[clang-format] Handle comments between access specifier and colon

[owenpan]

Summary

Fixes https://github.com/llvm/llvm-project/issues/56740.

clang/lib/Format/FormatToken.h

public:
 
   bool isStringLiteral() const { return tok::isStringLiteral(Tok.getKind()); }
 
   bool isObjCAtKeyword(tok::ObjCKeywordKind Kind) const {
     return Tok.isObjCAtKeyword(Kind);
   }
 
   bool isAccessSpecifier(bool ColonRequired = true) const {
-    return isOneOf(tok::kw_public, tok::kw_protected, tok::kw_private) &&
-           (!ColonRequired || (Next && Next->is(tok::colon)));
+    if (!isOneOf(tok::kw_public, tok::kw_protected, tok::kw_private))
+      return false;
+    if (!ColonRequired)
+      return true;
+    const auto NextNonComment = getNextNonComment();
+    return NextNonComment && NextNonComment->is(tok::colon);
   }
 
   bool canBePointerOrReferenceQualifier() const {
     return isOneOf(tok::kw_const, tok::kw_restrict, tok::kw_volatile,
                    tok::kw___attribute, tok::kw__Nonnull, tok::kw__Nullable,
                    tok::kw__Null_unspecified, tok::kw___ptr32, tok::kw___ptr64,
                    TT_AttributeMacro);
   }

clang/unittests/Format/FormatTest.cpp

verifyFormat("union C {\n"
                "};\n",
                Style);
   // Access modifiers should be indented one level below the record.
   verifyFormat("class C {\n"
                "  public:\n"
                "    int i;\n"
                "};\n",
                Style);
+  verifyFormat("class C {\n"
+               "  public /* comment */:\n"
+               "    int i;\n"
+               "};",
+               Style);
   verifyFormat("struct S {\n"
                "  private:\n"
                "    class C {\n"
                "        int j;\n"
                "\n"
                "      public:\n"
                "        C();\n"
                "    };\n"
TEST_F(FormatTest, IndentAccessModifiers) {
   // Test with a different indentation width;
   // also proves that the result is Style.AccessModifierOffset agnostic.
   Style.IndentWidth = 3;
   verifyFormat("class C {\n"
                "   public:\n"
                "      int i;\n"
                "};\n",
                Style);
+  verifyFormat("class C {\n"
+               "   public /**/:\n"
+               "      int i;\n"
+               "};",
+               Style);
 }
 
 TEST_F(FormatTest, LimitlessStringsAndComments) {
   auto Style = getLLVMStyleWithColumns(0);
   constexpr StringRef Code =
       "/**\n"
       " * This is a multiline comment with quite some long lines, at least for "
       "the LLVM Style.\n"