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Re: RFC: handling ISO C feature test macros
- From: Paul Eggert <eggert at cs dot ucla dot edu>
- To: Joseph Myers <joseph at codesourcery dot com>, libc-alpha at sourceware dot org
- Date: Fri, 20 May 2016 16:00:59 -0700
- Subject: Re: RFC: handling ISO C feature test macros
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 20 dot 1605202135440 dot 24104 at digraph dot polyomino dot org dot uk>
On 05/20/2016 03:00 PM, Joseph Myers wrote:
(_GNU_SOURCE should not cause __STDC_WANT_IEC_60559_BFP_EXT__ to be
defined because the user might define it with a different expansion.
Is this a pragmatic suggestion, or is this required by the standards?
Surely the former, as _GNU_SOURCE is reserved for any use, so a glibc
header can do whatever it wants if _GNU_SOURCE is defined. If
<features.h> #defines __STDC_WANT_IEC_60559_BFP_EXT__ when _GNU_SOURCE
is defined, the issignaling definitions could be conditioned simply on
If this idea won't fly for some reason, I mildly prefer your method (a)
to (b), as (a) is a bit easier for a casual reader to follow when
reading installed .h files.