Re: Build macOS shared modules as dylib rather than bundle

Peter Eisentraut <peter@eisentraut.org> writes:
> ... But this change triggers a new variant of this issue:
> https://www.postgresql.org/message-id/E1o4HOv-001Oyi-5n@gemulon.postgresql.org
> With the changed linker options, the symbol search order appears to
> be different, and so hash_search() gets found in the OS library first.

> To avoid that, I suggest to use some preprocessor defines to rename the
> symbols known to clash, in a way that we can continue to use the
> existing API names.

I don't love that solution.  If we simply put up with this name
resolution order, we leave ourselves open to being blindsided by
any future libc addition that Apple chooses to make.  The recent
strchrnul() kerfuffle is still causing me pain every day, so
maybe this is more front-of-mind than it would be at another time.
But I think it is worth our time to try to find a way to get back
the other resolution order.

> I suggest that we consider the dynahash change for PG18.  The Meson
> change will eventually come our way, and then everything on macOS will
> start crashing.  So the earlier we fix this the better.  Also, we can't
> backpatch this because of the ABI change, so once PG18 ships the window
> is over.

Arguably, changing library name resolution order is an ABI break
in itself.  If we can't fix that, I think we will have to mandate
that this change happens only at a major-release boundary.  Which
is going to be no fun for anybody, if meson is going to force it
on us across-the-board at some random time.  We should perhaps
push back on the idea that they get to decide when and how that
changes.

            regards, tom lane