Windows precompiled header support in GN

tools/gn/source_file_type.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TOOLS_GN_SOURCE_FILE_TYPE_H_
 #define TOOLS_GN_SOURCE_FILE_TYPE_H_
 
 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.

   SOURCE_H,
   SOURCE_M,
   SOURCE_MM,
   SOURCE_S,
   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);
 
 #endif  // TOOLS_GN_SOURCE_FILE_TYPE_H_