[libcxx-commits] [libcxx] [libc++] Make list constexpr as part of P3372R3 (PR #129799)

[Peng Liu via libcxx-commits]

================
@@ -239,12 +240,24 @@ void test_ctor_under_alloc_with_alloc() {
 #endif
 }
 
-int main(int, char**) {
+TEST_CONSTEXPR_CXX26 bool test() {
   basic_test();
   test_emplacable_concept();
   test_emplacable_concept_with_alloc();
-  test_ctor_under_alloc();
-  test_ctor_under_alloc_with_alloc();
+
+  if (!TEST_IS_CONSTANT_EVALUATED) {
+    test_ctor_under_alloc();
+    test_ctor_under_alloc_with_alloc();
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winner245 wrote:

I still find it challenging to make these two tests `constexpr`, because the `AllocatorConstructController` type must use a singleton pattern (as the test-types, test-allocator and test need to share the same controller), meaning that the controller object must be a `static` variable. Whether it is a local static (https://godbolt.org/z/8eYxoj9or) or class static (https://godbolt.org/z/xnzh693WK) variable, I found it not possible to achieve a constexpr implementation. 

https://github.com/llvm/llvm-project/pull/129799