Prototype assignment should take the type of the initializer and not require a literal

This is a feature request based on actual VS customer code.

TypeScript Version: 3.9.2

Search Terms: ES5 class javascript prototype assignment constructor function

Expected behavior: In the example below, the prototype for test.class should include properties from testPrototype.

Actual behavior: Per @sandersn this pattern is recognized in the binder and only uses syntactic information, therefore does not use the type information from testPrototype .

Related Issues: #39167 from same user code. Also #33454 maybe?

Code

var test = {};
test.testPrototype = {
    add: function (i) {
    }
}

test.class = function (name) {

    function getName() {
        return name;
    }

    this.name = getName();
}

test.class.prototype = test.testPrototype; 

var t = new test.class("test");
t.name
t.add // EXPECTED: Binds to `add` from the prototype, ACTUAL: doesn't


//
// Same pattern works when a literal is assigned to the prototype:
//

var test2 = {};

test2.class = function (name) {

    function getName() {
        return name;
    }

    this.name = getName();
}

// replaced `test.testPrototype` with a literal 
test2.class.prototype = {
    add: function (i) {
    }
}; 

var t2 = new test2.class("test");
t2.name
t2.add // ACTUAL: `add` bound correctly

{
  "compilerOptions": {
    "noImplicitAny": true,
    "strictFunctionTypes": true,
    "strictPropertyInitialization": true,
    "strictBindCallApply": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "esModuleInterop": true,
    "checkJs": true,
    "allowJs": true,
    "declaration": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "moduleResolution": 2,
    "target": "ES2017",
    "jsx": "React",
    "module": "ESNext"
  }
}

Playground Link: Provided

Comienza con la reproducción proporcionada en TypeScript Playground y el comportamiento del binder descrito en el issue, comparando la asignación del prototipo del literal de objeto con la asignación de test.testPrototype. El trabajo estará terminado cuando el tipo del inicializador proporcione propiedades del prototipo, de modo que t.add se reconozca en el ejemplo, mientras el caso de literal existente siga funcionando.