Bakul Shah via TUHS <tuhs@tuhs.org> writes:

> To build a set of objects you need to worry about at least the
> following:
> - build recipes for each of them (which may also depend on other
> things)
> - configuration parameters
> - dealing with differences on each platform
> - third party libraries & alternatives
> - toolchains (& may be cross-platform builds)
> - supporting/navigating different versions of the last 3 above
>
> You can't really precompute all this as there are far too many
> combinations and they keep changing.

Both the blog author (who is a long-time sysadmin with many 'war
stories') and myself understand all that.

i believe the idea is not for precomputing to be done by _builds_,
but to be done on and for a given machine and its configuration,
independent of any specific piece of software, which is then
_queried_ by builds. That precomputation would only need to be
re-run when one of the things under its purview changes.

If i compile something on one of my OpenBSD boxen in the morning,
and then compile some other thing in the afternoon, without an OS
upgrade in-between, autoconf isn't going to find that libc.so has
changed in-between. If i did the same thing on my Gentoo box, it's
theoretically possible that e.g. i've moved from glibc to musl
in-between, but in that case, precomputation could be done in
postinst (i.e. as part of the post-installation-of-musl process).