Fixed a bug in AnnotatedLine::startsWith when there are comments in the line.

[ioeric]

Summary

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

[djasper]

Can you add a test?

lib/Format/TokenAnnotator.h

143 ↗

(On Diff #53689)

It's a bit subtle that this works even if Tok is nullptr at this point. Maybe change to

return Tok && startsWithInternal( ...

to make this more clear.

[ioeric]

• Addressed reviewer comment.

[ioeric]

PING.

[djasper]

Looks good.

lib/Format/TokenAnnotator.h

128 ↗

(On Diff #53691)

s/outter/outer/

[ioeric]

• nit fixed

cfe/trunk/lib/Format/TokenAnnotator.h

while (Current) {
       Current->Role.reset();
       Current = Current->Next;
     }
   }
 
   /// \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
   /// function declaration. Asserts MightBeFunctionDecl.
   bool mightBeFunctionDefinition() const {
     assert(MightBeFunctionDecl);
     // FIXME: Line.Last points to other characters than tok::semi
     // and tok::lbrace.
public:
   bool ChildrenAffected;
 
 private:
   // Disallow copying.
   AnnotatedLine(const AnnotatedLine &) = delete;
   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...);
   }
 };
 
 /// \brief Determines extra information about the tokens comprising an
 /// \c UnwrappedLine.
 class TokenAnnotator {
 public:
   TokenAnnotator(const FormatStyle &Style, const AdditionalKeywords &Keywords)