Make preprocessor act in a GCC-compatible fashion when a macro is redefined

within its own argument list. The original definition is used for the immediate
expansion, but the new definition is used for any subsequent occurences within
the argument list or after the expansion.

llvm-svn: 162906

clang/include/clang/Lex/Preprocessor.h

@@ -569,7 +569,8 @@ public:
   ///
   /// ILEnd specifies the location of the ')' for a function-like macro or the
   /// identifier for an object-like macro.
-  void EnterMacro(Token &Identifier, SourceLocation ILEnd, MacroArgs *Args);
+  void EnterMacro(Token &Identifier, SourceLocation ILEnd, MacroInfo *Macro,
+                  MacroArgs *Args);
 
   /// EnterTokenStream - Add a "macro" context to the top of the include stack,
   /// which will cause the lexer to start returning the specified tokens.

clang/include/clang/Lex/TokenLexer.h

@@ -22,7 +22,7 @@ namespace clang {
   class Token;
   class MacroArgs;
 
-/// TokenLexer - This implements a lexer that returns token from a macro body
+/// TokenLexer - This implements a lexer that returns tokens from a macro body
 /// or token stream instead of lexing from a character buffer.  This is used for
 /// macro expansion and _Pragma handling, for example.
 ///
@@ -98,17 +98,18 @@ public:
   /// arguments.  Note that this ctor takes ownership of the ActualArgs pointer.
   /// ILEnd specifies the location of the ')' for a function-like macro or the
   /// identifier for an object-like macro.
-  TokenLexer(Token &Tok, SourceLocation ILEnd, MacroArgs *ActualArgs,
-             Preprocessor &pp)
+  TokenLexer(Token &Tok, SourceLocation ILEnd, MacroInfo *MI,
+             MacroArgs *ActualArgs, Preprocessor &pp)
     : Macro(0), ActualArgs(0), PP(pp), OwnsTokens(false) {
-    Init(Tok, ILEnd, ActualArgs);
+    Init(Tok, ILEnd, MI, ActualArgs);
   }
 
   /// Init - Initialize this TokenLexer to expand from the specified macro
   /// with the specified argument information.  Note that this ctor takes
   /// ownership of the ActualArgs pointer.  ILEnd specifies the location of the
   /// ')' for a function-like macro or the identifier for an object-like macro.
-  void Init(Token &Tok, SourceLocation ILEnd, MacroArgs *ActualArgs);
+  void Init(Token &Tok, SourceLocation ILEnd, MacroInfo *MI,
+            MacroArgs *ActualArgs);
 
   /// Create a TokenLexer for the specified token stream.  If 'OwnsTokens' is
   /// specified, this takes ownership of the tokens and delete[]'s them when

clang/lib/Lex/PPLexerChange.cpp

@@ -157,15 +157,15 @@ void Preprocessor::EnterSourceFileWithPTH(PTHLexer *PL,
 /// EnterMacro - Add a Macro to the top of the include stack and start lexing
 /// tokens from it instead of the current buffer.
 void Preprocessor::EnterMacro(Token &Tok, SourceLocation ILEnd,
-                              MacroArgs *Args) {
+                              MacroInfo *Macro, MacroArgs *Args) {
   PushIncludeMacroStack();
   CurDirLookup = 0;
 
   if (NumCachedTokenLexers == 0) {
-    CurTokenLexer.reset(new TokenLexer(Tok, ILEnd, Args, *this));
+    CurTokenLexer.reset(new TokenLexer(Tok, ILEnd, Macro, Args, *this));
   } else {
     CurTokenLexer.reset(TokenLexerCache[--NumCachedTokenLexers]);
-    CurTokenLexer->Init(Tok, ILEnd, Args);
+    CurTokenLexer->Init(Tok, ILEnd, Macro, Args);
   }
   if (CurLexerKind != CLK_LexAfterModuleImport)
     CurLexerKind = CLK_TokenLexer;

clang/lib/Lex/PPMacroExpansion.cpp

@@ -341,7 +341,7 @@ bool Preprocessor::HandleMacroExpandedIdentifier(Token &Identifier,
   }
 
   // Start expanding the macro.
-  EnterMacro(Identifier, ExpansionEnd, Args);
+  EnterMacro(Identifier, ExpansionEnd, MI, Args);
 
   // Now that the macro is at the top of the include stack, ask the
   // preprocessor to read the next token from it.

clang/lib/Lex/TokenLexer.cpp

@@ -23,12 +23,13 @@ using namespace clang;
 
 /// Create a TokenLexer for the specified macro with the specified actual
 /// arguments.  Note that this ctor takes ownership of the ActualArgs pointer.
-void TokenLexer::Init(Token &Tok, SourceLocation ELEnd, MacroArgs *Actuals) {
+void TokenLexer::Init(Token &Tok, SourceLocation ELEnd, MacroInfo *MI,
+                      MacroArgs *Actuals) {
   // If the client is reusing a TokenLexer, make sure to free any memory
   // associated with it.
   destroy();
 
-  Macro = PP.getMacroInfo(Tok.getIdentifierInfo());
+  Macro = MI;
   ActualArgs = Actuals;
   CurToken = 0;
 

clang/test/Preprocessor/macro_arg_directive.c

@@ -1,5 +1,12 @@
 // RUN: %clang_cc1 %s -fsyntax-only -verify
 
+#define a(x) enum { x }
+a(n =
+#undef a
+#define a 5
+  a);
+_Static_assert(n == 5, "");
+
 // header1.h
 void fail(const char *);
 #define MUNCH(...) \