Eliminate dependencies on "which", as we don't really need that to be
installed for proper testing. Don't number the tests, as that increases
the footprint of every patch that wants to add or remove tests. Make
the test output more informative, so that it's a bit easier to see what
went right (or wrong). Spelling and grammar improvements.
contrib/xml2 can get by without libxslt; the relevant features just
won't work. But if doesn't have libxml2, or if sepgsql doesn't have
libselinux, the link succeeds but the module then fails to work at load
time. To avoid that, link the require libraries unconditionally, so
that it will be clear at link-time that there is a problem.
Per discussion with Tom Lane and KaiGai Kohei.
The previous functions of assign hooks are now split between check hooks
and assign hooks, where the former can fail but the latter shouldn't.
Aside from being conceptually clearer, this approach exposes the
"canonicalized" form of the variable value to guc.c without having to do
an actual assignment. And that lets us fix the problem recently noted by
Bernd Helmle that the auto-tune patch for wal_buffers resulted in bogus
log messages about "parameter "wal_buffers" cannot be changed without
restarting the server". There may be some speed advantage too, because
this design lets hook functions avoid re-parsing variable values when
restoring a previous state after a rollback (they can store a pre-parsed
representation of the value instead). This patch also resolves a
longstanding annoyance about custom error messages from variable assign
hooks: they should modify, not appear separately from, guc.c's own message
about "invalid parameter value".
This is still pretty rough - among other things, the documentation
needs work, and the messages need a visit from the style police -
but this gets the basic framework in place.
KaiGai Kohei