Issue with Nested Laterals

[Aklakan]

Version

5.3.0-SNAPSHOT

What happened?

The following query reveals a bug where an unexpected exception is raised in BindingBuilder.checkAdd: Attempt to reassign ?s from 1 to 1. The issue is in QueryIterLateral which just adds the lhs and rhs binding to the builder although they may have variables in common.

SELECT * {
    BIND(1 AS ?s)
    LATERAL {
        BIND(?s AS ?x)
        LATERAL {
            BIND(?s AS ?y)
        }
    }
}

My proposed solution in the PR is to add a check whether bindings are compatible on their common variables.

(Edit: I removed the report about the issues I encountered with var scoping so that this issue can be closed independently.)

Relevant output and stacktrace

No response

Are you interested in making a pull request?

Yes