llvm/clang/test/SemaCXX/ms-constexpr-new.cpp

// RUN: %clang_cc1 -fms-compatibility -fms-compatibility-version=19.33 -std=c++20 -verify=supported %s
// RUN: %clang_cc1 -fms-compatibility -fms-compatibility-version=19.32 -std=c++20 -verify=unsupported %s
// supported-no-diagnostics

[[nodiscard]]
[[msvc::constexpr]] // unsupported-warning {{unknown attribute 'constexpr' ignored}}
inline void* operator new(decltype(sizeof(void*)), void* p) noexcept { return p; }

namespace std {
  constexpr int* construct_at(int* p, int v) {
    [[msvc::constexpr]] return ::new (p) int(v); // unsupported-warning {{unknown attribute 'constexpr' ignored}}
  }
}

constexpr bool check_construct_at() { int x; return *std::construct_at(&x, 42) == 42; }
static_assert(check_construct_at());