AbstractMethodError due to RenameLifted renaming trait setter implementations

[xuwei-k]

Compiler version

3.0.2-RC1-bin-20210609-fdbb94f-NIGHTLY, 3.0.1-RC1 and 3.0.0

Minimized code

package example

class A1
class A2
class A3

class TypeClass[A](val value: A)

object TypeClass {
  def apply[A](implicit a: TypeClass[A]): TypeClass[A] = a

  def get2[X1: TypeClass, X2: TypeClass]: (X1, X2) = {
    (TypeClass[X1].value, TypeClass[X2].value)
  }

  def get3[X1: TypeClass, X2: TypeClass, X3: TypeClass]: (X1, X2, X3) = {
    (TypeClass[X1].value, TypeClass[X2].value, TypeClass[X3].value)
  }

  implicit def a1: TypeClass[A1] = new TypeClass[A1](new A1)
  implicit def a2: TypeClass[A2] = new TypeClass[A2](new A2)
  implicit def a3: TypeClass[A3] = new TypeClass[A3](new A3)
}

trait Foo {

  val (a2, a3) = TypeClass.get2[A2, A3]

  val (x1, x2, x3) = TypeClass.get3[A1, A2, A3]

}

object Main {
  def main(args: Array[String]): Unit = {
    new Foo {}
  }
}

Output

[error] (run-main-11) java.lang.AbstractMethodError: example.Main$$anon$1.example$Foo$_setter_$example$Foo$$$1_$eq(Lscala/Tuple2;)V
[error] java.lang.AbstractMethodError: example.Main$$anon$1.example$Foo$_setter_$example$Foo$$$1_$eq(Lscala/Tuple2;)V
[error] 	at example.Foo.$init$(Main.scala:27)
[error] 	at example.Main$$anon$1.<init>(Main.scala:35)
[error] 	at example.Main$.main(Main.scala:35)
[error] 	at example.Main.main(Main.scala)
[error] 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error] 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[error] 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error] 	at java.lang.reflect.Method.invoke(Method.java:498)
[error] stack trace is suppressed; run last Compile / bgRun for the full output
[error] Nonzero exit code: 1
[error] (Compile / run) Nonzero exit code: 1

Expectation

[smarter]

Minimized:

package example

trait Foo {
  val (a2, a3) = ("", "")
  val (x1, x2, x3) = ("", "", "")
}

class A extends Foo

object Main {
  def main(args: Array[String]): Unit = {
    new A
  }
}

Exception in thread "main" java.lang.AbstractMethodError: example.A.example$Foo$_setter_$example$Foo$$$1_$eq(Lscala/Tuple2;)V
        at example.Foo.$init$(i12759.scala:4)
        at example.A.<init>(i12759.scala:8)
        at example.Main$.main(i12759.scala:12)
        at example.Main.main(i12759.scala)

After mixin we have:

trait Foo {
  // ...
  def example$Foo$_setter_$example$Foo$$$1_$eq(x$0: Tuple2): Unit
  def example$Foo$_setter_$example$Foo$$$2_$eq(x$0: Tuple3): Unit
}
class A extends Foo {
  // ...
  def example$Foo$_setter_$example$Foo$$$1_$eq(x$0: Tuple2): Unit =
    this.example$Foo$$$1 = x$0
  def example$Foo$_setter_$example$Foo$$$2_$eq(x$0: Tuple3): Unit =
    this.example$Foo$$$2 = x$0
}

which looks fine, but after RenameLifted we get:

class A extends Foo {
  // ..
  def example$Foo$_setter_$example$Foo$$$2_$eq(x$0: Tuple2): Unit =
    this.example$Foo$$$1 = x$0
  def example$Foo$_setter_$example$Foo$$$1_$eq(x$0: Tuple3): Unit =
    this.example$Foo$$$2 = x$0

Notice how the method names (but not their body) have been swapped: RenameLifted has incorrectly decided to rename them.