Help2man and Parallel Make Race

[Neil T . Dantam]

Hi,

I'm using help2man to build manpages that I'd like to distribute with
the source tarball.  I followed the instructions/example in the
automake manual, which has manpage foo.1 depend on foo.c and
configure.ac, then does a recursive make to build foo$(EXEEXT):
<http://www.gnu.org/software/automake/manual/html_node/Errors-with-distclean.html>

This does solve the problem of unnecessarily rebuilding manpages when
the binary is rebuilt/relinked, but it also seems to introduce a race
condition during parallel makes.  The problem is that there are now
two ways to build foo$(EXEEXT): (1) the normal automake rule from
bin_PROGRAMS/foo_SOURCES and (2) the recursive make for the rule for
foo.1.

To give a more concrete example, here is a snippet from my
Makefile.am:
        #...
        bin_PROGRAMS = achd
        #...
        achd_SOURCES = src/achd.c src/achutil.c
        achd_LDADD = libach.la
        ach_LDADD = libach.la
        #...
        doc/achd.1: src/achd.c $(top_srcdir)/configure.ac
                $(MAKE) $(AM_MAKEFLAGS) achd$(EXEEXT)
                mkdir -p doc
                help2man -h -\? -v -V --no-info -n "send ach messages over 
streams" ./achd$(EXEEXT) -o $@

And then, when the race fails, I get the following output (pruned
slightly):

    % make -kj2               
     cd . && /bin/bash /home/ntd/git/thebrain.golems.org/lib/ach/missing --run 
automake-1.11 --gnu Makefile
     cd . && /bin/bash ./config.status Makefile depfiles
    config.status: creating Makefile
    config.status: executing depfiles commands
    make  all-am
    make[1]: Entering directory `/home/ntd/git/thebrain.golems.org/lib/ach'
    /usr/bin/gcc -DHAVE_CONFIG_H -I.  -I./include    -MT achd.o -MD -MP -MF 
.deps/achd.Tpo -c -o achd.o `test -f 'src/achd.c' || echo './'`src/achd.c
    make  achd
    make[2]: Entering directory `/home/ntd/git/thebrain.golems.org/lib/ach'
    /usr/bin/gcc -DHAVE_CONFIG_H -I.  -I./include    -MT achd.o -MD -MP -MF 
.deps/achd.Tpo -c -o achd.o `test -f 'src/achd.c' || echo './'`src/achd.c
    mv -f .deps/achd.Tpo .deps/achd.Po
    /bin/bash ./libtool --tag=CC   --mode=link /usr/bin/gcc     -o achd achd.o 
achutil.o libach.la -lrt -lpthread 
    mv -f .deps/achd.Tpo .deps/achd.Po
    mv: cannot stat `.deps/achd.Tpo': No such file or directory
    make[2]: *** [achd.o] Error 1
    make[2]: Target `achd' not remade because of errors.
    make[2]: Leaving directory `/home/ntd/git/thebrain.golems.org/lib/ach'
    make[1]: *** [doc/achd.1] Error 2
    libtool: link: /usr/bin/gcc  -o .libs/achd achd.o achutil.o  
./.libs/libach.so -lrt -lpthread
    make[1]: Target `all-am' not remade because of errors.
    make[1]: Leaving directory `/home/ntd/git/thebrain.golems.org/lib/ach'
    make: *** [all] Error 2
    
So, it looks like the second `mv -f .deps/achd.Tpo .deps/achd.Po' is
failing because the dependency file was already moved.  Is there
something silly that I've missed here?

It seems that possible resolutions are:
* Don't do parallel makes
* Don't distribute prebuilt manpages
* Build the manpages in a SUBDIR that gets built after .

Using SUBDIRs seems like the best of those options, though still not
ideal since make may often recurse unnecessarily.  Is there any way to
do this without more recursive makes?

Thanks,
-ntd