Re: configure wrongly caches results

[Stepan Kasal]

Hi Pat,

On Mon, Sep 26, 2005 at 12:51:53AM +0200, Patrice Dumas wrote:
> So it seems that there is a kind of caching that cannot be disabled and
> that is preventing such tests to work.

Indeed, you can switch off the cache _file_, so that it is not read at
the beginning and written at the end, but you cannot switch off the
"internal" caching of autoconf.

> checking for netcdf.h... no
> checking for netcdf.h... (cached) no

... while you would expect:

checking for netcdf.h... no
checking for netcdf.h... yes

which really looks weird, so you added an echo to get:

checking for netcdf.h... no
checking for netcdf.h... found with libnc-dap
yes

Anyway, the internal cache is a limitation of current autoconf.

I think there is a very natural workaround/fix:

AC_CHECK_HEADERS([hdf2/netcdf.h])
AC_CHECK_HEADERS([libnc-dap/netcdf.h])

or, if there is possibility that netcdf.h includes other files from
the same directory:

CPPFLAGS_save=$CPPFLAGS
CPPFLAGS="$CPPFLAGS -I/usr/include/hdf2"
AC_CHECK_HEADERS([hdf2/netcdf.h])
CPPFLAGS="$CPPFLAGS_save"

CPPFLAGS_save=$CPPFLAGS
CPPFLAGS="$CPPFLAGS -I/usr/include/libnc-dap/"
AC_CHECK_HEADERS([libnc-dap/netcdf.h])
CPPFLAGS=$CPPFLAGS_save

BTW: The quotes in some of your assignments were redundant, so I removed
theme.  (Documented in the chapter on portable shell programming in the
Autoconf manual.)

Then you have defines HAVE_HDF2_NETCDF_H and HAVE_LIBNC_DAP_NETCDF_H.

Do you like it this way?

Stepan Kasal