plugin: Use correct schema when marshaling imported resource objects

Previously we were using the type name requested in the import to select
the schema, but a provider is free to return additional objects of other
types as part of an import result, and so it's important that we perform
schema selection separately for each returned object.

If we don't do this, we get confusing downstream errors where the
resulting object decodes to the wrong type and breaks various invariants
expected by Terraform Core.

The testResourceImportOther test in the test provider didn't catch this
previously because it happened to have an identical schema to the other
resource type being imported. Now the schema is changed and also there's
a computed attribute we can set as part of the refresh phase to make sure
we're completing the Read call properly during import. Refresh was working
correctly, but we didn't have any tests for it as part of the import flow.

builtin/providers/test/resource_import_other.go

@@ -1,6 +1,8 @@
 package test
 
 import (
+	"fmt"
+
 	"github.com/hashicorp/terraform/helper/schema"
 )
 
@@ -26,23 +28,9 @@ func testResourceImportOther() *schema.Resource {
 				Optional: true,
 				Default:  true,
 			},
-			"nested": {
+			"computed": {
-				Type:     schema.TypeSet,
-				Optional: true,
-				ForceNew: true,
-				Elem: &schema.Resource{
-					Schema: map[string]*schema.Schema{
-						"string": {
 				Type:     schema.TypeString,
-							Optional: true,
+				Computed: true,
-							Default:  "default nested",
-						},
-						"optional": {
-							Type:     schema.TypeString,
-							Optional: true,
-						},
-					},
-				},
 			},
 		},
 	}
@@ -74,10 +62,13 @@ func testResourceImportOtherUpdate(d *schema.ResourceData, meta interface{}) err
 }
 
 func testResourceImportOtherRead(d *schema.ResourceData, meta interface{}) error {
+	err := d.Set("computed", "hello!")
+	if err != nil {
+		return fmt.Errorf("failed to set 'computed' attribute: %s", err)
+	}
 	return nil
 }
 
 func testResourceImportOtherDelete(d *schema.ResourceData, meta interface{}) error {
-	d.SetId("")
 	return nil
 }

builtin/providers/test/resource_import_other_test.go

@@ -38,6 +38,8 @@ resource "test_resource_import_other" "foo" {
 						return fmt.Errorf("no instance with id import_other_main in state")
 					} else if got, want := is.Ephemeral.Type, "test_resource_import_other"; got != want {
 						return fmt.Errorf("import_other_main has wrong type %q; want %q", got, want)
+					} else if got, want := is.Attributes["computed"], "hello!"; got != want {
+						return fmt.Errorf("import_other_main has wrong value %q for its computed attribute; want %q", got, want)
 					}
 					if is, ok := byID["import_other_other"]; !ok {
 						return fmt.Errorf("no instance with id import_other_other in state")

helper/plugin/grpc_provider.go

@@ -794,8 +794,6 @@ func (s *GRPCProviderServer) ApplyResourceChange(_ context.Context, req *proto.A
 func (s *GRPCProviderServer) ImportResourceState(_ context.Context, req *proto.ImportResourceState_Request) (*proto.ImportResourceState_Response, error) {
 	resp := &proto.ImportResourceState_Response{}
 
-	block := s.getResourceSchemaBlock(req.TypeName)
-
 	info := &terraform.InstanceInfo{
 		Type: req.TypeName,
 	}
@@ -810,6 +808,12 @@ func (s *GRPCProviderServer) ImportResourceState(_ context.Context, req *proto.I
 		// copy the ID again just to be sure it wasn't missed
 		is.Attributes["id"] = is.ID
 
+		resourceType := is.Ephemeral.Type
+		if resourceType == "" {
+			resourceType = req.TypeName
+		}
+
+		block := s.getResourceSchemaBlock(resourceType)
 		newStateVal, err := hcl2shim.HCL2ValueFromFlatmap(is.Attributes, block.ImpliedType())
 		if err != nil {
 			resp.Diagnostics = convert.AppendProtoDiag(resp.Diagnostics, err)
@@ -828,11 +832,6 @@ func (s *GRPCProviderServer) ImportResourceState(_ context.Context, req *proto.I
 			return resp, nil
 		}
 
-		resourceType := is.Ephemeral.Type
-		if resourceType == "" {
-			resourceType = req.TypeName
-		}
-
 		importedResource := &proto.ImportResourceState_ImportedResource{
 			TypeName: resourceType,
 			State: &proto.DynamicValue{

plugin/grpc_provider.go

@@ -459,8 +459,6 @@ func (p *GRPCProvider) ApplyResourceChange(r providers.ApplyResourceChangeReques
 func (p *GRPCProvider) ImportResourceState(r providers.ImportResourceStateRequest) (resp providers.ImportResourceStateResponse) {
 	log.Printf("[TRACE] GRPCProvider: ImportResourceState")
 
-	resSchema := p.getResourceSchema(r.TypeName)
-
 	protoReq := &proto.ImportResourceState_Request{
 		TypeName: r.TypeName,
 		Id:       r.ID,
@@ -479,6 +477,7 @@ func (p *GRPCProvider) ImportResourceState(r providers.ImportResourceStateReques
 			Private:  imported.Private,
 		}
 
+		resSchema := p.getResourceSchema(resource.TypeName)
 		state := cty.NullVal(resSchema.Block.ImpliedType())
 		if imported.State != nil {
 			state, err = msgpack.Unmarshal(imported.State.Msgpack, resSchema.Block.ImpliedType())