use SimpleDiff and set "id" as RequiresReplace

Use the new SimpleDiff method of the provider so that the diff isn't
altered by ForceNew attributes.

Always set an "id" as RequiresReplace so core knows an instance will be
replaced, even if all ForceNew attributes are filtered out due to
ignore_changes.

helper/plugin/grpc_provider.go

@@ -402,7 +402,7 @@ func (s *GRPCProviderServer) PlanResourceChange(_ context.Context, req *proto.Pl
 	// turn the propsed state into a legacy configuration
 	config := terraform.NewResourceConfigShimmed(proposedNewStateVal, block)
 
-	diff, err := s.provider.Diff(info, priorState, config)
+	diff, err := s.provider.SimpleDiff(info, priorState, config)
 	if err != nil {
 		resp.Diagnostics = convert.AppendProtoDiag(resp.Diagnostics, err)
 		return resp, nil
@@ -450,6 +450,15 @@ func (s *GRPCProviderServer) PlanResourceChange(_ context.Context, req *proto.Pl
 		}
 	}
 
+	// If anything requires a new resource already, or the "id" field indicates
+	// that we will be creating a new resource, then we need to add that to
+	// RequiresReplace so that core can tell if the instance is being replaced
+	// even if changes are being suppressed via "ignore_changes".
+	id := plannedStateVal.GetAttr("id")
+	if len(requiresNew) > 0 || id.IsNull() || !id.IsKnown() {
+		requiresNew = append(requiresNew, "id")
+	}
+
 	requiresReplace, err := hcl2shim.RequiresReplace(requiresNew, block.ImpliedType())
 	if err != nil {
 		resp.Diagnostics = convert.AppendProtoDiag(resp.Diagnostics, err)

helper/resource/state_shim.go

@@ -25,6 +25,11 @@ func mustShimNewState(newState *states.State, schemas *terraform.Schemas) *terra
 func shimNewState(newState *states.State, schemas *terraform.Schemas) (*terraform.State, error) {
 	state := terraform.NewState()
 
+	// in the odd case of a nil state, let the helper packages handle it
+	if newState == nil {
+		return nil, nil
+	}
+
 	for _, newMod := range newState.Modules {
 		mod := state.AddModule(newMod.Addr)
 

helper/schema/shims_test.go

@@ -2023,12 +2023,6 @@ func TestShimSchemaMap_Diff(t *testing.T) {
 						New:         "foo",
 						RequiresNew: true,
 					},
-
-					// "address": &terraform.ResourceAttrDiff{
-					// 	Old:         "foo",
-					// 	New:         "",
-					// 	NewComputed: true,
-					// },
 				},
 			},
 
@@ -2074,12 +2068,6 @@ func TestShimSchemaMap_Diff(t *testing.T) {
 						New:         "foo",
 						RequiresNew: true,
 					},
-
-					// "ports.#": &terraform.ResourceAttrDiff{
-					// 	Old:         "1",
-					// 	New:         "",
-					// 	NewComputed: true,
-					// },
 				},
 			},