core: Always set ProviderAddr on EvalDiffDestroy

If we don't set it, we end up creating an invalid plan where the destroy
changes don't have a provider address set, which then later fails
decoding when round-tripped through a planfile.

This also includes some extra safety checks in EvalDiff and
EvalDiffDestroy so that we can catch this bug sooner in future.

This change is verified by
TestContext2Apply_plannedDestroyInterpolatedCount, which is now passing.

terraform/eval_diff.go

@@ -123,6 +123,9 @@ func (n *EvalDiff) Eval(ctx EvalContext) (interface{}, error) {
 	if providerSchema == nil {
 		return nil, fmt.Errorf("provider schema is unavailable for %s", n.Addr)
 	}
+	if n.ProviderAddr.ProviderConfig.Type == "" {
+		panic(fmt.Sprintf("EvalDiff for %s does not have ProviderAddr set", n.Addr.Absolute(ctx.Path())))
+	}
 
 	var diags tfdiags.Diagnostics
 
@@ -707,6 +710,14 @@ func (n *EvalDiffDestroy) Eval(ctx EvalContext) (interface{}, error) {
 	absAddr := n.Addr.Absolute(ctx.Path())
 	state := *n.State
 
+	if n.ProviderAddr.ProviderConfig.Type == "" {
+		if n.DeposedKey == "" {
+			panic(fmt.Sprintf("EvalDiffDestroy for %s does not have ProviderAddr set", absAddr))
+		} else {
+			panic(fmt.Sprintf("EvalDiffDestroy for %s (deposed %s) does not have ProviderAddr set", absAddr, n.DeposedKey))
+		}
+	}
+
 	// If there is no state or our attributes object is null then we're already
 	// destroyed.
 	if state == nil || state.Value.IsNull() {

terraform/node_resource_destroy_deposed.go

@@ -131,10 +131,11 @@ func (n *NodePlanDeposedResourceInstanceObject) EvalTree() EvalNode {
 					ProviderSchema: &providerSchema,
 				},
 				&EvalDiffDestroy{
-					Addr:       addr.Resource,
-					DeposedKey: n.DeposedKey,
-					State:      &state,
-					Output:     &change,
+					Addr:         addr.Resource,
+					ProviderAddr: n.ResolvedProvider,
+					DeposedKey:   n.DeposedKey,
+					State:        &state,
+					Output:       &change,
 				},
 				&EvalWriteDiff{
 					Addr:           addr.Resource,
@@ -244,9 +245,10 @@ func (n *NodeDestroyDeposedResourceInstanceObject) EvalTree() EvalNode {
 				ProviderSchema: &providerSchema,
 			},
 			&EvalDiffDestroy{
-				Addr:   addr.Resource,
-				State:  &state,
-				Output: &change,
+				Addr:         addr.Resource,
+				ProviderAddr: n.ResolvedProvider,
+				State:        &state,
+				Output:       &change,
 			},
 			// Call pre-apply hook
 			&EvalApplyPre{

terraform/node_resource_plan_destroy.go

@@ -68,9 +68,10 @@ func (n *NodePlanDestroyableResourceInstance) EvalTree() EvalNode {
 				Output: &state,
 			},
 			&EvalDiffDestroy{
-				Addr:   addr.Resource,
-				State:  &state,
-				Output: &change,
+				Addr:         addr.Resource,
+				ProviderAddr: n.ResolvedProvider,
+				State:        &state,
+				Output:       &change,
 			},
 			&EvalCheckPreventDestroy{
 				Addr:   addr.Resource,