[PostGIS] #6081: Test failure with SFCGAL 2.3.0

[PostGIS]

#6081: Test failure with SFCGAL 2.3.0
-----------------------------+-----------------------------
  Reporter:  Bas Couwenberg  |      Owner:  Loïc Bartoletti
      Type:  defect          |     Status:  new
  Priority:  medium          |  Milestone:  PostGIS 3.6.5
 Component:  sfcgal          |    Version:  3.6.x
Resolution:                  |   Keywords:
-----------------------------+-----------------------------
Comment (by Bas Couwenberg):

 Replying to [comment:1 robe]:
 > Did you get a chance to test this with 3.7.0dev.

 No, that's not in Debian.

 With the changes from master the build still fails:
 {{{
 -----------------------------------------------------------------------------
 --- ./sfcgal/regress/alphashape_expected        2026-06-15
 07:12:23.000000000 +0000
 +++ /tmp/pgis_reg/test_172_out  2026-06-15 07:15:17.155198743 +0000
 @@ -1,4 +1,4 @@
  CG_AlphaShape_default|MULTIPOLYGON(((2.3 3.6,2.6 4.4,2.7 5.4,2.3 6,2.4
 6.7,2.7 7.7,2.4 8.2,2.6 8.5,3.4 8.6,3.9 8.8,4.5 9,4.9 9.5,5.2 9.8,5.7
 9.7,6.4 9.7,7.2 9.5,7.6 8.8,7.5 8.4,8.3 7.2,8.5 7.1,8.8 5.8,8.9 5.3,9.1
 5,8.7 4.2,9 3,8.4 1.9,7.8 1.6,7.3 1.6,6.5 1.6,5.3 1.8,4.3 1.9,3.7 2.3,3
 2.2,2.8 3.3,2.3 3.6)))
  CG_AlphaShape_hole|MULTIPOLYGON(((2.3 3.6,2.6 4.4,2.7 5.4,2.3 6,2.4
 6.7,2.7 7.7,2.4 8.2,2.6 8.5,3.4 8.6,3.9 8.8,4.5 9,4.9 9.5,5.2 9.8,5.7
 9.7,6.4 9.7,7.2 9.5,7.6 8.8,7.5 8.4,8.3 7.2,8.5 7.1,8.8 5.8,8.9 5.3,9.1
 5,8.7 4.2,9 3,8.4 1.9,7.8 1.6,7.3 1.6,6.5 1.6,5.3 1.8,4.3 1.9,3.7 2.3,3
 2.2,2.8 3.3,2.3 3.6),(3.6 6.1,3.8 4.6,4.4 4.2,5.4 3.2,6.2 2.2,7.6 2.7,7.8
 4.3,8.1 4.7,8.2 5.4,8.1 6,7.7 6.7,6.8 7.3,6 8.1,4.3 8,4 7.5,3.6 6.8,3.6
 6.1)))
 -CG_OptimalAlphaShape_default|MULTIPOLYGON(((2.3 3.6,2.6 4.4,2.7 5.4,2.3
 6,2.4 6.7,2.7 7.7,2.4 8.2,2.6 8.5,3.4 8.6,3.9 8.8,4.5 9,4.9 9.5,5.2
 9.8,5.7 9.7,6.4 9.7,7.2 9.5,7.6 8.8,7.5 8.4,7.5 7.7,8.3 7.2,8.5 7.1,8.3
 6.4,8.8 5.8,8.9 5.3,9.1 5,8.7 4.2,9 3,8.8 2.9,8.4 1.9,7.8 1.6,7.3 1.6,6.5
 1.6,5.3 1.8,4.3 1.9,3.7 2.3,3 2.2,2.8 3.3,2.3 3.6)))
 -CG_OptimalAlphaShape_hole|MULTIPOLYGON(((2.3 3.6,2.6 4.4,2.7 5.4,2.3
 6,2.4 6.7,2.7 7.7,2.4 8.2,2.6 8.5,3.4 8.6,3.9 8.8,4.5 9,4.9 9.5,5.2
 9.8,5.7 9.7,6.4 9.7,7.2 9.5,7.6 8.8,7.5 8.4,7.5 7.7,8.3 7.2,8.5 7.1,8.3
 6.4,8.8 5.8,8.9 5.3,9.1 5,8.7 4.2,9 3,8.8 2.9,8.4 1.9,7.8 1.6,7.3 1.6,6.5
 1.6,5.3 1.8,4.3 1.9,3.7 2.3,3 2.2,2.8 3.3,2.3 3.6),(3.6 6.1,3.8 4.6,4.4
 4.2,4.8 3.4,5.4 3.2,5.5 2.6,6.2 2.2,7 2,7.6 2.7,8.1 2.9,7.8 4.3,8.1
 4.7,8.2 5.4,8.1 6,7.7 6.7,6.8 7.3,6 8.1,5 8.6,4.3 8,4 7.5,3.6 6.8,3.6
 6.1)))
 +CG_OptimalAlphaShape_default|MULTIPOLYGON(((2.3 3.6,2.6 4.4,2.7 5.4,2.3
 6,2.4 6.7,2.7 7.7,2.4 8.2,2.6 8.5,3.4 8.6,3.9 8.8,4.5 9,4.9 9.5,5.2
 9.8,5.7 9.7,6.4 9.7,7.2 9.5,7.6 8.8,7.5 8.4,7.5 7.7,8.3 7.2,8.5 7.1,8.8
 5.8,8.9 5.3,9.1 5,8.7 4.2,9 3,8.8 2.9,8.4 1.9,7.8 1.6,7.3 1.6,6.5 1.6,5.3
 1.8,4.3 1.9,3.7 2.3,3 2.2,2.8 3.3,2.3 3.6)))
 +CG_OptimalAlphaShape_hole|MULTIPOLYGON(((2.3 3.6,2.6 4.4,2.7 5.4,2.3
 6,2.4 6.7,2.7 7.7,2.4 8.2,2.6 8.5,3.4 8.6,3.9 8.8,4.5 9,4.9 9.5,5.2
 9.8,5.7 9.7,6.4 9.7,7.2 9.5,7.6 8.8,7.5 8.4,7.5 7.7,8.3 7.2,8.5 7.1,8.8
 5.8,8.9 5.3,9.1 5,8.7 4.2,9 3,8.8 2.9,8.4 1.9,7.8 1.6,7.3 1.6,6.5 1.6,5.3
 1.8,4.3 1.9,3.7 2.3,3 2.2,2.8 3.3,2.3 3.6),(3.6 6.1,3.8 4.6,4.4 4.2,4.8
 3.4,5.4 3.2,5.5 2.6,6.2 2.2,7 2,7.6 2.7,8.1 2.9,7.8 4.3,8.1 4.7,8.2
 5.4,8.1 6,7.7 6.7,6.8 7.3,6 8.1,5 8.6,4.3 8,4 7.5,3.6 6.8,3.6 6.1)))
 -----------------------------------------------------------------------------
 }}}

 > I think I was running into same issue with our raspberry pi ci but that
 seems all clear now.
 >
 > See #6068

 That doesn't apply to 3.6.4 because it changes
 `sfcgal/regress/alphashape_components*` which doesn't exist in 3.6.x which
 has `sfcgal/regress/alphashape*`.

 > So perhaps we need to backport some fixes.  Although in that case, it
 was only failing on the CG_OpitmalAlphaShape, but we mind have fixed the
 other issues earlier on.

 You may need to build your SFCGAL 2.3.0 with CGAL 6.2 as is the case in
 Debian unstable.

 Note that is broken on i386:
 https://gitlab.com/sfcgal/SFCGAL/-/work_items/326
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/6081#comment:2>
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