lkml.org 
[lkml]   [2019]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2 4/6] compiler-gcc.h: add asm_inline definition
On Thu, Sep 5, 2019 at 3:45 PM Segher Boessenkool
<segher@kernel.crashing.org> wrote:
>
> [ That's not what a feature test macro is; a feature test macro allows the
> user to select some optional behaviour. Things like _GNU_SOURCE. ]

Yes and no. GNU libc defines feature test macros like you say, but
C++'s feature macros are like Rasmus/Nick are saying. I think libc's
definition is weird, I would call those "feature selection macros"
instead, because the user is selecting between some features (whether
to enable or not, for instance), rather than testing for the features.

> Why would GCC want to have macros for all features it has? That would be
> quite a few new ones every release.

Maybe GCC wouldn't, but its users, they surely would. For anything
that 1) is a new language feature, 2) breaks backwards-compatibility
with previous (or other compilers) and 3) is expected to be used by
end users, yes, it would be very useful to have.

For the same reasons C++ is adding feature test macros all over the
place nowadays and it is considered good practice (see SD-6: SG10
Feature Test Recommendations).

Cheers,
Miguel

\
 
 \ /
  Last update: 2019-09-05 17:53    [W:0.114 / U:0.368 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site