fix PR7943, a corner case with the GNU __VA_ARGS__ comma
swallowing extension.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111701 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/TokenLexer.cpp b/lib/Lex/TokenLexer.cpp
index 49dc016..94719b0 100644
--- a/lib/Lex/TokenLexer.cpp
+++ b/lib/Lex/TokenLexer.cpp
@@ -268,6 +268,13 @@
// Remove the paste operator, report use of the extension.
PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma);
ResultToks.pop_back();
+
+ // If the comma was right after another paste (e.g. "X##,##__VA_ARGS__"),
+ // then removal of the comma should produce a placemarker token (in C99
+ // terms) which we model by popping off the previous ##, giving us a plain
+ // "X" when __VA_ARGS__ is empty.
+ if (!ResultToks.empty() && ResultToks.back().is(tok::hashhash))
+ ResultToks.pop_back();
}
continue;
}