From 51a53f92a57a9bd163156ade91221f056f510110 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Wed, 25 Mar 2009 21:08:24 +0000
Subject: [PATCH] fix PR3880, fixing a comma swallowing bug handling macros
 that only take ... arguments.

llvm-svn: 67706
---
 clang/lib/Lex/PPMacroExpansion.cpp               | 6 ++++++
 clang/test/Preprocessor/macro_fn_comma_swallow.c | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 6ec306196db0..f1c69d993415 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -403,6 +403,12 @@ MacroArgs *Preprocessor::ReadFunctionLikeMacroArgs(Token &MacroName,
     Tok.setLocation(EndLoc);
     Tok.setLength(0);
     ArgTokens.push_back(Tok);
+  } else if (NumActuals == 1 && ArgTokens.size() == 1) {
+    // If there is exactly one argument, and that argument is just an EOF token,
+    // then we have an empty "()" argument empty list.  This is fine, even if
+    // the macro expects one argument (the argument is just empty).  However, if
+    // the macro expects "...", then we need to know that it was elided.
+    isVarargsElided = MinArgsExpected == 1 && MI->isVariadic();
   }
   
   return MacroArgs::create(MI, &ArgTokens[0], ArgTokens.size(),isVarargsElided);
diff --git a/clang/test/Preprocessor/macro_fn_comma_swallow.c b/clang/test/Preprocessor/macro_fn_comma_swallow.c
index 4e06f89a160f..e985138a5c44 100644
--- a/clang/test/Preprocessor/macro_fn_comma_swallow.c
+++ b/clang/test/Preprocessor/macro_fn_comma_swallow.c
@@ -14,3 +14,8 @@ X2()
 X3(foo)
 
 
+
+// RUN: clang-cc %s -E | grep 'AA BB'
+// PR3880
+#define X4(...)  AA , ## __VA_ARGS__ BB
+X4()