Modify some Linux flags for better GYP fidelity in GN build.

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")
 import("//build/config/sysroot.gni")
 
 # compiler ---------------------------------------------------------------------
 #
 # Base compiler configuration.
@@ skipping 83 matching lines @@
 
     # CPU architecture. We may or may not be doing a cross compile now, so for
     # simplicity we always explicitly set the architecture.
     if (cpu_arch == "x64") {
       cflags += "-m64"
       ldflags += "-m64"
     } else if (cpu_arch == "x86") {
       cflags += "-m32"
       ldflags += "-m32"
     }
+
+    defines += [ "_FILE_OFFSET_BITS=64" ]
+
+    # Omit unwind support in official builds to save space. We can use breakpad
+    # for these builds.
+    if (is_chrome_branded && is_official_build) {
+      cflags += [
+        "-fno-unwind-tables",
+        "-fno-asynchronous-unwind-tables",
+      ]
+    } else {
+      cflags += [ "-funwind-tables" ]
+    }
   }
 
   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_linux) {
     cflags += [
       "-fPIC",
       "-pipe",  # Use pipes for communicating between sub-processes. Faster.
     ]
     if (!is_android) {
       cflags += [ "-pthread" ]
     }
 
-    # Use gold for linking on 64-bit Linux only (on 32-bit it runs out of
-    # address space, and it doesn't support cross-compiling).
     if (cpu_arch == "x64") {
+     # Enable libstdc++ debugging facilities to help catch problems early, see
+     # http://crbug.com/65151 .
+     # TODO(phajdan.jr): Should we enable this for all of POSIX?

[scottmg, 2014/01/10 19:58:07]

indent

+      defines += [ "__GLIBCXX_DEBUG=1" ]
+
+      # Use gold for linking on 64-bit Linux only (on 32-bit it runs out of
+      # address space, and it doesn't support cross-compiling).
       gold_path = rebase_path("//third_party/gold", ".", root_build_dir)
       ldflags += [
         "-B$gold_path",
 
         # There seems to be a conflict of --icf and -pie in gold which can
         # generate crashy binaries. As a security measure, -pie takes
         # precendence for now.
         # TODO(brettw) common.gypi has this only for target toolset.
         #"-Wl,--icf=safe",
         "-Wl,--icf=none",
@@ skipping 27 matching lines @@
       "-Wl,-z,relro",
     ]
   }
 
   # Clang-specific compiler flags setup.
   # ------------------------------------
   if (is_clang) {
     cflags += [
       "-fcolor-diagnostics",
     ]
+    cflags_cc += [
+      "-std=gnu++11",
+    ]
   }
 
   # Android-specific flags setup.
   # -----------------------------
   if (is_android) {
     cflags += [
       "-ffunction-sections",
       "-funwind-tables",
       "-fno-short-enums",
     ]
@@ skipping 419 matching lines @@
   } else {
     cflags = [ "-g1" ]
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }