diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2404,7 +2404,7 @@
   // An [[attribute]] can be before the identifier.
   while (FormatTok->isOneOf(tok::identifier, tok::coloncolon, tok::hashhash,
                             tok::kw___attribute, tok::kw___declspec,
-                            tok::kw_alignas, TT_AttributeSquare) ||
+                            tok::kw_alignas, tok::l_square, tok::r_square) ||
          ((Style.Language == FormatStyle::LK_Java ||
            Style.Language == FormatStyle::LK_JavaScript) &&
           FormatTok->isOneOf(tok::period, tok::comma))) {
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -8014,6 +8014,30 @@
                MultiLineFunctions);
 }
 
+TEST_F(FormatTest, AttributeClass) {
+  FormatStyle Style = getChromiumStyle(FormatStyle::LK_Cpp);
+  verifyFormat("class S {\n"
+               "  S(S&&) = default;\n"
+               "};",
+               Style);
+  verifyFormat("class [[nodiscard]] S {\n"
+               "  S(S&&) = default;\n"
+               "};",
+               Style);
+  verifyFormat("class __attribute((maybeunused)) S {\n"
+               "  S(S&&) = default;\n"
+               "};",
+               Style);
+  verifyFormat("struct S {\n"
+               "  S(S&&) = default;\n"
+               "};",
+               Style);
+  verifyFormat("struct [[nodiscard]] S {\n"
+               "  S(S&&) = default;\n"
+               "};",
+               Style);
+}
+
 TEST_F(FormatTest, AttributePenaltyBreaking) {
   FormatStyle Style = getLLVMStyle();
   verifyFormat("void ABCDEFGH::ABCDEFGHIJKLMN(\n"