[PATCH] D24372: [libcxx] Sprinkle constexpr over compressed_pair

[Eric Fiselier via cfe-commits]

static_cast<T&&>(t) also works as a constexpr C++11 forward.

On Sep 13, 2016 4:07 PM, "Keno Fischer" <kfischer at college.harvard.edu>
wrote:

> loladiro added inline comments.
>
> ================
> Comment at: include/memory:2137
> @@ -2132,3 +2136,3 @@
>
> -    _LIBCPP_INLINE_VISIBILITY
> +    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
>      __libcpp_compressed_pair_imp& operator=(__libcpp_compressed_pair_imp&&
> __p)
> ----------------
> mclow.lists wrote:
> > loladiro wrote:
> > > mclow.lists wrote:
> > > > Have you tested this on C++11?
> > > > I suspect that some of these need to be
> `_LIBCPP_CONSTEXPR_AFTER_CXX11`
> > > Well, as I mentioned there are other problems on C++11, namely forward
> not being constexpr (so even the simple constructors below can't be
> constant initialized in C++11). I would REALLY like for unique_ptr to be
> constant initialized even in C++11 mode. I feel like arguably the standard
> requires it by marking the constructor `constexpr`.
> > One way to deal with that is to define a call `__forward()` that is the
> same as `forward()` except that it's constexpr in C++11, and have
> compressed_pair call that.
> >
> I was worried that something in the definition of forward required C++14
> constexpr semantics? Is that not the case. If so this sounds like a good
> solution, and I can update the patch accordingly.
>
>
> Repository:
>   rL LLVM
>
> https://reviews.llvm.org/D24372
>
>
>
>
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