[libcxx-commits] [PATCH] D125283: reverts "[libc++] Explicitly reject `uniform_int_distribution<bool>` and `<char>`."

[Manoj Gupta via Phabricator via libcxx-commits]

manojgupta added inline comments.


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Comment at: libcxx/include/__random/uniform_int_distribution.h:242-243
     static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
-    typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t), uint32_t,
-                                 typename make_unsigned<result_type>::type>::type _UIntType;
+    using _UIntType =
+        _If<sizeof(result_type) <= sizeof(uint32_t), uint32_t, typename __unsigned_equivalent<result_type>::type>;
     const _UIntType _Rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
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cjdb wrote:
> ldionne wrote:
> > I don't think I understand how this works for `bool`. Since anything non-`0` will end up being considered `true` and only `0` is `false`, how do we achieve a uniform distribution by casting a uniformly-distributed `unsigned char` back to `bool`? Am I misunderstanding something?
> Good question, I don't have an answer. I can increase my sample size to boost confidence that the distribution is roughly uniform, if you'd like.
Shouldn't just checking for lowest bit ( val & 0x1)  work for bool uniform distribution?


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  https://reviews.llvm.org/D125283/new/

https://reviews.llvm.org/D125283