no longer need DestroyValueReferenceTransformer

since destroy nodes are no longer connected to values, there's no need
to try and wrangle their edges to prevent cycles during destroy.

terraform/graph_builder_apply.go

@@ -171,14 +171,10 @@ func (b *ApplyGraphBuilder) Steps() []GraphTransformer {
 			Destroy: b.Destroy,
 		},
 
-		// Handle destroy time transformations for output and local values.
-		// Reverse the edges from outputs and locals, so that
-		// interpolations don't fail during destroy.
-		// Create a destroy node for outputs to remove them from the state.
 		GraphTransformIf(
 			func() bool { return b.Destroy },
 			GraphTransformMulti(
-				&DestroyValueReferenceTransformer{},
+				// Create a destroy node for outputs to remove them from the state.
 				&DestroyOutputTransformer{},
 			),
 		),

terraform/transform_destroy_edge.go

@@ -56,7 +56,6 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 	// Build a map of what is being destroyed (by address string) to
 	// the list of destroyers.
 	destroyers := make(map[string][]GraphNodeDestroyer)
-	destroyerAddrs := make(map[string]addrs.AbsResourceInstance)
 
 	// Record the creators, which will need to depend on the destroyers if they
 	// are only being updated.
@@ -79,7 +78,6 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 			key := addr.String()
 			log.Printf("[TRACE] DestroyEdgeTransformer: %q (%T) destroys %s", dag.VertexName(n), v, key)
 			destroyers[key] = append(destroyers[key], n)
-			destroyerAddrs[key] = addr
 
 			resAddr := addr.Resource.Resource.Absolute(addr.Module).String()
 			destroyersByResource[resAddr] = append(destroyersByResource[resAddr], n)

terraform/transform_reference.go

@@ -176,42 +176,6 @@ func (t AttachDependenciesTransformer) Transform(g *Graph) error {
 	return nil
 }
 
-// DestroyReferenceTransformer is a GraphTransformer that reverses the edges
-// for locals and outputs that depend on other nodes which will be
-// removed during destroy. If a destroy node is evaluated before the local or
-// output value, it will be removed from the state, and the later interpolation
-// will fail.
-type DestroyValueReferenceTransformer struct{}
-
-func (t *DestroyValueReferenceTransformer) Transform(g *Graph) error {
-	vs := g.Vertices()
-	for _, v := range vs {
-		switch v.(type) {
-		case *NodeApplyableOutput, *NodeLocal:
-			// OK
-		default:
-			continue
-		}
-
-		// reverse any outgoing edges so that the value is evaluated first.
-		for _, e := range g.EdgesFrom(v) {
-			target := e.Target()
-
-			// only destroy nodes will be evaluated in reverse
-			if _, ok := target.(GraphNodeDestroyer); !ok {
-				continue
-			}
-
-			log.Printf("[TRACE] output dep: %s", dag.VertexName(target))
-
-			g.RemoveEdge(e)
-			g.Connect(dag.BasicEdge(target, v))
-		}
-	}
-
-	return nil
-}
-
 // PruneUnusedValuesTransformer is a GraphTransformer that removes local,
 // variable, and output values which are not referenced in the graph. If these
 // values reference a resource that is no longer in the state the interpolation