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Class property inference from constructor does not work with private class fields #39960

@lazytype

Description

@lazytype

TypeScript Version: 4.0.0-dev.20200803

Search Terms: class property inference, private class fields

Expected behavior: private class field's type is inferred from its assignment in the constructor

Actual behavior: typechecker reports implicit any for private class field

Related Issues:

Code

class Example {
  #test;

  constructor(test: number) {
    this.#test = test;
  }

  get test() {
    return this.#test
  }
}
Output
"use strict";
var __classPrivateFieldSet = (this && this.__classPrivateFieldSet) || function (receiver, privateMap, value) {
    if (!privateMap.has(receiver)) {
        throw new TypeError("attempted to set private field on non-instance");
    }
    privateMap.set(receiver, value);
    return value;
};
var __classPrivateFieldGet = (this && this.__classPrivateFieldGet) || function (receiver, privateMap) {
    if (!privateMap.has(receiver)) {
        throw new TypeError("attempted to get private field on non-instance");
    }
    return privateMap.get(receiver);
};
var _test;
class Example {
    constructor(test) {
        _test.set(this, void 0);
        __classPrivateFieldSet(this, _test, test);
    }
    get test() {
        return __classPrivateFieldGet(this, _test);
    }
}
_test = new WeakMap();
Compiler Options
{
  "compilerOptions": {
    "noImplicitAny": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "strictPropertyInitialization": true,
    "strictBindCallApply": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "esModuleInterop": true,
    "declaration": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "moduleResolution": 2,
    "target": "ES2017",
    "jsx": "React",
    "module": "ESNext"
  }
}

Playground Link: Provided

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