[clang-format/ObjC] Fix NS_SWIFT_NAME(foo(bar:baz:)) after ObjC method decl

[benhamilton]

Summary

In D44638, I partially fixed NS_SWIFT_NAME(foo(bar:baz:))-style
annotations on C functions, but didn't add a test for Objective-C
method declarations.

For ObjC method declarations which are annotated with NS_SWIFT_NAME(...),
we currently fail to annotate the final component of the selector
name as TT_SelectorName.

Because the token type is left unknown, clang-format will happily
cause a compilation error when it changes the following:

@interface Foo
- (void)doStuffWithFoo:(id)name
                   bar:(id)bar
                   baz:(id)baz
    NS_SWIFT_NAME(doStuff(withFoo:bar:baz:));
@end

to:

@interface Foo
- (void)doStuffWithFoo:(id)name
                   bar:(id)bar
                   baz:(id)baz
    NS_SWIFT_NAME(doStuff(withFoo:bar:baz
:));
@end

(note the linebreak before the final :).

The logic which decides whether or not to annotate the token before a
: with TT_SelectorName is pretty fragile, and has to handle some
pretty odd cases like pair-parameters:

[I drawRectOn:surface ofSize:aa:bbb atOrigin:cc:dd];

So, to minimize the effect of this change, I decided to only annotate
unknown identifiers before a : as TT_SelectorName for Objective-C
declaration lines.

Test Plan: New tests included. Confirmed tests failed before change and

passed after change. Ran tests with:
% make -j16 FormatTests && ./tools/clang/unittests/Format/FormatTests

cfe/trunk/lib/Format/TokenAnnotator.cpp

case tok::colon:
         if (Style.Language == FormatStyle::LK_TextProto) {
           if (FormatToken *Previous = Tok->getPreviousNonComment())
             Previous->Type = TT_SelectorName;
         }
       } else if (Contexts.back().ColonIsObjCMethodExpr ||
                  Line.startsWith(TT_ObjCMethodSpecifier)) {
         Tok->Type = TT_ObjCMethodExpr;
         const FormatToken *BeforePrevious = Tok->Previous->Previous;
+        // Ensure we tag all identifiers in method declarations as
+        // TT_SelectorName.
+        bool UnknownIdentifierInMethodDeclaration =
+            Line.startsWith(TT_ObjCMethodSpecifier) &&
+            Tok->Previous->is(tok::identifier) && Tok->Previous->is(TT_Unknown);
         if (!BeforePrevious ||
             // FIXME(bug 36976): ObjC return types shouldn't use TT_CastRParen.
             !(BeforePrevious->is(TT_CastRParen) ||
               (BeforePrevious->is(TT_ObjCMethodExpr) &&
                BeforePrevious->is(tok::colon))) ||
             BeforePrevious->is(tok::r_square) ||
-            Contexts.back().LongestObjCSelectorName == 0) {
+            Contexts.back().LongestObjCSelectorName == 0 ||
+            UnknownIdentifierInMethodDeclaration) {
           Tok->Previous->Type = TT_SelectorName;
           if (!Contexts.back().FirstObjCSelectorName)
             Contexts.back().FirstObjCSelectorName = Tok->Previous;
           else if (Tok->Previous->ColumnWidth >
                    Contexts.back().LongestObjCSelectorName)
             Contexts.back().LongestObjCSelectorName =
                 Tok->Previous->ColumnWidth;
         }

cfe/trunk/unittests/Format/FormatTestObjC.cpp

TEST_F(FormatTestObjC, ObjCSnippets) {
   verifyFormat("@import foo.bar;\n"
                "@import baz;");
 
   verifyFormat("@synthesize dropArrowPosition = dropArrowPosition_;");
 
   verifyFormat("@property(assign, nonatomic) CGFloat hoverAlpha;");
   verifyFormat("@property(assign, getter=isEditable) BOOL editable;");
 
+  Style.ColumnLimit = 50;
+  verifyFormat("@interface Foo\n"
+               "- (void)doStuffWithFoo:(id)name\n"
+               "                   bar:(id)bar\n"
+               "                   baz:(id)baz\n"
+               "    NS_SWIFT_NAME(doStuff(withFoo:bar:baz:));\n"
+               "@end");
+
   Style = getMozillaStyle();
   verifyFormat("@property (assign, getter=isEditable) BOOL editable;");
   verifyFormat("@property BOOL editable;");
 
   Style = getWebKitStyle();
   verifyFormat("@property (assign, getter=isEditable) BOOL editable;");
   verifyFormat("@property BOOL editable;");