Partial-eval is broken for partial object/set ref head rules

[johanfylling]

Short description

Partial evaluation fails to generate valid optimized support modules for partial object/set ref head rules.

Steps To Reproduce

Given the policy:

package bug

p.q[x] := y {
    x := input.x
    y := input.y
}

allow {
    p.q.foo
}

1. Partial Evaluation

When running opa eval --partial -fsource --shallow-inlining -d bug.rego 'data.bug.p.q[x]', we get the output:

# Query 1
data.partial.bug.p.q[x] = _term_0_0
_term_0_0

# Module 1
package partial.bug.p

 = __local1__1 {
	__local0__1 = input.x
	__local1__1 = input.y
}

Notice how the name and key of the generated optimized rule are missing; resulting in broken Rego.

2. Build with optimization

When running opa build bug.rego -O 1 -e 'bug/allow', we get a bundle with optimized Rego included at <bundle.tar.gz>/optimized/bug/p.rego:

package bug.p

 = __local1__2 {
	__local0__2 = input.x
	__local1__2 = input.y
}

Where, similar to (1), the generated Rego has missing rule name and key.

Expected behavior

When running opa eval (1), the expected output is:

# Query 1
data.partial.bug.p.q[x] = _term_0_0
_term_0_0

# Module 1
package partial.bug.p

q[__local0__1] = __local1__1 {
	__local0__1 = input.x
	__local1__1 = input.y
}

Similarly, when running opa build (2), the expected optimized Rego is:

package bug.p

q[__local0__2] = __local1__2 {
	__local0__2 = input.x
	__local1__2 = input.y
}