Also detect the CXX_target enviroment vairiable for compiler version

build/compiler_version.py

Index: build/compiler_version.py
diff --git a/build/compiler_version.py b/build/compiler_version.py
index b349199992caeefc5c63b227083a98a5400fda3f..eae7b176dd2187be3aa52d236f030aebc4d3e02f 100755
--- a/build/compiler_version.py
+++ b/build/compiler_version.py
@@ -33,21 +33,42 @@ def GetVersion(compiler):
     print >> sys.stderr, e
     return ""
 
-def main():
-  # Check if CXX environment variable exists and
-  # if it does use that compiler.
-  cxx = os.getenv("CXX", None)
+def GetVersionFromEnvironment(compiler_env):
+  """ Returns the version of compiler
+
+  If the compiler was set by the given environment variable and exists,
+  return its version, otherwise None is returned.
+  """
+  cxx = os.getenv(compiler_env, None)
   if cxx:
-    cxxversion = GetVersion(cxx)
-    if cxxversion != "":
-      print cxxversion
-      return 0
-  else:
-    # Otherwise we check the g++ version.
-    gccversion = GetVersion("g++")
-    if gccversion != "":
-      print gccversion
-      return 0
+    cxx_version = GetVersion(cxx)
+    if cxx_version != "":
+      return cxx_version
+  return None
+
+def main():
+  # Check if CXX_target or CXX environment variable exists an if it does use
+  # that compiler.
+  # TODO: Fix ninja (see http://crbug.com/140900) instead and remove this code
+  # In ninja's cross compile mode, the CXX_target is target compiler, while
+  # the CXX is host. The CXX_target needs be checked first, though the target
+  # and host compiler have different version, there seems no issue to use the
+  # target compiler's version number as gcc_version in Android.
+  cxx_version = GetVersionFromEnvironment("CXX_target")
+  if cxx_version:
+    print cxx_version
+    return 0
+
+  cxx_version = GetVersionFromEnvironment("CXX")
+  if cxx_version:
+    print cxx_version
+    return 0
+
+  # Otherwise we check the g++ version.
+  gccversion = GetVersion("g++")
+  if gccversion != "":
+    print gccversion
+    return 0
 
   return 1