[PATCH 06/13] Installed header hygiene (BZ#20366): Macros used in #if without checking whether they are defined.

Carlos O'Donell carlos@redhat.com
Wed Sep 21 18:41:00 GMT 2016


On 09/21/2016 02:05 PM, Joseph Myers wrote:
> On Wed, 21 Sep 2016, Carlos O'Donell wrote:
> 
>> At a high level I would expect _LIBC to always be defined as either 0 or 1.
> 
> _LIBC is effectively with external code, because it's used (with #if) in 
> code shared by gnulib.  So we can't change its semantics like that; 
> defining to 0 with installed glibc would break building gnulib.
 
Isn't that just a normal coordination issue with gnulib?

Changes in GCC routinely break building glibc, either intentional or
uintentional.

In this case there would be a dependency between this glibc version
and the usable versions of gnulib which could be built with that glibc?

I agree that such gratuitous breakage for a weak reason like installed
header hygiene would be a bad idea.

However, I don't think we should avoid the change, but rather coordinate
with gnulib if we ever need it. 

-- 
Cheers,
Carlos.



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