[Freeciv-Dev] (PR#2873) 1.14.0 Xaw client crash

["Jason Short via RT" <rt@xxxxxxxxxxxxxx>]

[stepan@xxxxxxxx - Thu Jan 23 20:33:56 2003]:

> acconfig.h is parsed by autoconf while generating configure and its
> contents are added to config.h.in. This has been made deprecated in
> autoconf > 2.13.

Yes, I understand this.  The problem seems to be an autoconf bug (or
"feature"); see below.

> The sad thing is that autoheader is not able to analyze calls to
> FC_CHECK_X_LIB macro, which calls AC_DEFINE_UNQUOTED. This macro is the
> only place where AC_DEFINE_* is called on variable and not constant. The
> proper fix is to add constant AC_DEFINE to every call of FC_CHECK_X_LIB in
> configure.ac (I wonder it does not crash more often, maybe HAVE_LIBXAW3D
> is the only one really used, but it should be defined everywhere just to
> be future-compatible).

Yes.

Per suggested that the problem was that AC_DEFINE_UNQUOTED needs three
arguments.  This appears not to be the case: even with the additional
two arguments it doesn't work.

The offender is the following line in m4/x.252:

    AC_DEFINE_UNQUOTED($ac_tr_lib)

$ac_tr_lib gets values like HAVE_LIBX11, HAVE_LIBXEXT, HAVE_LIBXT,
HAVE_LIBXMU, HAVE_LIBXPM, HAVE_LIBXAW3D, and HAVE_LIBXAW.  None of these
ever get defined in config.h, although only the HAVE_LIBXAW3D one seems
fatal (note HAVE_LIBXPM is no longer used; this is a separate issue for
which I should provide a patch).

According to this page, AC_DEFINE_UNQUOTED should work with variables:

http://www.gnu.org/manual/autoconf-2.53/html_node/Defining-Symbols.html
http://www.gnu.org/manual/autoconf-2.57/html_chapter/autoconf_7.html#SEC82

and yet it does not, either with my version (2.57) or that which was
used to generate the distribution's configure script.  This page seems
to indicate three arguments may be needed:

http://www.gnu.org/manual/autoconf-2.57/html_chapter/autoconf_4.html#SEC29

although it is a bit unspecific about the variable usage.

> List of all #defines (or strictly speaking #undefs) which are in
> acconfig.h and are not generated by autoheader (entries not found in
> configure.ac or m4/* are marked as unused - they may however be used in
> source; also it looks like acconfig.h is used as template for vms and
> amiga configs (hand-made of course)):
> 
> HAVE_LIBICE (unused)
> HAVE_LIBSM (unused)
> HAVE_LIBX11
> HAVE_LIBXAW
> HAVE_LIBXAW3D
> HAVE_LIBXEXT
> HAVE_LIBXMU
> HAVE_LIBXPM
> HAVE_LIBXT
> HAVE_CATGETS (unused)
> STRICT_WINDOWS (unused)
> GENERATING_MAC (unused)
> HAVE_OPENTRANSPORT (unused)
> PATH_SEPARATOR (unused)
> OPTION_FILE_NAME (unused)
> 
> From the list above it is obvious that only calls to FC_CHECK_X_LIB should
> be altered and everything will work properly.
> 
> So I summarize my patch-vision:
> 
> - add AC_DEFINE() to all FC_CHECK_X_LIB calls in configure.ac (maybe also
> in configure.in?)
> - add notice to m4/x.252 (and possibly to x.213 also) that AC_DEFINE must
> be called explicitly or acconfig.h must be altered (for x.213 only)

This seems reasonable.  But it seems likely that AC_DEFINE_UNQUOTED
*should* work, and we are just using it improperly.

The real bug here would then be that autoconf doesn't give us a warning
that the symbols aren't defined in config.h.in.

jason