[libc++][test] Fix MSVC warning C4127 in array.cons/initialization.pass.cpp

[StephanTLavavej]

This fixes MSVC warning C4127: conditional expression is constant.

Testing TEST_STD_AT_LEAST_20_OR_RUNTIME_EVALUATED by itself doesn't emit this warning, but the condition here is more complicated. I'm expanding the macro and mechanically simplifying the resulting code.

(Yeah, this warning is often annoying, and I introduced TEST_STD_AT_LEAST_20_OR_RUNTIME_EVALUATED to avoid this warning elsewhere, so it's disappointing that it doesn't make the compiler happy here. If this change is undesirable, I can replace it with ADDITIONAL_COMPILE_FLAGS(cl-style-warnings), but ideally I'd like to avoid having to suppress it.)

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Stephan T. Lavavej (StephanTLavavej)

Changes

This fixes MSVC warning C4127: conditional expression is constant.

Testing TEST_STD_AT_LEAST_20_OR_RUNTIME_EVALUATED by itself doesn't emit this warning, but the condition here is more complicated. I'm expanding the macro and mechanically simplifying the resulting code.

(Yeah, this warning is often annoying, and I introduced TEST_STD_AT_LEAST_20_OR_RUNTIME_EVALUATED to avoid this warning elsewhere, so it's disappointing that it doesn't make the compiler happy here. If this change is undesirable, I can replace it with ADDITIONAL_COMPILE_FLAGS(cl-style-warnings), but ideally I'd like to avoid having to suppress it.)

---

Full diff: https://github.com/llvm/llvm-project/pull/79793.diff

1 Files Affected:

• (modified) libcxx/test/std/containers/sequences/array/array.cons/initialization.pass.cpp (+4-1)

diff --git a/libcxx/test/std/containers/sequences/array/array.cons/initialization.pass.cpp b/libcxx/test/std/containers/sequences/array/array.cons/initialization.pass.cpp
index 7991d4738d9699..acd176cce91d9e 100644
--- a/libcxx/test/std/containers/sequences/array/array.cons/initialization.pass.cpp
+++ b/libcxx/test/std/containers/sequences/array/array.cons/initialization.pass.cpp
@@ -28,7 +28,10 @@ struct test_initialization {
             // Before C++20, default initialization doesn't work inside constexpr for
             // trivially default constructible types. This only apply to non-empty arrays,
             // since empty arrays don't hold an element of type T.
-            if (TEST_STD_AT_LEAST_20_OR_RUNTIME_EVALUATED || !std::is_trivially_default_constructible<T>::value) {
+#if TEST_STD_VER < 20
+            if (!TEST_IS_CONSTANT_EVALUATED || !std::is_trivially_default_constructible<T>::value)
+#endif
+            {
                 std::array<T, 1> a1; (void)a1;
                 std::array<T, 2> a2; (void)a2;
                 std::array<T, 3> a3; (void)a3;

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[StephanTLavavej]

Merged as all checks passed, except for a surely-unrelated XPASS in one configuration of std/experimental/simd/simd.class/simd_ctor_conversion.pass.cpp. Thanks! 😻