Linux: Detect host g++ version as well as target g++ version.

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1341 matching lines @@
       }],
       # Get binutils version so we can enable debug fission if we can.
       ['os_posix==1 and OS!="mac" and OS!="ios"', {
         'conditions': [
           # compiler_version doesn't work with clang
           # TODO(mithro): Land https://codereview.chromium.org/199793014/ so
           # compiler_version works with clang.
           # TODO(glider): set clang to 1 earlier for ASan and TSan builds so
           # that it takes effect here.
           ['clang==0 and asan==0 and lsan==0 and tsan==0 and msan==0', {
-            'binutils_version%': '<!pymod_do_main(compiler_version assembler)',
+            'binutils_version%': '<!pymod_do_main(compiler_version target assembler)',
           }],
           # On Android we know the binutils version in the toolchain.
           ['OS=="android"', {
             'binutils_version%': 222,
           }],
           ['host_arch=="x64"', {
             'binutils_dir%': 'third_party/binutils/Linux_x64/Release/bin',
           }],
           ['host_arch=="ia32"', {
             'binutils_dir%': 'third_party/binutils/Linux_ia32/Release/bin',
           }],
           # Our version of binutils in third_party/binutils
           ['linux_use_bundled_binutils==1', {
             'binutils_version%': 224,
           }],
         ],
       }, {
         'binutils_version%': 0,
       }],
       # The version of GCC in use, set later in platforms that use GCC and have
       # not explicitly chosen to build with clang. Currently, this means all
       # platforms except Windows, Mac and iOS.
       # TODO(glider): set clang to 1 earlier for ASan and TSan builds so that
       # it takes effect here.
       ['os_posix==1 and OS!="mac" and OS!="ios" and clang==0 and asan==0 and lsan==0 and tsan==0 and msan==0', {
         'conditions': [
           ['OS=="android"', {
-            # We directly set the gcc_version since we know what we use.
+            # We directly set the gcc versions since we know what we use.
             'conditions': [
               ['target_arch=="x64" or target_arch=="arm64"', {
+                'host_gcc_version%': 48,
                 'gcc_version%': 48,
               }, {
+                'host_gcc_version%': 46,
                 'gcc_version%': 46,
               }],
             ],
           }, {
-            'gcc_version%': '<!pymod_do_main(compiler_version)',
+            'host_gcc_version%': '<!pymod_do_main(compiler_version host compiler)',
+            'gcc_version%': '<!pymod_do_main(compiler_version target compiler)',
           }],
         ],
       }, {
+        'host_gcc_version%': 0,
         'gcc_version%': 0,
       }],
       ['OS=="win" and "<!pymod_do_main(dir_exists <(windows_sdk_default_path))"=="True"', {
         'windows_sdk_path%': '<(windows_sdk_default_path)',
       }, {
         'windows_sdk_path%': 'C:/Program Files (x86)/Windows Kits/8.0',
       }],
       ['OS=="win" and "<!pymod_do_main(dir_exists <(directx_sdk_default_path))"=="True"', {
         'directx_sdk_path%': '<(directx_sdk_default_path)',
       }, {
@@ skipping 2429 matching lines @@
                     ],
                   }],
                 ],
               }],
               # Newer gcc's support -fuse-ld, use the flag to force gold
               # selection.
               # gcc -- http://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Optimize-Options.html
               # TODO(mithro): Watch for clang support at following thread:
               # http://clang-developers.42468.n3.nabble.com/Adding-fuse-ld-support-to-clang-td4032180.html
               ['gcc_version>=48', {
-                'cflags': [
-                  '-fuse-ld=gold',
+                'target_conditions': [
+                  ['_toolset=="target"', {
+                    'cflags': [
+                      '-fuse-ld=gold',
+                    ],
+                    'ldflags': [
+                      '-fuse-ld=gold',
+                    ],
+                  }],
                 ],
-                'ldflags': [
-                  '-fuse-ld=gold',
+              }],
+              ['host_gcc_version>=48', {
+                'target_conditions': [
+                  ['_toolset=="host"', {
+                    'cflags': [
+                      '-fuse-ld=gold',
+                    ],
+                    'ldflags': [
+                      '-fuse-ld=gold',
+                    ],
+                  }],
                 ],
-              }]
+              }],
             ],
           }],
           ['linux_use_bundled_binutils==1', {
             'cflags': [
               '-B<!(cd <(DEPTH) && pwd -P)/<(binutils_dir)',
             ],
           }],
           ['linux_use_bundled_gold==1', {
             # Put our binutils, which contains gold in the search path. We pass
             # the path to gold to the compiler. gyp leaves unspecified what the
@@ skipping 1330 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }