GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"

[Philip Stoev]

MariaDB [test]> select astext(ST_INTERSECTION( MULTILINESTRINGFROMTEXT(' MULTILINESTRING( (3 5, 2 4, 2 5, 3 5) ) ') , LINESTRINGFROMTEXT(' LINESTRING( 5 5 , 9 3 , 5 5 , 6 1 ) ') ))\G
*************************** 1. row ***************************
astext(ST_INTERSECTION( MULTILINESTRINGFROMTEXT(' MULTILINESTRING( (3 5, 2 4, 2 5, 3 5) ) ') , LINESTRINGFROMTEXT(' LINESTRING( 5 5 , 9 3 , 5 5 , 6 1 ) ') )): GEOMETRYCOLLECTION()
1 row in set (0.00 sec)

GEOMETRYCOLLECTION() is not recognized by PostGIS as a valid value. PostGIS returns "GEOMETRYCOLLECTION EMPTY".

Also, trying to use GEOMETRYCOLLECTION() in a calculation results in a totally bogus result:

MariaDB [test]> SELECT ASTEXT(ENVELOPE(GEOMETRYFROMTEXT('GEOMETRYCOLLECTION()')))\G
*************************** 1. row ***************************
ASTEXT(ENVELOPE(GEOMETRYFROMTEXT('GEOMETRYCOLLECTION()'))): POLYGON((1.79769313486232e+308 1.79769313486232e+308,-1.79769313486232e+308 1.79769313486232e+308,-1.79769313486232e+308 -1.79769313486232e+308,1.79769313486232e+308 -1.79769313486232e+308,1.79769313486232e+308 1.79769313486232e+308))

[Philip Stoev (pstoev-askmonty)]

Same applies for other functions, e.g.

select ASTEXT(ST_DIFFERENCE( MULTIPOLYGONFROMTEXT(' MULTIPOLYGON( ( (3 5, 2 5, 2 4, 3 4, 3 5) ) ) ') , POLYGONFROMTEXT(' POLYGON( (3 5, 2 5, 2 4, 3 4, 3 5) ) ') )) ;