ST_AsSVG doesn't handle EMPTY inputs well

[pramsey]

As seen on the user list:

select assvg(difference(
LineFromText('LINESTRING(535568 198842,535549 198802,535505 198820,535524
198862,535568 198842)'),
difference(LineFromText('LINESTRING(535568 198842,535549 198802,535505
198820,535524 198862,535568 198842)'), LineFromText('LINESTRING(535900
198600,535900 199100)'))
),0,5)

Returns: empty row

But

select length(assvg(difference(
LineFromText('LINESTRING(535568 198842,535549 198802,535505 198820,535524
198862,535568 198842)'),
difference(LineFromText('LINESTRING(535568 198842,535549 198802,535505
198820,535524 198862,535568 198842)'), LineFromText('LINESTRING(535900
198600,535900 199100)'))
),0,5))

Returns: 5

Use lwgeom_is_empty() and return a null-terminated response pre-emptively.

[colivier]

Not able yet to reproduce it:

POSTGIS="1.5.1SVN" GEOS="3.2.0-CAPI-1.6.0" PROJ="Rel. 4.7.1, 23 September 2009" LIBXML="2.7.6" USE_STATS

(checked also with trunk branch)

select length(assvg(difference(                                                 LineFromText('LINESTRING(535568 198842,535549 198802,535505 198820,535524             198862,535568 198842)'),                                                              difference(LineFromText('LINESTRING(535568 198842,535549 198802,535505                198820,535524 198862,535568 198842)'), LineFromText('LINESTRING(535900                198600,535900 199100)'))                                                              ),0,5))                                                                               ;
 length 
--------
      0

[colivier]

In fact it look like a already known bug corrected in 1.5.1 and 1.4.2:

http://trac.osgeo.org/postgis/changeset/5210 http://trac.osgeo.org/postgis/ticket/409

I close the ticket as invalid