Matching `BigInt` against `Int` literal pattern leads to warning

[t9dupuy]

Compiler version

3.7.0

Minimized code

//> using scala 3.7.0

@main def main(): Unit =
  BigInt(1) match
    case 1 => println("matched")
    case _ => println("didn't match")

Output

compile

[warn] -- [E030] Match case Unreachable Warning: D:\scala\run\src\main\scala\Main.scala:7:9 
[warn] 7 |    case 1 => println("matched")
[warn]   |         ^
[warn]   |         Unreachable case

run

matched

Expectation

No warning.

[som-snytt]

Or, the warning is correct and pattern matching is broken. A literal pattern requires conformance, and an int is not a big int.

Welcome to Scala 2.13.16 (OpenJDK 64-Bit Server VM, Java 23.0.2).
Type in expressions for evaluation. Or try :help.

scala> BigInt(42) match { case 42 => "yes" case _ => "no" }
                               ^
       error: type mismatch;
        found   : Int(42)
        required: scala.math.BigInt

https://scala-lang.org/files/archive/spec/3.4/08-pattern-matching.html#literal-patterns

A related issue where patmat incorrectly defers to equals is #16821.