how to ship spidermonkey in your autotools project

While working on freej we'd need to update spidermonkey/mozjs to the latest version and while doing that integrate it better with the rest of autoconf/automake. AFAICT spidermonkey/mozjs is distributed as part of XULRunner nowadays.

The requirements are to make it easy to put a new version of spidermonkey into the tree and redistribute it with make dist and also to have a successful make distcheck.

The first step is a trick explained in automake manual about third-party Makefiles so we're using a GNUMakefile.in (git) to "proxy" the targets down to the real Makefile or to ignore some targets called by autotools, e.g:

# otherwise linking static libmozjs.a with dynamic libfreej.so won't work
CFLAGS += -fPIC

# the makefile to proxy targets to
js_makefile = $(builddir)/Makefile

# proxy these targets to the real makefile
all export js-config clean libs tools:
  $(MAKE) -f $(js_makefile) $(AM_MAKEFLAGS) $@

# targets required by autotools but which we don't need at all
.PHONY: dvi pdf ps info html installcheck check install uninstall
dvi pdf ps info html installcheck check install uninstall:

This more or less fixes the make part, now for the autoconf part there's a similar tecnique in the autoconf manual involving running arbitrary configuration commands. I first tried to treat spidermonkey as a separate project via AC_CONFIG_SUBDIRS as expained in Configuring Other Packages in Subdirectories but it didn't work and I forgot exactly why.

The configure.ac (git) snippet is something like this: (sorry no highlighting, highlight doesn't support m4 yet)

if test x$have_mozjs = xno || test x$static_mozjs = xyes; then
  dnl run lib/javascript/configure after freej's configure, building it static
  AC_CONFIG_COMMANDS([lib/javascript/.xulrunner-subdir],
    (cd lib/javascript &&
      CXXFLAGS="$GLOBAL_CFLAGS $CXXFLAGS -fPIC" \
      CFLAGS="$GLOBAL_CFLAGS $CFLAGS -fPIC" \
      $ac_srcdir/configure --enable-static \
        --enable-js-static-build --disable-jit) || exit $?
  ])
fi

This will run spidermonkey configure after the main configure, at this point config.status will also expand GNUmakefile.in into GNUmakefile with the correct variables. The final step after all this work is of course to add the spidermonkey directory to SUBDIRS (e.g. SUBDIRS += lib/javascript), after that make will hopefully recurse into lib/javascript and use our GNUmakefile.

While this is nice it doesn't cater for the make dist family of autotools targets which build the real distribution tarball.

To accomplish this I've used an explicit list of spidermonkey files that will end up in the tarball and made make distdir to copy only those files plus GNUmakefile.in and the list itself (.js-distfiles). Which is the second part of the GNUmakefile.in above, i.e. distdir/distfiles targets plus distclean to clean them up, see comments in the file as well.

I hope this is somewhat useful to people who are trying to properly (autotools-wise) ship spidermonkey in their project, comments welcome as usual

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