Off by one error in properties with underscore prefix

[DylanRJohnston]

interface Foo {
  _brand: 'Foo' // One underscore
}

interface Bar {
  __brand: 'Bar' // Two underscores
}

interface Baz {
  ___brand: 'Baz' // Three underscores
}

type FooBrand1 = Foo['_brand']

type BarBrand2 = Bar['__brand'] // [ts] Property '__brand' does not exist on type 'Bar'.
type BarBrand3 = Bar['___brand']

type BazBrand3 = Baz['___brand'] // [ts] Property '___brand' does not exist on type 'Baz'.
type BazBrand4 = Baz['____brand']

[j-oliveras]

Duplicate of #15334 or maybe related. You can try with typescript@next if is resolved.

[DylanRJohnston]

Yep, sorry for the dupe ticket, closing.