r236374 - [modules] Don't bother creating a ModuleMacro representing a #undef that overrides nothing.

[Richard Smith]

Author: rsmith
Date: Fri May  1 20:14:40 2015
New Revision: 236374

URL: http://llvm.org/viewvc/llvm-project?rev=236374&view=rev
Log:
[modules] Don't bother creating a ModuleMacro representing a #undef that overrides nothing.

Modified:
    cfe/trunk/lib/Lex/PPLexerChange.cpp

Modified: cfe/trunk/lib/Lex/PPLexerChange.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/PPLexerChange.cpp?rev=236374&r1=236373&r2=236374&view=diff
==============================================================================
--- cfe/trunk/lib/Lex/PPLexerChange.cpp (original)
+++ cfe/trunk/lib/Lex/PPLexerChange.cpp Fri May  1 20:14:40 2015
@@ -685,8 +685,11 @@ void Preprocessor::LeaveSubmodule() {
         // FIXME: Issue a warning if multiple headers for the same submodule
         // define a macro, rather than silently ignoring all but the first.
         bool IsNew;
-        addModuleMacro(Info.M, II, Def, Macro.second.getOverriddenMacros(),
-                       IsNew);
+        // Don't bother creating a module macro if it would represent a #undef
+        // that doesn't override anything.
+        if (Def || !Macro.second.getOverriddenMacros().empty())
+          addModuleMacro(Info.M, II, Def, Macro.second.getOverriddenMacros(),
+                         IsNew);
         break;
       }
     }