schema: type checker doesn't work with in on typed arrays

[anderseknert]

schema/input.json

{
    "type": "object",
    "properties": {
        "numbers": {
            "type": "array",
            "items": {
                "type": "number"
            }
        }
    },
    "additionalProperties": false
}

Below policy should not compile, as "admin" is not a number.

policy.rego

package policy

# METADATA
# schemas:
#   - input: schema.input
allow {
    "admin" in input.numbers
}

Switching to use old style iteration however does enforce the type:

"admin" == input.numbers[_]

opa eval -f pretty --schema schema/ -d policy.rego data.policy.allow
1 error occurred: policy/policy.rego:8: rego_type_error: match error
	left  : string
	right : number

[anderseknert]

Looked briefly into this, and while the in is rewritten into an eq check, it seems the type information is somehow lost when looking up the type of the transformed var (__local1__ or whatever). Not immediately apparent to me why.