Merge pull request #21711 from hashicorp/jbardin/upgrade-blocks

Ensure all object attrs & empty blocks in upgrade

helper/plugin/grpc_provider.go

@@ -15,6 +15,7 @@ import (
 	"github.com/hashicorp/terraform/configs/configschema"
 	"github.com/hashicorp/terraform/helper/schema"
 	proto "github.com/hashicorp/terraform/internal/tfplugin5"
+	"github.com/hashicorp/terraform/plans/objchange"
 	"github.com/hashicorp/terraform/plugin/convert"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -283,6 +284,17 @@ func (s *GRPCProviderServer) UpgradeResourceState(_ context.Context, req *proto.
 		return resp, nil
 	}
 
+	// Now we need to make sure blocks are represented correctly, which means
+	// that missing blocks are empty collections, rather than null.
+	// First we need to CoerceValue to ensure that all object types match.
+	val, err = schemaBlock.CoerceValue(val)
+	if err != nil {
+		resp.Diagnostics = convert.AppendProtoDiag(resp.Diagnostics, err)
+		return resp, nil
+	}
+	// Normalize the value and fill in any missing blocks.
+	val = objchange.NormalizeObjectFromLegacySDK(val, schemaBlock)
+
 	// encode the final state to the expected msgpack format
 	newStateMP, err := msgpack.Marshal(val, schemaBlock.ImpliedType())
 	if err != nil {

helper/plugin/grpc_provider_test.go

@@ -262,6 +262,18 @@ func TestUpgradeState_flatmapState(t *testing.T) {
 				Type:     schema.TypeInt,
 				Required: true,
 			},
+			"block": {
+				Type:     schema.TypeList,
+				Optional: true,
+				Elem: &schema.Resource{
+					Schema: map[string]*schema.Schema{
+						"attr": {
+							Type:     schema.TypeString,
+							Optional: true,
+						},
+					},
+				},
+			},
 		},
 		// this MigrateState will take the state to version 2
 		MigrateState: func(v int, is *terraform.InstanceState, _ interface{}) (*terraform.InstanceState, error) {
@@ -426,8 +438,9 @@ func TestUpgradeState_flatmapState(t *testing.T) {
 			}
 
 			expected := cty.ObjectVal(map[string]cty.Value{
-				"id":   cty.StringVal("bar"),
-				"four": cty.NumberIntVal(4),
+				"block": cty.ListValEmpty(cty.Object(map[string]cty.Type{"attr": cty.String})),
+				"id":    cty.StringVal("bar"),
+				"four":  cty.NumberIntVal(4),
 			})
 
 			if !cmp.Equal(expected, val, valueComparer, equateEmpty) {