Zack Weinberg wrote:
On Tue, Jun 18, 2024, at 12:02 AM, Jacob Bachmeyer wrote:
[...]
Wait... all of configure's non-system dependencies are in the release
tarball and presumably (if "make dist" worked correctly) backdated
older than configure when the tarball is unpacked.
In my experience, tarballs cannot be trusted to get this right, *and*
tar implementations cannot be trusted to unpack them accurately
(e.g. despite POSIX I have run into implementations that defaulted to
the equivalent of GNU tar's --touch mode). Subsequent bounces through
downstream repackaging do not help. Literally as I type this I am
watching gettext 0.22 run its ridiculous number of configure scripts a
second time from inside `make`.
First, "make dist" should get the tarball right. Second, absent some
special flag (--enable-maintainer-mode?), a package using Automake
should have no problem if all distributed files have the same timestamp.
I see a possibility of a lazy tar(1) implementation not restoring
timestamps at all, with the result that the unpacked files get mtimes in
the order they were unpacked from the archive. Perhaps "make dist"
should sort the files into the proper order while packing the tarball?
Automake should have the dependency graph available while generating the
"make dist" commands...
Does "make dist" need to touch configure to ensure that it is newer
than its dependencies before rolling the tarball?
It ought to, but I don't think that will be more than a marginal
improvement, and touching the top-level configure won't be enough,
you'd need to do a full topological sort on the dependency graph
leading into every configure + every Makefile.in + every other
generated-but-shipped file and make sure that each tier of generated
files is newer than its inputs.
I wonder if a more effective approach would be to disable the rules to
regenerate configure, Makefile.in, etc. unless either --enable-maintainer-mode
or we detect that we are building out of a VCS checkout.
I thought that that /was/ the effect of --enable-maintainer-mode? I
would also suggest not handling VCS checkouts specially. If you want
the Makefile rules for generating GNU build system scripts, you should
have to say --enable-maintainer-mode. Otherwise, you can always use the
tools directly or put an autogen.sh or bootstrap.sh or similar in the VCS.
-- Jacob
