[Format/ObjC] Fix [foo bar]->baz formatting as lambda arrow

Summary:
Currently, `UnwrappedLineParser` thinks an arrow token after
an ObjC method expression is a C++ lambda arrow, so it formats:

```
[foo bar]->baz
```

as:

```
[foo bar] -> baz
```

Because `UnwrappedLineParser` runs before `TokenAnnotator`, it can't
know if the arrow token is after an ObjC method expression or not.

This diff makes `TokenAnnotator` remove the TT_LambdaArrow on
the arrow token if it follows an ObjC method expression.

Test Plan: New test added. Ran test with:
  % ninja FormatTests && ./tools/clang/unittests/Format/FormatTests
  Confirmed test failed before diff and passed after diff.

Reviewers: krasimir, djasper, sammccall

Reviewed By: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57923

llvm-svn: 353531

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 45896d86ad0..c7ddbf5926a 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -520,6 +520,10 @@ private:
           if (Parent && Parent->is(TT_PointerOrReference))
             Parent->Type = TT_BinaryOperator;
         }
+        // An arrow after an ObjC method expression is not a lambda arrow.
+        if (CurrentToken->Type == TT_ObjCMethodExpr && CurrentToken->Next &&
+            CurrentToken->Next->is(TT_LambdaArrow))
+          CurrentToken->Next->Type = TT_Unknown;
         Left->MatchingParen = CurrentToken;
         CurrentToken->MatchingParen = Left;
         // FirstObjCSelectorName is set when a colon is found. This does