Re: glibc 2.27: 3 weeks till release

[Carlos O'Donell <carlos at redhat dot com>]

On 01/11/2018 08:03 AM, Rafal Luzynski wrote:
> 11.01.2018 04:44 "Dmitry V. Levin" <ldv@altlinux.org> wrote:
>> [...]
>> * There are issues not listed in the release page that change ABI:
>>
>> + Implement allocate_once [2]
>>
>> This is close to be committed.
>>
>> + libidn2-based IDNA implementation [3]
>>
>> This qualifies as security bug fixes.
>>
>> + Regression caused by setjmp changes [4]
>>
>> There is going to be another ABI change if these changes are reverted.
>>
>> [1] https://sourceware.org/glibc/wiki/Release/2.27
>> [2] https://sourceware.org/ml/libc-alpha/2018-01/msg00288.html
>> [3] https://sourceware.org/ml/libc-alpha/2018-01/msg00335.html
>> [4] https://sourceware.org/ml/libc-alpha/2018-01/msg00268.html
> 
> Shouldn't we consider my patches for alternative month names as ABI
> change as well? Just to reiterate:
> 
> * nl_langinfo() family:
>   + the meaning of MON_x and ABMON_x constants has been changed,

This is a API change, but not an ABI change.

>   + new constants: ALTMON_x and _NL_ABALTMON_x have been added, they
>     work as their appropriate MON_x and ABMON_x variants previously;

This is an addition to the ABI, there are new constants with values,
and yes, that is an ABI change, but not a negative one IMO, and we
should get your work committed in this cycle.

> * strftime() family:
>   + the meaning of %B, %b, and %h has been changed (because of the
>     above change),
>   + new format specifiers: %OB, %Ob, %Oh have been added and they
>     work as %B, %b, and %h previously;

This is an API change, but not an ABI change.

> * strptime() family:
>   + the new format specifiers: %OB, %Ob, %Oh are valid,
>   + %B, %b, %h, %OB, %Ob, %Oh accept all forms of month names,
>     including the new ones.

Likewise.

> There is no backward compatibility provided.  It has been discussed
> and decided that this is a bug fix and providing the backward
> compatibility causes more problems with almost no benefit.
> That means that the change will be visible also in old binaries
> running with the new glibc.

Correct. That is not an ABI change though.

> Note that the negative impact of this change is smaller than the
> negative impact of the current bug.

Agreed.

-- 
Cheers,
Carlos.