Hello Markus, thanks for the reports. * Duft Markus wrote on Thu, Oct 16, 2008 at 03:46:51PM CEST: > > > > I just noticed, that when i enable a config.cache that is used by more > > than one package is problematic, when the first on checks for the build > > system type only, and the second for both build and host system type. > > This is, because the host system type check uses ac_cv_build_alias, > > which is set only if build system type (ac_cv_build) is not cached. > > > > Now the first package caches the build system type, but not the host > > system type, and the second package cannot configure, since the call to > > config.sub misses an argument (since ac_cv_build_alias is used, which > > is empty, since build system type was cached)... FWIW, I'm not yet sure whether this is a valid problem. Even if it is, you should be able to work around it by adding AC_CANONICAL_HOST to the toplevel configure.ac. But anyway, before discussing validity let's try to reproduce it: I haven't been able to do so yet. Here's what I tried. Please modify the example so that it shows the failure (maybe it only needs different flags passed to configure?) # in an otherwise empty directory: cat >configure.ac <<\EOF AC_INIT([build-alias-bug], [1]) AM_INIT_AUTOMAKE([foreign]) AC_CONFIG_SUBDIRS([sub1 sub2]) AC_CONFIG_FILES([Makefile]) AC_OUTPUT EOF echo "SUBDIRS = sub1 sub2" > Makefile.am mkdir sub1 sub2 cat > sub1/configure.ac <<\EOF AC_INIT([sub1], [1]) AM_INIT_AUTOMAKE([foreign]) AC_CANONICAL_BUILD AC_CONFIG_FILES([Makefile]) AC_OUTPUT EOF : >sub1/Makefile.am cat > sub2/configure.ac <<\EOF AC_INIT(sub2, 1) AM_INIT_AUTOMAKE([foreign]) AC_CANONICAL_HOST AC_CONFIG_FILES([Makefile]) AC_OUTPUT EOF : > sub2/Makefile.am autoreconf -vi ./configure --host=i386-pc-freebsd --build=x86-unknown-linux-gnu make distclean ./configure --host=i386-pc-freebsd make distclean ./configure --build=x86-unknown-linux-gnu # end of example > Another cache problem is with updating the cache file. This seems rather > unsafe for parallel builds using the same cache file. What about not > using cat for updating, but writing into a separate file, and moving it > over the original file (and not checking the mv return code). This way > the worst that can happen, is that cache values are lost if two > configure scripts try to update simultaneously - which shouldn't be too > critical, since they are simply checked again the next time.... I recently posted a patch to do just this. It wasn't applied, one reason being that we didn't see a way how two configure scripts could be running simultaneously; with AC_CONFIG_SUBDIRS at least (the GCC tree uses a different way but uses per-configure cache files). How do you get two concurrent configure scripts updating the same config.cache file? Thanks, Ralf _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx http://lists.gnu.org/mailman/listinfo/autoconf
