[libcxx] reworks invocable and regular_invocable tests

[cjdb]

Summary

The tests for std::invocable and std::regular_invocable were
woefully incomplete. This patch closes many of the gaps (though some
probably remain).

[• Quuxplusone]

Personally, I don't think these 1000 new lines of code provide enough benefit to offset their cost. The lines-to-useful-tests ratio is very low.

[ldionne]

In D99398#2652342, @Quuxplusone wrote:

Personally, I don't think these 1000 new lines of code provide enough benefit to offset their cost. The lines-to-useful-tests ratio is very low.

Can you elaborate?

There seems to have been a fixation on line counts lately. If it increases test coverage and does not introduce new duplication, then this change is beneficial.

[ldionne]

This LGTM as far as I'm concerned but I'd like to hear Arthur out.

[• Quuxplusone]

Well, it hinges on what you mean by

and does not introduce new duplication

From my POV, obviously this patch introduces MASSIVE duplication. Lines 1-500 are very similar to lines 501-1000. That's literally all. I don't think we should have 1000 lines of highly repetitive tests, just to test a three-line metafunction. It makes it harder for the maintainer to see what's actually tested and what's not.

(Minorly, I think line 258 doesn't match the style we've been using for other constexpr tests. These constexpr functions could all be using assert in the bodies and return true at the end.)

[cjdb]

In D99398#2653006, @Quuxplusone wrote:

Well, it hinges on what you mean by

and does not introduce new duplication

From my POV, obviously this patch introduces MASSIVE duplication. Lines 1-500 are very similar to lines 501-1000. That's literally all. I don't think we should have 1000 lines of highly repetitive tests, just to test a three-line metafunction. It makes it harder for the maintainer to see what's actually tested and what's not.

Each test checks something different, so there aren't any "highly repetitive tests".

The reason the tests are duplicated across two files is because regular_invocable<T> = invocable<T>, and the easiest way to ensure that is to make sure that they pass identical tests. Short of moving everything common into a header and using a macro, there isn't a way to eliminate said duplication across files.

(Minorly, I think line 258 doesn't match the style we've been using for other constexpr tests. These constexpr functions could all be using assert in the bodies and return true at the end.)

It matches the style of all previous concepts tests.

[mstorsjo]

libcxx/test/std/concepts/concepts.callable/concept.invocable/invocable.compile.pass.cpp

232 ↗

(On Diff #333886)

This static assert (and the other one regarding long below on line 237, and two asserts in the other file) fails when building for Windows. On Windows (both 32 and 64 bit), long is the same size as int. Not familiar with why this passes on 32 bit linux then (where long also is the same size as int) but not on Windows - apparently there are differences in how distinct the two types are considered, or something else?

libcxx/test/std/concepts/callable/functions.h

-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-#ifndef CALLABLE_FUNCTIONS_H
-#define CALLABLE_FUNCTIONS_H
-
-namespace RegularInvocable {
-struct A {
-  int I = 13;
-  constexpr int F() const noexcept { return 42; }
-  constexpr int G(int X) { return 2 * X + 1; }
-  constexpr int H(int J) && { return I * J; }
-};
-
-constexpr int F() noexcept { return 13; }
-constexpr int G(int I) { return 2 * I + 1; }
-} // namespace RegularInvocable
-
-namespace Predicate {
-struct L2rSorted {
-  template <class T>
-  constexpr bool operator()(T const& A, T const& B, T const& C) const noexcept {
-    return A <= B && B <= C;
-  }
-};
-
-struct NotAPredicate {
-  void operator()() const noexcept {}
-};
-} // namespace Predicate
-
-namespace Relation {
-int Greater(int X, int Y) noexcept { return X > Y; }
-} // namespace Relation
-
-#endif // CALLABLE_FUNCTIONS_H

libcxx/test/std/concepts/callable/invocable.compile.pass.cpp

 // concept invocable;
 
 #include <chrono>
 #include <concepts>
 #include <memory>
 #include <random>
 #include <type_traits>
 
-#include "functions.h"
+template <class R, class... Args>
+[[nodiscard]] constexpr bool check_invocable() {
+  constexpr bool result = std::invocable<R(Args...), Args...>;
+  static_assert(std::invocable<R(Args...) noexcept, Args...> == result);
+  static_assert(std::invocable<R (*)(Args...), Args...> == result);
+  static_assert(std::invocable<R (*)(Args...) noexcept, Args...> == result);
+  static_assert(std::invocable<R (&)(Args...), Args...> == result);
+  static_assert(std::invocable<R (&)(Args...) noexcept, Args...> == result);
 
-// clang-format off
-template <class F, class... Args>
-requires std::invocable<F, Args...>
-constexpr void ModelsInvocable(F, Args&&...) noexcept{}
+  return result;
+}
 
-template <class F, class... Args>
-requires(!std::invocable<F, Args...>)
-constexpr void NotInvocable(F, Args&&...) noexcept {}
-// clang-format on
+static_assert(check_invocable<void>());
+static_assert(check_invocable<void, int>());
+static_assert(check_invocable<void, int&>());
+static_assert(check_invocable<void, int*, double>());
+static_assert(check_invocable<int>());
+static_assert(check_invocable<int, int[]>());
+
+struct S;
+static_assert(check_invocable<int, int S::*, std::nullptr_t>());
+static_assert(check_invocable<int, int (S::*)(), int (S::*)(int), int>());
+static_assert(std::invocable<void (*)(int const&), int&>);
+static_assert(std::invocable<void (*)(int const&), int&&>);
+static_assert(std::invocable<void (*)(int volatile&), int&>);
+static_assert(std::invocable<void (*)(int const volatile&), int&>);
+
+static_assert(!std::invocable<void(), int>);
+static_assert(!std::invocable<void(int)>);
+static_assert(!std::invocable<void(int*), double*>);
+static_assert(!std::invocable<void (*)(int&), double*>);
+static_assert(std::invocable<int S::*, std::unique_ptr<S> >);
+static_assert(std::invocable<int S::*, std::shared_ptr<S> >);
+static_assert(!std::invocable<void (*)(int&&), int&>);
+static_assert(!std::invocable<void (*)(int&&), int const&>);
 
 static_assert(!std::invocable<void>);
 static_assert(!std::invocable<void*>);
 static_assert(!std::invocable<int>);
 static_assert(!std::invocable<int&>);
 static_assert(!std::invocable<int&&>);
 
-int main(int, char**) {
-  {
-    using namespace RegularInvocable;
+namespace function_objects {
+struct function_object {
+  void operator()();
+};
+static_assert(std::invocable<function_object>);
+static_assert(!std::invocable<function_object const>);
+static_assert(!std::invocable<function_object volatile>);
+static_assert(!std::invocable<function_object const volatile>);
+static_assert(std::invocable<function_object&>);
+static_assert(!std::invocable<function_object const&>);
+static_assert(!std::invocable<function_object volatile&>);
+static_assert(!std::invocable<function_object const volatile&>);
+
+struct const_function_object {
+  void operator()(int) const;
+};
+static_assert(std::invocable<const_function_object, int>);
+static_assert(std::invocable<const_function_object const, int>);
+static_assert(!std::invocable<const_function_object volatile, int>);
+static_assert(!std::invocable<const_function_object const volatile, int>);
+static_assert(std::invocable<const_function_object&, int>);
+static_assert(std::invocable<const_function_object const&, int>);
+static_assert(!std::invocable<const_function_object volatile&, int>);
+static_assert(!std::invocable<const_function_object const volatile&, int>);
+
+struct volatile_function_object {
+  void operator()(int, int) volatile;
+};
+static_assert(std::invocable<volatile_function_object, int, int>);
+static_assert(!std::invocable<volatile_function_object const, int, int>);
+static_assert(std::invocable<volatile_function_object volatile, int, int>);
+static_assert(
+    !std::invocable<volatile_function_object const volatile, int, int>);
+static_assert(std::invocable<volatile_function_object&, int, int>);
+static_assert(!std::invocable<volatile_function_object const&, int, int>);
+static_assert(std::invocable<volatile_function_object volatile&, int, int>);
+static_assert(
+    !std::invocable<volatile_function_object const volatile&, int, int>);
+
+struct cv_function_object {
+  void operator()(int[]) const volatile;
+};
+static_assert(std::invocable<cv_function_object, int*>);
+static_assert(std::invocable<cv_function_object const, int*>);
+static_assert(std::invocable<cv_function_object volatile, int*>);
+static_assert(std::invocable<cv_function_object const volatile, int*>);
+static_assert(std::invocable<cv_function_object&, int*>);
+static_assert(std::invocable<cv_function_object const&, int*>);
+static_assert(std::invocable<cv_function_object volatile&, int*>);
+static_assert(std::invocable<cv_function_object const volatile&, int*>);
+
+struct lvalue_function_object {
+  void operator()() &;
+};
+static_assert(!std::invocable<lvalue_function_object>);
+static_assert(!std::invocable<lvalue_function_object const>);
+static_assert(!std::invocable<lvalue_function_object volatile>);
+static_assert(!std::invocable<lvalue_function_object const volatile>);
+static_assert(std::invocable<lvalue_function_object&>);
+static_assert(!std::invocable<lvalue_function_object const&>);
+static_assert(!std::invocable<lvalue_function_object volatile&>);
+static_assert(!std::invocable<lvalue_function_object const volatile&>);
+
+struct lvalue_const_function_object {
+  void operator()(int) const&;
+};
+static_assert(std::invocable<lvalue_const_function_object, int>);
+static_assert(std::invocable<lvalue_const_function_object const, int>);
+static_assert(!std::invocable<lvalue_const_function_object volatile, int>);
+static_assert(
+    !std::invocable<lvalue_const_function_object const volatile, int>);
+static_assert(std::invocable<lvalue_const_function_object&, int>);
+static_assert(std::invocable<lvalue_const_function_object const&, int>);
+static_assert(!std::invocable<lvalue_const_function_object volatile&, int>);
+static_assert(
+    !std::invocable<lvalue_const_function_object const volatile&, int>);
+
+struct lvalue_volatile_function_object {
+  void operator()(int, int) volatile&;
+};
+static_assert(!std::invocable<lvalue_volatile_function_object, int, int>);
+static_assert(!std::invocable<lvalue_volatile_function_object const, int, int>);
+static_assert(
+    !std::invocable<lvalue_volatile_function_object volatile, int, int>);
+static_assert(
+    !std::invocable<lvalue_volatile_function_object const volatile, int, int>);
+static_assert(std::invocable<lvalue_volatile_function_object&, int, int>);
+static_assert(
+    !std::invocable<lvalue_volatile_function_object const&, int, int>);
+static_assert(
+    std::invocable<lvalue_volatile_function_object volatile&, int, int>);
+static_assert(
+    !std::invocable<lvalue_volatile_function_object const volatile&, int, int>);
+
+struct lvalue_cv_function_object {
+  void operator()(int[]) const volatile&;
+};
+static_assert(!std::invocable<lvalue_cv_function_object, int*>);
+static_assert(!std::invocable<lvalue_cv_function_object const, int*>);
+static_assert(!std::invocable<lvalue_cv_function_object volatile, int*>);
+static_assert(!std::invocable<lvalue_cv_function_object const volatile, int*>);
+static_assert(std::invocable<lvalue_cv_function_object&, int*>);
+static_assert(std::invocable<lvalue_cv_function_object const&, int*>);
+static_assert(std::invocable<lvalue_cv_function_object volatile&, int*>);
+static_assert(std::invocable<lvalue_cv_function_object const volatile&, int*>);
+//
+struct rvalue_function_object {
+  void operator()() &&;
+};
+static_assert(std::invocable<rvalue_function_object>);
+static_assert(!std::invocable<rvalue_function_object const>);
+static_assert(!std::invocable<rvalue_function_object volatile>);
+static_assert(!std::invocable<rvalue_function_object const volatile>);
+static_assert(!std::invocable<rvalue_function_object&>);
+static_assert(!std::invocable<rvalue_function_object const&>);
+static_assert(!std::invocable<rvalue_function_object volatile&>);
+static_assert(!std::invocable<rvalue_function_object const volatile&>);
+
+struct rvalue_const_function_object {
+  void operator()(int) const&&;
+};
+static_assert(std::invocable<rvalue_const_function_object, int>);
+static_assert(std::invocable<rvalue_const_function_object const, int>);
+static_assert(!std::invocable<rvalue_const_function_object volatile, int>);
+static_assert(
+    !std::invocable<rvalue_const_function_object const volatile, int>);
+static_assert(!std::invocable<rvalue_const_function_object&, int>);
+static_assert(!std::invocable<rvalue_const_function_object const&, int>);
+static_assert(!std::invocable<rvalue_const_function_object volatile&, int>);
+static_assert(
+    !std::invocable<rvalue_const_function_object const volatile&, int>);
+
+struct rvalue_volatile_function_object {
+  void operator()(int, int) volatile&&;
+};
+static_assert(std::invocable<rvalue_volatile_function_object, int, int>);
+static_assert(!std::invocable<rvalue_volatile_function_object const, int, int>);
+static_assert(
+    std::invocable<rvalue_volatile_function_object volatile, int, int>);
+static_assert(
+    !std::invocable<rvalue_volatile_function_object const volatile, int, int>);
+static_assert(!std::invocable<rvalue_volatile_function_object&, int, int>);
+static_assert(
+    !std::invocable<rvalue_volatile_function_object const&, int, int>);
+static_assert(
+    !std::invocable<rvalue_volatile_function_object volatile&, int, int>);
+static_assert(
+    !std::invocable<rvalue_volatile_function_object const volatile&, int, int>);
+
+struct rvalue_cv_function_object {
+  void operator()(int[]) const volatile&&;
+};
+static_assert(std::invocable<rvalue_cv_function_object, int*>);
+static_assert(std::invocable<rvalue_cv_function_object const, int*>);
+static_assert(std::invocable<rvalue_cv_function_object volatile, int*>);
+static_assert(std::invocable<rvalue_cv_function_object const volatile, int*>);
+static_assert(!std::invocable<rvalue_cv_function_object&, int*>);
+static_assert(!std::invocable<rvalue_cv_function_object const&, int*>);
+static_assert(!std::invocable<rvalue_cv_function_object volatile&, int*>);
+static_assert(!std::invocable<rvalue_cv_function_object const volatile&, int*>);
+
+struct multiple_overloads {
+  bool operator()();
+  void operator()(int);
+  int operator()(double);
+};
+static_assert(std::invocable<multiple_overloads&>);
+static_assert(std::invocable<multiple_overloads&, short>);
+static_assert(std::invocable<multiple_overloads&, int>);
+static_assert(!std::invocable<multiple_overloads&, long>);
+static_assert(std::invocable<multiple_overloads&, double>);
+static_assert(std::invocable<multiple_overloads&, float>);
+static_assert(std::invocable<multiple_overloads&, short&>);
+static_assert(std::invocable<multiple_overloads&, int&>);
+static_assert(!std::invocable<multiple_overloads&, long&>);
+static_assert(std::invocable<multiple_overloads&, float&>);
+static_assert(std::invocable<multiple_overloads&, double&>);
+} // namespace function_objects
 
-    ModelsInvocable(F);
-    NotInvocable(F, 0);
+namespace pointer_to_member_functions {
+// clang-format off
+  template<class Member, class T, class... Args>
+  [[nodiscard]] constexpr bool check_member_is_invocable()
+  {
+    constexpr bool result = std::invocable<Member, T, Args...>;
+    using uncv_t = std::remove_cvref_t<T>;
+    static_assert(std::invocable<Member, uncv_t*, Args...> == result);
+    static_assert(std::invocable<Member, std::unique_ptr<uncv_t>, Args...> == result);
+    static_assert(std::invocable<Member, std::reference_wrapper<uncv_t>, Args...> == result);
+    static_assert(!std::invocable<Member, std::nullptr_t, Args...>);
+    static_assert(!std::invocable<Member, int, Args...>);
+    static_assert(!std::invocable<Member, int*, Args...>);
+    static_assert(!std::invocable<Member, double*, Args...>);
+    struct S2 {};
+    static_assert(!std::invocable<Member, S2*, Args...>);
+    return result;
+  }
+// clang-format on
 
-    ModelsInvocable(G, 2);
-    NotInvocable(G);
-    NotInvocable(G, 3, 0);
+static_assert(check_member_is_invocable<int S::*, S>());
+static_assert(std::invocable<int S::*, S&>);
+static_assert(std::invocable<int S::*, S const&>);
+static_assert(std::invocable<int S::*, S volatile&>);
+static_assert(std::invocable<int S::*, S const volatile&>);
+static_assert(std::invocable<int S::*, S&&>);
+static_assert(std::invocable<int S::*, S const&&>);
+static_assert(std::invocable<int S::*, S volatile&&>);
+static_assert(std::invocable<int S::*, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)(int), S, int>());
+static_assert(!check_member_is_invocable<int (S::*)(int), S>());
+using unqualified = void (S::*)();
+static_assert(std::invocable<unqualified, S&>);
+static_assert(!std::invocable<unqualified, S const&>);
+static_assert(!std::invocable<unqualified, S volatile&>);
+static_assert(!std::invocable<unqualified, S const volatile&>);
+static_assert(std::invocable<unqualified, S&&>);
+static_assert(!std::invocable<unqualified, S const&&>);
+static_assert(!std::invocable<unqualified, S volatile&&>);
+static_assert(!std::invocable<unqualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)(double) const, S, double>());
+using const_qualified = void (S::*)() const;
+static_assert(std::invocable<const_qualified, S&>);
+static_assert(std::invocable<const_qualified, S const&>);
+static_assert(!std::invocable<const_qualified, S volatile&>);
+static_assert(!std::invocable<const_qualified, S const volatile&>);
+static_assert(std::invocable<const_qualified, S&&>);
+static_assert(std::invocable<const_qualified, S const&&>);
+static_assert(!std::invocable<const_qualified, S volatile&&>);
+static_assert(!std::invocable<const_qualified, S const volatile&&>);
+
+static_assert(
+    check_member_is_invocable<int (S::*)(double[]) volatile, S, double*>());
+using volatile_qualified = void (S::*)() volatile;
+static_assert(std::invocable<volatile_qualified, S&>);
+static_assert(!std::invocable<volatile_qualified, S const&>);
+static_assert(std::invocable<volatile_qualified, S volatile&>);
+static_assert(!std::invocable<volatile_qualified, S const volatile&>);
+static_assert(std::invocable<volatile_qualified, S&&>);
+static_assert(!std::invocable<volatile_qualified, S const&&>);
+static_assert(std::invocable<volatile_qualified, S volatile&&>);
+static_assert(!std::invocable<volatile_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)(int, S&) const volatile, S,
+                                        int, S&>());
+using cv_qualified = void (S::*)() const volatile;
+static_assert(std::invocable<cv_qualified, S&>);
+static_assert(std::invocable<cv_qualified, S const&>);
+static_assert(std::invocable<cv_qualified, S volatile&>);
+static_assert(std::invocable<cv_qualified, S const volatile&>);
+static_assert(std::invocable<cv_qualified, S&&>);
+static_assert(std::invocable<cv_qualified, S const&&>);
+static_assert(std::invocable<cv_qualified, S volatile&&>);
+static_assert(std::invocable<cv_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() &, S&>());
+using lvalue_qualified = void (S::*)() &;
+static_assert(std::invocable<lvalue_qualified, S&>);
+static_assert(!std::invocable<lvalue_qualified, S const&>);
+static_assert(!std::invocable<lvalue_qualified, S volatile&>);
+static_assert(!std::invocable<lvalue_qualified, S const volatile&>);
+static_assert(!std::invocable<lvalue_qualified, S&&>);
+static_assert(!std::invocable<lvalue_qualified, S const&&>);
+static_assert(!std::invocable<lvalue_qualified, S volatile&&>);
+static_assert(!std::invocable<lvalue_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() const&, S>());
+using lvalue_const_qualified = void (S::*)() const&;
+static_assert(std::invocable<lvalue_const_qualified, S&>);
+static_assert(std::invocable<lvalue_const_qualified, S const&>);
+static_assert(!std::invocable<lvalue_const_qualified, S volatile&>);
+static_assert(!std::invocable<lvalue_const_qualified, S const volatile&>);
+static_assert(std::invocable<lvalue_const_qualified, S&&>);
+static_assert(std::invocable<lvalue_const_qualified, S const&&>);
+static_assert(!std::invocable<lvalue_const_qualified, S volatile&&>);
+static_assert(!std::invocable<lvalue_const_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() volatile&, S&>());
+using lvalue_volatile_qualified = void (S::*)() volatile&;
+static_assert(std::invocable<lvalue_volatile_qualified, S&>);
+static_assert(!std::invocable<lvalue_volatile_qualified, S const&>);
+static_assert(std::invocable<lvalue_volatile_qualified, S volatile&>);
+static_assert(!std::invocable<lvalue_volatile_qualified, S const volatile&>);
+static_assert(!std::invocable<lvalue_volatile_qualified, S&&>);
+static_assert(!std::invocable<lvalue_volatile_qualified, S const&&>);
+static_assert(!std::invocable<lvalue_volatile_qualified, S volatile&&>);
+static_assert(!std::invocable<lvalue_volatile_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() const volatile&, S&>());
+using lvalue_cv_qualified = void (S::*)() const volatile&;
+static_assert(std::invocable<lvalue_cv_qualified, S&>);
+static_assert(std::invocable<lvalue_cv_qualified, S const&>);
+static_assert(std::invocable<lvalue_cv_qualified, S volatile&>);
+static_assert(std::invocable<lvalue_cv_qualified, S const volatile&>);
+static_assert(!std::invocable<lvalue_cv_qualified, S&&>);
+static_assert(!std::invocable<lvalue_cv_qualified, S const&&>);
+static_assert(!std::invocable<lvalue_cv_qualified, S volatile&&>);
+static_assert(!std::invocable<lvalue_cv_qualified, S const volatile&&>);
+
+using rvalue_unqualified = void (S::*)() &&;
+static_assert(!std::invocable<rvalue_unqualified, S&>);
+static_assert(!std::invocable<rvalue_unqualified, S const&>);
+static_assert(!std::invocable<rvalue_unqualified, S volatile&>);
+static_assert(!std::invocable<rvalue_unqualified, S const volatile&>);
+static_assert(std::invocable<rvalue_unqualified, S&&>);
+static_assert(!std::invocable<rvalue_unqualified, S const&&>);
+static_assert(!std::invocable<rvalue_unqualified, S volatile&&>);
+static_assert(!std::invocable<rvalue_unqualified, S const volatile&&>);
+
+using rvalue_const_unqualified = void (S::*)() const&&;
+static_assert(!std::invocable<rvalue_const_unqualified, S&>);
+static_assert(!std::invocable<rvalue_const_unqualified, S const&>);
+static_assert(!std::invocable<rvalue_const_unqualified, S volatile&>);
+static_assert(!std::invocable<rvalue_const_unqualified, S const volatile&>);
+static_assert(std::invocable<rvalue_const_unqualified, S&&>);
+static_assert(std::invocable<rvalue_const_unqualified, S const&&>);
+static_assert(!std::invocable<rvalue_const_unqualified, S volatile&&>);
+static_assert(!std::invocable<rvalue_const_unqualified, S const volatile&&>);
+
+using rvalue_volatile_unqualified = void (S::*)() volatile&&;
+static_assert(!std::invocable<rvalue_volatile_unqualified, S&>);
+static_assert(!std::invocable<rvalue_volatile_unqualified, S const&>);
+static_assert(!std::invocable<rvalue_volatile_unqualified, S volatile&>);
+static_assert(!std::invocable<rvalue_volatile_unqualified, S const volatile&>);
+static_assert(std::invocable<rvalue_volatile_unqualified, S&&>);
+static_assert(!std::invocable<rvalue_volatile_unqualified, S const&&>);
+static_assert(std::invocable<rvalue_volatile_unqualified, S volatile&&>);
+static_assert(!std::invocable<rvalue_volatile_unqualified, S const volatile&&>);
+
+using rvalue_cv_unqualified = void (S::*)() const volatile&&;
+static_assert(!std::invocable<rvalue_cv_unqualified, S&>);
+static_assert(!std::invocable<rvalue_cv_unqualified, S const&>);
+static_assert(!std::invocable<rvalue_cv_unqualified, S volatile&>);
+static_assert(!std::invocable<rvalue_cv_unqualified, S const volatile&>);
+static_assert(std::invocable<rvalue_cv_unqualified, S&&>);
+static_assert(std::invocable<rvalue_cv_unqualified, S const&&>);
+static_assert(std::invocable<rvalue_cv_unqualified, S volatile&&>);
+static_assert(std::invocable<rvalue_cv_unqualified, S const volatile&&>);
+} // namespace pointer_to_member_functions
+
+// std::invocable-specific
+static_assert(
+    std::invocable<std::uniform_int_distribution<>, std::mt19937_64&>);
 
-    NotInvocable(&A::I);
-    NotInvocable(&A::F);
+[[nodiscard]] constexpr bool check_lambda(auto, auto...) { return false; }
 
-    {
-      A X;
-      ModelsInvocable(&A::I, X);
-      ModelsInvocable(&A::F, X);
-      ModelsInvocable(&A::G, X, 0);
-      NotInvocable(&A::G, X);
-      NotInvocable(&A::G, 0);
-      NotInvocable(&A::H);
-
-      A const& Y = X;
-      ModelsInvocable(&A::I, Y);
-      ModelsInvocable(&A::F, Y);
-      NotInvocable(&A::G, Y, 0);
-      NotInvocable(&A::H, Y, 0);
-    }
+// clang-format off
+template<class F, class... Args>
+requires std::invocable<F, Args...>
+[[nodiscard]] constexpr bool check_lambda(F, Args&&...)
+  return true;
+// clang-format on
 
-    ModelsInvocable(&A::I, A{});
-    ModelsInvocable(&A::F, A{});
-    ModelsInvocable(&A::G, A{}, 0);
-    ModelsInvocable(&A::H, A{}, 0);
+[[nodiscard]] constexpr bool check_lambdas() {
+  static_assert(check_lambda([] {}));
+  static_assert(check_lambda([](int) {}, 0));
+  static_assert(check_lambda([](int) {}, 0L));
+  static_assert(!check_lambda([](int) {}, nullptr));
 
-    {
-      auto Up = std::make_unique<A>();
-      ModelsInvocable(&A::I, Up);
-      ModelsInvocable(&A::F, Up);
-      ModelsInvocable(&A::G, Up, 0);
-      NotInvocable(&A::H, Up, 0);
-    }
-    {
-      auto Sp = std::make_shared<A>();
-      ModelsInvocable(&A::I, Sp);
-      ModelsInvocable(&A::F, Sp);
-      ModelsInvocable(&A::G, Sp, 0);
-      NotInvocable(&A::H, Sp, 0);
-    }
-  }
-  {
-    using namespace Predicate;
-    {
-      ModelsInvocable(L2rSorted{}, 0, 1, 2);
-      NotInvocable(L2rSorted{});
-      NotInvocable(L2rSorted{}, 0);
-      NotInvocable(L2rSorted{}, 0, 1);
-    }
-    {
-      auto Up = std::make_unique<L2rSorted>();
-      ModelsInvocable(&L2rSorted::operator()<int>, Up, 0, 1, 2);
-      NotInvocable(&L2rSorted::operator()<int>, Up);
-      NotInvocable(&L2rSorted::operator()<int>, Up, 0);
-      NotInvocable(&L2rSorted::operator()<int>, Up, 0, 1);
-    }
-    {
-      auto Sp = std::make_shared<L2rSorted>();
-      ModelsInvocable(&L2rSorted::operator()<int>, Sp, 0, 1, 2);
-      NotInvocable(&L2rSorted::operator()<int>, Sp);
-      NotInvocable(&L2rSorted::operator()<int>, Sp, 0);
-      NotInvocable(&L2rSorted::operator()<int>, Sp, 0, 1);
-    }
-  }
-  {
-    auto G = std::mt19937_64(
-        std::chrono::high_resolution_clock().now().time_since_epoch().count());
-    auto D = std::uniform_int_distribution<>();
-    ModelsInvocable(D, G);
-  }
-  return 0;
+  int i = 0;
+  return check_lambda([](int&) {}, i);
 }
+
+static_assert(check_lambdas());
+
+int main(int, char**) { return 0; }

libcxx/test/std/concepts/callable/regularinvocable.compile.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-no-concepts
 
 // template<class T, class U>
 // concept regular_invocable;
 
+#include <chrono>
 #include <concepts>
 #include <memory>
 #include <random>
 #include <type_traits>
 
-#include "functions.h"
+template <class R, class... Args>
+[[nodiscard]] constexpr bool check_invocable() {
+  constexpr bool result = std::regular_invocable<R(Args...), Args...>;
+  static_assert(std::regular_invocable<R(Args...) noexcept, Args...> == result);
+  static_assert(std::regular_invocable<R (*)(Args...), Args...> == result);
+  static_assert(std::regular_invocable<R (*)(Args...) noexcept, Args...> ==
+                result);
+  static_assert(std::regular_invocable<R (&)(Args...), Args...> == result);
+  static_assert(std::regular_invocable<R (&)(Args...) noexcept, Args...> ==
+                result);
 
-// clang-format off
-template <class F, class... Args>
-requires std::regular_invocable<F, Args...>
-constexpr void ModelsRegularInvocable(F, Args&&...) noexcept {}
+  return result;
+}
 
-template <class F, class... Args>
-requires (!std::regular_invocable<F, Args...>)
-constexpr void NotRegularInvocable(F, Args&&...) noexcept {}
-// clang-format on
+static_assert(check_invocable<void>());
+static_assert(check_invocable<void, int>());
+static_assert(check_invocable<void, int&>());
+static_assert(check_invocable<void, int*, double>());
+static_assert(check_invocable<int>());
+static_assert(check_invocable<int, int[]>());
+
+struct S;
+static_assert(check_invocable<int, int S::*, std::nullptr_t>());
+static_assert(check_invocable<int, int (S::*)(), int (S::*)(int), int>());
+static_assert(std::regular_invocable<void (*)(int const&), int&>);
+static_assert(std::regular_invocable<void (*)(int const&), int&&>);
+static_assert(std::regular_invocable<void (*)(int volatile&), int&>);
+static_assert(std::regular_invocable<void (*)(int const volatile&), int&>);
+
+static_assert(!std::regular_invocable<void(), int>);
+static_assert(!std::regular_invocable<void(int)>);
+static_assert(!std::regular_invocable<void(int*), double*>);
+static_assert(!std::regular_invocable<void (*)(int&), double*>);
+static_assert(std::regular_invocable<int S::*, std::unique_ptr<S> >);
+static_assert(std::regular_invocable<int S::*, std::shared_ptr<S> >);
+static_assert(!std::regular_invocable<void (*)(int&&), int&>);
+static_assert(!std::regular_invocable<void (*)(int&&), int const&>);
 
 static_assert(!std::regular_invocable<void>);
 static_assert(!std::regular_invocable<void*>);
 static_assert(!std::regular_invocable<int>);
 static_assert(!std::regular_invocable<int&>);
 static_assert(!std::regular_invocable<int&&>);
 
-int main(int, char**) {
-  {
-    using namespace RegularInvocable;
-
-    ModelsRegularInvocable(F);
-    NotRegularInvocable(F, 0);
-
-    ModelsRegularInvocable(G, 2);
-    NotRegularInvocable(G);
-    NotRegularInvocable(G, 3, 0);
-
-    NotRegularInvocable(&A::I);
-    NotRegularInvocable(&A::F);
+namespace function_objects {
+struct function_object {
+  void operator()();
+};
+static_assert(std::regular_invocable<function_object>);
+static_assert(!std::regular_invocable<function_object const>);
+static_assert(!std::regular_invocable<function_object volatile>);
+static_assert(!std::regular_invocable<function_object const volatile>);
+static_assert(std::regular_invocable<function_object&>);
+static_assert(!std::regular_invocable<function_object const&>);
+static_assert(!std::regular_invocable<function_object volatile&>);
+static_assert(!std::regular_invocable<function_object const volatile&>);
+
+struct const_function_object {
+  void operator()(int) const;
+};
+static_assert(std::regular_invocable<const_function_object, int>);
+static_assert(std::regular_invocable<const_function_object const, int>);
+static_assert(!std::regular_invocable<const_function_object volatile, int>);
+static_assert(
+    !std::regular_invocable<const_function_object const volatile, int>);
+static_assert(std::regular_invocable<const_function_object&, int>);
+static_assert(std::regular_invocable<const_function_object const&, int>);
+static_assert(!std::regular_invocable<const_function_object volatile&, int>);
+static_assert(
+    !std::regular_invocable<const_function_object const volatile&, int>);
+
+struct volatile_function_object {
+  void operator()(int, int) volatile;
+};
+static_assert(std::regular_invocable<volatile_function_object, int, int>);
+static_assert(
+    !std::regular_invocable<volatile_function_object const, int, int>);
+static_assert(
+    std::regular_invocable<volatile_function_object volatile, int, int>);
+static_assert(
+    !std::regular_invocable<volatile_function_object const volatile, int, int>);
+static_assert(std::regular_invocable<volatile_function_object&, int, int>);
+static_assert(
+    !std::regular_invocable<volatile_function_object const&, int, int>);
+static_assert(
+    std::regular_invocable<volatile_function_object volatile&, int, int>);
+static_assert(!std::regular_invocable<volatile_function_object const volatile&,
+                                      int, int>);
+
+struct cv_function_object {
+  void operator()(int[]) const volatile;
+};
+static_assert(std::regular_invocable<cv_function_object, int*>);
+static_assert(std::regular_invocable<cv_function_object const, int*>);
+static_assert(std::regular_invocable<cv_function_object volatile, int*>);
+static_assert(std::regular_invocable<cv_function_object const volatile, int*>);
+static_assert(std::regular_invocable<cv_function_object&, int*>);
+static_assert(std::regular_invocable<cv_function_object const&, int*>);
+static_assert(std::regular_invocable<cv_function_object volatile&, int*>);
+static_assert(std::regular_invocable<cv_function_object const volatile&, int*>);
+
+struct lvalue_function_object {
+  void operator()() &;
+};
+static_assert(!std::regular_invocable<lvalue_function_object>);
+static_assert(!std::regular_invocable<lvalue_function_object const>);
+static_assert(!std::regular_invocable<lvalue_function_object volatile>);
+static_assert(!std::regular_invocable<lvalue_function_object const volatile>);
+static_assert(std::regular_invocable<lvalue_function_object&>);
+static_assert(!std::regular_invocable<lvalue_function_object const&>);
+static_assert(!std::regular_invocable<lvalue_function_object volatile&>);
+static_assert(!std::regular_invocable<lvalue_function_object const volatile&>);
+
+struct lvalue_const_function_object {
+  void operator()(int) const&;
+};
+static_assert(std::regular_invocable<lvalue_const_function_object, int>);
+static_assert(std::regular_invocable<lvalue_const_function_object const, int>);
+static_assert(
+    !std::regular_invocable<lvalue_const_function_object volatile, int>);
+static_assert(
+    !std::regular_invocable<lvalue_const_function_object const volatile, int>);
+static_assert(std::regular_invocable<lvalue_const_function_object&, int>);
+static_assert(std::regular_invocable<lvalue_const_function_object const&, int>);
+static_assert(
+    !std::regular_invocable<lvalue_const_function_object volatile&, int>);
+static_assert(
+    !std::regular_invocable<lvalue_const_function_object const volatile&, int>);
+
+struct lvalue_volatile_function_object {
+  void operator()(int, int) volatile&;
+};
+static_assert(
+    !std::regular_invocable<lvalue_volatile_function_object, int, int>);
+static_assert(
+    !std::regular_invocable<lvalue_volatile_function_object const, int, int>);
+static_assert(!std::regular_invocable<lvalue_volatile_function_object volatile,
+                                      int, int>);
+static_assert(!std::regular_invocable<
+              lvalue_volatile_function_object const volatile, int, int>);
+static_assert(
+    std::regular_invocable<lvalue_volatile_function_object&, int, int>);
+static_assert(
+    !std::regular_invocable<lvalue_volatile_function_object const&, int, int>);
+static_assert(std::regular_invocable<lvalue_volatile_function_object volatile&,
+                                     int, int>);
+static_assert(!std::regular_invocable<
+              lvalue_volatile_function_object const volatile&, int, int>);
+
+struct lvalue_cv_function_object {
+  void operator()(int[]) const volatile&;
+};
+static_assert(!std::regular_invocable<lvalue_cv_function_object, int*>);
+static_assert(!std::regular_invocable<lvalue_cv_function_object const, int*>);
+static_assert(
+    !std::regular_invocable<lvalue_cv_function_object volatile, int*>);
+static_assert(
+    !std::regular_invocable<lvalue_cv_function_object const volatile, int*>);
+static_assert(std::regular_invocable<lvalue_cv_function_object&, int*>);
+static_assert(std::regular_invocable<lvalue_cv_function_object const&, int*>);
+static_assert(
+    std::regular_invocable<lvalue_cv_function_object volatile&, int*>);
+static_assert(
+    std::regular_invocable<lvalue_cv_function_object const volatile&, int*>);
+//
+struct rvalue_function_object {
+  void operator()() &&;
+};
+static_assert(std::regular_invocable<rvalue_function_object>);
+static_assert(!std::regular_invocable<rvalue_function_object const>);
+static_assert(!std::regular_invocable<rvalue_function_object volatile>);
+static_assert(!std::regular_invocable<rvalue_function_object const volatile>);
+static_assert(!std::regular_invocable<rvalue_function_object&>);
+static_assert(!std::regular_invocable<rvalue_function_object const&>);
+static_assert(!std::regular_invocable<rvalue_function_object volatile&>);
+static_assert(!std::regular_invocable<rvalue_function_object const volatile&>);
+
+struct rvalue_const_function_object {
+  void operator()(int) const&&;
+};
+static_assert(std::regular_invocable<rvalue_const_function_object, int>);
+static_assert(std::regular_invocable<rvalue_const_function_object const, int>);
+static_assert(
+    !std::regular_invocable<rvalue_const_function_object volatile, int>);
+static_assert(
+    !std::regular_invocable<rvalue_const_function_object const volatile, int>);
+static_assert(!std::regular_invocable<rvalue_const_function_object&, int>);
+static_assert(
+    !std::regular_invocable<rvalue_const_function_object const&, int>);
+static_assert(
+    !std::regular_invocable<rvalue_const_function_object volatile&, int>);
+static_assert(
+    !std::regular_invocable<rvalue_const_function_object const volatile&, int>);
+
+struct rvalue_volatile_function_object {
+  void operator()(int, int) volatile&&;
+};
+static_assert(
+    std::regular_invocable<rvalue_volatile_function_object, int, int>);
+static_assert(
+    !std::regular_invocable<rvalue_volatile_function_object const, int, int>);
+static_assert(
+    std::regular_invocable<rvalue_volatile_function_object volatile, int, int>);
+static_assert(!std::regular_invocable<
+              rvalue_volatile_function_object const volatile, int, int>);
+static_assert(
+    !std::regular_invocable<rvalue_volatile_function_object&, int, int>);
+static_assert(
+    !std::regular_invocable<rvalue_volatile_function_object const&, int, int>);
+static_assert(!std::regular_invocable<rvalue_volatile_function_object volatile&,
+                                      int, int>);
+static_assert(!std::regular_invocable<
+              rvalue_volatile_function_object const volatile&, int, int>);
+
+struct rvalue_cv_function_object {
+  void operator()(int[]) const volatile&&;
+};
+static_assert(std::regular_invocable<rvalue_cv_function_object, int*>);
+static_assert(std::regular_invocable<rvalue_cv_function_object const, int*>);
+static_assert(std::regular_invocable<rvalue_cv_function_object volatile, int*>);
+static_assert(
+    std::regular_invocable<rvalue_cv_function_object const volatile, int*>);
+static_assert(!std::regular_invocable<rvalue_cv_function_object&, int*>);
+static_assert(!std::regular_invocable<rvalue_cv_function_object const&, int*>);
+static_assert(
+    !std::regular_invocable<rvalue_cv_function_object volatile&, int*>);
+static_assert(
+    !std::regular_invocable<rvalue_cv_function_object const volatile&, int*>);
+
+struct multiple_overloads {
+  bool operator()();
+  void operator()(int);
+  int operator()(double);
+};
+static_assert(std::regular_invocable<multiple_overloads&>);
+static_assert(std::regular_invocable<multiple_overloads&, short>);
+static_assert(std::regular_invocable<multiple_overloads&, int>);
+static_assert(!std::regular_invocable<multiple_overloads&, long>);
+static_assert(std::regular_invocable<multiple_overloads&, double>);
+static_assert(std::regular_invocable<multiple_overloads&, float>);
+static_assert(std::regular_invocable<multiple_overloads&, short&>);
+static_assert(std::regular_invocable<multiple_overloads&, int&>);
+static_assert(!std::regular_invocable<multiple_overloads&, long&>);
+static_assert(std::regular_invocable<multiple_overloads&, float&>);
+static_assert(std::regular_invocable<multiple_overloads&, double&>);
+} // namespace function_objects
 
-    {
-      A X;
-      ModelsRegularInvocable(&A::I, X);
-      ModelsRegularInvocable(&A::F, X);
-      ModelsRegularInvocable(&A::G, X, 0);
-      NotRegularInvocable(&A::G, X);
-      NotRegularInvocable(&A::G, 0);
-      NotRegularInvocable(&A::H);
-
-      A const& Y = X;
-      ModelsRegularInvocable(&A::I, Y);
-      ModelsRegularInvocable(&A::F, Y);
-      NotRegularInvocable(&A::G, Y, 0);
-      NotRegularInvocable(&A::H, Y, 0);
-    }
+namespace pointer_to_member_functions {
+// clang-format off
+  template<class Member, class T, class... Args>
+  [[nodiscard]] constexpr bool check_member_is_invocable()
+    constexpr bool result = std::regular_invocable<Member, T, Args...>;
+    using uncv_t = std::remove_cvref_t<T>;
+    static_assert(std::regular_invocable<Member, uncv_t*, Args...> == result);
+    static_assert(std::regular_invocable<Member, std::unique_ptr<uncv_t>, Args...> == result);
+    static_assert(std::regular_invocable<Member, std::reference_wrapper<uncv_t>, Args...> == result);
+    static_assert(!std::regular_invocable<Member, std::nullptr_t, Args...>);
+    static_assert(!std::regular_invocable<Member, int, Args...>);
+    static_assert(!std::regular_invocable<Member, int*, Args...>);
+    static_assert(!std::regular_invocable<Member, double*, Args...>);
+    struct S2 {};
+    static_assert(!std::regular_invocable<Member, S2*, Args...>);
+    return result;
+// clang-format on
 
-    ModelsRegularInvocable(&A::I, A{});
-    ModelsRegularInvocable(&A::F, A{});
-    ModelsRegularInvocable(&A::G, A{}, 0);
-    ModelsRegularInvocable(&A::H, A{}, 0);
+static_assert(check_member_is_invocable<int S::*, S>());
+static_assert(std::regular_invocable<int S::*, S&>);
+static_assert(std::regular_invocable<int S::*, S const&>);
+static_assert(std::regular_invocable<int S::*, S volatile&>);
+static_assert(std::regular_invocable<int S::*, S const volatile&>);
+static_assert(std::regular_invocable<int S::*, S&&>);
+static_assert(std::regular_invocable<int S::*, S const&&>);
+static_assert(std::regular_invocable<int S::*, S volatile&&>);
+static_assert(std::regular_invocable<int S::*, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)(int), S, int>());
+static_assert(!check_member_is_invocable<int (S::*)(int), S>());
+using unqualified = void (S::*)();
+static_assert(std::regular_invocable<unqualified, S&>);
+static_assert(!std::regular_invocable<unqualified, S const&>);
+static_assert(!std::regular_invocable<unqualified, S volatile&>);
+static_assert(!std::regular_invocable<unqualified, S const volatile&>);
+static_assert(std::regular_invocable<unqualified, S&&>);
+static_assert(!std::regular_invocable<unqualified, S const&&>);
+static_assert(!std::regular_invocable<unqualified, S volatile&&>);
+static_assert(!std::regular_invocable<unqualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)(double) const, S, double>());
+using const_qualified = void (S::*)() const;
+static_assert(std::regular_invocable<const_qualified, S&>);
+static_assert(std::regular_invocable<const_qualified, S const&>);
+static_assert(!std::regular_invocable<const_qualified, S volatile&>);
+static_assert(!std::regular_invocable<const_qualified, S const volatile&>);
+static_assert(std::regular_invocable<const_qualified, S&&>);
+static_assert(std::regular_invocable<const_qualified, S const&&>);
+static_assert(!std::regular_invocable<const_qualified, S volatile&&>);
+static_assert(!std::regular_invocable<const_qualified, S const volatile&&>);
+
+static_assert(
+    check_member_is_invocable<int (S::*)(double[]) volatile, S, double*>());
+using volatile_qualified = void (S::*)() volatile;
+static_assert(std::regular_invocable<volatile_qualified, S&>);
+static_assert(!std::regular_invocable<volatile_qualified, S const&>);
+static_assert(std::regular_invocable<volatile_qualified, S volatile&>);
+static_assert(!std::regular_invocable<volatile_qualified, S const volatile&>);
+static_assert(std::regular_invocable<volatile_qualified, S&&>);
+static_assert(!std::regular_invocable<volatile_qualified, S const&&>);
+static_assert(std::regular_invocable<volatile_qualified, S volatile&&>);
+static_assert(!std::regular_invocable<volatile_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)(int, S&) const volatile, S,
+                                        int, S&>());
+using cv_qualified = void (S::*)() const volatile;
+static_assert(std::regular_invocable<cv_qualified, S&>);
+static_assert(std::regular_invocable<cv_qualified, S const&>);
+static_assert(std::regular_invocable<cv_qualified, S volatile&>);
+static_assert(std::regular_invocable<cv_qualified, S const volatile&>);
+static_assert(std::regular_invocable<cv_qualified, S&&>);
+static_assert(std::regular_invocable<cv_qualified, S const&&>);
+static_assert(std::regular_invocable<cv_qualified, S volatile&&>);
+static_assert(std::regular_invocable<cv_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() &, S&>());
+using lvalue_qualified = void (S::*)() &;
+static_assert(std::regular_invocable<lvalue_qualified, S&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S const&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S volatile&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S const volatile&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S&&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S const&&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S volatile&&>);
+static_assert(!std::regular_invocable<lvalue_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() const&, S>());
+using lvalue_const_qualified = void (S::*)() const&;
+static_assert(std::regular_invocable<lvalue_const_qualified, S&>);
+static_assert(std::regular_invocable<lvalue_const_qualified, S const&>);
+static_assert(!std::regular_invocable<lvalue_const_qualified, S volatile&>);
+static_assert(
+    !std::regular_invocable<lvalue_const_qualified, S const volatile&>);
+static_assert(std::regular_invocable<lvalue_const_qualified, S&&>);
+static_assert(std::regular_invocable<lvalue_const_qualified, S const&&>);
+static_assert(!std::regular_invocable<lvalue_const_qualified, S volatile&&>);
+static_assert(
+    !std::regular_invocable<lvalue_const_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() volatile&, S&>());
+using lvalue_volatile_qualified = void (S::*)() volatile&;
+static_assert(std::regular_invocable<lvalue_volatile_qualified, S&>);
+static_assert(!std::regular_invocable<lvalue_volatile_qualified, S const&>);
+static_assert(std::regular_invocable<lvalue_volatile_qualified, S volatile&>);
+static_assert(
+    !std::regular_invocable<lvalue_volatile_qualified, S const volatile&>);
+static_assert(!std::regular_invocable<lvalue_volatile_qualified, S&&>);
+static_assert(!std::regular_invocable<lvalue_volatile_qualified, S const&&>);
+static_assert(!std::regular_invocable<lvalue_volatile_qualified, S volatile&&>);
+static_assert(
+    !std::regular_invocable<lvalue_volatile_qualified, S const volatile&&>);
+
+static_assert(check_member_is_invocable<int (S::*)() const volatile&, S&>());
+using lvalue_cv_qualified = void (S::*)() const volatile&;
+static_assert(std::regular_invocable<lvalue_cv_qualified, S&>);
+static_assert(std::regular_invocable<lvalue_cv_qualified, S const&>);
+static_assert(std::regular_invocable<lvalue_cv_qualified, S volatile&>);
+static_assert(std::regular_invocable<lvalue_cv_qualified, S const volatile&>);
+static_assert(!std::regular_invocable<lvalue_cv_qualified, S&&>);
+static_assert(!std::regular_invocable<lvalue_cv_qualified, S const&&>);
+static_assert(!std::regular_invocable<lvalue_cv_qualified, S volatile&&>);
+static_assert(!std::regular_invocable<lvalue_cv_qualified, S const volatile&&>);
+
+using rvalue_unqualified = void (S::*)() &&;
+static_assert(!std::regular_invocable<rvalue_unqualified, S&>);
+static_assert(!std::regular_invocable<rvalue_unqualified, S const&>);
+static_assert(!std::regular_invocable<rvalue_unqualified, S volatile&>);
+static_assert(!std::regular_invocable<rvalue_unqualified, S const volatile&>);
+static_assert(std::regular_invocable<rvalue_unqualified, S&&>);
+static_assert(!std::regular_invocable<rvalue_unqualified, S const&&>);
+static_assert(!std::regular_invocable<rvalue_unqualified, S volatile&&>);
+static_assert(!std::regular_invocable<rvalue_unqualified, S const volatile&&>);
+
+using rvalue_const_unqualified = void (S::*)() const&&;
+static_assert(!std::regular_invocable<rvalue_const_unqualified, S&>);
+static_assert(!std::regular_invocable<rvalue_const_unqualified, S const&>);
+static_assert(!std::regular_invocable<rvalue_const_unqualified, S volatile&>);
+static_assert(
+    !std::regular_invocable<rvalue_const_unqualified, S const volatile&>);
+static_assert(std::regular_invocable<rvalue_const_unqualified, S&&>);
+static_assert(std::regular_invocable<rvalue_const_unqualified, S const&&>);
+static_assert(!std::regular_invocable<rvalue_const_unqualified, S volatile&&>);
+static_assert(
+    !std::regular_invocable<rvalue_const_unqualified, S const volatile&&>);
+
+using rvalue_volatile_unqualified = void (S::*)() volatile&&;
+static_assert(!std::regular_invocable<rvalue_volatile_unqualified, S&>);
+static_assert(!std::regular_invocable<rvalue_volatile_unqualified, S const&>);
+static_assert(
+    !std::regular_invocable<rvalue_volatile_unqualified, S volatile&>);
+static_assert(
+    !std::regular_invocable<rvalue_volatile_unqualified, S const volatile&>);
+static_assert(std::regular_invocable<rvalue_volatile_unqualified, S&&>);
+static_assert(!std::regular_invocable<rvalue_volatile_unqualified, S const&&>);
+static_assert(
+    std::regular_invocable<rvalue_volatile_unqualified, S volatile&&>);
+static_assert(
+    !std::regular_invocable<rvalue_volatile_unqualified, S const volatile&&>);
+
+using rvalue_cv_unqualified = void (S::*)() const volatile&&;
+static_assert(!std::regular_invocable<rvalue_cv_unqualified, S&>);
+static_assert(!std::regular_invocable<rvalue_cv_unqualified, S const&>);
+static_assert(!std::regular_invocable<rvalue_cv_unqualified, S volatile&>);
+static_assert(
+    !std::regular_invocable<rvalue_cv_unqualified, S const volatile&>);
+static_assert(std::regular_invocable<rvalue_cv_unqualified, S&&>);
+static_assert(std::regular_invocable<rvalue_cv_unqualified, S const&&>);
+static_assert(std::regular_invocable<rvalue_cv_unqualified, S volatile&&>);
+static_assert(
+    std::regular_invocable<rvalue_cv_unqualified, S const volatile&&>);
+} // namespace pointer_to_member_functions
 
-    {
-      auto Up = std::make_unique<A>();
-      ModelsRegularInvocable(&A::I, Up);
-      ModelsRegularInvocable(&A::F, Up);
-      ModelsRegularInvocable(&A::G, Up, 0);
-      NotRegularInvocable(&A::H, Up, 0);
-    }
-    {
-      auto Sp = std::make_shared<A>();
-      ModelsRegularInvocable(&A::I, Sp);
-      ModelsRegularInvocable(&A::F, Sp);
-      ModelsRegularInvocable(&A::G, Sp, 0);
-      NotRegularInvocable(&A::H, Sp, 0);
-    }
-  }
-  {
-    using namespace Predicate;
-    {
-      ModelsRegularInvocable(L2rSorted{}, 0, 1, 2);
-      NotRegularInvocable(L2rSorted{});
-      NotRegularInvocable(L2rSorted{}, 0);
-      NotRegularInvocable(L2rSorted{}, 0, 1);
-    }
-    {
-      auto Up = std::make_unique<L2rSorted>();
-      ModelsRegularInvocable(&L2rSorted::operator()<int>, Up, 0, 1, 2);
-      NotRegularInvocable(&L2rSorted::operator()<int>, Up);
-      NotRegularInvocable(&L2rSorted::operator()<int>, Up, 0);
-      NotRegularInvocable(&L2rSorted::operator()<int>, Up, 0, 1);
-    }
-    {
-      auto Sp = std::make_shared<L2rSorted>();
-      ModelsRegularInvocable(&L2rSorted::operator()<int>, Sp, 0, 1, 2);
-      NotRegularInvocable(&L2rSorted::operator()<int>, Sp);
-      NotRegularInvocable(&L2rSorted::operator()<int>, Sp, 0);
-      NotRegularInvocable(&L2rSorted::operator()<int>, Sp, 0, 1);
-    }
-  }
-  // {
-  // RNG doesn't model regular_invocable, left here for documentation
-  //  auto G = std::mt19937_64(std::random_device()());
-  //  auto D = std::uniform_int_distribution<>();
-  //  models_invocable(D, G);
-  // }
-  return 0;
+[[nodiscard]] constexpr bool check_lambda(auto, auto...) { return false; }
+
+// clang-format off
+template<class F, class... Args>
+requires std::invocable<F, Args...>
+[[nodiscard]] constexpr bool check_lambda(F, Args&&...)
+  return false;
+
+template<class F, class... Args>
+requires std::regular_invocable<F, Args...> && true
+[[nodiscard]] constexpr bool check_lambda(F, Args&&...)
+  return true;
+// clang-format on
+
+[[nodiscard]] constexpr bool check_lambdas() {
+  static_assert(check_lambda([] {}));
+  static_assert(check_lambda([](int) {}, 0));
+  static_assert(check_lambda([](int) {}, 0L));
+  static_assert(!check_lambda([](int) {}, nullptr));
+
+  int i = 0;
+  return check_lambda([](int&) {}, i);
 }
+
+static_assert(check_lambdas());
+
+int main(int, char**) { return 0; }