Hello, >> the attached patch constexpr-ifies <limits> as specified in FDIS as well as >> removes the >> workarounds in libc++'s random number generators due to missing constexpr >> (the workarounds >> don't work when using a non-standard PRNG). The corresponding tests are >> modified as well. >> >> Please review and, if ok, commit. >> >> >> With many thanks in advance, >> Jonathan > > Thanks Jonathan. I've been meaning to take care of this. The current libc++ > is a mess with respect to constexpr. > > One of the things I want to do is to allow libc++ to emulate correct behavior > even when it is compiled in C++03 mode. And I don't believe this patch will > do this.
No, it indeed does not. As libc++ currently uses said hack in <__config>, I simply worked from there. I was not aware of the desired C++03 backwards compatibility. BTW, are new C++11 headers supposed to be backwards compatible, too? > [...] > This is just wrong, but taking it out is going to take a little more work. I > haven't nailed down exactly how we want to support both C++03 and C++11 mode, > but I'm imagining something similar to the way we're handling noexcept: > > #ifndef _LIBCPP_HAS_NO_CONSTEXPR > #define _CONSTEXPR_1 constexpr > #define _CONSTEXPR_0 constexpr > #else > #define _CONSTEXPR_1 const > #define _CONSTEXPR_0 > #endif > > (better macro names would be great!) How about _CONSTEXPR_FUNC for a constexpr function/method and _CONSTEXPR_STATIC for a constexpr static member constant: #ifndef _LIBCPP_HAS_NO_CONSTEXPR #define _CONSTEXPR_STATIC static constexpr #define _CONSTEXPR_FUNC constexpr #else #define _CONSTEXPR_STATIC static const #define _CONSTEXPR_FUNC #endif I took the liberty of trying this out with <limits>; the patch is attached (I did not touch <random> this time). Jonathan
limits.diff
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