internal/core/adt: changes needed for new evaluator

These changes prepare for changes in the new evaluator
implementation. Submitting these in a separate CL will
allow us to bisect to this CL in case these cause errors
in the old evaluator.

The new evaluator may set the value when the cycle
placeholder has not removed yet. Treat this case.

The new evaluator cannot use getNodeContext.
In these use cases, the nodeContext is always available.
So by avoiding calling getNodeContext, we can use this
code for both the old and new evaluator.

Signed-off-by: Marcel van Lohuizen <[email protected]>
Change-Id: I0acd9ff5a0b2225b54ffcf0db362f74e417d323f
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1167921
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

Author: mpvl

internal/core/adt/composite.go

@@ -928,7 +928,7 @@ func (v *Vertex) Source() ast.Node {
 
 // AddConjunct adds the given Conjuncts to v if it doesn't already exist.
 func (v *Vertex) AddConjunct(c Conjunct) *Bottom {
-	if v.BaseValue != nil {
+	if v.BaseValue != nil && !isCyclePlaceholder(v.BaseValue) {
 		// TODO: investigate why this happens at all. Removing it seems to
 		// change the order of fields in some cases.
 		//

internal/core/adt/eval.go

@@ -671,8 +671,7 @@ func (n *nodeContext) incompleteErrors(final bool) *Bottom {
 		// n := d.node.getNodeContext(ctx)
 		// n.addBottom(err)
 		if final && c.vertex != nil && c.vertex.status != finalized {
-			n := c.vertex.getNodeContext(n.ctx, 0)
-			n.addBottom(err)
+			c.vertex.state.addBottom(err)
 			c.vertex = nil
 		}
 	}
@@ -700,8 +699,7 @@ func (n *nodeContext) incompleteErrors(final bool) *Bottom {
 		// n := d.node.getNodeContext(ctx)
 		// n.addBottom(err)
 		if c.vertex != nil && c.vertex.status != finalized {
-			n := c.vertex.getNodeContext(n.ctx, 0)
-			n.addBottom(err)
+			c.vertex.state.addBottom(err)
 			c.vertex = nil
 		}
 	}