Use of uninitialized value $line in pattern match (m//) at /usr/bin/automake line 4077

[Jeremy Sequoia]

automake fails to build the Makefiles for libXfont from git. See:
http://tinderbox.x.org/builds/2011-03-24-0016/logs/libXfont/#build

This is with current (as of a few days ago) Ubuntu 11.04 including automake 1:1.11.1-1ubuntu1

To reproduce:
git clone git://anongit.freedesktop.org/xorg/lib/libXfont
cd libXfont
autoreconf -fvi

[Jeremy Sequoia (jeremyhu)]

Here's the context:

  if (-f 'aclocal.m4')
    {
      &define_variable ("ACLOCAL_M4", '$(top_srcdir)/aclocal.m4', INTERNAL);

      my $aclocal = new Automake::XFile "< aclocal.m4";
      my $line = $aclocal->getline;
      $regen_aclocal = $line =~ 'generated automatically by aclocal';
    }

[Jeremy Sequoia (jeremyhu)]

It seems that for some reason "aclocal.m4" was present but empty ... so this should just have better error detection for that case.