Re: [PATCH 1/2] Remove _IO_MTSAFE_IO from public headers.

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 06/04/2017 17:41, Zack Weinberg wrote:
> On Thu, Apr 6, 2017 at 4:29 PM, Adhemerval Zanella
> <adhemerval.zanella@linaro.org> wrote:
>> On 22/03/2017 09:55, Zack Weinberg wrote:
>>> _IO_MTSAFE_IO controls whether stdio is *built* with support for
>>> multithreading.  In the distant past it might also have worked as a
>>> feature selection macro, allowing library *users* to select
>>> thread-safe or lock-free stdio at application build time, I haven't
>>> done the archaeology.  Nowadays, defining _IO_MTSAFE_IO while using
>>> the installed headers, or in _ISOMAC mode, will cause libio.h to throw
>>> syntax errors.
>>
>> What prevent us to just get rid of _IO_MTSAFE_IO and just build/assume
>> stdio with multithread support?
> 
> I think that's a desirable goal, but I don't want to do that in this
> patchset because I suspect it will be messy *inside* libc.  And I'd
> start by getting it out of the public headers, anyway.

Why do you think so? The make fragment sysdeps/pthread/Makeconfig already
sets libc-reentrant regardless, so _IO_MTSAFE_IO is already being defined
in all objects that might use it (and I suspect it has been this way for
some time already).

> 
> (I'd like to stop installing libio.h at all, too, but that's probably
> going to be nastier:
> https://codesearch.debian.net/search?q=libio.h&perpkg=1)
> 

Agreed.