Preproceessor: fix #if skipping under -traditional-cpp.

When parsing directives within skipped #if blocks, we don't want to retain
any whitespace. Previously we were just skipping comments, but it's not
possible to skip comments and retain other whitespace. This change matches
the usual behavior for parsing directives (i.e. the behavior outside of
skipped #if blocks).

<rdar://problem/13267695>

llvm-svn: 175840

2 files changed, 17 insertions, 1 deletions

diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 54457c36cfd..10446832124 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -258,7 +258,7 @@ void Preprocessor::SkipExcludedConditionalBlock(SourceLocation IfTokenLoc,
     // directive mode.  Tell the lexer this so any newlines we see will be
     // converted into an EOD token (this terminates the macro).
     CurPPLexer->ParsingPreprocessorDirective = true;
-    if (CurLexer) CurLexer->SetCommentRetentionState(false);
+    if (CurLexer) CurLexer->SetKeepWhitespaceMode(false);
 
 
     // Read the next token, the directive flavor.
diff --git a/clang/test/Preprocessor/traditional-cpp.c b/clang/test/Preprocessor/traditional-cpp.c
index 72024546ff3..5a94c00c969 100644
--- a/clang/test/Preprocessor/traditional-cpp.c
+++ b/clang/test/Preprocessor/traditional-cpp.c
@@ -62,3 +62,19 @@ bracket2(spaces)
 /* If this were working, this check would be on.
  * CHECK-NOT: {{^}}>>>  spaces  <<<{{$}}
  */
+
+
+/* Check that #if 0 blocks work as expected */
+#if 0
+#error "this is not an error"
+
+#if 1
+a b c in skipped block
+#endif
+
+/* Comments are whitespace too */
+
+#endif
+/* CHECK-NOT: {{^}}a b c in skipped block{{$}}
+ * CHECK-NOT: {{^}}/* Comments are whitespace too
+ */