Type pattern not widening scrutinee type

[EugeneFlesselle]

Compiler version

3.5.1-RC1-bin-SNAPSHOT-nonbootstrapped-git-cd8c5ed

Minimized code

Minimized from i7294.scala with @hamzaremmal

object Test:

  trait Foo:
    val x: Any

  ??? match
    case f: Foo =>
      (f: Foo).x // ok
      f.x // error

Output

-- [E007] Type Mismatch Error: tests/playground/example.scala:11:6 -------------
11 |      f.x // error
   |      ^
   |Found:    (f : Nothing)
   |Required: ?{ x: ? }
   |Note that implicit conversions were not tried because the result of an implicit conversion
   |must be more specific than ?{ x: <?> }

Expectation

no error

[EugeneFlesselle]

Actually not sure this is an error since the following is accepted:

(??? : Option[Int]) match
    case a: Any => a.get

[hamzaremmal]

Note that this is the behavior under the -source 3.6

[odersky]

It's because ??? has type Nothing, so the pattern has type Nothing as well. We use what we know from the scrutinee and from the pattern to type the pattern, so this looks as expected.

[dwijnand]

I agree.