targetName with AnyVal affects multiple methods, which can cause invalid bytecode

[v6ak]

Compiler version

3.2.1

Minimized code

import scala.annotation.targetName

implicit final class SomeOps(e: Int) extends AnyVal:
  @targetName("a")
  def -(other: Seq[Int]) = ???
  @targetName("b")
  def -(other: Seq[Long]) = ???

@main
def main(): Unit = 1 - Seq.empty[Int]

Output

Exception in thread "sbt-bg-threads-19" java.lang.ClassFormatError: Duplicate method name "b" with signature "(ILscala.collection.immutable.Seq;)Lscala.runtime.Nothing$;" in class file main$package$SomeOps$
	at java.base/java.lang.ClassLoader.defineClass1(Native Method)
…

Brief analysis

The implementing class seems to use name "b" for both methods:

~/AnyVal-targetName-bug% javap -cp target/scala-3.2.1/classes 'main$package$SomeOps$' | grep Seq
  public final scala.runtime.Nothing$ b(int, scala.collection.immutable.Seq<java.lang.Object>);
  public final scala.runtime.Nothing$ b(int, scala.collection.immutable.Seq<java.lang.Object>);

The bytecode of the wrapper class seems to be valid, but even the a method calls the main$package$SomeOps$.b:(ILscala/collection/immutable/Seq;)Lscala/runtime:

% javap -c -cp target/scala-3.2.1/classes 'main$package$SomeOps' | grep Seq --after=100
  public scala.runtime.Nothing$ a(scala.collection.immutable.Seq<java.lang.Object>);
    Code:
       0: getstatic     #19                 // Field main$package$SomeOps$.MODULE$:Lmain$package$SomeOps$;
       3: aload_0
       4: invokevirtual #39                 // Method main$package$SomeOps$$e:()I
       7: aload_1
       8: invokevirtual #51                 // Method main$package$SomeOps$.b:(ILscala/collection/immutable/Seq;)Lscala/runtime/Nothing$;
      11: areturn

  public scala.runtime.Nothing$ b(scala.collection.immutable.Seq<java.lang.Object>);
    Code:
       0: getstatic     #19                 // Field main$package$SomeOps$.MODULE$:Lmain$package$SomeOps$;
       3: aload_0
       4: invokevirtual #39                 // Method main$package$SomeOps$$e:()I
       7: aload_1
       8: invokevirtual #51                 // Method main$package$SomeOps$.b:(ILscala/collection/immutable/Seq;)Lscala/runtime/Nothing$;
      11: areturn
}

Expectation

I expect:

1. the generated bytecode of main$package$SomeOps$ to be valid and
2. the app to produce scala.NotImplementedError: an implementation is missing and
3. the generated bytecode of main$package$SomeOps.a(scala.collection.immutable.Seq) to call a, not b. (i.e., main$package$SomeOps$.a:(ILscala/collection/immutable/Seq;)Lscala/runtime, not main$package$SomeOps$.b:(ILscala/collection/immutable/Seq;)Lscala/runtime)