Linestring empty when intersecting vertical line with a square

[cactusbone]

Hello, I've stumbled on something weird :

Using

SELECT ST_Astext(
	ST_Intersection(
		ST_GeomFromText('LINESTRING(1 1, 1 2)'),
		ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))')
	)
)

returns LINESTRING EMPTY

on PostGIS 3.2 ("POSTGIS=""3.2.3 2f97b6c"" [EXTENSION] PGSQL=""140"" GEOS=""3.9.0-CAPI-1.16.2"" SFCGAL=""1.3.8"" PROJ=""7.2.1"" GDAL=""GDAL 3.2.2, released 2021/03/05"" LIBXML=""2.9.10"" LIBJSON=""0.15"" LIBPROTOBUF=""1.3.3"" WAGYU=""0.5.0 (Internal)"" RASTER" or "POSTGIS=""3.2.1 5fae8e5"" [EXTENSION] PGSQL=""140"" GEOS=""3.9.0-CAPI-1.16.2"" SFCGAL=""1.3.8"" PROJ=""7.2.1"" GDAL=""GDAL 3.2.2, released 2021/03/05"" LIBXML=""2.9.10"" LIBJSON=""0.15"" LIBPROTOBUF=""1.3.3"" WAGYU=""0.5.0 (Internal)"" TOPOLOGY RASTER")

It works on PostGIS 2.5 ("POSTGIS=""2.5.1 r17027"" [EXTENSION] PGSQL=""110"" GEOS=""3.7.1-CAPI-1.11.1 27a5e771"" SFCGAL=""1.3.6"" PROJ=""Rel. 5.2.0, September 15th, 2018"" GDAL=""GDAL 2.4.0, released 2018/12/14"" LIBXML=""2.9.4"" LIBJSON=""0.12.1"" LIBPROTOBUF=""1.2.1"" TOPOLOGY RASTER")

It's the same with horizontal lines

SELECT ST_Astext(
	ST_Intersection(
		ST_GeomFromText('LINESTRING(1 1, 2 1)'),
		ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))')
	)
)

However it works when the line is neither horizontal nor vertical or when it touches the intersection

Queries that work:

SELECT ST_Astext(ST_Intersection(
	ST_GeomFromText('LINESTRING(1 1, 2 2)'),
	ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))')
))

SELECT ST_Astext(ST_Intersection(
	ST_GeomFromText('LINESTRING(1 1, 2 1.000000000001)'),
	ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))')
))

SELECT ST_Astext(
	ST_Intersection(
		ST_GeomFromText('LINESTRING(0 0, 0 1)'),
		ST_GeomFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))')
	)
)

[mdavis]

This is a GEOS bug that was ​fixed in recent versions (3.9.1, etc).