checking of argument compatibility right; although the problem is only exposed
with multiple-input aggregates in which some arguments are polymorphic and
some are not. Per bug #3852 from Sokolov Yura.
wrong thing when inlining polymorphic SQL functions, because it was using the
function's declared return type where it should have used the actual result
type of the current call. In 8.1 and 8.2 this causes obvious failures even if
you don't have assertions turned on; in 8.0 and 7.4 it would only be a problem
if the inlined expression were used as an input to a function that did
run-time type determination on its inputs. Add a regression test, since this
is evidently an under-tested area.
the opportunity to treat COUNT(*) as a zero-argument aggregate instead
of the old hack that equated it to COUNT(1); this is materially cleaner
(no more weird ANYOID cases) and ought to be at least a tiny bit faster.
Original patch by Sergey Koposov; review, documentation, simple regression
tests, pg_dump and psql support by moi.
It also works to create a non-polymorphic aggregate from polymorphic
functions, should you want to do that. Regression test added, docs still
lacking. By Joe Conway, with some kibitzing from Tom Lane.
