Synthetic `copy` generated when provided one is present

[OndrejSpanel]

Compiler version

3.0.0
3.5.2

Minimized code

object Main {
  case class F(state: String, ext: Int) {
    def copy(state: Char): F = F(state.toString, ext)
  }

  def main(args: Array[String]): Unit = {
    val f = F("A", 0)
    println(f.copy('B'))
    println(f.copy("B", 2))
  }
}

Output

F(B,0)
F(B,2)

Expectation

The second variant should not compile, as it does not compile in Scala 2.13.15.

Specs say in https://scala-lang.org/files/archive/spec/3.4/05-classes-and-objects.html:

A method named copy is implicitly added to every case class unless the class already has a member (directly defined or inherited) with that name

It seems compiler adds a synthetic copy in spite of one being defined by me. If this is intended, documentation should be updated, but I do not remember reading about such change from Scala 2 to Scala 3.

Note

This was encountered in softwaremill/quicklens#256

[KacperFKorban]

This was discussed at the compiler meeting today. The conclusion was that Scala 3 behavior is correct, so this is probably a spec issue.
CC: @sjrd