[U-Boot] [U-Boot, v0, 07/20] vsprintf.c: add wide string (%ls) support

[Alexander Graf]

> Am 09.08.2017 um 14:38 schrieb Rob Clark <robdclark at gmail.com>:
> 
>> On Tue, Aug 8, 2017 at 6:03 PM, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>>> On 08/04/2017 09:31 PM, Rob Clark wrote:
>>> 
>>> @@ -528,8 +549,13 @@ repeat:
>>>                      continue;
>>> 
>>>              case 's':
>>> -                     str = string(str, end, va_arg(args, char *),
>>> -                                  field_width, precision, flags);
>>> +                     if (qualifier == 'l') {
>> 
>> %ls refers to wchar with implementation dependent width in the C standard.
>> There is no qualifier for 16-bit wchar. Couldn't we use %us here in
>> reference to the u-notation ( u'MyString' ). This would leave the path
>> open for a standard compliant '%ls'.
>> 
> 
> So two drawbacks I'm running into when converting to c11 u"string"
> style, compared to the -fshort-wchar:
> 
> 1) with -fshort-wchar plus %ls, gcc knows how to typecheck the
> printf/sprintf/etc args
> 2) introducing a non-standard conversion character (since there
> doesn't seem to be a standard one) means we need to drop -Wformat
> 
> So far, afaict, the only argument against -fshort-wchar seems to be
> that someday ext4 might support utf32 filenames?  (And really
> -fshort-wchar doesn't preclude that.  So I'm not sure this is a valid
> argument.)
> 
> So independent of c11 (which might be a good idea for other reasons),
> I'm back to thinking we should use -fshort-wchar.  Possibly as a
> kconfig option that EFI_LOADER selects.. or possibly just
> unconditionally.
> 
> Thoughts?

If we select it, I'd rather have it be unconditional, to not oprn potential for undetected breakage.

Alex

> 
> BR,
> -R