3 files changed, 39 insertions, 10 deletions
diff --git a/clang/Lex/MacroInfo.cpp b/clang/Lex/MacroInfo.cpp
index 28579a46bc0..f5ce986a570 100644
--- a/clang/Lex/MacroInfo.cpp
+++ b/clang/Lex/MacroInfo.cpp
@@ -12,13 +12,41 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/Preprocessor.h"
 #include <iostream>
 using namespace llvm;
 using namespace clang;
 
-/// isEqualTo - Return true if the specified macro definition is equal to this
-/// macro in spelling, arguments, and whitespace.  This is used to emit
-/// duplicate definition warnings.
-bool MacroInfo::isEqualTo(const MacroInfo &Other) const {
+/// isIdenticalTo - Return true if the specified macro definition is equal to
+/// this macro in spelling, arguments, and whitespace.  This is used to emit
+/// duplicate definition warnings.  This implements the rules in C99 6.10.3.
+bool MacroInfo::isIdenticalTo(const MacroInfo &Other, Preprocessor &PP) const {
+  // TODO: Check param count, variadic, function likeness.
+  
+  // Check # tokens in replacement match.
+  if (ReplacementTokens.size() != Other.ReplacementTokens.size())
+    return false;
+  
+  // Check all the tokens.
+  for (unsigned i = 0, e = ReplacementTokens.size(); i != e; ++i) {
+    const LexerToken &A = ReplacementTokens[i];
+    const LexerToken &B = Other.ReplacementTokens[i];
+    if (A.getKind() != B.getKind() || 
+        A.isAtStartOfLine() != B.isAtStartOfLine() ||
+        A.hasLeadingSpace() != B.hasLeadingSpace())
+      return false;
+    
+    // If this is an identifier, it is easy.
+    if (A.getIdentifierInfo() || B.getIdentifierInfo()) {
+      if (A.getIdentifierInfo() != B.getIdentifierInfo())
+        return false;
+      continue;
+    }
+    
+    // Otherwise, check the spelling.
+    if (PP.getSpelling(A) != PP.getSpelling(B))
+      return false;
+  }
+  
   return true;
 }
diff --git a/clang/Lex/Preprocessor.cpp b/clang/Lex/Preprocessor.cpp
index 66acd6c7bd5..6aa6fe273f3 100644
--- a/clang/Lex/Preprocessor.cpp
+++ b/clang/Lex/Preprocessor.cpp
@@ -1400,8 +1400,8 @@ void Preprocessor::HandleDefineDirective(LexerToken &DefineTok) {
       Diag(OtherMI->getDefinitionLoc(), diag::pp_macro_not_used);
 
     // Macros must be identical.  This means all tokes and whitespace separation
-    // must be the same.
-    if (!MI->isEqualTo(*OtherMI)) {
+    // must be the same.  C99 6.10.3.2.
+    if (!MI->isIdenticalTo(*OtherMI, *this)) {
       Diag(MI->getDefinitionLoc(), diag::ext_pp_macro_redef,
            MacroNameTok.getIdentifierInfo()->getName());
       Diag(OtherMI->getDefinitionLoc(), diag::ext_pp_macro_redef2);
diff --git a/clang/include/clang/Lex/MacroInfo.h b/clang/include/clang/Lex/MacroInfo.h
index ca668a5ae6a..7fd4be2f9e8 100644
--- a/clang/include/clang/Lex/MacroInfo.h
+++ b/clang/include/clang/Lex/MacroInfo.h
@@ -19,6 +19,7 @@
 
 namespace llvm {
 namespace clang {
+  class Preprocessor;
     
 /// MacroInfo - Each identifier that is #define'd has an instance of this class
 /// associated with it, used to implement macro expansion.
@@ -57,10 +58,10 @@ public:
   ///
   SourceLocation getDefinitionLoc() const { return Location; }
   
-  /// isEqualTo - Return true if the specified macro definition is equal to this
-  /// macro in spelling, arguments, and whitespace.  This is used to emit
-  /// duplicate definition warnings.
-  bool isEqualTo(const MacroInfo &Other) const;
+  /// isIdenticalTo - Return true if the specified macro definition is equal to
+  /// this macro in spelling, arguments, and whitespace.  This is used to emit
+  /// duplicate definition warnings.  This implements the rules in C99 6.10.3.
+  bool isIdenticalTo(const MacroInfo &Other, Preprocessor &PP) const;
   
   /// setIsBuiltinMacro - Set or clear the isBuiltinMacro flag.
   ///