Implement P3860R1 Make atomic_ref<T> Convertible To atomic_ref<const T>
#5846
+233
−21
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Fixes #5838.
Notes:
constexpris intentionally not added because it should belong to P3309R3 "constexpratomicAndatomic_ref". The new constructor should be marked_CONSTEXPR26in a future PR.explicit atomic_ref(_Ty&&) = delete;overload to disallow bogus explicit construction ofatomic_ref<const T>fromatomic_ref<volatile T>oratomic_ref<const volatile T>. Such construction is currently unfortunately well-formed because of theoperator Tconversion function. I've mailed LWG Chair to file an LWG issue for this. Edit: The issue is now LWG-4472.is_convertible_v<_Uty (*)[], _Ty (*)[]>, which is consistent with pre-existing detections inunique_ptr,shared_ptr,span,mdspan, andranges::subrange. Conversions related to array of unknown bound types are not yet tested because MSVC and EDG (and even GCC) seem to be buggy for the the changes in WG21-P0388R4.