clang: Instead of having update.sh clobber out/, add a define with the current revision.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 096f1a95a7fa287cf7ebc5642f6850b0edd59427..e5c984944c682157b6fca8ba4b60759c48aeb4f7 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -2316,6 +2316,14 @@
           ],
         },
       }],
+      ['clang==1 and OS!="win"', {
+        # This is here so that all files get recompiled after a clang roll and
+        # when turning clang on or off.
+        # (defines are passed via the command line, and build systems rebuild
+        # things when their commandline changes). Nothing should ever read this
+        # define.
+        'defines': ['CR_CLANG_REVISION=<!(<(DEPTH)/tools/clang/scripts/update.sh --print-revision)'],

[hans, 2014/05/08 20:11:21]

Could we just shell out to clang and ask it which version it is?

[Nico, 2014/05/08 20:17:29]

Since --version prints 3 lines, it'd require some sed'ing, and I don't like sed
calls in gyp files, so I'd have to write a script for that. So this seems
simpler. (Also, once everything is on update.py, this could use pymod_do_main).

+      }],
       ['enable_rlz==1', {
         'defines': ['ENABLE_RLZ'],
       }],