configure.in: Look for flex

configure.in: Look for flex

[Ludovic Courtès]

Hi,

The following change updates `README' and `configure.in' so that they
mention flex.

Thanks,
Ludovic.


2005-06-16  Ludovic Courtès  <ludovic.courtes@laas.fr>

	* configure.in:  Look for `flex'.

	* README:  Mention flex as a requirement.


Index: README
===================================================================
RCS file: /cvsroot/guile/guile/guile-core/README,v
retrieving revision 1.98
diff -u -B -b -r1.98 README
--- README	8 Mar 2005 00:54:46 -0000	1.98
+++ README	15 Jun 2005 11:40:03 -0000
@@ -61,6 +61,8 @@
     libltdl is used for loading extensions at run-time.  It is
     available from http://www.gnu.org/software/libtool/
 
+  - flex, a fast lexical analyzer generator, available from
+    http://www.gnu.org/software/flex/
 
 Special Instructions For Some Systems =====================================
 
Index: configure.in
===================================================================
RCS file: /cvsroot/guile/guile/guile-core/configure.in,v
retrieving revision 1.267
diff -u -B -b -r1.267 configure.in
--- configure.in	5 Jun 2005 18:15:21 -0000	1.267
+++ configure.in	15 Jun 2005 11:40:03 -0000
@@ -77,6 +77,11 @@
 AC_CHECK_PROG(have_makeinfo, makeinfo, yes, no)
 AM_CONDITIONAL(HAVE_MAKEINFO, test "$have_makeinfo" = yes)
 
+AC_CHECK_PROG([have_flex], [flex], [yes], [no])
+if test "x$have_flex" = "xno"; then
+  AC_MSG_ERROR([flex not found.  See README.])
+fi
+
 AM_PATH_LISPDIR
 


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Re: configure.in: Look for flex

[Kevin Ryde]

ludovic.courtes@laas.fr (Ludovic Courtès) writes:
>
> +  AC_MSG_ERROR([flex not found.  See README.])

No, this shouldn't be an error.  The dist includes the generated C
code so you don't need lex in a normal build.

(You need lex if you change the ".l", and in a maintainer build maybe,
so a configure check is good, but it shouldn't be an error.)


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Re: configure.in: Look for flex

[Rob Browning]

Kevin Ryde <user42@zip.com.au> writes:

> (You need lex if you change the ".l", and in a maintainer build maybe,
> so a configure check is good, but it shouldn't be an error.)

Or, we might just add a test with a suitable error message to the make
rule that uses flex...

        flex --version || ...

But I'd guess that the normal

  -bash: flex: command not found

might be informative enough.

What would the configure check actually get us?

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Re: configure.in: Look for flex

[Kevin Ryde]

Rob Browning <rlb@defaultvalue.org> writes:
>
>         flex --version || ...

Or the "missing" script, maybe, if autoconf/automake doesn't already
set that up.

> What would the configure check actually get us?

Only allowing the system lex instead of insisting on flex, I think.
(Which may or may not actually be a good thing :-).


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Re: configure.in: Look for flex

[Ludovic Courtès]

Hi,

Kevin Ryde <user42@zip.com.au> writes:

> No, this shouldn't be an error.  The dist includes the generated C
> code so you don't need lex in a normal build.
>
> (You need lex if you change the ".l", and in a maintainer build maybe,
> so a configure check is good, but it shouldn't be an error.)

Since flex is needed when building from CVS and not needed when building
from a distribution, what about something like the following:

  if test "x$USE_MAINTAINER_MODE" = "xyes"; then
    AC_MSG_ERROR([flex not found.  See README.])
  else
    AC_MSG_WARN([flex not found but only needed when building from CVS.])
  fi

Then this means that the error message would only be triggered for
people who passed the `--enable-maintainer-mode' option to `configure'
(which /should/ be the case for people building from CVS, but I'm not
sure this is actually the case since I didn't even use it myself ;-)).

BTW, why is the flex-generated file included in the distribution?

Thanks,
Ludovic.


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Re: configure.in: Look for flex

[Kevin Ryde]

ludovic.courtes@laas.fr (Ludovic Courtès) writes:
>
> Since flex is needed when building from CVS and not needed when building
> from a distribution, what about something like the following:

I think AM_PROG_LEX probably does everything you need, with no
explicit warning code needed.  It looks like it sets up the "missing"
script to give a warning in those cases where lex is wanted.

> Then this means that the error message would only be triggered for
> people who passed the `--enable-maintainer-mode' option to `configure'
> (which /should/ be the case for people building from CVS, but I'm not
> sure this is actually the case since I didn't even use it myself ;-)).

If the generated file is checked into the cvs and the dates are right
then you won't need flex for a maintainer build, unless you actually
change the source.

(Maintainer-mode is mostly about regenerating configure, Makefile.in,
etc when the inputs change.)

> BTW, why is the flex-generated file included in the distribution?

Reducing dependencies (see "Releases" in the gnu standards manual),
apparently.  


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Re: configure.in: Look for flex

[Ludovic Courtès]

Kevin Ryde <user42@zip.com.au> writes:

> If the generated file is checked into the cvs and the dates are right
> then you won't need flex for a maintainer build, unless you actually
> change the source.

Actually I needed it, hence this thread.  ;-)

`AM_PROG_FLEX' is probably the right thing, yes.

Thanks,
Ludovic.


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Re: configure.in: Look for flex

[Marius Vollmer]

ludovic.courtes@laas.fr (Ludovic Courtès) writes:

> Kevin Ryde <user42@zip.com.au> writes:
>
>> If the generated file is checked into the cvs and the dates are right
>> then you won't need flex for a maintainer build, unless you actually
>> change the source.
>
> Actually I needed it, hence this thread.  ;-)
>
> `AM_PROG_FLEX' is probably the right thing, yes.

There is only AM_PROG_LEX... also, just putting it in configure.in
will of course not help much, we would also have to change the
Makefile.  I don't think this is worth the trouble... just put flex in
your path and you are done... :-)

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