private class property is unprotected if key is numeric

[pushkine]

Bug Report

🕗 Version & Regression Information

ts stable & nightly

⏯ Playground Link

Playground Link

💻 Code

class Foo {
	private readonly r1337 = 1337;
	private readonly 1337 = 1337;
}

const foo = new Foo();

foo.r1337 = 
  foo.r1337 + 1;

foo[1337] = 
  foo[1337] + 1;

🙁 Actual behavior

foo.r1337 = 
//  ^^^^^        ERROR: Cannot assign to 'r1337' because it is a read-only property.
  foo.r1337 + 1;
//    ^^^^^      ERROR: Property 'r1337' is private and only accessible within class 'Foo'.

foo[1337] = 
//  ^^^^         ERROR: Cannot assign to  '1337' because it is a read-only property.
  foo[1337] + 1;
//    ^^^^       (No error)

Writing foo[1337] is denied because it is a readonly class property.
Reading foo[1337] is allowed although it is a private class property.

🙂 Expected behavior

foo[1337] = 
//  ^^^^         Cannot assign to '1337' because it is a read-only property.
  foo[1337] + 1;
//    ^^^^       ERROR: Property  '1337' is private and only accessible within class 'Foo'.

Reading foo[1337] throws an error because it is a private class property.

[whzx5byb]

This is an intended behavior. See #19335.

[pushkine]

This is an intended behavior. See #19335.

I am aware of how the indexed access notation works, this issue is specifically about numeric properties.

I believe that the computed property notation is an escape hatch. It is not intended to forbid class properties from using the privacy feature when their key is numeric.

A numeric property can only be accessed using the bracket notation. I am not opting-in to the indexed access, I'm not accessing it using foo[i] or foo["1337"] . I declared it using a bracket-less notation private 1337 = 1337;, not private "1337" or private [1337]. I did all that in a class without indexed properties and I tried using every related compiler option under the sun. Still that property won't be private. I do not think that forbidding numeric keys from being private is intended.

[whzx5byb]

A numeric property can only be accessed using the bracket notation.

Here is the limitation: Any property access inside square brackets will ignore protected or private modifiers. The compiler doesn't distinguish between foo[i] and foo["1337"] and foo[1337].

[pushkine]

The fact that Typescript allows making that property private, but actually never enforces its privacy is a bug.

It should either not allow privacy modifiers on numeric properties because they're defacto not supported or it should enforce privacy when accessing that property.

[RyanCavanaugh]

It should either not allow privacy modifiers on numeric properties because they're defacto not supported or it should enforce privacy when accessing that property.

Numeric names are certainly very rare and breaking someone's program on purpose to fix the perceived inconsistency doesn't seem like a great trade-off here.

[parzhitsky]

As came up in #60974 (comment), symbol keys also suffer from the same thing. My intuition is that they are much more widely used than numeric keys. Do we have the same policy for them as well?