[libcxx-commits] [libcxx] [libc++][test] Fix MSVC warning C4127 in `array.cons/initialization.pass.cpp` (PR #79793)

[via libcxx-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Stephan T. Lavavej (StephanTLavavej)

<details>
<summary>Changes</summary>

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
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;

``````````

</details>


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