Read orphaned resources during plan

This forces orphaned resources to be re-read during planning, removing
them from the state if they no longer exist.

This needs to be done for a bare `refresh` execution, since Terraform
should remove instances that don't exist and are not in the
configuration from the state. They should also be removed from state so
there is no Delete change planned, as not all providers will gracefully
handle a delete operation on a resource that does not exist.

terraform/graph_builder_plan.go

@@ -191,6 +191,7 @@ func (b *PlanGraphBuilder) init() {
 	b.ConcreteResourceOrphan = func(a *NodeAbstractResourceInstance) dag.Vertex {
 		return &NodePlannableResourceInstanceOrphan{
 			NodeAbstractResourceInstance: a,
+			skipRefresh:                  b.skipRefresh,
 		}
 	}
 }

terraform/node_resource_plan_orphan.go

@@ -9,6 +9,8 @@ import (
 // it is ready to be applied and is represented by a diff.
 type NodePlannableResourceInstanceOrphan struct {
 	*NodeAbstractResourceInstance
+
+	skipRefresh bool
 }
 
 var (
@@ -35,7 +37,7 @@ func (n *NodePlannableResourceInstanceOrphan) Execute(ctx EvalContext, op walkOp
 	var change *plans.ResourceInstanceChange
 	var state *states.ResourceInstanceObject
 
-	_, providerSchema, err := GetProvider(ctx, n.ResolvedProvider)
+	provider, providerSchema, err := GetProvider(ctx, n.ResolvedProvider)
 	if err != nil {
 		return err
 	}
@@ -45,6 +47,40 @@ func (n *NodePlannableResourceInstanceOrphan) Execute(ctx EvalContext, op walkOp
 		return err
 	}
 
+	if !n.skipRefresh {
+		// Refresh this instance even though it is going to be destroyed, in
+		// order to catch missing resources. If this is a normal plan,
+		// providers expect a Read request to remove missing resources from the
+		// plan before apply, and may not handle a missing resource during
+		// Delete correctly.  If this is a simple refresh, Terraform is
+		// expected to remove the missing resource from the state entirely
+		refresh := &EvalRefresh{
+			Addr:           addr.Resource,
+			ProviderAddr:   n.ResolvedProvider,
+			Provider:       &provider,
+			ProviderMetas:  n.ProviderMetas,
+			ProviderSchema: &providerSchema,
+			State:          &state,
+			Output:         &state,
+		}
+		_, err = refresh.Eval(ctx)
+		if err != nil {
+			return err
+		}
+
+		writeRefreshState := &EvalWriteState{
+			Addr:           addr.Resource,
+			ProviderAddr:   n.ResolvedProvider,
+			ProviderSchema: &providerSchema,
+			State:          &state,
+			targetState:    refreshState,
+		}
+		_, err = writeRefreshState.Eval(ctx)
+		if err != nil {
+			return err
+		}
+	}
+
 	diffDestroy := &EvalDiffDestroy{
 		Addr:         addr.Resource,
 		State:        &state,