Minimal changes to support constexpr allocation in MSVC #1313
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* Define `_CONSTEXPR20_DYNALLOC` macro to `constexpr` when the compiler defines `__cpp_constexpr_dynamic_alloc` and `inline` otherwise. * Implement and test `ranges::construct_at` and `ranges::destroy_at`, mark them (and `std` flavors) `_CONSTEXPR20_DYNALLOC`. * Implement `ranges::destroy` and `ranges::destroy_n` which share machinery with `ranges::destroy_at` with minimal test coverage. (More to follow.) [This is a dual of internal MSVC-PR-275909.]
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Full disclosure: there's really no reason for |
| auto construct_at(_Ty* const _Location, _Types&&... _Args) noexcept(noexcept(::new (const_cast<void*>( | ||
| static_cast<const volatile void*>(_Location))) _Ty(_STD forward<_Types>(_Args)...))) // strengthened | ||
| _CONSTEXPR20_DYNALLOC auto construct_at(_Ty* const _Location, _Types&&... _Args) noexcept( | ||
| noexcept(::new (const_cast<void*>(static_cast<const volatile void*>(_Location))) |
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HM in the uninitialized_meow PR we introduced a voidify Funktion. If it is not too far out we should wait until it is merged or reproduce it here
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The whole point of pushing this through before finishing test coverage is to avoid blocking the compiler team. If we get uninit_meow merged in time, I'll make the voidify change here. Otherwise, I'll do so in the followup. (Leaving this comment open as a reminder.)
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MSVC-PR-276291 is internally out for review, containing uninit_meow, so it's a race 🚀
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Does that mean we can have a look at constexpr container after this is merged (excluding string and vector of course) |
_CONSTEXPR20_DYNALLOCmacro toconstexprwhen the compiler defines__cpp_constexpr_dynamic_allocandinlineotherwise.ranges::construct_atandranges::destroy_at, mark them (andstdflavors)_CONSTEXPR20_DYNALLOC.ranges::destroyandranges::destroy_nwhich share machinery withranges::destroy_atwith minimal test coverage. (More to follow.)[This is a dual of internal MSVC-PR-275909.]
Partially implements #37 and #39.