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Re: AC_PROG_CC fails when target C library is missing fopen
From: |
Ralf Wildenhues |
Subject: |
Re: AC_PROG_CC fails when target C library is missing fopen |
Date: |
Tue, 11 Aug 2009 00:11:41 +0200 |
User-agent: |
Mutt/1.5.20 (2009-06-15) |
Hello,
* Ralf Corsepius wrote on Thu, Aug 06, 2009 at 07:02:25AM CEST:
> On 08/05/2009 07:56 PM, Adam Sampson wrote:
> >What's going on? Well, the AC_PROG_CC test now tries to compile a little
> >program that uses fopen -- but the AVR-GCC toolchain uses avr-libc,
> >which doesn't provide fopen.
> We are facing a similar regression with autoconf-2.64 and rtems.
>
> The fopen check pulls in a chain of file-io related symbols, causing
> all AC_PROG_CC to fail, because rtems has them outside of libc.
>
> >Any suggestions? I suppose one option would be to try to persuade the
> >avr-libc maintainers to add a dummy fopen() implementation that always
> >returns NULL...
> That's what we (rtems) currently are doing.
>
> Unfortunately, this approach opens a can of worms, because when
> doing so, AC_CHECK_FUNC etc. will return bogus results (false
> positives) when checking for presence of fopen and other file-io
> related functions (e.g. while using autoconf to build the library
> providing fopen etc).
>
> IMO, it would be best to revert the change in autoconf.
I don't see in this discussion where the main argument to switch to
using fopen is addressed:
<http://thread.gmane.org/gmane.comp.sysutils.autoconf.patches/6656>
IOW, how do you prevent AC_COMPUTE_INT and friends from getting you
wrong answers on your system (if you happen to have a simulator around)?
I wouldn't want to revert the fopen change unless we also don't regress
on the other question?
I don't quite understand Paolo's suggested patch yet, but if you require
that cross compilation be enabled you need to pass both --host and
--build.
Thanks,
Ralf
- AC_PROG_CC fails when target C library is missing fopen, Adam Sampson, 2009/08/06
- Re: AC_PROG_CC fails when target C library is missing fopen, Ralf Corsepius, 2009/08/06
- Re: AC_PROG_CC fails when target C library is missing fopen, Paolo Bonzini, 2009/08/07
- Re: AC_PROG_CC fails when target C library is missing fopen, Adam Sampson, 2009/08/07
- Re: AC_PROG_CC fails when target C library is missing fopen, Paolo Bonzini, 2009/08/07
- Re: AC_PROG_CC fails when target C library is missing fopen, Paolo Bonzini, 2009/08/07
- Re: AC_PROG_CC fails when target C library is missing fopen, Adam Sampson, 2009/08/12
- Re: AC_PROG_CC fails when target C library is missing fopen, Ralf Wildenhues, 2009/08/13
- Re: AC_PROG_CC fails when target C library is missing fopen, Paolo Bonzini, 2009/08/13
Re: AC_PROG_CC fails when target C library is missing fopen,
Ralf Wildenhues <=
- Re: AC_PROG_CC fails when target C library is missing fopen, Paolo Bonzini, 2009/08/10
- Re: AC_PROG_CC fails when target C library is missing fopen, Eric Blake, 2009/08/12
- Re: AC_PROG_CC fails when target C library is missing fopen, Ralf Corsepius, 2009/08/12
- Re: AC_PROG_CC fails when target C library is missing fopen, Ralf Corsepius, 2009/08/19
- Re: AC_PROG_CC fails when target C library is missing fopen, Paolo Bonzini, 2009/08/19