BUILD.gn (4746B)
1 import("//chromium/build/config/c++/c++.gni") 2 import("//chromium/build/config/chrome_build.gni") 3 import("//chromium/build/config/chromeos/ui_mode.gni") 4 import("//chromium/build/config/compiler/compiler.gni") 5 import("//chromium/build/config/dcheck_always_on.gni") 6 import("//buildtools/deps_revisions.gni") 7 8 assert(use_custom_libcxx, "should only be used if use_custom_libcxx is set") 9 10 # This is included by reference in the //build/config/compiler:runtime_library 11 # config that is applied to all targets. It is here to separate out the logic 12 # that is specific to libc++. Please see that target for advice on what should 13 # go in :runtime_library vs. :compiler. 14 config("runtime_library") { 15 cflags = [] 16 cflags_cc = [] 17 defines = [] 18 include_dirs = [] 19 ldflags = [] 20 libs = [] 21 22 # Fixed libc++ configuration macros are in 23 # buildtools/third_party/libc++/__config_site. This config only has defines 24 # that vary depending on gn args, and non-define flags. 25 26 if (!libcxx_is_shared) { 27 # Don't leak any symbols on a static build. 28 defines += [ "_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS" ] 29 if (!export_libcxxabi_from_executables && !is_win) { 30 defines += [ "_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS" ] 31 } 32 } 33 34 include_dirs += [ "//buildtools/third_party/libc++" ] 35 36 # libc++ has two levels of additional checking: 37 # 1. _LIBCPP_ENABLE_ASSERTIONS enables assertions for bounds checking. 38 # We always enable this in __config_site, in all build configurations. 39 # 2. _LIBCPP_ENABLE_DEBUG_MODE enables iterator debugging and other 40 # expensive checks. Enable these only if enable_iterator_debugging is on. 41 if (enable_iterator_debugging) { 42 defines += [ "_LIBCPP_ENABLE_DEBUG_MODE" ] 43 } 44 45 # Fuzzers build parts of the code with asan enabled and some with it 46 # disabled. That's incompatible with _LIBCPP_INSTRUMENTED_WITH_ASAN, see 47 # https://crbug.com/347026228#comment25 48 # TODO(thakis): Enable on apple if https://llvm.org/PR96099 gets fixed. 49 if (is_asan && !use_fuzzing_engine && !is_apple) { 50 defines += [ "_LIBCPP_INSTRUMENTED_WITH_ASAN=1" ] 51 } else { 52 defines += [ "_LIBCPP_INSTRUMENTED_WITH_ASAN=0" ] 53 } 54 55 defines += [ "CR_LIBCXX_REVISION=$libcxx_revision" ] 56 57 # Temporarily add a define to force a rebuild when changing 58 # buildtools/third_party/libc++/__config_site which isn't picked up by 59 # dependency tracking (because it's an #include of headers included via 60 # -isysroot). 61 # TODO(thakis): Remove this after a few days. 62 defines += [ "TMP_REBUILD_HACK" ] 63 64 if (is_win) { 65 # Intentionally not using libc++abi on Windows because libc++abi only 66 # implements the Itanium C++ ABI, and not the Microsoft ABI which we use on 67 # Windows (and we need to use in order to interoperate correctly with COM 68 # among other things). 69 assert(!export_libcxxabi_from_executables, 70 "Don't use libcxxabi on Windows.") 71 72 cflags_cc += 73 [ "-I" + rebase_path("$libcxx_prefix/include", root_build_dir) ] 74 75 # Add a debug visualizer for Microsoft's debuggers so that they can display 76 # libc++ types well. 77 if (libcxx_natvis_include) { 78 # chrome.natvis listed as an input in //buildtools/third_party/libc++ to 79 # guarantee relinking on changes. 80 ldflags += [ "/NATVIS:" + rebase_path("libc++.natvis", root_build_dir) ] 81 } 82 } else { 83 cflags_cc += [ 84 "-nostdinc++", 85 "-isystem" + rebase_path("$libcxx_prefix/include", root_build_dir), 86 "-isystem" + rebase_path("$libcxxabi_prefix/include", root_build_dir), 87 ] 88 89 cflags_objcc = cflags_cc 90 91 # Make sure we don't link against the system libstdc++ or libc++. 92 if (is_clang) { 93 ldflags += [ "-nostdlib++" ] 94 } else { 95 # Gcc has a built-in abs() definition with default visibility. 96 # If it was not disabled, it would conflict with libc++'s abs() 97 # with hidden visibility. 98 cflags += [ "-fno-builtin-abs" ] 99 100 ldflags += [ "-nodefaultlibs" ] 101 102 # Unfortunately, there's no way to disable linking against just libc++ 103 # (gcc doesn't have -notstdlib++: 104 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83931); -nodefaultlibs 105 # removes all of the default libraries, so add back the ones that we need. 106 libs += [ 107 "c", 108 "gcc_s", 109 "m", 110 "rt", 111 ] 112 } 113 } 114 115 # In a world without NaCl, the `runtime_library` config would also configure 116 # the `_LIBCPP_ENABLE_ASSERTIONS` define to enable hardening when using the 117 # custom hermetic libc++. However, this is currently added by the `compiler` 118 # config instead, since this hardening define should also be used by the NaCl 119 # saigo toolchain, which uses a prebuilt libc++ that is distinct from the 120 # custom hermetic libc++. 121 }