P0896R4_P1614R2_comparisons/test.cpp: Remove compiler bug workarounds

[StephanTLavavej]

The compiler bugs that we reported as Microsoft-internal VSO-905257 and VSO-1070391 were resolved as fixed in VS 2019 16.7 Preview 1. When that's available, we should remove the following workarounds in our tests:

STL/tests/std/tests/P0896R4_P1614R2_comparisons/test.cpp

Lines 261 to 277 in 0cbd1b2

	#if defined(__clang__) || defined(__EDG__) // TRANSITION, VSO-905257
	STATIC_ASSERT(test_compare_three_way<int, int, strong_ordering>());
	STATIC_ASSERT(test_compare_three_way<int, long, strong_ordering>());
	STATIC_ASSERT(test_compare_three_way<float, float, partial_ordering>());
	STATIC_ASSERT(test_compare_three_way<float, double, partial_ordering>());
	STATIC_ASSERT(test_compare_three_way<long, double, partial_ordering>());
	STATIC_ASSERT(test_compare_three_way<bool, int, void>());
	STATIC_ASSERT(test_compare_three_way<some_enum, some_enum, strong_ordering>());
	STATIC_ASSERT(test_compare_three_way<some_enum, int, void>());
	STATIC_ASSERT(test_compare_three_way<int*, int*, strong_ordering>());
	STATIC_ASSERT(test_compare_three_way<int*, void*, strong_ordering>());
	STATIC_ASSERT(test_compare_three_way<int (*)(), int (*)(), void>());
	STATIC_ASSERT(test_compare_three_way<int (*)(), void (*)(), void>());
	#endif // TRANSITION, VSO-905257

STL/tests/std/tests/P0896R4_P1614R2_comparisons/test.cpp

Lines 300 to 312 in 0cbd1b2

	template <class T, class U, class R>
	constexpr void assert_three_way(T const& t, U const& u, R const result) { // TRANSITION, VSO-905257
	#if !defined(__clang__) && !defined(__EDG__)
	// <=> expressions that resolve to builtin operators are incorrectly lvalues of const-qualified type on MSVC, so
	// they are rejected by std::three_way_comparable and std::three_way_comparable_with.
	if constexpr (!std::is_class_v<std::remove_cvref_t<T>> && !std::is_class_v<std::remove_cvref_t<U>>) {
	return;
	} else
	#endif // !defined(__clang__) && !defined(__EDG__)
	{
	assert(compare_three_way{}(t, u) == result);
	}
	}

STL/tests/std/tests/P0896R4_P1614R2_comparisons/test.cpp

Lines 506 to 508 in 0cbd1b2

	#if defined(__clang__) || defined(__EDG__) // TRANSITION, VSO-1070391
	test_equality_comparable(&has_members::f, &has_members::g, strong_ordering::less); // Ditto "not equal"
	#endif // TRANSITION, VSO-1070391

[StephanTLavavej]

This issue appears to be a superset of #493, except that they disagree about when VSO-905257 was fixed.

[SuperWig]

VSO-905257 still fails in preview 1.
Though the second snippet passes if the static assert in main is removed.

[SuperWig]

After actually doing investigation of why that's the case.
The following is what is failing

STATIC_ASSERT(test_compare_three_way<long, double, partial_ordering>());

And these in constexpr

test_partially_ordered(3.14, NaN, partial_ordering::unordered);
test_partially_ordered(3.14f, NaN, partial_ordering::unordered);
test_partially_ordered(3.14, NaNf, partial_ordering::unordered);

Worth making a PR with the changes made? Using this issue for the transition comments.

[StephanTLavavej]

Thanks for looking into this! I think a PR would let us more easily analyze the remaining failures and what compiler/library issues still need to be fixed.