Re: Failure building collectd when autoconf has been updated to 2.72

[Michael Tremer <michael.tremer@ipfire.org>]

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Hello Adolf,

In the build script we are running autoreconf which will regenerate the configure script:

  https://git.ipfire.org/?p=ipfire-2.x.git;a=blob;f=lfs/collectd;h=d1d4ea721386803c31599315de956373417c2dcf;hb=HEAD#l119

Is there any output of that command? There should be some warnings which might help us to find out what we need to change.

> On 13 Nov 2024, at 10:30, Adolf Belka <adolf.belka(a)ipfire.org> wrote:
> 
> Hi All,
> 
> I did an update run with autoconf taking it from 2.71 to 2.72
> 
> autoconf built without any problems, however collectd then failed for a syntax error in the configure file.
> 
> Confirmed that this was due to autoconf by changing the versions back and forward and the problem went away and then came back again.
> 
> The collectd build error message is
> 
> checking for size_t... yes
> checking for uid_t... yes
> checking for gid_t... yes
> ./configure: line 18710: syntax error near unexpected token `newline'
> ./configure: line 18710: `yes:'
> make: *** [collectd:120: /usr/src/log/collectd-4.10.9] Error 2
> 
> The section around line 18710 in the configure file is
> 
> 18707    do :
> 18708       as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
> 18709    ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
> 18710    if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :

There is an extra : here which is probably what causes the syntax error.

> 18711      cat >>confdefs.h <<_ACEOF
> 18712    #define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
> 18713    _ACEOF
> 18714
> 18715    else
> 18716      with_libiptc="no (header file missing)"
> 18717    fi
> 
> However there are 15 occurrences of the exact same text as line 18710 in the configure file so I am not convinced if that line is the root cause for the syntax error but some other earlier error that causes a knock-on effect.
> 
> However, my knowledge of the coding syntax is definitely not enough to figure out what needs to be fixed/changed.
> 
> As collectd is a very old version it is likely that some structural coding or syntax was fine in the past but now with the change from autoconf-2.71 to 2.72 it is no longer allowed, or is flagged up when in the past it was just ignored.
> 
> There are quite a few changes in autoconf-2.72 with some being marked as backwards compatibilities. All of them except one say that existing configure scripts will continue working. The one that doesn't mention that is the following change:-
> 
>   Configure scripts no longer support pre-1989 C compilers.
>   Specifically, compilers that *only* implement the original “K&R”
>   function definition syntax, and not the newer “prototyped” syntax,
>   will not be able to parse the test programs now emitted by
>   AC_CHECK_FUNC, AC_LANG_CALL, and similar macros.  AC_PROG_CC still
>   accepts such compilers, but this may change in the near future.
> 
>   This change was necessary in order to support the upcoming 2024
>   edition of the C standard (often referred to as “C23”), which will
>   officially remove the function declaration syntax used by
>   AC_CHECK_FUNC in Autoconf 2.71 and earlier.  We feel that support
>   for compilers that support only C 2024 is more useful, nowadays,
>   than support for compilers that don’t implement a core feature of
>   C 1989.
> 
> However I am unable to figure out from this if the problem I am experiencing is related to this or not. I would not have thought so as I don't believe we are using a pre-1989 C compiler.
> 
> Any ideas from anyone on how to fix this issue?
> 
> There is nothing critical from a security or other vulnerability aspect in autoconf-2.72 but it would be nice to figure this out before we get to a stage where it has to be made to work.
> 
> 
> Regards,
> 
> Adolf.
>