P.select() failing to extract any type, but succeeds for all other types

[drazik]

Describe the bug

While trying to use @swan-io/boxed integration with ts-pattern, I found a case in which P.select() should extract an any value, but instead returns a parent level data structure type. This only occurs if the "selected" value is of type any. In other cases, the guessed type is OK.

You can see the original discussion on @swan-io/boxed repo, but here is the most important part:

My problem is on the line 28. I am trying to extract the Result.Ok value using P.select(), but the compiler says that this is the Result.Ok itself, instead of the value it holds.

TypeScript playground with a minimal reproduction case

Example with error: Playground

Example without error: Playground

Versions

• TypeScript version: 5.7.2
• ts-pattern version: 5.5.0
• environment: Node v22.11.0