Windows precompiled header support in GN

tools/gn/source_file_type.h

Index: tools/gn/source_file_type.h
diff --git a/tools/gn/source_file_type.h b/tools/gn/source_file_type.h
index f738daacb4602957bb8ca72730fc7229b8d61505..315a87d2fd0746a91dbdccbef0968a501e1c34f7 100644
--- a/tools/gn/source_file_type.h
+++ b/tools/gn/source_file_type.h
@@ -7,8 +7,10 @@
 
 class SourceFile;
 
+// This should be sequential integers starting from 0 so they can be used as
+// array indices.
 enum SourceFileType {
-  SOURCE_UNKNOWN,
+  SOURCE_UNKNOWN = 0,
   SOURCE_ASM,
   SOURCE_C,
   SOURCE_CC,

[scottmg, 2015/06/26 22:30:13]

_CPP might be better to be less confusing with toolchain TYPE_CC.

[brettw, 2015/06/29 21:36:10]

Good idea, I found this confusing myself.

@@ -19,6 +21,9 @@ enum SourceFileType {
   SOURCE_RC,
   SOURCE_O,  // Object files can be inputs, too. Also counts .obj.
   SOURCE_DEF,
+
+  // Must be last.
+  SOURCE_NUMTYPES,
 };
 
 SourceFileType GetSourceFileType(const SourceFile& file);