_compare(typval_T *typ1, typval_T *typ2, exprtype_T type, bool ic)
 FUNC_ATTR_NONNULL_ALL
{
 varnumber_T n1, n2;
 const bool type_is = type == EXPR_IS || type == EXPR_ISNOT;

 if (type_is && typ1->v_type != typ2->v_type) {
   // For "is" a different type always means false, for "isnot"
   // it means true.
   n1 = type == EXPR_ISNOT;
 } else if (typ1->v_type == VAR_BLOB || typ2->v_type == VAR_BLOB) {
   if (type_is) {
     n1 = typ1->v_type == typ2->v_type
          && typ1->vval.v_blob == typ2->vval.v_blob;
     if (type == EXPR_ISNOT) {
       n1 = !n1;
     }
   } else if (typ1->v_type != typ2->v_type
              || (type != EXPR_EQUAL && type != EXPR_NEQUAL)) {
     if (typ1->v_type != typ2->v_type) {
       emsg(_("E977: Can only compare Blob with Blob"));
     } else {
       emsg(_(e_invalblob));
     }
     tv_clear(typ1);
     return FAIL;
   } else {
     // Compare two Blobs for being equal or unequal.
     n1 = tv_blob_equal(typ1->vval.v_blob, typ2->vval.v_blob);
     if (type == EXPR_NEQUAL) {
       n1 = !n1;
     }
   }
 } else if (typ1->v_type == VAR_LIST || typ2->v_type == VAR_LIST) {
   if (type_is) {
     n1 = typ1->v_type == typ2->v_type
          && typ1->vval.v_list == typ2->vval.v_list;
     if (type == EXPR_ISNOT) {
       n1 = !n1;
     }
   } else if (typ1->v_type != typ2->v_type
              || (type != EXPR_EQUAL && type != EXPR_NEQUAL)) {
     if (typ1->v_type != typ2->v_type) {
       emsg(_("E691: Can only compare List with List"));
     } else {
       emsg(_("E692: Invalid operation for List"));
     }
     tv_clear(typ1);
     return FAIL;
   } else {
     // Compare two Lists for being equal or unequal.
     n1 = tv_list_equal(typ1->vval.v_list, typ2->vval.v_list, ic);
     if (type == EXPR_NEQUAL) {
       n1 = !n1;
     }
   }
 } else if (typ1->v_type == VAR_DICT || typ2->v_type == VAR_DICT) {
   if (type_is) {
     n1 = typ1->v_type == typ2->v_type
          && typ1->vval.v_dict == typ2->vval.v_dict;
     if (type == EXPR_ISNOT) {
       n1 = !n1;
     }
   } else if (typ1->v_type != typ2->v_type
              || (type != EXPR_EQUAL && type != EXPR_NEQUAL)) {
     if (typ1->v_type != typ2->v_type) {
       emsg(_("E735: Can only compare Dictionary with Dictionary"));
     } else {
       emsg(_("E736: Invalid operation for Dictionary"));
     }
     tv_clear(typ1);
     return FAIL;
   } else {
     // Compare two Dictionaries for being equal or unequal.
     n1 = tv_dict_equal(typ1->vval.v_dict, typ2->vval.v_dict, ic);
     if (type == EXPR_NEQUAL) {
       n1 = !n1;
     }
   }
 } else if (tv_is_func(*typ1) || tv_is_func(*typ2)) {
   if (type != EXPR_EQUAL && type != EXPR_NEQUAL
       && type != EXPR_IS && type != EXPR_ISNOT) {
     emsg(_("E694: Invalid operation for Funcrefs"));
     tv_clear(typ1);
     return FAIL;
   }
   if ((typ1->v_type == VAR_PARTIAL && typ1->vval.v_partial == NULL)
       || (typ2->v_type == VAR_PARTIAL && typ2->vval.v_partial == NULL)) {
     // When both partials are NULL, then they are equal.
     // Otherwise they are not equal.
     n1 = (typ1->vval.v_partial == typ2->vval.v_partial);
   } else if (type_is) {
     if (typ1->v_type == VAR_FUNC && typ2->v_type == VAR_FUNC) {
       // strings are considered the same if their value is
       // the same
       n1 = tv_equal(typ1, typ2, ic);
     } else if (typ1->v_type == VAR_PARTIAL && typ2->v_type == VAR_PARTIAL) {
       n1 = typ1->vval.v_partial == typ2->vval.v_partial;
     } else {
       n1 = false;
     }
   } else {
     n1 = tv_equal(typ1, typ2, ic);
   }
   if (type == EXPR_NEQUAL || type == EXPR_ISNOT) {
     n1 = !n1;
   }
 } else if ((typ1->v_type == VAR_FLOAT || typ2->v_type == VAR_FLOAT)
            && type != EXPR_MATCH && type != EXPR_NOMATCH) {
   // If one of the two variables is a float, compare as a float.
   // When using "=~" or "!~", always compare as string.
   const float_T f1 = tv_get_float(typ1);
   const float_T f2 = tv_get_float(typ2);
   n1 = false;
   switch (type) {
   case EXPR_IS:
   case EXPR_EQUAL:
     n1 = f1 == f2; break;
   case EXPR_ISNOT:
   case EXPR_NEQUAL:
     n1 = f1 != f2; break;
   case EXPR_GREATER:
     n1 = f1 > f2; break;
   case EXPR_GEQUAL:
     n1 = f1 >= f2; break;
   case EXPR_SMALLER:
     n1 = f1 < f2; break;
   case EXPR_SEQUAL:
     n1 = f1 <= f2; break;
   case EXPR_UNKNOWN:
   case EXPR_MATCH:
   case EXPR_NOMATCH:
     break;  // avoid gcc warning
   }
 } else if ((typ1->v_type == VAR_NUMBER || typ2->v_type == VAR_NUMBER)
            && type != EXPR_MATCH && type != EXPR_NOMATCH) {
   // If one of the two variables is a number, compare as a number.
   // When using "=~" or "!~", always compare as string.
   n1 = tv_get_number(typ1);
   n2 = tv_get_number(typ2);
   switch (type) {
   case EXPR_IS:
   case EXPR_EQUAL:
     n1 = n1 == n2; break;
   case EXPR_ISNOT:
   case EXPR_NEQUAL:
     n1 = n1 != n2; break;
   case EXPR_GREATER:
     n1 = n1 > n2; break;
   case EXPR_GEQUAL:
     n1 = n1 >= n2; break;
   case EXPR_SMALLER:
     n1 = n1 < n2; break;
   case EXPR_SEQUAL:
     n1 = n1 <= n2; break;
   case EXPR_UNKNOWN:
   case EXPR_MATCH:
   case EXPR_NOMATCH:
     break;  // avoid gcc warning
   }
 } else {
   char buf1[NUMBUFLEN];
   char buf2[NUMBUFLEN];
   const char *const s1 = tv_get_string_buf(typ1, buf1);
   const char *const s2 = tv_get_string_buf(typ2, buf2);
   int i;
   if (type != EXPR_MATCH && type != EXPR_NOMATCH) {
     i = mb_strcmp_ic(ic, s1, s2);
   } else {
     i = 0;
   }
   n1 = false;
   switch (type) {
   case EXPR_IS:
   case EXPR_EQUAL:
     n1 = i == 0; break;
   case EXPR_ISNOT:
   case EXPR_NEQUAL:
     n1 = i != 0; break;
   case EXPR_GREATER:
     n1 = i > 0; break;
   case EXPR_GEQUAL:
     n1 = i >= 0; break;
   case EXPR_SMALLER:
     n1 = i < 0; break;
   case EXPR_SEQUAL:
     n1 = i <= 0; break;

   case EXPR_MATCH:
   case EXPR_NOMATCH:
     n1 = pattern_match(s2, s1, ic);
     if (type == EXPR_NOMATCH) {
       n1 = !n1;
     }
     break;
   case EXPR_UNKNOWN:
     break;  // avoid gcc warning
   }
 }
 tv_clear(typ1);
 typ1->v_type = VAR_NUMBER;
 typ1->vval.v_number = n1;
 return OK;
}

/// Convert any type to a string, never give an error.
/// When "quotes" is true add quotes to a string.
/// Returns an allocated string.
char *typval_tostring(typval_T *arg, bool quotes)
{
 if (arg == NULL) {
   return xstrdup("(does not exist)");
 }
 if (!quotes && arg->v_type == VAR_STRING) {
   return xstrdup(arg->vval.v_string == NULL ? "" : arg->vval.v_string);
 }
 return encode_tv2string(arg, NULL);
}