Object destructing strips default values on typescript, errors on flow

Sorry for bad title, but here is something I noticed after moving some variables into an object (hence why the first bit is wrong)

const test = {
  foo = {
    bar: 'baz'
  },
  foo = [
    'bar', 'baz'
  ]
}

This object isn’t correct (foo = instead of foo:), but instead of giving an error when formatting it turns into

const test = {
  foo,
  foo,
};

[azz]

Raised this issue here: https://github.com/eslint/typescript-eslint-parser/issues/332

Seems this might be the right issue to track for flow: https://github.com/facebook/flow/issues/183 (Though it has been open since Dec 10, 2014)

[azz]

Actually TypeScript still uses ObjectLiteralExpression instead of ObjectBindingPattern in the following case:

({ foo = [] } = bar);

Prettier currently prints this as

// --parser typescript
({ foo } = bar);
// --parser babylon
({ foo = [] } = bar);
// --parser flow
SyntaxError: Unexpected token = (1:8)
> 1 | ({ foo = [] } = bar);
    |        ^

Babylon is the only one that is correct.