Wunused:imports false positive, wrong import scope

[gaelrenoux]

Compiler version

3.5.2

Minimized code

import Dog.Owner

class Dog(owner: Owner) {
  import Dog.*
  
  val getOwner: Owner = owner
}

object Dog {
  class Owner
}

Output

[warn] -- [E198] Unused Symbol Warning: /home/gael/Repositories/Gael/bug-reproduction/import-failure/src/main/scala/Dog.scala:1:11 
[warn] 1 |import Dog.Owner
[warn]   |           ^^^^^
[warn]   |           unused import
[warn] one warning found

Expectation

Import should not be reported. Removing the import makes the compilation fail, as expected. Removing the internal import import Dog.* makes the message disappear.

[som-snytt]

The "inner" import may be deemed unused; it is not ambiguous because it resolves the same symbol as the "outer" import.

In the PR, there are no nesting levels, so it picks the highest precedence binding, assuming correctness.

(An inner import Car.* would be erroneous, for example.)

Scala 2 does not warn because the compiler marks the inner import as used after reconciling with the outer import.