Conditional type on enum is not inferring type in switch statement

[allevaton]

TypeScript Version: 3.5.0-dev.20190515

Search Terms: conditional type, enum, value, switch, inference

Code

I have a conditional type mapping an enum descriptor to real types:

export type PropertyDataToValue<T extends Forge.PropertyData>
  = T extends Forge.PropertyData.NONE ? null | undefined
  : T extends Forge.PropertyData.BoolProperty ? boolean
  : T extends Forge.PropertyData.FloatProperty ? number
  : T extends Forge.PropertyData.IntegerProperty ? number
  : T extends Forge.PropertyData.UnsignedIntegerProperty ? number
  : T extends Forge.PropertyData.StringProperty ? string
  : T extends Forge.PropertyData.Vector3Property ? Vector3
  : T extends Forge.PropertyData.Vector4Property ? Vector4
  : never;

Later, I want to switch on property data types, like so:

function valueToPropertyData<T extends Forge.PropertyData>(
  propertyType: T,
  value: PropertyDataToValue<T>,
) {
  switch (propertyType) {
    case Forge.PropertyData.StringProperty:
      // Here: `value` is of type PropertyDataToValue<T>
      return;
  }
}

Expected behavior:
In the "case", I'd expect value to be inferred as a string type. Similarly for each conditional type.

Actual behavior:

In the "case", value is of type PropertyDataToValue

Playground Link:

Playground URL

Related Issues:

I found this that seems related, but not quite: #23578

[jack-williams]

Duplicate of #24085

[allevaton]

Duplicate of #24085

Thanks for finding that, I'll close this.