[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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178671 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 57 insertions, 17 deletions

diff --git a/include/clang/Lex/MacroInfo.h b/include/clang/Lex/MacroInfo.h
index d7e72fb5c6..64323b7c76 100644
--- a/include/clang/Lex/MacroInfo.h
+++ b/include/clang/Lex/MacroInfo.h
@@ -145,9 +145,12 @@ public:
   /// \brief 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;
+  /// \param Syntactically if true, the macro definitions can be identical even
+  /// if they use different identifiers for the function macro parameters.
+  /// Otherwise the comparison is lexical and this implements the rules in
+  /// C99 6.10.3.
+  bool isIdenticalTo(const MacroInfo &Other, Preprocessor &PP,
+                     bool Syntactically) const;
 
   /// \brief Set or clear the isBuiltinMacro flag.
   void setIsBuiltinMacro(bool Val = true) {
diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index b27c06a19c..fce3d33780 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -991,7 +991,8 @@ static void checkConfigMacro(Preprocessor &PP, StringRef ConfigMacro,
   // If the current macro definition is the same as the predefined macro
   // definition, it's okay.
   if (LatestDef.getMacroInfo() == PredefinedDef.getMacroInfo() ||
-      LatestDef.getMacroInfo()->isIdenticalTo(*PredefinedDef.getMacroInfo(),PP))
+      LatestDef.getMacroInfo()->isIdenticalTo(*PredefinedDef.getMacroInfo(),PP,
+                                              /*Syntactically=*/true))
     return;
 
   // The macro definitions differ.
diff --git a/lib/Lex/MacroInfo.cpp b/lib/Lex/MacroInfo.cpp
index dc091f625b..5abafe1cb7 100644
--- a/lib/Lex/MacroInfo.cpp
+++ b/lib/Lex/MacroInfo.cpp
@@ -61,11 +61,17 @@ unsigned MacroInfo::getDefinitionLengthSlow(SourceManager &SM) const {
   return DefinitionLength;
 }
 
-// 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 {
+/// \brief Return true if the specified macro definition is equal to
+/// this macro in spelling, arguments, and whitespace.
+///
+/// \param Syntactically if true, the macro definitions can be identical even
+/// if they use different identifiers for the function macro parameters.
+/// Otherwise the comparison is lexical and this implements the rules in
+/// C99 6.10.3.
+bool MacroInfo::isIdenticalTo(const MacroInfo &Other, Preprocessor &PP,
+                              bool Syntactically) const {
+  bool Lexically = !Syntactically;
+
   // Check # tokens in replacement, number of args, and various flags all match.
   if (ReplacementTokens.size() != Other.ReplacementTokens.size() ||
       getNumArgs() != Other.getNumArgs() ||
@@ -74,10 +80,12 @@ bool MacroInfo::isIdenticalTo(const MacroInfo &Other, Preprocessor &PP) const {
       isGNUVarargs() != Other.isGNUVarargs())
     return false;
 
-  // Check arguments.
-  for (arg_iterator I = arg_begin(), OI = Other.arg_begin(), E = arg_end();
-       I != E; ++I, ++OI)
-    if (*I != *OI) return false;
+  if (Lexically) {
+    // Check arguments.
+    for (arg_iterator I = arg_begin(), OI = Other.arg_begin(), E = arg_end();
+         I != E; ++I, ++OI)
+      if (*I != *OI) return false;
+  }
 
   // Check all the tokens.
   for (unsigned i = 0, e = ReplacementTokens.size(); i != e; ++i) {
@@ -95,7 +103,15 @@ bool MacroInfo::isIdenticalTo(const MacroInfo &Other, Preprocessor &PP) const {
 
     // If this is an identifier, it is easy.
     if (A.getIdentifierInfo() || B.getIdentifierInfo()) {
-      if (A.getIdentifierInfo() != B.getIdentifierInfo())
+      if (A.getIdentifierInfo() == B.getIdentifierInfo())
+        continue;
+      if (Lexically)
+        return false;
+      // With syntactic equivalence the parameter names can be different as long
+      // as they are used in the same place.
+      int AArgNum = getArgumentNum(A.getIdentifierInfo());
+      int BArgNum = Other.getArgumentNum(B.getIdentifierInfo());
+      if (AArgNum == -1 || AArgNum != BArgNum)
         return false;
       continue;
     }
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index 3fc19e41f8..07c1867010 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -1949,9 +1949,9 @@ void Preprocessor::HandleDefineDirective(Token &DefineTok) {
       if (OtherMI->isBuiltinMacro())
         Diag(MacroNameTok, diag::ext_pp_redef_builtin_macro);
       // Macros must be identical.  This means all tokens and whitespace
-      // separation must be the same.  C99 6.10.3.2.
+      // separation must be the same.  C99 6.10.3p2.
       else if (!OtherMI->isAllowRedefinitionsWithoutWarning() &&
-               !MI->isIdenticalTo(*OtherMI, *this)) {
+               !MI->isIdenticalTo(*OtherMI, *this, /*Syntactic=*/LangOpts.MicrosoftExt)) {
         Diag(MI->getDefinitionLoc(), diag::ext_pp_macro_redef)
           << MacroNameTok.getIdentifierInfo();
         Diag(OtherMI->getDefinitionLoc(), diag::note_previous_definition);
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 4c2d2197e4..4c4277c30f 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/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:
diff --git a/test/Modules/Inputs/macros_left.h b/test/Modules/Inputs/macros_left.h
index a8aac75a2f..076b0464e6 100644
--- a/test/Modules/Inputs/macros_left.h
+++ b/test/Modules/Inputs/macros_left.h
@@ -12,3 +12,5 @@
 #define LEFT_RIGHT_DIFFERENT3 float
 
 #define LEFT_RIGHT_DIFFERENT float
+
+#define FN_ADD(a,b) (a+b)
diff --git a/test/Modules/Inputs/macros_right.h b/test/Modules/Inputs/macros_right.h
index 445f579cf6..dbbd2c3643 100644
--- a/test/Modules/Inputs/macros_right.h
+++ b/test/Modules/Inputs/macros_right.h
@@ -15,3 +15,5 @@
 
 #undef TOP_RIGHT_REDEF
 #define TOP_RIGHT_REDEF float
+
+#define FN_ADD(x, y) (x+y)
diff --git a/test/Modules/macros.c b/test/Modules/macros.c
index c715ec9651..fc448d9989 100644
--- a/test/Modules/macros.c
+++ b/test/Modules/macros.c
@@ -125,6 +125,7 @@ void test2() {
 void test3() {
   double d;
   LEFT_RIGHT_DIFFERENT *dp = &d; // okay
+  int x = FN_ADD(1,2);
 }
 
 #ifndef TOP_RIGHT_UNDEF
diff --git a/test/Preprocessor/macro_misc.c b/test/Preprocessor/macro_misc.c
index 53d99821cc..3feaa210f7 100644
--- a/test/Preprocessor/macro_misc.c
+++ b/test/Preprocessor/macro_misc.c
@@ -21,3 +21,17 @@
 #define FUNC_LIKE3(a) ( a)  // expected-note {{previous definition is here}}
 #define FUNC_LIKE3(a) (a) // expected-warning {{'FUNC_LIKE3' macro redefined}}
 
+// RUN: %clang_cc1 -fms-extensions -DMS_EXT %s -Eonly -verify
+#ifndef MS_EXT
+// This should under C99.
+#define FUNC_LIKE4(a,b) (a+b)  // expected-note {{previous definition is here}}
+#define FUNC_LIKE4(x,y) (x+y) // expected-warning {{'FUNC_LIKE4' macro redefined}}
+#else
+// This shouldn't under MS extensions.
+#define FUNC_LIKE4(a,b) (a+b)
+#define FUNC_LIKE4(x,y) (x+y)
+
+// This should.
+#define FUNC_LIKE5(a,b) (a+b) // expected-note {{previous definition is here}}
+#define FUNC_LIKE5(x,y) (y+x) // expected-warning {{'FUNC_LIKE5' macro redefined}}
+#endif