[clang-format] Allow a comment to follow a C# attribute specifier

[jbcoe]

Summary

Add comments to the list of tokens that can follow the ']' at the end of a C# attribute specifier to prevent comments after attribute specifiers from being formatted as continuations.

[MyDeveloperDay]

Nit: please give the revision a description

clang/lib/Format/TokenAnnotator.cpp

bool isCSharpAttributeSpecifier(const FormatToken &Tok) {
 
     // Move past the end of ']'.
     AttrTok = AttrTok->Next;
     if (!AttrTok)
       return false;
 
     // Limit this to being an access modifier that follows.
     if (AttrTok->isOneOf(tok::kw_public, tok::kw_private, tok::kw_protected,
-                         tok::kw_class, tok::kw_static, tok::l_square,
-                         Keywords.kw_internal)) {
+                         tok::comment, tok::kw_class, tok::kw_static,
+                         tok::l_square, Keywords.kw_internal)) {
       return true;
     }
 
     // incase its a [XXX] retval func(....
     if (AttrTok->Next &&
         AttrTok->Next->startsSequence(tok::identifier, tok::l_paren))
       return true;
 

clang/unittests/Format/FormatTestCSharp.cpp

TEST_F(FormatTestCSharp, Attributes) {
 
   verifyFormat("[TestMethod(\"start\", HelpText = \"Starts the server "
                "listening on provided host\")]\n"
                "public string Host\n"
                "{\n"
                "    set;\n"
                "    get;\n"
                "}");
+
+  verifyFormat(
+      "[DllImport(\"Hello\", EntryPoint = \"hello_world\")]\n"
+      "// The const char* returned by hello_world must not be deleted.\n"
+      "private static extern IntPtr HelloFromCpp();)");
 }
 
 TEST_F(FormatTestCSharp, CSharpUsing) {
   FormatStyle Style = getGoogleStyle(FormatStyle::LK_CSharp);
   Style.SpaceBeforeParens = FormatStyle::SBPO_Always;
   verifyFormat("public void foo () {\n"
                "  using (StreamWriter sw = new StreamWriter (filenameA)) {}\n"
                "  using () {}\n"