[libc++][test] Mark optional test functions as TEST_CONSTEXPR_CXX20

[StephanTLavavej]

P2231R1 "Missing constexpr in std::optional and std::variant" was accepted as a C++20 Defect Report, not a C++17 Defect Report. Accordingly, test_empty_emplace() and check_reset() should be marked as TEST_CONSTEXPR_CXX20. Note that their static_asserts are properly guarded:

llvm-project/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp

Lines 270 to 272 in 4ce6542

	#if TEST_STD_VER > 17
	static_assert(test_empty_emplace());
	#endif

llvm-project/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp

Lines 53 to 55 in 4ce6542

	#if TEST_STD_VER >= 20
	static_assert(check_reset());
	#endif

Found while running libc++'s tests with MSVC's STL, as we activate our constexpr here for C++20 and above.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Stephan T. Lavavej (StephanTLavavej)

Changes

P2231R1 "Missing constexpr in std::optional and std::variant" was accepted as a C++20 Defect Report, not a C++17 Defect Report. Accordingly, test_empty_emplace() and check_reset() should be marked as TEST_CONSTEXPR_CXX20. Note that their static_asserts are properly guarded:

llvm-project/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp

Lines 270 to 272 in 4ce6542

	#if TEST_STD_VER > 17
	static_assert(test_empty_emplace());
	#endif

llvm-project/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp

Lines 53 to 55 in 4ce6542

	#if TEST_STD_VER >= 20
	static_assert(check_reset());
	#endif

Found while running libc++'s tests with MSVC's STL, as we activate our constexpr here for C++20 and above.

---

Full diff: https://github.com/llvm/llvm-project/pull/94172.diff

2 Files Affected:

• (modified) libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp (+1-1)
• (modified) libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp (+1-1)

diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp
index 17a1e94b0ba6e..631052cad94b9 100644
--- a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp
@@ -210,7 +210,7 @@ void test_on_test_type() {
     }
 }
 
-constexpr bool test_empty_emplace()
+TEST_CONSTEXPR_CXX20 bool test_empty_emplace()
 {
     optional<const int> opt;
     auto &v = opt.emplace(42);
diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
index 112ee213b42a6..c8c0b01060608 100644
--- a/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
@@ -31,7 +31,7 @@ struct X
 
 bool X::dtor_called = false;
 
-constexpr bool check_reset()
+TEST_CONSTEXPR_CXX20 bool check_reset()
 {
     {
         optional<int> opt;

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