-Wunused gives false positives for generator value with a guard

[rochala]

Compiler version

3.3.1-RC1-bin-20230213-8c616bf-NIGHTLY

Minimized code

//> using scala "3.3.1-RC1-bin-20230213-8c616bf-NIGHTLY"
//> using options "-Wunused:all"

@main
def hello =
  for {
    i <- 1 to 2 if true
    _ = println(i)
  } yield ()

Output

Compiling project (Scala 3.3.1-RC1-bin-20230213-8c616bf-NIGHTLY, JVM)
[warn] ./src/scala3/FileA.scala:8:5: unused local definition
[warn]     i <- 1 to 2 if true
[warn]     ^

Expectation

Don't report i as unused local definition

[KacperFKorban]

This is due to the fact that a for like

for {
  i <- 1.to(2)
  if true
} yield i

will be desugared to

1.to(2).withFilter { i =>
  true
}.map { i =>
  i
}

So i in the withFilter call is unused.