Re: Use \if/\endif to remove non-libxml2 expected output in regression tests

Daniel Gustafsson  writes:
>> On 12 Jun 2026, at 09:49, Michael Paquier  wrote:
>> I'd like to backpatch that down to v14, to ease future maintenance.
>> Any comments and/or objections?

> Skipping tests when the underlying library/platform support is missing is in
> line with how the TAP tests already do it.  We would lose coverage of invoking
> XML functions without libxml support, which risk hiding bugs in the error-
> handling (which is already the case with the TAP tests etc).

Yeah.  Also, I think this isn't really moving the support goalposts
very far, because xml_2.out will still require maintenance whenever
we touch xml.out, and that's the harder file to update if you don't
have a suitable version of libxml2 at hand.  So I'm not in favor of
this as it stands.  If we could find a way to get rid of xml_2.out
as well, then maybe dropping coverage of the error paths would be a
good tradeoff.

Diff'ing xml.out and xml_2.out, I see the differences are omissions
of input fragments in some error reports, eg:

@@ -335,8 +323,6 @@
 &idontexist;
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-&idontexist;
-                                    ^
 SELECT xmlparse(document '');
       xmlparse       
 ---------------------

I wonder if anyone's ever looked into exactly why that happens and
whether we could do something to restore the missing context.

			regards, tom lane