When we expect two arguments but have zero, make sure to add

two empty arguments.  Also, add an assert so that this bug
manifests as an assertion failure, not a valgrind problem.

This fixes rdar://6880648 - [cpp] crash in ArgNeedsPreexpansion


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71616 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 6 insertions, 0 deletions

diff --git a/lib/Lex/MacroArgs.cpp b/lib/Lex/MacroArgs.cpp
index 2646a61e51..cba69b7d79 100644
--- a/lib/Lex/MacroArgs.cpp
+++ b/lib/Lex/MacroArgs.cpp
@@ -72,6 +72,7 @@ const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
     if (Result->is(tok::eof))
       --Arg;
   }
+  assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
   return Result;
 }
 
diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index 48c166daba..18dcfb25e7 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -427,6 +427,11 @@ MacroArgs *Preprocessor::ReadFunctionLikeMacroArgs(Token &MacroName,
     Tok.setLocation(EndLoc);
     Tok.setLength(0);
     ArgTokens.push_back(Tok);
+
+    // If we expect two arguments, add both as empty.
+    if (NumActuals == 0 && MinArgsExpected == 2)
+      ArgTokens.push_back(Tok);
+    
   } else if (NumActuals > MinArgsExpected && !MI->isVariadic()) {
     // Emit the diagnostic at the macro name in case there is a missing ).
     // Emitting it at the , could be far away from the macro name.