Add test case gml namespace, missing will cause a warning.

[w345731923]

gml does not add the namespace when converting, which causes libxml2 to throw a warning.
postgis 3.4.0
CGAL 5.4.5
PROJ="8.2.1
LIBXML="2.9.11"
LIBJSON="0.15"

2023-11-10 12:18:36.706 CST [23404] LOG: execute : SET SESSION search_path TO 'public'
namespace warning : Namespace prefix gml is not defined
<gml:LineString srsName="EPSG:4269">
^
2023-11-10 12:18:36.715 CST [23404] LOG: execute : SELECT ST_GeomFromGML($$
<gml:LineString srsName="EPSG:4269">
gml:coordinates
-71.16028,42.258729 -71.160837,42.259112 -71.161143,42.25932
</gml:coordinates>
</gml:LineString>
$$)

reference https://www.ogc.org/standard/gml/
《 5.1 XML namespaces 》

All components of the GML schema are defined in the namespace with the identifier "http://www.opengis.net/gml/3.2", for which the prefix gml or the default namespace is used within this International Standard.

2023-11-10 12:29:49.619 CST [23404] LOG: execute : SELECT ST_GeomFromGML($$
<gml:LineString xmlns:gml="http://www.opengis.net/gml"
srsName="EPSG:4269">
gml:coordinates
-71.16028,42.258729 -71.160837,42.259112 -71.161143,42.25932
</gml:coordinates>
</gml:LineString>
$$)

[w345731923]

@strk

Hi Sandro,
Something went wrong with regression testing.
https://github.com/postgis/postgis/actions/runs/6820765253/job/18550181118?pr=751

regress/core/regress_buffer_params .. failed (diff expected obtained: /tmp/pgis_reg/test_51_diff)

--- ./regress/core/regress_buffer_params_expected 2023-11-10 04:30:53.558070129 +0000
+++ /tmp/pgis_reg/test_51_out 2023-11-10 04:32:38.021623410 +0000
@@ -1,5 +1,5 @@
point quadsegs=2|POLYGON((1 0,0.7071 -0.7071,0 -1,-0.7071 -0.7071,-1 0,-0.7071 0.7071,0 1,0.7071 0.7071,1 0))
-line quadsegs=2|POLYGON((10 2,11.414 1.414,12 0,11.414 -1.414,10 -2,0 -2,-1.414 -1.414,-2 2.449e-16,-1.414 1.414,0 2,10 2))
+line quadsegs=2|POLYGON((10 2,11.414 1.414,12 0,11.414 -1.414,10 -2,0 -2,-1.414 -1.414,-2 0,-1.414 1.414,0 2,10 2))
line quadsegs=2 endcap=flat|POLYGON((10 2,10 -2,0 -2,0 2,10 2))
line quadsegs=2 endcap=butt|POLYGON((10 2,10 -2,0 -2,0 2,10 2))
line quadsegs=2 endcap=square|POLYGON((10 2,12 2,12 -2,0 -2,-2 -2,-2 2,10 2))

Will modifying the example affect regression testing?
I did not modify the regress_buffer_params_expected and regress_buffer_params.sql files.

[pramsey]

rebase from master, should fix the CI failure.

[pramsey]

I don't find that omitting the namespace causes an error.

SELECT ST_GeomFromGML($$
    <gml:LineString  
                        srsName="EPSG:4269">
        <gml:coordinates>
            -71.16028,42.258729 -71.160837,42.259112 -71.161143,42.25932
        </gml:coordinates>
    </gml:LineString>
$$);

[w345731923]

I don't find that omitting the namespace causes an error.

SELECT ST_GeomFromGML($$
    <gml:LineString  
                        srsName="EPSG:4269">
        <gml:coordinates>
            -71.16028,42.258729 -71.160837,42.259112 -71.161143,42.25932
        </gml:coordinates>
    </gml:LineString>
$$);

When logging_collector=on, it will be printed in the log but not on the console. Please check the logs.
When logging_collector=off, warnings are printed in psql.

[w345731923]

I found the warning location.
Reference https://gitlab.gnome.org/GNOME/libxml2/-/blob/master/SAX2.c
Line 1641

[strk]

The namespace definition should be in the document header, we don't want to repeat it on every geometry.
The function supports tweaking the namespace being used too, in case you want it empty (do you get the warning if it's empty?)
https://postgis.net/docs/ST_AsGML.html

[strk]

I'm actually ok with the change, doesn't hurt for sure

[w345731923]

The namespace definition should be in the document header, we don't want to repeat it on every geometry. The function supports tweaking the namespace being used too, in case you want it empty (do you get the warning if it's empty?) https://postgis.net/docs/ST_AsGML.html

ST_AsGML is normal, but warnings are issued during conversion, such as ST_GeomFromGML.

[strk]

I've merged your change as of dc000e9 - thank you