error: '' is already registered with AC_CONFIG_FILES

[Stephen Henry]

Hi,

We are using autoconf as part of our build system but have run into an error. 
When invoking autoconf, the following error is reported:

configure.in:295: error: '<filename>' is already registered with AC_CONFIG_FILES

where: <filename> is the name of a Makefile.am in our project.

The construct in which this error appears is:

AS_IF([test...],
[AC_CONFIG_FILES([
        ... list of Makefiles in various directories
        [AS_IF([test...],
                 [makefile1.am
                  makefile2.am
                  makefile3.am])]
        ])
])

I have verified that the list does not contain duplicate Makefile entries. The 
configuration script works fine when I remove the [AS_IF] statement, but not 
when it is included. I am fairly confident that the syntax used is correct and 
I have removed all trailing whitespace etc... Also, all of the Makefiles have 
been verified to be in UNIX format.

I am using autoconf 2.68 and m4 1.4.15.

Any help would be appreciated.

Kind regards,

Steve