Make Preprocessor::Lex non-recursive.

Before this patch, Lex() would recurse whenever the current lexer changed (e.g.
upon entry into a macro). This patch turns the recursion into a loop: the
various lex routines now don't return a token when the current lexer changes,
and at the top level Preprocessor::Lex() now loops until it finds a token.
Normally, the recursion wouldn't end up being very deep, but the recursion depth
can explode in edge cases like a bunch of consecutive macros which expand to
nothing (like in the testcase test/Preprocessor/macro_expand_empty.c in this
patch).

<rdar://problem/14569770>

llvm-svn: 190980

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
index f5555291a83..045e60add1f 100644
--- a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
+++ b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
@@ -555,7 +555,7 @@ static bool findDirectives(SourceManager &SM, FileID FID,
   VerifyDiagnosticConsumer::DirectiveStatus Status =
     VerifyDiagnosticConsumer::HasNoDirectives;
   while (Tok.isNot(tok::eof)) {
-    RawLex.Lex(Tok);
+    RawLex.LexFromRawLexer(Tok);
     if (!Tok.is(tok::comment)) continue;
 
     std::string Comment = RawLex.getSpelling(Tok, SM, LangOpts);