"never used" warning in for comprehension with filter even though variable is used

[gaeljw]

reproduction steps

Using Scala 2.12.11 (with Ywarn-unused... and -Xfatal-warnings flags),

def getA(): Future[String] = ???
def getB(a: String): Future[Int] = ???

for {
  a <- getA() if a == "foo"
  b <- getB(a) if b == 0
} yield a

Error:(28, 7) parameter value b in value $anonfun is never used
      b <- getB(a) if b == 0

problem

Hi

I believe the above piece of code which triggers the "never used" warning should not.
Am I right or am I missing something?

I didn't try on 2.13 yet.

[SethTisue]

duplicate of #11175 which we consolidated under #10287