Autoconf 2.57d instability

[Eric Sunshine]

Hello,

I have been testing Autoconf 2.57d with the configure.ac and aclocal.m4  
which I created for the Crystal Space project  
(http://crystal.sourceforge.net/), and I am experiencing some instability  
which had not occurred with previous Autoconf releases.  The Crystal Space  
configure.ac, which is fairly sizeable, compiles correctly on Linux, Windows  
(Msys), and NextStep using Autoconf 2.56 and 2.57, however the compilation  
fails with Autoconf 2.57d.  For convenience, I created a minimal package  
containing just configure.ac and aclocal.m4 in case someone is interested in  
helping to debug these problems.  The package is available here:

http://crystal.sourceforge.net/cs-conf-2.57d-broken.tar.bz2

On Linux, the compilation fails with the following error:

linux% autoconf
configure.ac:762: /usr//bin/m4: Warning: Excess arguments to built-in  
`m4_pushdef' ignored
autom4te: /usr//bin/m4 failed with exit status: 1

The line for which this error is issued is innocuous enough.  The reason for  
the failure is not obvious.  If I comment out this line, then the same error  
is issued again later in the file.  If I comment out that line, then it is  
issued for a different line; etc.

On NextStep, Autoconf 2.57d causes GNU m4 1.4 to crash.  This problem did  
not occur with earlier release Autoconf releases.  For example, using the  
same configure.ac and aclocal.m4:

nextstep% autoconf
sh: 5163 Memory fault
autom4te: /LocalLibrary/bin/gnum4 failed with exit status: 139

How can I go about debugging these problems?  What type of debugging  
facilities are available for resolving these sorts of problems, and where  
exactly should I be looking?

-- ES