From 89be04720148a342c73fd65aac88880f9edde09f Mon Sep 17 00:00:00 2001
From: Eric Liu <ioeric@google.com>
Date: Tue, 19 Apr 2016 19:25:33 +0000
Subject: [PATCH] Fixed a bug in AnnotatedLine::startsWith when there are
 comments in the line.

Summary: When there are comments in the line, one token may be checked multiple times.

Reviewers: mprobst, djasper

Subscribers: ioeric, cfe-commits, klimek

Differential Revision: http://reviews.llvm.org/D19106

llvm-svn: 266803
---
 clang/lib/Format/TokenAnnotator.h | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/clang/lib/Format/TokenAnnotator.h b/clang/lib/Format/TokenAnnotator.h
index 5329f1f3f2fc..141e8b4106a3 100644
--- a/clang/lib/Format/TokenAnnotator.h
+++ b/clang/lib/Format/TokenAnnotator.h
@@ -83,7 +83,7 @@ public:
   /// \c true if this line starts with the given tokens in order, ignoring
   /// comments.
   template <typename... Ts> bool startsWith(Ts... Tokens) const {
-    return startsWith(First, Tokens...);
+    return startsWithInternal(First, Tokens...);
   }
 
   /// \c true if this line looks like a function definition instead of a
@@ -124,15 +124,24 @@ private:
   void operator=(const AnnotatedLine &) = delete;
 
   template <typename A, typename... Ts>
-  bool startsWith(FormatToken *Tok, A K1) const {
+  bool startsWithInternal(const FormatToken *Tok, A K1) const {
+    // Even though we skip comments in the outer `startWithInternal` function,
+    // this loop is still necessary if it is invoked by the public interface
+    // `startsWith`.
     while (Tok && Tok->is(tok::comment))
       Tok = Tok->Next;
     return Tok && Tok->is(K1);
   }
 
   template <typename A, typename... Ts>
-  bool startsWith(FormatToken *Tok, A K1, Ts... Tokens) const {
-    return startsWith(Tok, K1) && startsWith(Tok->Next, Tokens...);
+  bool startsWithInternal(const FormatToken *Tok, A K1, Ts... Tokens) const {
+    // Skip comments before calling `startsWithInternal(Tok, K1)` so that  the
+    // second call to `startsWithInternal` takes the correct `Tok->Next`, which
+    // should be the next token of the token checked in the first call.
+    while (Tok && Tok->is(tok::comment))
+      Tok = Tok->Next;
+    return Tok && startsWithInternal(Tok, K1) &&
+           startsWithInternal(Tok->Next, Tokens...);
   }
 };