I would like to propose a new rule:no-duplicate-union-intersection.

This rule reports duplicates in unions and intersections. The autofixer will remove all duplicates, keeping the first one.

The following lines will be reported:

typeA=1|2|3|1;typeB='foo'|'bar'|'foo';typeC=A|B|A|B;

This will be autofixed to:

typeA=1|2|3;typeB='foo'|'bar';typeC=A|B;

The rule won’t try to resolve references. This may be an addition for later.

If this is accepted, I’m willing to implement this.