Three bugs caught by FindBugs

[sir-wabbit]

Using pointer equality to compare different types

val receiverIsSuper = (method.name eq sym) && enclosingClass.appliedRef.widen <:< recvWiden

on line 276 in dotty.tools.dotc.transform.TailRec

Self comparison of value with itself

  private class Set3[+Elem <: AnyRef](x0: AnyRef, x1: AnyRef, x2: AnyRef) extends SimpleIdentitySet[Elem] {
    def size = 3
    def + [E >: Elem <: AnyRef](x: E): SimpleIdentitySet[E] =
      if (contains(this)) this // <---- WAT
      else {

on line 62 of dotty.tools.dotc.util.SimpleIdentitySet

Method ignores return value

    val boundsText = domainLambdas
      " bounds = " + {
        val assocs =
          for (param <- domainParams)
          yield
            param.binder.paramNames(param.paramNum) + ": " + entryText(entry(param))
        assocs.mkString("\n")
    }

in dotty.tools.dotc.core.OrderingConstraint, line 639

[allanrenucci]

val receiverIsSuper = (method.name eq sym) && enclosingClass.appliedRef.widen <:< recvWiden

It should be method.name == sym.name.

However the current implementation is very inconsistent. With the fix you would get one error for:

class Foo {
  def foo = 1
}

class Test extends Foo {
  @tailrec
  final override def foo = super.foo // error
}

and two errors for:

class Foo {
  def foo() = 1
}

class Test extends Foo {
  @tailrec
  final override def foo() = super.foo() // error // error
}

[allanrenucci]

in dotty.tools.dotc.core.OrderingConstraint, line 639

Should probably be:

    val boundsText =
      " bounds = " + {
        val assocs =
          for (param <- domainParams)
          yield
            param.binder.paramNames(param.paramNum) + ": " + entryText(entry(param))
        assocs.mkString("\n")
    }

[smarter]

All three bugs have been fixed.