Is it possible to use $Values for enums, without using Object.freeze?

[bluepnume]

The latest flow release shows the following example:

const Enum = Object.freeze({
  X: 'x',
  Y: 'y',
});
type EnumT = $Values<typeof Enum>
('a': EnumT); // Fails

Is it possible to do this without the run-time Object.freeze()? This raises browser-support and performance concerns.

I tried this but it didn't work:

type FrozenEnum = { +[string]: string }
const Enum : FrozenEnum = {
  X: 'x',
  Y: 'y',
};
type EnumT = $Values<typeof Enum>
('a': EnumT); // Doesn't fail but should

How can I mark the Enum as being frozen, without using Object.freeze?

[zerobias]

@bluepnume Not exactly what you want to see, but you might not need the runtime to declare something. Thanks to comment syntax this works as well

const Enum = /*::Object.freeze(*/{
  X: 'x',
  Y: 'y',
}/*::);*/
type EnumT = $Values<typeof Enum>
('a': EnumT); // Fails

[TrySound]

I guess this can be closed in favor of #627

/cc @vkurchatkin