[libcxx-commits] [libcxx] [libc++] Use a custom once_flag implementation for locale::id::__get() (PR #212235)

[Nikolas Klauser via libcxx-commits]

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@@ -563,9 +563,29 @@ void locale::facet::__on_zero_shared() noexcept { delete this; }
 // locale::id
 
 long locale::id::__get() {
-  constinit static int32_t next_id = 0;
-  call_once(__flag_, [&] { __id_ = __libcpp_atomic_add(&next_id, 1); });
-  return __id_ - 1;
+  constexpr __id_type uninitialized = 0;
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philnik777 wrote:

We could, but making it an enum class would mean we'd have to cast all over the place. I don't think that improve readability. If we don't make it an enum class I don't see why we'd want to move these to the header.

https://github.com/llvm/llvm-project/pull/212235