3 files changed, 24 insertions, 16 deletions

diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 51ee02e4dba..3bf65e5f87d 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -79,6 +79,13 @@ public:
   }
 };
 
+/// \brief Context in which macro name is used.
+enum MacroUse {
+  MU_Other  = 0,  // other than #define or #undef
+  MU_Define = 1,  // macro name specified in #define
+  MU_Undef  = 2   // macro name specified in #undef
+};
+
 /// \brief Engages in a tight little dance with the lexer to efficiently
 /// preprocess tokens.
 ///
@@ -1360,7 +1367,7 @@ public:
   /// followed by EOD.  Return true if the token is not a valid on-off-switch.
   bool LexOnOffSwitch(tok::OnOffSwitch &OOS);
 
-  bool CheckMacroName(Token &MacroNameTok, char isDefineUndef);
+  bool CheckMacroName(Token &MacroNameTok, MacroUse isDefineUndef);
 
 private:
 
@@ -1404,7 +1411,7 @@ private:
   ///
   /// This emits a diagnostic, sets the token kind to eod,
   /// and discards the rest of the macro line if the macro name is invalid.
-  void ReadMacroName(Token &MacroNameTok, char isDefineUndef = 0);
+  void ReadMacroName(Token &MacroNameTok, MacroUse isDefineUndef = MU_Other);
 
   /// The ( starting an argument list of a macro definition has just been read.
   /// Lex the rest of the arguments and the closing ), updating \p MI with
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 739ebd41c31..04f3b29bd5b 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -100,7 +100,7 @@ void Preprocessor::DiscardUntilEndOfDirective() {
   } while (Tmp.isNot(tok::eod));
 }
 
-bool Preprocessor::CheckMacroName(Token &MacroNameTok, char isDefineUndef) {
+bool Preprocessor::CheckMacroName(Token &MacroNameTok, MacroUse isDefineUndef) {
   // Missing macro name?
   if (MacroNameTok.is(tok::eod))
     return Diag(MacroNameTok, diag::err_pp_missing_macro_name);
@@ -128,12 +128,12 @@ bool Preprocessor::CheckMacroName(Token &MacroNameTok, char isDefineUndef) {
     MacroNameTok.setIdentifierInfo(II);
   }
 
-  if (isDefineUndef && II->getPPKeywordID() == tok::pp_defined) {
+  if ((isDefineUndef != MU_Other) && II->getPPKeywordID() == tok::pp_defined) {
     // Error if defining "defined": C99 6.10.8/4, C++ [cpp.predefined]p4.
     return Diag(MacroNameTok, diag::err_defined_macro_name);
   }
 
-  if (isDefineUndef == 2 && II->hasMacroDefinition() &&
+  if (isDefineUndef == MU_Undef && II->hasMacroDefinition() &&
       getMacroInfo(II)->isBuiltinMacro()) {
     // Warn if undefining "__LINE__" and other builtins, per C99 6.10.8/4
     // and C++ [cpp.predefined]p4], but allow it as an extension.
@@ -147,17 +147,18 @@ bool Preprocessor::CheckMacroName(Token &MacroNameTok, char isDefineUndef) {
 /// \brief Lex and validate a macro name, which occurs after a
 /// \#define or \#undef.
 ///
-/// This sets the token kind to eod and discards the rest
-/// of the macro line if the macro name is invalid.  \p isDefineUndef is 1 if
-/// this is due to a a \#define, 2 if \#undef directive, 0 if it is something
-/// else (e.g. \#ifdef).
-void Preprocessor::ReadMacroName(Token &MacroNameTok, char isDefineUndef) {
+/// This sets the token kind to eod and discards the rest of the macro line if
+/// the macro name is invalid.
+///
+/// \param MacroNameTok Token that is expected to be a macro name.
+/// \papam isDefineUndef Context in which macro is used.
+void Preprocessor::ReadMacroName(Token &MacroNameTok, MacroUse isDefineUndef) {
   // Read the token, don't allow macro expansion on it.
   LexUnexpandedToken(MacroNameTok);
 
   if (MacroNameTok.is(tok::code_completion)) {
     if (CodeComplete)
-      CodeComplete->CodeCompleteMacroName(isDefineUndef == 1);
+      CodeComplete->CodeCompleteMacroName(isDefineUndef == MU_Define);
     setCodeCompletionReached();
     LexUnexpandedToken(MacroNameTok);
   }
@@ -1194,7 +1195,7 @@ void Preprocessor::HandleIdentSCCSDirective(Token &Tok) {
 /// \brief Handle a #public directive.
 void Preprocessor::HandleMacroPublicDirective(Token &Tok) {
   Token MacroNameTok;
-  ReadMacroName(MacroNameTok, 2);
+  ReadMacroName(MacroNameTok, MU_Undef);
   
   // Error reading macro name?  If so, diagnostic already issued.
   if (MacroNameTok.is(tok::eod))
@@ -1221,7 +1222,7 @@ void Preprocessor::HandleMacroPublicDirective(Token &Tok) {
 /// \brief Handle a #private directive.
 void Preprocessor::HandleMacroPrivateDirective(Token &Tok) {
   Token MacroNameTok;
-  ReadMacroName(MacroNameTok, 2);
+  ReadMacroName(MacroNameTok, MU_Undef);
   
   // Error reading macro name?  If so, diagnostic already issued.
   if (MacroNameTok.is(tok::eod))
@@ -1897,7 +1898,7 @@ void Preprocessor::HandleDefineDirective(Token &DefineTok,
   ++NumDefined;
 
   Token MacroNameTok;
-  ReadMacroName(MacroNameTok, 1);
+  ReadMacroName(MacroNameTok, MU_Define);
 
   // Error reading macro name?  If so, diagnostic already issued.
   if (MacroNameTok.is(tok::eod))
@@ -2145,7 +2146,7 @@ void Preprocessor::HandleUndefDirective(Token &UndefTok) {
   ++NumUndefined;
 
   Token MacroNameTok;
-  ReadMacroName(MacroNameTok, 2);
+  ReadMacroName(MacroNameTok, MU_Undef);
 
   // Error reading macro name?  If so, diagnostic already issued.
   if (MacroNameTok.is(tok::eod))
diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp
index 8408aa2314d..a3f5d938ce0 100644
--- a/clang/lib/Lex/PPExpressions.cpp
+++ b/clang/lib/Lex/PPExpressions.cpp
@@ -103,7 +103,7 @@ static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
   }
 
   // If we don't have a pp-identifier now, this is an error.
-  if (PP.CheckMacroName(PeekTok, 0))
+  if (PP.CheckMacroName(PeekTok, MU_Other))
     return true;
 
   // Otherwise, we got an identifier, is it defined to something?