Makefile variables depending on configure args - how?

[Markus Werle]

Sorry folks,

this question seemed so simple, but obviously thinking "auto"
differs a lot from what I was used to. Shame on me, but the docs
did not reveal an answer.

Consider my configure.in contains
----------------------------------
# diet headers?
AC_MSG_CHECKING([path to diet headers (http://diet.sf.net/)])
AC_ARG_WITH(diet,
    AC_HELP_STRING([--with-diet=DIET_PREFIX],
            [place where diet headers reside]),
    [ DIETDIR="$withval"; echo $withval; ],
    AC_MSG_ERROR([Please rerun using flag --with-diet=DIET_PREFIX ]) )

CPPFLAGS="-I$DIETDIR $CPPFLAGS"
--------------------------------------


Now in my Makefile.am I want to do 2 things:

First of all I want to add $DIET to VPATH
Second: I want to use $DIET e.g in other definitions:

test_linalg_SOURCES = $(DIET)/demos/linalg/TestLinalg.C

But somehow variable DIET is not propagated from configure.in
to Makefile.am. Is there a workaround for this?

Any solutions welcome,

best regards,

Markus