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

BUG=360082

Review URL: https://codereview.chromium.org/247623003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@265572 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -1359,7 +1359,7 @@
           # 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"', {
@@ -1387,19 +1387,23 @@
       ['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"', {
@@ -3850,13 +3854,29 @@
               # 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', {

build/compiler_version.py

@@ -18,6 +18,33 @@
 compiler_version_cache = {}  # Map from (compiler, tool) -> version.
 
 
+def Usage(program_name):
+  print '%s MODE TOOL' % os.path.basename(program_name)
+  print 'MODE: host or target.'
+  print 'TOOL: assembler or compiler or linker.'
+  return 1
+
+
+def ParseArgs(args):
+  if len(args) != 2:
+    raise Exception('Invalid number of arguments')
+  mode = args[0]
+  tool = args[1]
+  if mode not in ('host', 'target'):
+    raise Exception('Invalid mode: %s' % mode)
+  if tool not in ('assembler', 'compiler', 'linker'):
+    raise Exception('Invalid tool: %s' % tool)
+  return mode, tool
+
+
+def GetEnvironFallback(var_list, default):
+  """Look up an environment variable from a possible list of variable names."""
+  for var in var_list:
+    if var in os.environ:
+      return os.environ[var]
+  return default
+
+
 def GetVersion(compiler, tool):
   tool_output = tool_error = None
   cache_key = (compiler, tool)
@@ -73,7 +100,13 @@ def GetVersion(compiler, tool):
 
 
 def main(args):
-  ret_code, result = ExtractVersion(args)
+  try:
+    (mode, tool) = ParseArgs(args[1:])
+  except Exception, e:
+    sys.stderr.write(e.message + '\n\n')
+    return Usage(args[0])
+
+  ret_code, result = ExtractVersion(mode, tool)
   if ret_code == 0:
     print result
   return ret_code
@@ -82,29 +115,29 @@ def main(args):
 def DoMain(args):
   """Hook to be called from gyp without starting a separate python
   interpreter."""
-  ret_code, result = ExtractVersion(args)
+  (mode, tool) = ParseArgs(args)
+  ret_code, result = ExtractVersion(mode, tool)
   if ret_code == 0:
     return result
   raise Exception("Failed to extract compiler version for args: %s" % args)
 
 
-def ExtractVersion(args):
-  tool = "compiler"
-  if len(args) == 1:
-    tool = args[0]
-  elif len(args) > 1:
-    print "Unknown arguments!"
+def ExtractVersion(mode, tool):
+  # Check if various CXX environment variables exist and use them if they
+  # exist. The preferences and fallback order is a close approximation of
+  # GenerateOutputForConfig() in GYP's ninja generator.
+  # The main difference being not supporting GYP's make_global_settings.
+  environments = ['CXX_target', 'CXX']
+  if mode == 'host':
+    environments = ['CXX_host'] + environments;
+  compiler = GetEnvironFallback(environments, 'c++')
 
-  # Check if CXX environment variable exists and if it does use that
-  # compiler, otherwise check g++.
-  compiler = os.getenv("CXX", "g++")
   if compiler:
     compiler_version = GetVersion(compiler, tool)
     if compiler_version != "":
       return (0, compiler_version)
-
   return (1, None)
 
 
 if __name__ == "__main__":
-  sys.exit(main(sys.argv[1:]))
+  sys.exit(main(sys.argv))