`-Wunused:all` and named function arguments

[amumurst]

I tried adding the new unused flag (from #16157) to my work codebase and was surprised that it warned when a named arguments function defined inline gives unused warnings. This is even if it uses underscore.

Compiler version

With nightly: 3.3.0-RC1-bin-20230112-be10bc6-NIGHTLY

Minimized code

//> using scala "3.3.0-RC1-bin-20230112-be10bc6-NIGHTLY"
//> using option "-Wunused:all"

def foo(func: Int => String, value: Int): String = func(value)

println(foo(number => number.toString, value = 5)) //No warn
println(foo(func = number => number.toString, value = 5)) ///Warns twice
println(foo(func = _.toString, value = 5)) //Warns once

Output

[warn] ./unused-function-param.sc:7:20: unused explicit parameter
[warn] println(foo(func = number => number.toString, value = 5)) //Warns twice
[warn]                    ^^^^^^
[warn] ./unused-function-param.sc:7:27: unused local definition
[warn] println(foo(func = number => number.toString, value = 5)) //Warns twice
[warn]                           ^
[warn] ./unused-function-param.sc:8:20: unused local definition
[warn] println(foo(func = _.toString, value = 5)) //Warns once
[warn]  

Expectation

There is nothing unused here as far as I can tell, so it should not give a warning.

[amumurst]

Another similar-ish reproduction

def foo(a: Option[String]) = a.foreach(println)
val x: Option[Int] = Some(1)
foo(a = x.map(_.toString)) //Warns
foo(x.map(_.toString)) //No warn

[PaulCoral]

Fixed here #16684