Revert "[libc++] Fix tests for clang::no_specializations for C++17 and C++20"

This reverts commit 4df9c17.

Reason: buildbot breakage
(https://lab.llvm.org/buildbot/#/builders/24/builds/4598/steps/10/logs/stdio)

Author: thurstond

libcxx/include/__type_traits/result_of.h

@@ -22,7 +22,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TYPE_TRAITS)
 template <class _Callable>
-struct _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_NO_SPECIALIZATIONS result_of;
+struct _LIBCPP_DEPRECATED_IN_CXX17 result_of;
 
 template <class _Fp, class... _Args>
 struct _LIBCPP_TEMPLATE_VIS result_of<_Fp(_Args...)> : __invoke_result<_Fp, _Args...> {};

libcxx/test/libcxx/ranges/no_specializations.verify.cpp

@@ -13,9 +13,7 @@
 
 #include <ranges>
 
-#include "test_macros.h"
-
-#if !__has_warning("-Winvalid-specialization") || TEST_STD_VER <= 20
+#if !__has_warning("-Winvalid-specialization")
 // expected-no-diagnostics
 #else
 struct S {};

libcxx/test/libcxx/type_traits/no_specializations.verify.cpp

@@ -36,22 +36,15 @@ SPECIALIZE_TRAIT(make_unsigned);        // expected-error {{cannot be specialize
 SPECIALIZE_TRAIT(remove_all_extents);   // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(remove_const);         // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(remove_cv);            // expected-error {{cannot be specialized}}
+SPECIALIZE_TRAIT(remove_cvref);         // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(remove_extent);        // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(remove_pointer);       // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(remove_reference);     // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(remove_volatile);      // expected-error {{cannot be specialized}}
+SPECIALIZE_TRAIT(type_identity);        // expected-error {{cannot be specialized}}
 SPECIALIZE_TRAIT(underlying_type);      // expected-error {{cannot be specialized}}
-
-#  if TEST_STD_VER <= 17
-SPECIALIZE_TRAIT(result_of); // expected-error {{cannot be specialized}}
-#  endif
-
-#  if TEST_STD_VER >= 20
-SPECIALIZE_TRAIT(remove_cvref);     // expected-error {{cannot be specialized}}
-SPECIALIZE_TRAIT(type_identity);    // expected-error {{cannot be specialized}}
-SPECIALIZE_TRAIT(unwrap_reference); // expected-error {{cannot be specialized}}
-SPECIALIZE_TRAIT(unwrap_ref_decay); // expected-error {{cannot be specialized}}
-#  endif
+SPECIALIZE_TRAIT(unwrap_reference);     // expected-error {{cannot be specialized}}
+SPECIALIZE_TRAIT(unwrap_ref_decay);     // expected-error {{cannot be specialized}}
 
 #  undef SPECIALIZE_TRAIT
 #  define SPECIALIZE_UTT(Trait)                                                                                        \
@@ -103,6 +96,7 @@ SPECIALIZE_UTT(is_move_assignable);                 // expected-error 2 {{cannot
 SPECIALIZE_UTT(is_move_constructible);              // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_BTT(is_nothrow_assignable);              // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_nothrow_constructible);           // expected-error 2 {{cannot be specialized}}
+SPECIALIZE_BTT(is_nothrow_convertible);             // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_nothrow_copy_assignable);         // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_nothrow_copy_constructible);      // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_nothrow_default_constructible);   // expected-error 2 {{cannot be specialized}}
@@ -136,6 +130,7 @@ SPECIALIZE_UTT(is_trivially_default_constructible); // expected-error 2 {{cannot
 SPECIALIZE_UTT(is_trivially_destructible);          // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_trivially_move_assignable);       // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_trivially_move_constructible);    // expected-error 2 {{cannot be specialized}}
+SPECIALIZE_UTT(is_unbounded_array);                 // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_union);                           // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_unsigned);                        // expected-error 2 {{cannot be specialized}}
 SPECIALIZE_UTT(is_void);                            // expected-error 2 {{cannot be specialized}}
@@ -145,12 +140,11 @@ SPECIALIZE_UTT(rank);                               // expected-error 2 {{cannot
 
 #  if TEST_STD_VER <= 17
 SPECIALIZE_UTT(is_literal_type); // expected-error 2 {{cannot be specialized}}
+SPECIALIZE_UTT(result_of);       // expected-error 2 {{cannot be specialized}}
 #  endif
 
 #  if TEST_STD_VER >= 20
-SPECIALIZE_UTT(is_bounded_array);       // expected-error 2 {{cannot be specialized}}
-SPECIALIZE_BTT(is_nothrow_convertible); // expected-error 2 {{cannot be specialized}}
-SPECIALIZE_UTT(is_unbounded_array);     // expected-error 2 {{cannot be specialized}}
+SPECIALIZE_UTT(is_bounded_array); // expected-error 2 {{cannot be specialized}}
 #  endif
 
 #  if TEST_STD_VER >= 23
@@ -177,8 +171,6 @@ struct std::conditional<true, S, S>; // expected-error {{cannot be specialized}}
 template <>
 struct std::enable_if<true, S>; // expected-error {{cannot be specialized}}
 
-#if TEST_STD_VER >= 20
 template <>
 struct std::integral_constant<S, {}>; // expected-error {{cannot be specialized}}
 #endif
-#endif