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

[Hugh Sasse Staff Elec Eng]

On Fri, 4 Mar 2005, John W. Eaton wrote:

> On  4-Mar-2005, Stepan Kasal <address@hidden> wrote:
>
> | My idea was to have AC_MSG_NEED with args
> |    (@var{dependency-name}, @var{dependency-text}, @ovar{priority})
> | used like
> |
>
> I think I understand why you want these kinds of messages.  There have
        [correct reasons elided]
> Given that we now have nice packaging systems, messages like the one
> you propose above are not always the best advice.  On a modern
        [...]
> So perhaps it is best to just have the messages say something like
>
>  You need the lexical analyzer flex to rebuild lex.c from lex.l.
>  If your OS has a package system, you may be able to use that to
>  install a recent copy.

I think it's better to say it's a GNU program or whatever, so people
can find out which form (rpm, gentoo, ???,  package) which is probably
listed at the program's site somewhere.  But there still needs to be
some kind of message, whatever form it takes.
> I hesitate to add something like
>
>  If not, then you can find flex at ftp://ftp.gnu.org/gnu/flex.
>
> because the URL may change, and it means that either the person

In the case of The Free Software Foundation, not that often, but in
theory, yes.

> writing configure.in will need to know about all these things (even
> they may not have a clue where flex really comes from if they just get

They do have access to other people helping them with patches, 
and surely the authors of a given program should know which other
programs that depends on, because they write it with a certain
amount of portability in mind?

> it from their package system) or you have to embed this knowledge in
> autoconf, which seems bad and would only work for a few tools in

So where does it go, then?  People have said not to put it in a text
file, because that is hard to maintain and takes no account of the
dynmaic nature of configure.  You're saying it shouldn't go in
autoconf.  Nobody is saying that this macro has to be used for
every single dependency, but it makes expressing this information
easy where it is known.  Where it is not known then we are
suggesting AC_MSG_END or soemthing similar, to make some text appear
at the end, even if it's just "you ain't got no lex, Lieutenant Dan"
:-).

> autoconf which have specific macros (bison, flex/lex, ...).

It would also work for user defined tests as well, just that first
tag would have to be different.
> jwe