[PostGIS] #5862: TopoGeo_add* silently corrupt topology: edge crosses edge, mixed face labeling in ring

[PostGIS]

#5862: TopoGeo_add* silently corrupt topology: edge crosses edge, mixed face
labeling in ring
--------------------------------+------------------------
  Reporter:  Lars Aksel Opsahl  |      Owner:  strk
      Type:  defect             |     Status:  new
  Priority:  high               |  Milestone:
 Component:  topology           |    Version:  master
Resolution:                     |   Keywords:  robustness
--------------------------------+------------------------
Comment (by Lars Aksel Opsahl):

 Replying to [comment:11 strk]:
 > For the record, the distances of those two internal vertices of Edge2
 from Edge1 are:
 > {{{
 > =# select n, ST_Distance(e1.geom, ST_PointN(e2.geom, n))
 >    from t5862.edge e1, t5862.edge e2, generate_series(2,3) n
 >    where e1.edge_id = 1 and e2.edge_id = 2;
 >  n |      st_distance
 > ---+------------------------
 >  2 |  4.855711461806118e-16
 >  3 | 2.8243441995579915e-15
 > (2 rows)
 > }}}

 Can this info be used to throw an topology exception ?

 Since we are not able to handle so close points it's better to get a
 topology error when trying add that line instead of a topology error in
 the database, I think.

 Then it's up the caller to decide what to with this line.
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5862#comment:14>
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