Failure building collectd when autoconf has been updated to 2.72

[Adolf Belka <adolf.belka@ipfire.org>]

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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 :
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.