Optional manuals? Or pre-compiled in distribution? - packaging

Question

I'm working on a personal project written in C++, and I'm using GNU Autotools as build system.
I would like to distribute my software together with manual pages, but I'm not very fond of Groff. For this reason I decided to write everything in Asciidoc and to compile it in Groff with a2x.
While I'm quite satisfied with the result, I noticed that installing Asciidoc might require a lot of disk space. For instance asciidoc-base in Debian Stretch requires 1928 MB of dependencies! (Edit: not even true. I forgot to disable suggested/recommended, but the use case is relevant anyway).
One solution would be to make it optional. To achieve this my configure.ac contains the following lines:
AC_CHECK_PROG([asciidoc], [a2x], [a2x], [false])
AM_CONDITIONAL([ASCIIDOC_AVAIL], [test x$asciidoc != xfalse])
…and the man/Makefile.am file is defined as follows:
if ASCIIDOC_AVAIL
man1_MANS = foo.1
man5_MANS = foo.conf.5
foo.1: foo.1.txt
$(asciidoc) --doctype manpage --format manpage ./$<
foo.conf.5: foo.conf.5.txt
$(asciidoc) --doctype manpage --format manpage ./$<
clean:
rm $(man1_MANS) $(man5_MANS)
endif
Even though this seems to work, I'm not very happy with it. I don't like the idea of not providing a manual.
Would it be advisable to pre-compile the man pages as part of the make dist step? In the same way as the distribution foo-x.y.z.tar.gz contains the configure script (which is not checked in the VCS but generated by autoreconf), I could make foo.1 and foo.conf.5 pre-compiled, and distributed with the source tarball.
Provided that this is acceptable from the "best practices" standpoint, how can I achieve it? I tried to declare them as EXTRA_DIST (EXTRA_DIST = man1_MANS man5_MANS) but I didn't have much luck.
Any idea?
EDIT: the Best way to add generated files to distribution? question seems to be related, even though I doubt there's a built in mechanism for my specific case.

Answer 1

even though I doubt there's a built in mechanism for my specific case.
Actually, there is such a mechanism described here, about halfway down that page. The dist_ prefix is what you are looking for:
dist_man1_MANS = foo.1
dist_man5_MANS = foo.conf.5
if ASCIIDOC_AVAIL
foo.1: foo.1.txt
$(asciidoc) --doctype manpage --format manpage ./$<
foo.conf.5: foo.conf.5.txt
$(asciidoc) --doctype manpage --format manpage ./$<
CLEANFILES += $(dist_man1_MANS) $(dist_man5_MANS)
endif

Answer 2

OP here.
Thanks to to ldav1s's answer, I came out with a good definition for my man/Makefile.am file. I put it here as an answer, but the whole credit goes to ldav1s.
Here it goes:
dist_man1_MANS = foo.1
dist_man5_MANS = foo.conf.5
EXTRA_DIST = foo.1.txt foo.conf.5.txt
if ASCIIDOC_AVAIL
foo.1: foo.1.txt
$(asciidoc) --doctype manpage --format manpage ./$<
foo.conf.5: foo.conf.5.txt
$(asciidoc) --doctype manpage --format manpage ./$<
endif
CLEANFILES = $(dist_man1_MANS) $(dist_man5_MANS)
Some useful information about it:
The manpages foo.1 and foo.conf.5 are generated during make dist thanks to the dist_ prefix (as pointed out by ldav1s). The two manpages are included in the distribution tarball.
By having the sources foo.1.txt and foo.conf.5.txt in the EXTRA_DIST I get those two files to be distributed as well. This is required, since the distribution tarball would include only the compiled manpages.
Declaring CLEANFILES will result in make clean to delete the compiled manpages.
Just to get the idea, with this configuration I can run make dist and obtain a tarball with the following proprieties:
The tarball will already contain the compiled manpages together with the asciidoc sources.
Running ./configure && make immediately after extracting the tarball won't compile the manpages, as they are already available.
Running ./configure && make clean immediately after extracting the tarball will remove the compiled manpages (even if they were included in the distribution tarball);
I tried to verify the behaviour of the build system when asciidoc is installed, and when it is not installed: I get exactly what I wanted in the first place.
If asciidoc is not installed (thus ./configure won't detect it), running ./configure && make clean && make won't recompile the manpages
If asciidoc is installed, running ./configure && make clean && make will recompile the manpages.