Re: Future of libio vtable compatibility

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 18/06/2018 14:41, Zack Weinberg wrote:
> On Mon, Jun 18, 2018 at 1:13 PM, Florian Weimer <fw@deneb.enyo.de> wrote:
>>
>> We could require that vtable compatibility requires setting an
>> environment variable in glibc 2.28.  This might finally allow us to
>> gather some data.  Either nobody needs backwards compatibility, or our
>> backwards compatibility is just too perfect.  It's difficult to tell
>> why we don't see more bug reports in this area.
> 
> This is not quite the same thing as vtable compatibility, but based on
> having had to read a bunch of the relevant code for the bits/types/
> work, I suspect that programs that require the "old" FILE struct have
> been broken for some time.
> 
> zw
> 

I do think the libio compatibility is really more a burden than a 
solution. If I recall correctly, we already have it broken in some
occasions (for instance [1]) to fix actual reported bugs. And I 
think it is quite unproductive to keep compatibility to quite broken
API which does not seem to used anywhere and which requires an
extra burden in both testing and development for the sake of
compatibility (which we can't effectively test by the way).

[1] https://sourceware.org/ml/libc-alpha/2017-04/msg00356.html