Matching on an `Expr` that takes in a context function fails when the context param is used at call site

[arainko]

Compiler version

3.3.0, 3.3.1-RC3, 3.3.2-RC1-bin-20230710-ed319e8-NIGHTLY

Minimized code

//> using scala "3.3.1-RC3"

import scala.quoted.*

object ReproMacro {
  inline def readPath[A, B](inline config: Config[A, B]) = ${ readPathMacro[A, B]('config) }

  def readPathMacro[A: Type, B: Type](expr: Expr[Config[A, B]])(using Quotes) = {
    import quotes.reflect.*

    expr match {
      case '{ Field.const[a, b, tpe]($selector) } =>
        // the type of 'selector' is just a Expr[Function1[a, tpe]] instead of Expr[Selector ?=> Function1[a, tpe]]
        val weirdInferredType: Expr[a => tpe] = selector
        report.info(s"Matched!")
        '{}
      case other =>
        report.errorAndAbort("woops, I did not match")
    }
  }
}

trait Selector {
  extension [A](self: A) def at[B <: A]: B
}

trait Config[A, B]

object Field {
  def const[A, B, FieldTpe](selector: Selector ?=> A => FieldTpe): Config[A, B] = ???
}

final case class Example(int: Int)

@main def main = {
  // compiles just fine
  ReproMacro.readPath[Example, Example](Field.const(_.int))

  // doesn't compile
  ReproMacro.readPath[Example, Example](Field.const(_.int.at[Int]))
}

Output

Compiling project (Scala 3.3.1-RC3, JVM)
[error] ./Field.scala:18:3: woops, I did not match
[error]   ReproMacro.readPath[Example, Example](Field.const(_.int.at[Int]))
[error]   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Expectation

Both

ReproMacro.readPath[Example, Example](Field.const(_.int))

and

ReproMacro.readPath[Example, Example](Field.const(_.int.at[Int]))

should compile.

[nicolasstucki]

Minimized

import scala.quoted.*

def readPathMacro[A: Type, B: Type](expr: Expr[Any])(using Quotes) =
  expr match
    case '{ foo($y) } => y: Expr[Int ?=> Int]

def foo(x: Int ?=> Int): Any = ???

When we type a splice with a contextual function type, there is an issue. We seem to be dropping the contextual parameters. Possibly a bad interaction with the logic that tries to apply the implicit arguments.

This wrong type might be causing the runtime failure as well.