Linux: Enable ODR violation detection.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 if (cpu_arch == "mipsel" || cpu_arch == "mips64el") {
   import("//build/config/mips.gni")
@@ skipping 53 matching lines @@
 
 # TODO(GYP): is_ubsan, is_ubsan_vptr
 if (!is_win) {
   using_sanitizer = is_asan || is_lsan || is_tsan || is_msan
 }
 
 # compiler ---------------------------------------------------------------------
 #
 # Base compiler configuration.
 #
-# See also "runtime_library" below for related stuff and a discusison about
+# See also "runtime_library" below for related stuff and a discussion about
 # where stuff should go. Put warning related stuff in the "warnings" config.
 
 config("compiler") {
   cflags = []
   cflags_c = []
   cflags_cc = []
   ldflags = []
   defines = []
 
   # In general, Windows is totally different, but all the other builds share
@@ skipping 290 matching lines @@
       # TODO(brettw) common.gypi has this only for target toolset.
       "-Wl,--icf=safe",
 
       # Experimentation found that using four linking threads
       # saved ~20% of link time.
       # https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
       # Only apply this to the target linker, since the host
       # linker might not be gold, but isn't used much anyway.
       "-Wl,--threads",
       "-Wl,--thread-count=4",
+      "-Wl,--detect-odr-violations",
     ]
   }
 
   if (linux_use_bundled_binutils) {
     binutils_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
                                 root_build_dir)
     cflags += [ "-B$binutils_path" ]
   }
 
   # Clang-specific compiler flags setup.
@@ skipping 73 matching lines @@
     }
   }
 }
 
 config("compiler_arm_fpu") {
   if (cpu_arch == "arm" && !is_android_webview_build) {
     cflags = [ "-mfpu=$arm_fpu" ]
   }
 }
 
+# //third_party/libphonenumber is the only existing code that needs this.
+# http://crbug.com/456021
+# New code should fix their ODR violations instead of ignoring them.
+config("compiler_allow_odr_violations") {
+  if (use_gold) {
+    ldflags = [ "-Wl,--no-detect-odr-violations" ]
+  }
+}

[Nico, 2015/02/06 15:46:04]

You can have a local config in the libphonenumber build file, like so:
https://codereview.chromium.org/722513003/diff/120001/third_party/libphonenum...
(…oh hey, the example is in libphonenumber too!)

[Lei Zhang, 2015/02/06 23:44:55]

Oh, I tried that, but I needed to duplicate the |use_gold| variable. Is there a
way to reference a variable in another .gn file?

+
 # runtime_library -------------------------------------------------------------
 #
 # Sets the runtime library and associated options.
 #
 # How do you determine what should go in here vs. "compiler" above? Consider if
 # a target might choose to use a different runtime library (ignore for a moment
 # if this is possible or reasonable on your system). If such a target would want
 # to change or remove your option, put it in the runtime_library config. If a
 # target wants the option regardless, put it in the compiler config.
 
@@ skipping 563 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }