mixin generics fix

OMG what a nightmare
A time sink

microsoft/TypeScript#32080

Author: ShaMan123

src/mixins/collection.mixin.ts

@@ -1,7 +1,6 @@
 import { fabric } from '../../HEADER';
 import { FabricObject } from '../shapes/fabricObject.class';
-
-type Constructor<T = object> = new (...args: any[]) => T;
+import { Constructor } from '../typedefs';
 
 export function createCollectionMixin<TBase extends Constructor>(Base: TBase) {
   class Collection extends Base {
@@ -155,6 +154,7 @@ export function createCollectionMixin<TBase extends Constructor>(Base: TBase) {
     }
   }
 
+  // https://github.com/microsoft/TypeScript/issues/32080
   return Collection as typeof Collection & TBase;
 }
 

src/typedefs.ts

@@ -15,6 +15,9 @@ type TNonFunctionPropertyNames<T> = {
 }[keyof T];
 export type TClassProperties<T> = Pick<T, TNonFunctionPropertyNames<T>>;
 
+// https://github.com/microsoft/TypeScript/issues/32080
+export type Constructor<T = object> = new (...args: any[]) => T;
+
 const enum Degree {}
 const enum Radian {}
 

src/util/applyMixins.ts

@@ -1,9 +1,9 @@
-type TClass = { new (...args: any[]): any };
+import { Constructor } from '../typedefs';
 
 /***
  * https://www.typescriptlang.org/docs/handbook/mixins.html#alternative-pattern
  */
-export function applyMixins<T extends TClass, S extends TClass>(
+export function applyMixins<T extends Constructor, S extends Constructor>(
   derivedCtor: T,
   constructors: S[]
 ) {
@@ -18,5 +18,5 @@ export function applyMixins<T extends TClass, S extends TClass>(
         );
     });
   });
-  return derivedCtor;
+  return derivedCtor as T & { prototype: InstanceType<T & S> };
 }