[preprocessor] Allow comparing two macro definitions syntactically instead of only lexically.

Syntactically means the function macro parameter names do not need to use the same
identifiers in order for the definitions to be considered identical.

Syntactic equivalence is a microsoft extension for macro redefinitions and we'll also
use this kind of comparison to check for ambiguous macros coming from modules.

rdar://13562254

llvm-svn: 178671

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 4c2d2197e49..4c4277c30fd 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -1604,7 +1604,8 @@ void ASTReader::installImportedMacro(IdentifierInfo *II, MacroDirective *MD,
     MacroDirective::DefInfo PrevDef = Prev->getDefinition();
     MacroInfo *PrevMI = PrevDef.getMacroInfo();
     MacroInfo *NewMI = DefMD->getInfo();
-    if (NewMI != PrevMI && !PrevMI->isIdenticalTo(*NewMI, PP)) {
+    if (NewMI != PrevMI && !PrevMI->isIdenticalTo(*NewMI, PP,
+                                                  /*Syntactically=*/true)) {
       // Before marking the macros as ambiguous, check if this is a case where
       // the system macro uses a not identical definition compared to a macro
       // from the clang headers. For example: