internal/core/adt: dereference overlay

When we finalize the rewrites, it should
be done on the overlay, not the original
node.

Not sure why this worked at all. It seems
like this was the result of closeParent,
which effectively blocked most rewrites.
But in practice that didn't seem to
matter either.

In an upcoming CL we will actually rely
on the rewrites.

Issue #3935

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I35a78a6062507c7d0c67a925ea2a698b9d59acc8
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1215576
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: mpvl

internal/core/adt/eval.go

@@ -1066,9 +1066,6 @@ type nodeContext struct {
 	vLists []*Vertex
 	exprs  []envExpr
 
-	// TODO: remove
-	closeParent *nodeContext
-
 	// These fields are used to track type checking.
 	reqDefIDs    []refInfo
 	replaceIDs   []replaceID

internal/core/adt/overlay.go

@@ -142,20 +142,13 @@ func (ctx *overlayContext) cloneRoot(root *nodeContext) *nodeContext {
 	v.state.vertexMap = ctx.vertexMap
 
 	for _, v := range ctx.vertices {
+		v = v.overlay
+
 		n := v.state
-		if n == nil || n.closeParent == nil {
+		if n == nil {
 			continue
 		}
 
-		if p := n.closeParent.node; p.overlay != nil {
-			// Use the new nodeContext if the node was cloned. Otherwise it
-			// is fine to use the old one.
-			n.closeParent = p.state
-			if p.state == nil {
-				panic("unexpected nil nodeContext")
-			}
-		}
-
 		// The group of the root closeContext should point to the Conjuncts field
 		// of the Vertex. As we already allocated the group, we use that allocation,
 		// but "move" it to v.Conjuncts.