Weird ... 17.12 only bug? I tried some online MSVC versions (Godbolt
has 16.0 to 17.10), and was not able to reproduce this problem either.

https://godbolt.org/z/YevKKhWT4

On Fri, 25 Apr 2025 at 17:14, Vladimir Grigoriev via Std-Discussion
<std-discussion_at_[hidden]> wrote:
>
> I am using MS VS2022 of version 17.12. Maybe in the newly vesion of MS VS2022 (17.13) the bug was fixed.
>
> With best regards
> (Vlad from Moscow)
>
> You can meet me at http://cpp.forum24.ru/ or www.stackoverflow.com or http://ru.stackoverflow.com
>
>
>
> Пятница, 25 апреля 2025, 11:20 +03:00 от Bo Persson via Std-Discussion <std-discussion_at_[hidden]>:
>
> On 2025-04-25 at 00:38, Vladimir Grigoriev via Std-Discussion wrote:
> > In the C++20 Standard there is written (9.7.1 Enumeration declarations):
> > 7 For an enumeration whose underlying type is not fixed, the underlying
> > type is an integral type that can represent all the enumerator values
> > defined in the enumeration. If no integral type can represent all the
> > enumerator values, the enumeration is ill-formed. It is implementation-
> > defined which integral type is used as the underlying type *except that
> > the underlying type shall not be larger than int unless the value of an
> > enumerator cannot fit in an int or unsigned int*. If the enumerator-list
> > is empty, the underlying type is as if the enumeration had a single
> > enumerator with value 0.
> > However if to run this simple program
> >
> > |#include <iostream> #include <type_traits> int main() { int vals[]
> > { 2,3,5,7,11 }; enum { N = sizeof vals / sizeof vals[0] }; std::cout <<
> > std::boolalpha; std::cout <<
> > "std::is_same_v<std::underlying_type_t<decltype( N )>, size_t> = " <<
> > std::is_same_v<std::underlying_type_t<decltype( N )>, size_t> << '\n'; }|
> >
> > |then the MS VS2022 outputs *true *though size_t is an alias for the
> > type unsigned long long and the constant value used as an initializer
> > of the enumerator *N *at least can fit in an object of the type
> > unsigned int.|
>
> For me it outputs false, and the IDE popup says that the type is int.
>
>
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-- 
Yongwei Wu
URL: http://wyw.dcweb.cn/