JSDoc: Support @readonly tag

[ghost]

TypeScript Version: nightly (2.5.0-dev.20170712)

Code

class C {
	constructor() {
		/**
		 * @readonly
		 * @type {number}
		 */
		this.x = 0;
	}

	m() {
		this.x = "1"; // Error
		this.x = 1; // No error
	}
}

Expected behavior:

Both lines in m are errors.

Actual behavior:

No error when trying to write to @readonly property.

[niedzielski]

This would be awesome! There's already support for Readonly and readonly in JSDoc closure syntax. E.g.:

/** 
 * @typedef {Readonly<{
 *   foo: ReadonlyArray<Foo>
 *   bar: number
 * }>} Baz
 */

/**
 * @typedef {{
 *   readonly foo: ReadonlyArray<Foo>
 *   readonly bar: number
 * }} Baz
 */

Both of the above examples work as expected. However, resolving this ticket would enable readonly support for member properties too:

/**
 * @typedef {Object} Baz
 * @prop {ReadonlyArray<Foo>} foo This syntax supports comments.
 * @prop {number} bar But there's no support for marking properties as @readonly.
 */