Compiles to invalid JS: computed class property

[helixbass]

@GeoffreyBooth I came across this while working on class AST:

This:

class A
  [b]: 3

compiles to:

var A;

A = (function() {
  class A {};

  A.prototype.[b] = 3;

  return A;

}).call(this);

which doesn't parse

Does it make sense to allow computed class properties like this?

If so, it's probably just a question of omitting the . when compiling (so here generate A.prototype[b] = 3 instead)?

Fwiw, it looks like this didn't compile (as Coffeescript source) in Coffeescript 1.x. I didn't trace when it became allowed Coffeescript syntax

[helixbass]

For the static case, it's currently inconsistent as far as allowed syntax:

# this compiles
class A
  @[b] = 3

# but this doesn't
class A
  @[b]: 3

but the version that compiles (@[b] = 3) generates valid JS it appears (A[b] = 3)

[GeoffreyBooth]

I guess it might as well compile, since we support the same for objects since #4803. That might’ve been the PR where this broke for classes.

Can we fix this on master?