fix ts 3.5 regression, Fixes #1348 (#1353)

* fix ts 3.5 regression

* further fixes

* some more improvements while at it

* code review fixes

Author: xaviergonz

packages/mobx-state-tree/src/core/mst-operations.ts

@@ -30,7 +30,8 @@ import {
     assertArg,
     assertIsValidIdentifier,
     IActionContext,
-    getRunningActionContext
+    getRunningActionContext,
+    IAnyComplexType
 } from "../internal"
 
 /** @hidden */
@@ -44,7 +45,7 @@ export type TypeOrStateTreeNodeToStateTreeNode<
  * @param object
  * @returns
  */
-export function getType(object: IAnyStateTreeNode): IAnyType {
+export function getType(object: IAnyStateTreeNode): IAnyComplexType {
     assertIsStateTreeNode(object, 1)
 
     return getStateTreeNode(object).type
@@ -380,7 +381,7 @@ export function hasParent(target: IAnyStateTreeNode, depth: number = 1): boolean
  * @param depth How far should we look upward? 1 by default.
  * @returns
  */
-export function getParent<IT extends IAnyStateTreeNode | IAnyType>(
+export function getParent<IT extends IAnyStateTreeNode | IAnyComplexType>(
     target: IAnyStateTreeNode,
     depth = 1
 ): TypeOrStateTreeNodeToStateTreeNode<IT> {
@@ -404,7 +405,7 @@ export function getParent<IT extends IAnyStateTreeNode | IAnyType>(
  * @param type
  * @returns
  */
-export function hasParentOfType(target: IAnyStateTreeNode, type: IAnyType): boolean {
+export function hasParentOfType(target: IAnyStateTreeNode, type: IAnyComplexType): boolean {
     // check all arguments
     assertIsStateTreeNode(target, 1)
     assertIsType(type, 2)
@@ -424,7 +425,7 @@ export function hasParentOfType(target: IAnyStateTreeNode, type: IAnyType): bool
  * @param type
  * @returns
  */
-export function getParentOfType<IT extends IAnyType>(
+export function getParentOfType<IT extends IAnyComplexType>(
     target: IAnyStateTreeNode,
     type: IT
 ): IT["Type"] {
@@ -449,7 +450,7 @@ export function getParentOfType<IT extends IAnyType>(
  * @param target
  * @returns
  */
-export function getRoot<IT extends IAnyType | IAnyStateTreeNode>(
+export function getRoot<IT extends IAnyComplexType | IAnyStateTreeNode>(
     target: IAnyStateTreeNode
 ): TypeOrStateTreeNodeToStateTreeNode<IT> {
     // check all arguments
@@ -523,7 +524,7 @@ export function resolvePath(target: IAnyStateTreeNode, path: string): any {
  * @param identifier
  * @returns
  */
-export function resolveIdentifier<IT extends IAnyType>(
+export function resolveIdentifier<IT extends IAnyModelType>(
     type: IT,
     target: IAnyStateTreeNode,
     identifier: ReferenceIdentifier
@@ -814,12 +815,12 @@ export interface IModelReflectionPropertiesData {
 export function getPropertyMembers(
     typeOrNode: IAnyModelType | IAnyStateTreeNode
 ): IModelReflectionPropertiesData {
-    let type
+    let type: IAnyModelType
 
     if (isStateTreeNode(typeOrNode)) {
         type = getType(typeOrNode) as IAnyModelType
     } else {
-        type = typeOrNode
+        type = typeOrNode as IAnyModelType
     }
 
     assertArg(type, t => isModelType(t), "model type or model instance", 1)

packages/mobx-state-tree/src/core/node/node-utils.ts

@@ -10,7 +10,10 @@ import {
     AnyNode,
     IAnyType,
     IType,
-    assertArg
+    assertArg,
+    STNValue,
+    Instance,
+    IAnyComplexType
 } from "../../internal"
 
 /**
@@ -52,7 +55,7 @@ export type TypeOfValue<T extends IAnyStateTreeNode> = T extends IStateTreeNode<
  * Represents any state tree node instance.
  * @hidden
  */
-export interface IAnyStateTreeNode extends IStateTreeNode<IAnyType> {}
+export interface IAnyStateTreeNode extends STNValue<any, IAnyType> {}
 
 /**
  * Returns true if the given value is a node in a state tree.
@@ -62,9 +65,9 @@ export interface IAnyStateTreeNode extends IStateTreeNode<IAnyType> {}
  * @param value
  * @returns true if the value is a state tree node.
  */
-export function isStateTreeNode<IT extends IAnyType = IAnyType>(
+export function isStateTreeNode<IT extends IAnyComplexType = IAnyComplexType>(
     value: any
-): value is IStateTreeNode<IT> {
+): value is STNValue<Instance<IT>, IT> {
     return !!(value && value.$treenode)
 }
 

packages/mobx-state-tree/src/core/type/type.ts

@@ -59,6 +59,7 @@ export enum TypeFlags {
 export const cannotDetermineSubtype = "cannotDetermine"
 
 /**
+ * A state tree node value.
  * @hidden
  */
 export type STNValue<T, IT extends IAnyType> = T extends object ? T & IStateTreeNode<IT> : T