add a ppcallback hook for macro definitions.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68883 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Lex/PPCallbacks.h b/include/clang/Lex/PPCallbacks.h
index cd7c5e4..d2e3f35 100644
--- a/include/clang/Lex/PPCallbacks.h
+++ b/include/clang/Lex/PPCallbacks.h
@@ -55,10 +55,15 @@
                              const std::string &Str) {
   }
   
-  /// MacroExpands - This is called Preprocessor::HandleMacroExpandedIdentifier
-  /// when a macro invocation is found.
+  /// MacroExpands - This is called by
+  /// Preprocessor::HandleMacroExpandedIdentifier when a macro invocation is
+  /// found.
   virtual void MacroExpands(const Token &Id, const MacroInfo* MI) {
   }
+  
+  /// MacroDefined - This hook is called whenever a macro definition is seen.
+  virtual void MacroDefined(const IdentifierInfo *II, const MacroInfo *MI) {
+  }
 };
 
 }  // end namespace clang
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index ba321a7..52f673c 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -1402,6 +1402,10 @@
   }
   
   setMacroInfo(MacroNameTok.getIdentifierInfo(), MI);
+  
+  // If the callbacks want to know, tell them about the macro definition.
+  if (Callbacks)
+    Callbacks->MacroDefined(MacroNameTok.getIdentifierInfo(), MI);
 }
 
 /// HandleUndefDirective - Implements #undef.