Pattern match issue in macro

[etorreborre]

Minimized code

import scala.quoted._

case class FileName private(name: String)

object FileName {
  def unsafe(s: String) = new FileName(s)

  implicit inline def ToFileName(s: String): FileName =
    ${createFileName('{s})}

  def fileNameFromString(s: String): Either[String, FileName] =
    Right(FileName.unsafe(s))

  def createFileName(fileName: Expr[String])(using qctx: QuoteContext): Expr[FileName] =
    fileName match {
      case e@Const(s) =>
        '{fileNameFromString($e) match {
            case Right(fn) =>
              fn
            case Left(_) =>
              ${qctx.throwError(s"$s is not a valid file name! It must not contain a /", fileName)}
         }}

      case _ =>
        qctx.throwError(s"$fileName is not a valid file name. It must be a literal string", fileName)
    }
}

 val fileName1: FileName = ToFileName("fileName1")

Output

 
 -- Error: /Users/etorreborre/projects/specs2/specs2-five/common/shared/src/test/scala/org/specs2/io/DirectoryPathSpec.scala:13:38
[error] 13 | val fileName1: FileName = ToFileName("fileName1")
[error]    |                                      ^^^^^^^^^^^
[error]    |             fileName1 is not a valid file name! It must not contain a /

Expectation

It looks like the pattern match is always matching on the error case Left even if the function returns Right. My expectation is that pattern matching should work in quotations.

Please tell me if there's any alternative formulation which would work.

[nicolasstucki]

@etorreborre the error is correct, the code is just buggy. I added a fixed version of the code in #8674. You missed an inline in ToFileName and then you should probably not stage the inner match.

[etorreborre]

You missed an inline in ToFileName

It's right after the implicit :-).

you should probably not stage the inner match.

I tried to write it differently but I was getting "staging level" issues. I'll try again on the next Dotty version.

[etorreborre]

Thanks for the quick fix!