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To: cygwin@cygwin.com
Subject: Re: Bug in GCC / libstdc++: Space character categorized as
 non-printable by std::ctype<wchar_t>
In-Reply-To: <CANspNZndk8p0-oArho-AW+QpmkXPEcHS9kXRHXuNc0ALax80vw@mail.gmail.com>
 (Kristian Spangsege via Cygwin's message of "Fri, 14 Jun 2024 17:37:13
 +0200")
References: <CANspNZndk8p0-oArho-AW+QpmkXPEcHS9kXRHXuNc0ALax80vw@mail.gmail.com>
Date: Sat, 27 Jul 2024 08:58:20 +0200
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From: ASSI via Cygwin <cygwin@cygwin.com>
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Kristian Spangsege via Cygwin writes:
> In C++, a space character is reported as non-printable by
> `std::ctype<wchar_t>` in the "C" locale (the only locale supported by
> `std::ctype`). In other words, the following expression evaluates to
> `false`:
>
>     ctype.is(std::ctype_base::print, ctype.widen(' '))
>
> where `ctype` is obtained by `std::use_facet<std::ctype<wchar_t>>(loc)` and
> `loc` is the "C" locale.
>
> It should have been evaluated to `true` because a space character is
> required by the C++ standard to be categorized as printable.
>
> Also, it is reported as printable by `std::iswprint(int ch)`.
>
> Also, the non-wide space character is reported as printable, i.e,
> `std::use_facet<std::ctype<char>>(loc)::is(std::ctype_base::print, ' ')` is
> `true`.
>
> Also, `ctype.is(std::ctype_base::print, ctype.widen(' '))` is `true` with
> MinGW, with GCC on Linux, and with Visual Studio.

This sounds like it might be a bug in newlib, so you should either
report it there or else it would be the newlib integration for gcc.  In
any case this needs to be fixed upstream.


Regards,
Achim.
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