Re: [PATCH] Use PKG_CHECK_MODULES to detect the libxml2 library - Mailing list pgsql-hackers

From Daniel Gustafsson
Subject Re: [PATCH] Use PKG_CHECK_MODULES to detect the libxml2 library
Date
Msg-id EEE0258A-C7AA-465F-8A09-4D592FF17ECE@yesql.se
Whole thread Raw
In response to Re: [PATCH] Use PKG_CHECK_MODULES to detect the libxml2 library  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [PATCH] Use PKG_CHECK_MODULES to detect the libxml2 library  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> On 12 Mar 2020, at 17:39, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> I also
> concluded that if the user has set XML2_CONFIG, it's pretty clear
> that her intent is to use whatever that is pointing at, so we should
> not use pkg-config in that case either.

+1

> I'd originally thought that we might back-patch this, but I'm now of
> the opinion that we probably should not.  If pkg-config is present,
> this can change the default behavior about where we get libxml from,
> which seems like something not to do in minor releases.  (OTOH, it'd
> only matter if the default pkg-config choice is different from the
> default xml2-config choice, so maybe the risk of breakage is small
> enough to be acceptable?)

I read this is as a preventative patch to stay ahead of future changes to
packaging.  If these changes do materialize, won't they be equally likely to
hit installations for backbranch minors as v13?  Changing behavior in a minor
release is however not ideal, but perhaps the risk/benefit analysis comes down
to releases not compiling being worse?

I haven't had the chance to test the patch, but the changes to configure.in
reads perfectly fine. In the docs though:

> +         To use a libxml installation that is in an unusual location, you

We refer to both libxml and libxml2 in these paragraphs.  Since upstream is
consistently referring to it as libxml2, maybe we should take this as
opportunity to switch to that for the docs?

cheers ./daniel


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