[clang-format] [PR52015] clang-format should put __attribute__((foo)) on its own line before @interface / @implementation / @protocol

[MyDeveloperDay]

Summary

https://bugs.llvm.org/show_bug.cgi?id=52015

A newline should be place between attribute and @ for objectivec

__attribute__((objc_subclassing_restricted))  
@interface Foo
@end

at present it formats as

__attribute__((objc_subclassing_restricted))   @interface Foo
@end

[benhamilton]

Thank you!

clang/lib/Format/TokenAnnotator.cpp

if (isAllmanBrace(Left) || isAllmanBrace(Right)) {
     return (Line.startsWith(tok::kw_class) && Style.BraceWrapping.AfterClass) ||
            (Line.startsWith(tok::kw_struct) && Style.BraceWrapping.AfterStruct);
   }
 
   if (Left.is(TT_ObjCBlockLBrace) &&
       Style.AllowShortBlocksOnASingleLine == FormatStyle::SBS_Never)
     return true;
 
+  // Ensure wrapping after __attribute__((XX)) and @interface etc.
+  if (Left.is(TT_AttributeParen) && Right.is(TT_ObjCDecl))
+    return true;
+
   if (Left.is(TT_LambdaLBrace)) {
     if (IsFunctionArgument(Left) &&
         Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_Inline)
       return false;
 
     if (Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_None ||
         Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_Inline ||
         (!Left.Children.empty() &&

clang/unittests/Format/FormatTestObjC.cpp

verifyFormat("if (argc < 5)\n"
                "  [obj func:arg2];");
 
   verifyFormat("if (argc < 5) [[unlikely]]\n"
                "  [obj func:arg];\n"
                "else [[likely]]\n"
                "  [obj func:arg2];");
 }
 
+TEST_F(FormatTestObjC, Attributes) {
+  verifyFormat("__attribute__((objc_subclassing_restricted))\n"
+               "@interface Foo\n"
+               "@end");
+  verifyFormat("__attribute__((objc_subclassing_restricted))\n"
+               "@protocol Foo\n"
+               "@end");
+  verifyFormat("__attribute__((objc_subclassing_restricted))\n"
+               "@implementation Foo\n"
+               "@end");
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang