Use clang on mac if XCode >= 4.5

tools/gyp/find_mac_gcc_version.py

Index: tools/gyp/find_mac_gcc_version.py
diff --git a/tools/gyp/find_mac_gcc_version.py b/tools/gyp/find_mac_gcc_version.py
index 0af84120b6b22e9d1fa09b094252090c345124b9..1622ef1bc03efbf056a218204721c06e250f1e74 100755
--- a/tools/gyp/find_mac_gcc_version.py
+++ b/tools/gyp/find_mac_gcc_version.py
@@ -21,10 +21,13 @@ def main():
     major = int(matches[0][0])
     minor = int(matches[0][1])
 
-    if major >= 4:
-      return 'com.apple.compilers.llvmgcc42'
-    elif major == 3 and minor >= 1:
+    if major == 3 and minor >= 1:
       return '4.2'
+    elif major == 4 and minor < 5:
+      return 'com.apple.compilers.llvmgcc42'
+    elif major == 4 and minor == 5:

[ricow1, 2013/04/24 14:01:47]

minor >= 5?
if xcode is selecting it automatically anyway I don't see why we should disallow
people that at some point upgrades to compile

[kustermann, 2013/04/24 14:10:06]

I discussed this with ivan offline: we can't be sure that the next XCode will
ship with 'com.apple.compilers.llvm.clang.1_0' (maybe they'll ship with
'com.apple.compilers.llvm.clang.2_0').

But since this case is very unlikely, I could change it?

[kustermann, 2013/04/24 14:42:59]

Ivan pointed out we can install XCode 4.6. I tried it and it works there as
well. I've changed it now to 'minor >= 5'. 

[hausner, 2013/04/24 20:33:20]

I have XCode 4.6.1 (4H512) on my new laptop that I installed last week. It uses
clang now to compile, and fails while compiling v8.

Interestingly, I have 4.6 (4H127) on the desktop. It uses gcc (after your
change)! The V8 build passes on this machine.

On 2013/04/24 14:42:59, kustermann wrote:

[kustermann, 2013/04/24 20:59:10]

This should not happen. I tried it on my macbook (with 4.6.1 [4H512]) and it
failed because of the warning in v8/src/parser.cc.
Could you check if it still uses gcc after doing
- 'gclient runhooks' (-> generating project files with clang instead of gcc)
- removing the build folder (-> no incremental build of v8)

+      # XCode seems to select the specific clang version automatically
+      return 'com.apple.compilers.llvm.clang.1_0'
     else:
       raise Exception('Unknown XCode Version "%s"' % version_match)
   else: