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Fix false unused import warning for given CanEqual in pattern matching #25231

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Fix false unused import warning for given CanEqual in pattern matching #25231

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Add regression test for #25227: unused given import in pattern matching
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@Bbn08
Bbn08 committed Feb 19, 2026
commit 079bf8c9610f60ad4fb81e171f5675d30aef96d2
21 changes: 21 additions & 0 deletions tests/warn/i25227.scala
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//> using options -Wunused:all

import scala.language.strictEquality

object Givens:
given CanEqual[Any, Null] = CanEqual.derived
given CanEqual[Null, Any] = CanEqual.derived

object Test:
import Givens.given // no warn: used by `case null =>`

def m(value: Any): Boolean = value match
case null => true
case _ => false

object TestUnused:
import Givens.given // warn: not used here

def m(value: Any): Boolean = value match
case _: String => true
case _ => false
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