[libcxx-commits] [libcxx] [libc++] Allow a disengaged `optional` to be `constexpr` since C++20 (PR #192888)

[via libcxx-commits]

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@@ -402,6 +402,12 @@ struct __optional_destruct_base<_Tp, false> {
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void reset() noexcept {
     if (__engaged_) {
       __val_.~value_type();
+      // TODO: Remove the workaround when supported compilers have CWG2424 implemented.
+#    if _LIBCPP_STD_VER >= 20
+      if consteval {
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eiytoq wrote:

Should we use `__libcpp_is_constant_evaluated()` instead of `if consteval` here, since `if consteval` is a C++23 extension?
```suggestion
      if (__libcpp_is_constant_evaluated()) {
```

https://github.com/llvm/llvm-project/pull/192888