Improved error recovery for _Pragma

Summary:
Currently, if the argument to _Pragma is not a parenthesised string
literal, the bad token will be consumed, as well as the ')', if present.
If additional bad tokens are passed to the _Pragma, this results in
extra error messages which may distract from the true problem.

The proposed patch causes all tokens to be consumed until the closing
')' or a new line, whichever is reached first.

Reviewers: hfinkel, rsmith

Subscribers: hubert.reinterpretcast, fraggamuffin, rnk, cfe-commits

Differential Revision: http://reviews.llvm.org/D8308

Patch by Rachel Craik!

llvm-svn: 243692

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/Lex/Pragma.cpp b/clang/lib/Lex/Pragma.cpp
index 5eb665549e8..db8e3055b85 100644
--- a/clang/lib/Lex/Pragma.cpp
+++ b/clang/lib/Lex/Pragma.cpp
@@ -191,9 +191,13 @@ void Preprocessor::Handle_Pragma(Token &Tok) {
   Lex(Tok);
   if (!tok::isStringLiteral(Tok.getKind())) {
     Diag(PragmaLoc, diag::err__Pragma_malformed);
-    // Skip this token, and the ')', if present.
+    // Skip bad tokens, and the ')', if present.
     if (Tok.isNot(tok::r_paren) && Tok.isNot(tok::eof))
       Lex(Tok);
+    while (Tok.isNot(tok::r_paren) &&
+           !Tok.isAtStartOfLine() &&
+           Tok.isNot(tok::eof))
+      Lex(Tok);
     if (Tok.is(tok::r_paren))
       Lex(Tok);
     return _PragmaLexing.failed();