Re: RFE: configure -> dependency list on exit.

[Dan Manthey]

On Thu, 24 Feb 2005, Paul Eggert wrote:

> Dan Manthey <address@hidden> writes:
>
> > AS_PACKAGE_SUGGEST([flex 2.5.x],[http://gnu.org/whereever_flex_is.html])
>
> OK, but what is the practical difference between that, and something
> like this?
>
> AC_MSG_FAILURE([you need a suitable implementation of "lex" to build
>   this package.  We suggest the latest stable version of flex
>   <http://www.gnu.org/software/flex/>.])

        I was thinking of AS_PACKAGE_SUGGEST (which I'm sure is a bad
name) as simply a formatting macro.  It might be reasonable to have it as
a macro rather than simple next because it might allow collecting all such
messages into a single place (like the putative DEPENDENCIES file
discussed).


> my_warning='you lack a suitable implementation of "lex", so you won't
>    be able to build this program reliably if you modify .l files.'
>
> and then append something like this to your configure.ac file:
>
> case $my_warning in
> ?*) AC_MSG_WARN("$my_warning");;
> esac

        I figured this would basically be what AC_MSG_END would do, except
possibly push it off to a file rather than a variable, in case the
contents were large (which seems more likely if the errors include long
explanations of what kind of package is needed and where to find it).


> An advantage of this sort of approach is that one can experiment with
> these ideas now, to accomplish something in this area.  That is, one
> can implement them with one's own macros; they don't require any
> changes to Autoconf.  Later, if the ideas work well in practice, we
> can think about how to add Autoconf macros for them (perhaps simply by
> incorporating the experimental macros).

        Indeed, though it is worth noting that sensible use of these ideas
may be dependent on conditional tests, which I don't think Stepan's
AC_DEFUN'ing AC_IF quite solves (as helpful as it is as an interim
solution).  It looks like Hugh would _strongly_ desire an actual macro
AC_MSG_END (even if it's as simple as Paul's code above) for the simple
fact that it would encourage use of such messages.

-Dan