[Format/ObjC] Add NS_SWIFT_NAME() and CF_SWIFT_NAME() to WhitespaceSe…

…nsitiveMacros

The argument passed to the preprocessor macros `NS_SWIFT_NAME(x)` and
`CF_SWIFT_NAME(x)` is stringified before passing to
`__attribute__((swift_name("x")))`.

ClangFormat didn't know about this stringification, so its custom parser
tried to parse the argument(s) passed to the macro as if they were
normal function arguments.

That means ClangFormat currently incorrectly inserts whitespace
between `NS_SWIFT_NAME` arguments with colons and dots, so:

```
extern UIWindow *MainWindow(void) NS_SWIFT_NAME(getter:MyHelper.mainWindow());
```

becomes:

```
extern UIWindow *MainWindow(void) NS_SWIFT_NAME(getter : MyHelper.mainWindow());
```

which clang treats as a parser error:

```
error: 'swift_name' attribute has invalid identifier for context name [-Werror,-Wswift-name-attribute]
```

Thankfully, D82620 recently added the ability to treat specific macros
as "whitespace sensitive", meaning their arguments are implicitly
treated as strings (so whitespace is not added anywhere inside).

This diff adds `NS_SWIFT_NAME` and `CF_SWIFT_NAME` to
`WhitespaceSensitiveMacros` so their arguments are implicitly treated
as whitespace-sensitive.

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

Reviewed By: sammccall

Differential Revision: https://reviews.llvm.org/D89425

clang/lib/Format/Format.cpp

@@ -964,6 +964,8 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   LLVMStyle.WhitespaceSensitiveMacros.push_back("STRINGIZE");
   LLVMStyle.WhitespaceSensitiveMacros.push_back("PP_STRINGIZE");
   LLVMStyle.WhitespaceSensitiveMacros.push_back("BOOST_PP_STRINGIZE");
+  LLVMStyle.WhitespaceSensitiveMacros.push_back("NS_SWIFT_NAME");
+  LLVMStyle.WhitespaceSensitiveMacros.push_back("CF_SWIFT_NAME");
 
   // Defaults that differ when not C++.
   if (Language == FormatStyle::LK_TableGen) {

clang/unittests/Format/FormatTestObjC.cpp

@@ -1024,6 +1024,12 @@ TEST_F(FormatTestObjC, ObjCSnippets) {
   verifyFormat("@property(assign, nonatomic) CGFloat hoverAlpha;");
   verifyFormat("@property(assign, getter=isEditable) BOOL editable;");
 
+  verifyFormat("extern UIWindow *MainWindow(void) "
+               "NS_SWIFT_NAME(getter:MyHelper.mainWindow());");
+
+  verifyFormat("extern UIWindow *MainWindow(void) "
+               "CF_SWIFT_NAME(getter:MyHelper.mainWindow());");
+
   Style.ColumnLimit = 50;
   verifyFormat("@interface Foo\n"
                "- (void)doStuffWithFoo:(id)name\n"