move InstanceState shim into schema.Resource

This was the resource can rebuild the flatmapped state using the
schema and ResourceData, providing us the the correct set key values.

helper/schema/resource.go

@@ -155,6 +155,27 @@ type Resource struct {
 	Timeouts *ResourceTimeout
 }
 
+// ShimInstanceStateFromValue converts a cty.Value to a
+// terraform.InstanceState.
+func (r *Resource) ShimInstanceStateFromValue(state cty.Value) (*terraform.InstanceState, error) {
+	// Get the raw shimmed value. While this is correct, the set hashes don't
+	// match those from the Schema.
+	s := terraform.NewInstanceStateShimmedFromValue(state, r.SchemaVersion)
+
+	// We now rebuild the state through the ResourceData, so that the set indexes
+	// match what helper/schema expects.
+	data, err := schemaMap(r.Schema).Data(s, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	s = data.State()
+	if s == nil {
+		s = &terraform.InstanceState{}
+	}
+	return s, nil
+}
+
 // See Resource documentation.
 type CreateFunc func(*ResourceData, interface{}) error
 
@@ -550,8 +571,7 @@ func (r *Resource) upgradeState(s *terraform.InstanceState, meta interface{}) (*
 		return nil, err
 	}
 
-	s = InstanceStateFromStateValue(stateVal, r.SchemaVersion)
-	return s, nil
+	return r.ShimInstanceStateFromValue(stateVal)
 }
 
 // InternalValidate should be called to validate the structure

helper/schema/shims.go

@@ -23,7 +23,7 @@ func DiffFromValues(prior, planned cty.Value, res *Resource) (*terraform.Instanc
 // only needs to be created for the apply operation, and any customizations
 // have already been done.
 func diffFromValues(prior, planned cty.Value, res *Resource, cust CustomizeDiffFunc) (*terraform.InstanceDiff, error) {
-	instanceState := InstanceStateFromStateValue(prior, res.SchemaVersion)
+	instanceState := terraform.NewInstanceStateShimmedFromValue(prior, res.SchemaVersion)
 
 	configSchema := res.CoreConfigSchema()
 
@@ -85,11 +85,3 @@ func JSONMapToStateValue(m map[string]interface{}, block *configschema.Block) (c
 func StateValueFromInstanceState(is *terraform.InstanceState, ty cty.Type) (cty.Value, error) {
 	return is.AttrsAsObjectValue(ty)
 }
-
-// InstanceStateFromStateValue converts a cty.Value to a
-// terraform.InstanceState. This function requires the schema version used by
-// the provider, because the legacy providers used the private Meta data in the
-// InstanceState to store the schema version.
-func InstanceStateFromStateValue(state cty.Value, schemaVersion int) *terraform.InstanceState {
-	return terraform.NewInstanceStateShimmedFromValue(state, schemaVersion)
-}