GNU bug report logs - #74387
Cannot use ifdef and other Make conditionals

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: bug-automake <at> gnu.org
Subject: Cannot nest Make conditionals inside Automake conditionals
Date: Sun, 17 Nov 2024 13:07:52 +0900

[Message part 1 (text/plain, inline)]

Hello,

Consider the following:

--8<---------------cut here---------------start------------->8---
$ guix shell --pure automake autoconf coreutils grep \
  --with-latest=automake --with-latest=autoconf --without-tests=automake

[...]

[env]$ autoconf --version
autoconf (GNU Autoconf) 2.72
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+/Autoconf: GNU GPL version 3 or later
<https://gnu.org/licenses/gpl.html>, <https://gnu.org/licenses/exceptions.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by David J. MacKenzie and Akim Demaille.

[env]$ automake --version
automake (GNU automake) 1.17
Features: subsecond-mtime

Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv2+: GNU GPL version 2 or later
  <https://gnu.org/licenses/gpl-2.0.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Tom Tromey <tromey <at> redhat.com>
       and Alexandre Duret-Lutz <adl <at> gnu.org>.

[env]$ cat configure.ac
AC_INIT([if-without-endif-bug], [0.0.0])

AM_INIT_AUTOMAKE([foreign])

AM_CONDITIONAL([CAN_RUN_TESTS], [true])

AC_CONFIG_FILES([Makefile])

AC_OUTPUT

[env]$ cat Makefile.am
if CAN_RUN_TESTS

SH_TESTS = dummy/test1.sh dummy/test2.sh
SH_TESTS_SLOW = dummy/slow-test.sh

TESTS = $(SH_TESTS)

# By default, filter out slow tests.  The slow tests can be requested
# by setting the WITH_SLOW_TESTS Make variable.
ifdef WITH_SLOW_TESTS
TESTS += $(SH_TESTS_SLOW)
else
$(info Skipping slow tests; set WITH_SLOW_TESTS=1 to run them)
endif

endif

$ autoreconf -vif
autoreconf: export WARNINGS=
autoreconf: Entering directory '.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal --force 
autoreconf: configure.ac: tracing
autoreconf: configure.ac: not using Libtool
autoreconf: configure.ac: not using Intltool
autoreconf: configure.ac: not using Gtkdoc
autoreconf: running: /gnu/store/6vdjwn5yjnwir2279h0mfc5ws9wnz8d7-autoconf-2.72/bin/autoconf --force
autoreconf: configure.ac: not using Autoheader
autoreconf: running: automake --add-missing --copy --force-missing
Makefile.am:16: error: endif without if
autoreconf: error: automake failed with exit status: 1
--8<---------------cut here---------------end--------------->8---

In other words, Automake doesn't handle nesting pure Make conditionals
(ifeq, ifneq, ifdef, offended) inside an Automake conditional block (if).

My attaching the configure.ac and Makefile.am files for convenience.

[configure.ac (application/octet-stream, attachment)]

[Makefile.am (application/octet-stream, attachment)]

[Message part 4 (text/plain, inline)]

Thanks for maintaining Automake!

-- 
Maxim

Message #10 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals (was: Cannot nest Make
 conditionals inside Automake conditionals)
Date: Sun, 17 Nov 2024 13:56:34 +0900

Hi,

The problem appears simpler than I first thought; it seems Automake is
hard-coded to expect 'endif' to be matched with its own 'if'; causing parsing
errors when attempting to use Make's conditional such as ifdef, ifeq,
etc. that also end with 'endif'.

This was reported 23 years ago here: https://lists.gnu.org/archive/html/bug-automake/2001-11/msg00015.html

There is workaround proposed that makes use of an output variable to hide the
'endif' behind it:

--8<---------------cut here---------------start------------->8---
ENDIF=endif
AC_SUBST(ENDIF)

and to apply this in Makefile.am:
ifdef f
        ..
@ENDIF@
--8<---------------cut here---------------end--------------->8---

I've tested the above and it appear to work, but perhaps Automake could
accommodate Make snippets better?

-- 
Thanks,
Maxim

Message #13 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: Karl Berry <karl <at> freefriends.org>
To: maxim.cournoyer <at> gmail.com
Cc: 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals (was: Cannot nest Make
 conditionals inside Automake conditionals)
Date: Sun, 17 Nov 2024 15:35:08 -0700

Hi Maxim - thanks for the report and doing the research to find that old
answer. Do you have any ideas for a better solution? I can't think of
one. We can't change Automake syntax now. Nor does it seem maintainble
for automake to have special knowledge of all of make's builtin
conditionals and match them too.

I'll see about adding something to the manual about the workaround,
at least. --thanks, karl.

Message #16 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Karl Berry <karl <at> freefriends.org>
Cc: 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals
Date: Tue, 19 Nov 2024 22:33:50 +0900

Hi Karl,

Karl Berry <karl <at> freefriends.org> writes:

> Hi Maxim - thanks for the report and doing the research to find that old
> answer. Do you have any ideas for a better solution? I can't think of
> one. We can't change Automake syntax now. Nor does it seem maintainble
> for automake to have special knowledge of all of make's builtin
> conditionals and match them too.
>
> I'll see about adding something to the manual about the workaround,
> at least. --thanks, karl.

The workaround got rid of the Automake syntax checks, but I faced more
problems passed that.  It was very confusing; the Make conditionals
would not work as I expected.  I could give it another look to see if I
can distill some interesting points from that experiment; I still have
my minimal example around.

-- 
Thanks,
Maxim

Message #19 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: Karl Berry <karl <at> freefriends.org>
To: maxim.cournoyer <at> gmail.com
Cc: 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals
Date: Tue, 19 Nov 2024 14:28:35 -0700

Hi Maxim,

    the Make conditionals would not work as I expected.  

Since Automake rearranges things quite a lot when generating the
Makefile from Makefile.am, I'm not too surprised there can be problems.

    I could give it another look to see if I
    can distill some interesting points from that experiment

If you have time, it couldn't hurt, though I fear there is no real
solution :(. (At least without automake recognizing every make
conditional, which isn't anything I'll be implementing). --thanks, karl.

Message #22 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: "Zack Weinberg" <zack <at> owlfolio.org>
To: maxim.cournoyer <at> gmail.com
Cc: 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals
Date: Tue, 19 Nov 2024 18:45:51 -0500

Automake conditionals were originally created because make conditionals aren't portable. In principle, if you are willing to require GNU make (or any other specific Make that has conditionals) you shouldn't *need* Automake conditionals.

Of course, things may not be that simple anymore. Can you please give some examples of the things you are trying to do, that seem to require use of both kinds of conditionals?

zw

Message #25 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: "Zack Weinberg" <zack <at> owlfolio.org>
Cc: 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals
Date: Sun, 24 Nov 2024 22:40:52 +0900

Hi Zack,

"Zack Weinberg" <zack <at> owlfolio.org> writes:

> Automake conditionals were originally created because make
> conditionals aren't portable. In principle, if you are willing to
> require GNU make (or any other specific Make that has conditionals)
> you shouldn't *need* Automake conditionals.
>
> Of course, things may not be that simple anymore. Can you please give some examples of the things you are trying to do, that seem to require use of both kinds of conditionals?

I was trying to come up with an environment variable to control whether
expensive tests of the test suite should be run or not,
e.g. depending on WITH_SLOW_TESTS=1 or WITH_SLOW_TESTS=0.

I didn't want to use an Autoclave conditional, as these are baked in the
build system following 'configure', i.e., not dynamic enough (I want the
ability to switch this on or off anytime I run the tests -- not just at
configure time).

This is where I thought of employing Make's native conditionals, which
would have enabled checking the value of the WITH_SLOW_TESTS environment
variable every time Make is run.

In the end, I've worked around the issue by moving the skip check/logic
in each test that I wanted to skip.  That's a bit ugly as when running
the test individually you need to remember to set WITH_SLOW_TESTS=1 to
really have it run, but it's the best I've found thus far.

For the full context of what I was working on, see the patches submit
for consideration to GNU Guix [0].

[0]  https://issues.guix.gnu.org/74394

I guess this can be closed, though I'd still be interested if there are
better ways to accomplish skipping some tests than what I've ended up
using, as that seems like some shortcoming that build system tinkerers
having gotten used to the likes of Meson, where you can script pretty
much anything, would not easily accept.

-- 
Thanks,
Maxim

Message #28 received at 74387 <at> debbugs.gnu.org (full text, mbox):

From: Karl Berry <karl <at> freefriends.org>
To: maxim.cournoyer <at> gmail.com, 74387 <at> debbugs.gnu.org
Subject: Re: bug#74387: Cannot use Make conditionals
Date: Sun, 23 Feb 2025 14:34:43 -0700

Hi Maxim - I think so much depends on the details of a given project
that I lack ideas for something to do in general.

One possibility that occurs to me in your case is to turn your automake
conditional into a make conditional, instead of mixing them.

Another possibility might be to move the make-specific stuff out of the
automake conditional and simplify away the +=, as in something like:

ifdef WITH_SLOW_TESTS
SLOW_TESTS = $(SH_TESTS_SLOW)
else
SLOW_TESTS = 
endif # WITH_SLOW_TESTS

if CAN_RUN_TESTS
..
TESTS = $(SH_TESTS) $(SLOW_TESTS)
endif CAN_RUN_TESTS

No real idea if it will avoid the other problems you had.

I guess I'm going to close this for lack of any way forward, but feel
free to reply/reopen or open a new issue if desired. --thanks, karl.

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