[PostGIS] #5754: ST_ForcePolygonCCW unexpectedly modifies line geometries

[PostGIS]

#5754: ST_ForcePolygonCCW unexpectedly modifies line geometries
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  Reporter:  nti      |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  high     |  Milestone:  PostGIS 3.4.5
 Component:  postgis  |    Version:  3.4.x
Resolution:           |   Keywords:
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Comment (by pramsey):

 This seems to be very long-standing, and can be traced to the fact that,
 while ST_Reverse() reverses all geometry types, the ST_ForcePolygonCW and
 ST_ForcePolygonCCW functions only reverse polygonal types. And there's
 logic in the pipe that checks "is this CCW? then reverse it". So polygonal
 types get handled correctly, and lines get reversed every time. Which is
 what you're seeing.

 A quick in-place fix is
 {{{
 CREATE OR REPLACE FUNCTION ST_ForcePolygonCCW(geometry)
         RETURNS geometry
         AS $$ SELECT
                 CASE WHEN ST_GeometryType($1) IN ('ST_Polygon',
 'ST_MultiPolygon')
                 THEN ST_Reverse(ST_ForcePolygonCW($1))
                 ELSE $1 END $$
         LANGUAGE 'sql' IMMUTABLE STRICT PARALLEL SAFE;
 }}}

 A better fix would involve trying to centralize the "should I try and
 orient this" logic into a single place, as it's currently in 5 places (and
 more with this temporary fix).

 Unfortunately it seems there's no way to fix this without changing the SQL
 definition for ST_ForcePolygonCCW which makes a patch-level fix a "no go",
 so this will have to be for the 3.7 milestone.
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5754#comment:3>
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