Weird error messages with duplicate AC_OUTPUT entries

[Ralf Corsepius]

Hi,

When a configure.ac contains duplicate entries in its AC_OUTPUT,
running autoconf-2.53c generates bizarre error messages:

# cat configure.ac
AC_PREREQ(2.53c)
AC_INIT([hello],[0.0])
AC_CONFIG_SRCDIR([hello.c])
AM_INIT_AUTOMAKE([foreign])
AC_PROG_CC
AC_PROG_RANLIB
AC_CONFIG_FILES([Makefile Makefile])
AC_OUTPUT

# aclocal
# autoconf
configure.ac:7: error: `Makefile' is already registered with
AC_CONFIG_FILES.
/usr/src/packages/BUILD/autoconf-2.53c/lib/autoconf/status.m4:844:
AC_CONFIG_FILES is expanded from...
configure.ac:7: the top level
autom4te: /usr/bin/m4 failed with exit status: 1

Also note: This also exposes a path from autoconf's the directory where
autoconf had been build. This directory is completely meaningless (and
not available) to users if using a installed copy of autoconf.

Ralf