From: Bruno Haible <bruno@clisp.org>
To: Zack Weinberg <zack@owlfolio.org>, Michael Matz <matz@suse.de>,
Paul Eggert <eggert@cs.ucla.edu>
Cc: Jonathan Wakely <jwakely.gcc@gmail.com>,
Aaron Ballman <aaron@aaronballman.com>,
c-std-porting@lists.linux.dev,
Autoconf Development <autoconf@gnu.org>,
gcc@gcc.gnu.org, cfe-commits@lists.llvm.org, bug-gnulib@gnu.org
Subject: Re: How can Autoconf help with the transition to stricter compilation defaults?
Date: Thu, 17 Nov 2022 22:35:44 +0100 [thread overview]
Message-ID: <2685416.gqKg17ZAdu@nimes> (raw)
In-Reply-To: <8101f5cb-082b-8c25-bdf0-7d1cd2531388@cs.ucla.edu>
Paul Eggert wrote:
> > AC_CHECK_FUNC *should not* just probe for linkability of a symbol
>
> ... Autoconf cannot
> be expected to know every signature of every function in every library.
Clang will surely not acquire knowledge about "every library", right,
only about the C library according to relevant standards (ISO C, POSIX)?
> ... In the meantime if
> Clang becomes pickier by default it would be helpful if there were a
> well-defined way to shut off Clang's pickiness.
To me it seems the problem is not Clang's pickiness, but rather the
assumptions that it makes about the target environment. There is a
documented way to ask Clang and GCC "assume a free-standing implementation,
not an environment that has the ISO C / POSIX / LSB / ... functions":
1) -ffreestanding [1][2]
2) -fno-builtin
Can we assume that these options will continue to work?
If so, all Autoconf needs to do is to pass these options to the compiler
in AC_CHECK_FUNC checks. Then we don't need to add knowledge about each
of the hundreds of standard libc functions into Autoconf.
Bruno
[1] https://clang.llvm.org/docs/ClangCommandLineReference.html
[2] https://gcc.gnu.org/onlinedocs/gcc-12.2.0/gcc/C-Dialect-Options.html
next prev parent reply other threads:[~2022-11-17 21:35 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-10 17:16 Zack Weinberg
2022-11-10 17:52 ` Nick Bowler
2022-11-10 17:58 ` Jonathan Wakely
2022-11-10 18:12 ` Jonathan Wakely
2022-11-10 18:44 ` Aaron Ballman
2022-11-12 2:56 ` Zack Weinberg
2022-11-10 18:05 ` Rich Felker
2022-11-10 21:44 ` Florian Weimer
2022-11-12 3:22 ` Zack Weinberg
2022-11-10 18:08 ` Florian Weimer
2022-11-12 3:40 ` Zack Weinberg
2022-11-12 3:43 ` Sam James
2022-11-12 14:27 ` Zack Weinberg
2022-11-12 3:45 ` Joseph Myers
2022-11-12 15:59 ` Wookey
2022-11-12 16:12 ` Zack Weinberg
2022-11-10 18:19 ` Aaron Ballman
2022-11-10 21:05 ` Paul Eggert
2022-11-11 15:11 ` Aaron Ballman
2022-11-13 0:43 ` Paul Eggert
2022-11-14 12:41 ` Aaron Ballman
2022-11-14 18:14 ` Paul Eggert
2022-11-14 18:30 ` Florian Weimer
2022-11-14 18:35 ` Aaron Ballman
2022-11-15 14:50 ` Jonathan Wakely
2022-11-15 19:08 ` Paul Eggert
2022-11-15 19:27 ` Jonathan Wakely
2022-11-15 20:27 ` Paul Eggert
2022-11-15 20:57 ` Aaron Ballman
2022-11-15 23:09 ` Paul Eggert
2022-11-15 23:43 ` Ben Boeckel
2022-11-16 14:26 ` Michael Matz
2022-11-16 14:40 ` Alexander Monakov
2022-11-16 15:01 ` Michael Matz
2022-11-16 15:27 ` Richard Biener
2022-11-16 15:35 ` Sam James
2022-11-16 15:59 ` Michael Matz
2022-11-16 16:20 ` Jonathan Wakely
2022-11-16 16:34 ` Michael Matz
2022-11-16 16:46 ` Jonathan Wakely
2022-11-16 18:17 ` Paul Eggert
2022-11-16 18:40 ` Jeffrey Walton
2022-11-17 18:45 ` Paul Eggert
2022-11-16 18:59 ` Zack Weinberg
2022-11-17 18:58 ` Paul Eggert
2022-11-17 21:35 ` Bruno Haible [this message]
2022-11-17 22:27 ` Paul Eggert
2022-11-17 13:30 ` Michael Matz
2022-11-15 20:36 ` Aaron Ballman
2022-11-15 5:03 ` Sam James
2022-11-15 13:30 ` Zack Weinberg
2022-11-15 13:34 ` Sam James
2022-11-16 0:08 ` Bob Friesenhahn
2022-11-13 0:43 ` Paul Eggert
2022-11-17 13:57 ` Jason Merrill
2022-11-10 20:19 ` Paul Eggert
[not found] ` <d785b19371e8419f5a5817d7cdb429db91614a3a.camel@orlitzky.com>
2022-11-11 3:08 ` Sam James
2022-11-11 3:33 ` Zack Weinberg
2022-11-11 8:40 ` Sam James
2022-11-11 9:02 ` Paul Eggert
2022-11-12 14:09 ` Zack Weinberg
2022-11-11 23:25 ` Sam James
2022-11-12 0:53 ` Paul Eggert
2022-11-12 4:00 ` Sam James
2022-11-11 9:15 ` Sam James
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