[clang-format/ObjC] Correctly annotate single-component ObjC method invocations

Summary:
Previously, clang-format's parser would fail to annotate the
selector in a single-component Objective-C method invocation with
`TT_SelectorName`. For example, the following:

  [foo bar];

would parse `bar` as `TT_Unknown`:

  M=0 C=1 T=Unknown S=0 B=0 BK=0 P=140 Name=identifier L=34 PPK=2
  FakeLParens= FakeRParens=0 II=0x559d5db51770 Text='bar'

This caused us to fail to insert a space after a closing cast rparen,
so the following:

  [((Foo *)foo) bar];

would format as:

  [((Foo *)foo)bar];

This diff fixes the issue by ensuring we annotate the selector
in a single-component Objective-C method invocation as
`TT_SelectorName`.

Test Plan: New tests added. Ran tests with:
  % make -j16 FormatTests && ./tools/clang/unittests/Format/FormatTests

Reviewers: djasper, jolesiak

Reviewed By: jolesiak

Subscribers: Wizard, klimek, hokein, cfe-commits

Differential Revision: https://reviews.llvm.org/D47028

llvm-svn: 332727

clang/lib/Format/TokenAnnotator.cpp

@@ -501,6 +501,12 @@ private:
         }
         if (StartsObjCMethodExpr && CurrentToken->Previous != Left) {
           CurrentToken->Type = TT_ObjCMethodExpr;
+          // If we haven't seen a colon yet, make sure the last identifier
+          // before the r_square is tagged as a selector name component.
+          if (!ColonFound && CurrentToken->Previous &&
+              CurrentToken->Previous->is(TT_Unknown) &&
+              canBeObjCSelectorComponent(*CurrentToken->Previous))
+            CurrentToken->Previous->Type = TT_SelectorName;
           // determineStarAmpUsage() thinks that '*' '[' is allocating an
           // array of pointers, but if '[' starts a selector then '*' is a
           // binary operator.

clang/unittests/Format/FormatTestObjC.cpp

@@ -792,6 +792,10 @@ TEST_F(FormatTestObjC, FormatObjCMethodExpr) {
                "      a = 42;\n"
                "    }];");
 
+  // Space between cast rparen and selector name component.
+  verifyFormat("[((Foo *)foo) bar];");
+  verifyFormat("[((Foo *)foo) bar:1 blech:2];");
+
   // Message receiver taking multiple lines.
   Style.ColumnLimit = 20;
   // Non-corner case.