How do I ignore a system file picked up by `configure' generated from AC_CHECK_HEADERS

We using an automated build system which downloads and compiles source. The only interface I have to control the behaviour of the compilation is by setting ENV VARs and the arguments given to `./configure'.

The issue is that the 'configure' script (of the particular source I'm compiling) checks for a system header file, which if found, adversely affects the compilation process. (the compilation process will avoid compiling libraries which it believes are already installed on the local system when the above mentioned system header file is found.)

Since this is an automated process, I cannot modify the 'configure' script in anyway, and as mentioned can only specify the environment variables and arguments passed to `configure'. The configure script uses the AC_CHECK_HEADERS macro to generate the code to do the check for the system file. Is there anyway to avoid a check of a specific system file from the configure arguments?

The troublesome header file is in the path /usr/include/pcap/.

Thanks

Solution

Well there's a few things you could try:

remove foo.h from AC_CHECK_HEADERS and always build the library
use AC_CHECK_HEADER for foo.h and check for /usr/include/pcap/foo.h and don't AC_DEFINE(HAVE_FOO_H) if /usr/include/pcap/foo.h is there.
you could use AC_ARG_ENABLE or AC_ARG_WITH to turn off the offending test on a host-by-host basis via arguments to configure. So the answer to that question is yes.

All of these assume you can modify configure.ac and regenerate configure. If you can't do that you might have to modify configure (in an automated fashion, of course).