[clang-format] C# formatting a class with inheritance followed by an attribute specifier assume its a braces initializer

[MyDeveloperDay]

Summary

https://bugs.llvm.org/show_bug.cgi?id=44340

The rule that prevents ... {} [[....]] being treated as a braced initializer for C++ causes problems for C# with attributes, causing it to be incorrectly classified and then messing up the subsequent formatting. (see bug for details of formatting)

[mitchell-stellar]

LGTM

clang/lib/Format/UnwrappedLineParser.cpp

case tok::r_brace:
               NextTok->isOneOf(tok::comma, tok::period, tok::colon,
                                tok::r_paren, tok::r_square, tok::l_brace,
                                tok::ellipsis) ||
               (NextTok->is(tok::identifier) &&
                !PrevTok->isOneOf(tok::semi, tok::r_brace, tok::l_brace)) ||
               (NextTok->is(tok::semi) &&
                (!ExpectClassBody || LBraceStack.size() != 1)) ||
               (NextTok->isBinaryOperator() && !NextIsObjCMethod);
-          if (NextTok->is(tok::l_square)) {
+          if (!Style.isCSharp() && NextTok->is(tok::l_square)) {
             // We can have an array subscript after a braced init
             // list, but C++11 attributes are expected after blocks.
             NextTok = Tokens->getNextToken();
             ++ReadTokens;
             ProbablyBracedList = NextTok->isNot(tok::l_square);
           }
         }
         if (ProbablyBracedList) {

clang/unittests/Format/FormatTestCSharp.cpp

TEST_F(FormatTestCSharp, AttributesIndentation) {
   verifyFormat("public A(B b) : base(b)\n"
                "{\n"
                "    [SuppressMessage]\n"
                "    public override X Y()\n"
                "    {\n"
                "    }\n"
                "}\n",
                Style);
+
+  verifyFormat("public A : Base\n"
+               "{\n"
+               "}\n"
+               "[Test]\n"
+               "public Foo()\n"
+               "{\n"
+               "}\n",
+               Style);
+
+  verifyFormat("namespace\n"
+               "{\n"
+               "public A : Base\n"
+               "{\n"
+               "}\n"
+               "[Test]\n"
+               "public Foo()\n"
+               "{\n"
+               "}\n"
+               "}\n",
+               Style);
 }
 
 TEST_F(FormatTestCSharp, CSharpSpaceBefore) {
   FormatStyle Style = getGoogleStyle(FormatStyle::LK_CSharp);
   Style.SpaceBeforeParens = FormatStyle::SBPO_Always;
 
   verifyFormat("List<string> list;", Style);
   verifyFormat("Dictionary<string, string> dict;", Style);