[clang-format] Add support for generic Obj-C categories

[danielmartin]

Summary

Objective C supports lightweight generics in categories. This patch
adds support for that in clang-format.

[djasper]

Looks good.

lib/Format/UnwrappedLineParser.cpp

2099

nit: Seems like this comment would fit on one line.

[danielmartin]

Make comment fit in one line

[shafik]

@rjmccall @Eugene.Zelenko this looks like it might still be relevant.

[rjmccall]

Is that really the way we want to recommend formatting that, with the generics clause separated from the class name but not separated from the category clause? I'd expect the opposite: write the generics clause with no separation after the class name but with separation from the category clause, e.g. NSHashTable<ObjectType> (MYFoundation).

NOTE: Clang-Format Team Automated Review Comment

It looks like your clang-format review does not contain any unit tests, please try to ensure all code changes have a unit test (unless this is an NFC or refactoring, adding documentation etc..)

Add your unit tests in clang/unittests/Format and you can build with ninja FormatTests. We recommend using the verifyFormat(xxx) format of unit tests rather than EXPECT_EQ as this will ensure you change is tolerant to random whitespace changes (see FormatTest.cpp as an example)

For situations where your change is altering the TokenAnnotator.cpp which can happen if you are trying to improve the annotation phase to ensure we are correctly identifying the type of a token, please add a token annotator test in TokenAnnotatorTest.cpp

lib/Format/UnwrappedLineParser.cpp

if (FormatTok->Tok.is(tok::colon)) {
     nextToken(); // base class name
   } else if (FormatTok->Tok.is(tok::l_paren))
     // Skip category, if present.
     parseParens();
 
   if (FormatTok->Tok.is(tok::less))
     parseObjCProtocolList();
 
+  // After a protocol list, we can have a category (Obj-C generic category).
+  if (FormatTok->Tok.is(tok::l_paren))
+    parseParens();
+
   if (FormatTok->Tok.is(tok::l_brace)) {
     if (Style.BraceWrapping.AfterObjCDeclaration)
       addUnwrappedLine();
     parseBlock(/*MustBeDeclaration=*/true);
   }
 
   // With instance variables, this puts '}' on its own line.  Without instance
   // variables, this ends the @interface line.

unittests/Format/FormatTestObjC.cpp

verifyFormat(
       "- (NSAttributedString *)attributedStringForSegment:(NSUInteger)segment\n"
       "                                             index:(NSUInteger)index\n"
       "                                nonDigitAttributes:\n"
       "                                    (NSDictionary *)noDigitAttributes;");
   verifyFormat("[someFunction someLooooooooooooongParameter:@[\n"
                "  NSBundle.mainBundle.infoDictionary[@\"a\"]\n"
                "]];");
 }
+
+TEST_F(FormatTestObjC, FormatGenericObjCCategory) {
+  verifyFormat(
+      "@interface NSHashTable <ObjectType>(MYFoundation)\n"
+      "- (void)xyz_addObjectsFromArray:(nonnull NSArray<ObjectType> *)array;\n"
+      "@end");
+}
 } // end namespace
 } // end namespace format
 } // end namespace clang