Re: [Xen-devel] [PATCH] Xen: remove -fshort-wchar gcc flag

[Arnd Bergmann <arnd@xxxxxxxx>]

On Thursday, August 11, 2016 6:51:33 AM CEST Jan Beulich wrote:
> >>> On 11.08.16 at 14:39, <arnd@xxxxxxxx> wrote:
> > A previous patch added the --no-wchar-size-warning to the Makefile to
> > avoid this harmless warning:
> > 
> > arm-linux-gnueabi-ld: warning: drivers/xen/efi.o uses 2-byte wchar_t yet 
> > the 
> > output is to use 4-byte wchar_t; use of wchar_t values across objects may 
> > fail
> > 
> > Changing kbuild to use thin archives instead of recursive linking
> > unfortunately brings the same warning back during the final link.
> > 
> > This time, we remove the -fshort-wchar flag that originally caused
> > the warning, hopefully fixing the problem for good. I don't see
> > any reason for having the flag in the first place, as the Xen code
> > does not use wchar_t at all.
> 
> It uses efi_char16_t, and by dropping -fshort-wchar you'd open
> up a trap for anyone to fall into who were to add wide string
> literals to that same file. EFI using 16-bit characters requires
> code interfacing with EFI to do so too.

I don't understand. How is this different from other source files
that use efi_char16_t or the wchar_t definition from include/linux/nls.h?

As far as I can tell, they all use 16-bit characters, but none of the
others sets the flag. Maybe we should just always build with -fshort-wchar
from the top-level Makefile?

        Arnd

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