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Date: Wed, 18 Feb 2015 16:04:29 +0200
From: Sergey Dmitrouk <sdmitrouk@...esssoftek.com>
To: <musl@...ts.openwall.com>
Subject: Re: wchar_t and -fshort-wchar
OK, I see, thanks for the explanation. I agree there are problems with
short wchar_t, but in my specific case they are mostly irrelevant (no need
for dynamic loader or conversions that involve code points with values
above 0xffff). I mainly wanted to inform you about this build issue, in
case you would like to do something about it.
On Wed, Feb 18, 2015 at 03:54:13AM -0800, Szabolcs Nagy wrote:
> * Sergey Dmitrouk <sdmitrouk@...esssoftek.com> [2015-02-18 12:53:37 +0200]:
> > musl seems to build fine with -fshort-wchar, but when client applications
>
> that cannot possibly work
>
> wchar_t is assumed to be a unicode code point so short wchar_t is broken
>
> > are built against musl all uses of wide character literals fail due to wide
> > type defined internally by a compiler differs from the type of `wchar_t` in
> > musl headers.
> >
> > I faced this on ARM where `wchar_t` is defined as `unsigned int` by
> > musl but it's `unsigned short` from compilers point of view. I'd expect
> > similar issues with other targets.
> >
>
> http://arminfo.emea.arm.com/help/topic/com.arm.doc.ihi0042e/IHI0042E_aapcs.pdf
>
> says
>
> "The preferred type of wchar_t is unsigned int. However,
> a virtual platform may elect to use unsigned short instead.
> A platform standard must document its choice"
>
> on musl/glibc/.. the platform standard is unsigned int
>
> > Would it make sense to use `__WCHAR_TYPE__` for `wchar_t` when it's
> > available (it's already used for i386, but for different reason)?
> > Presumably, as compiler is responsible for creating wide literals, libc
> > would better agree with it on the type.
> >
> > Of course, this makes sense only if you intend to support builds with
> > `-fshort-wchar` flag, which are not very common I believe.
> >
>
> this is an abi change so a different loader path name etc should be
> used then (you should create a new subarch in musl's terminology)
>
> but i'm not sure how you plan to fix up mb to wc functions for
> such a subarch..
>
> > Best regards,
> > Sergey
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