Re: [Grep-devel] handling of non-BMP characters

[Corinna Vinschen]

On Dec 19 08:51, Bruno Haible wrote:
> Corinna Vinschen wrote in
> <https://lists.gnu.org/archive/html/grep-devel/2018-12/msg00039.html>:
> > it would be
> > pretty nice if that code could get reverted back in to support
> > non-BMP charsets even on Cygwin.
> 
> I agree that support for beyond-BMP characters should be added back to 'grep'.
> 
> Your earlier fix from 2013-08-16 (and the fact that the test failure is
> occurring exactly on Windows and AIX platforms) shows that the problem is
> with wchar_t being only 16-bit wide on these platforms.
> 
> The type 'char32_t' has been introduced in C11 to overcome this limitation.[1]
> 
> I propose to
> 
>   1) introduce in gnulib support for <uchar.h>, char32_t, and mbrtoc32, so
>      that we can use these instead of <wchar.h>, wchar_t, and mbrtowc
>      portably,
> 
>   2) change those gnulib modules that don't behave well with beyond-BMP
>      characters on Windows and AIX to use char32_t instead of wchar_t.
> 
> Then the 'grep' code can be changed in a similar way, and this will
> fix the bug on Cygwin and AIX (though not on native Windows [2]).
> 
> The advantage of this approach are minimal code changes in 'grep': just
> change some type and function names here and there, and add code for
> the additional (size_t)(-3) return value of mbrtoc32.

IIUC this would also drop the requirement for #ifdef CYGWIN'ed code.
Sounds like a great idea to me!


Corinna



> 
> Bruno
> 
> [1] 
> https://stackoverflow.com/questions/21264035/why-did-c11-introduce-the-char16-t-and-char32-t-types
> [2] https://lists.gnu.org/archive/html/bug-gnulib/2011-02/msg00175.html