rql #83202 Typing OR clauses not as expected [open]

generic_rel is quite generic a relation which can link a CWUser for example to pretty anything ( '*' in the schema). The problematic RQL request looks like

SET U generic_rel X WHERE ... , A rel1 X OR B rel2 X

where the ... introduces the A and B variables and the rel1 and rel2 relations actually have distinct objet types.

The error raised is

TypeResolverException: Unable to resolve variables types in [...]

The point is that the type system associate one type variable to the X symbol, thus leading to a unification error. Said otherwise, the algorithm does not introduce union/sum types.

I would have expected the following semantics

SET U generic_rel X0 WHERE ... , A rel1 X1 OR B rel2 X2

With X1 typed T1 according to rel1, X2 T2 according to rel2 and X0 as (T1 | T2).

Or in an equivalent way

SET U generic_rel X1 WHERE ... , A rel1 X1
SET U generic_rel X2 WHERE ... , B rel2 X2

NB: This is an "unexpected behaviour" kind of report. It is yet undecided whether this should become an improvement ticket for RQL capabilities or for the documentation of its desired limitations.

done in<not specified>
closed by<not specified>