Splice accessing path-dependent type with parameter crashes the compiler

[jodersky]

Compiler version

master branch 3.3.0-RC1-bin-SNAPSHOT-nonbootstrapped-git-263eada

and also on latest official release, 3.2.1

Minimized code

class GlobalReader[E]
trait Api:
  type Reader[E]

object Macros:
  import quoted.Expr
  import quoted.Quotes
  import quoted.Type

  def get[T](using Type[T]) = ??? // this is a placeholder, it could be Expr.summon for example

  def bugImpl[A <: Api: Type](using qctx: Quotes)(api: Expr[A]) =
    import qctx.reflect.*

    val e = TypeRepr.of[Int] // e is constructed using the reflect api directly

    e.asType match
      case '[t] =>
        '{
          type GR = GlobalReader[t]

          val p = $api
          type PR = p.Reader[t]

          ${
            // ok
            get[GR]

            // crash
            // java.lang.AssertionError: assertion failed: unresolved symbols: type t$given1$_$3 (line 32) #18110 when pickling /home/jodersky/p/bug/macro2.scala while running pickleQuotes on /home/jodersky/p/bug/macro2.scala
            get[PR]

            // workaround
            get(using Type.of[PR])
          }
        }

Output (click arrow to expand)

Compile with -Xcheck-macros -Ycheck:all

checking /home/jodersky/p/bug/macro2.scala after phase typer
checking /home/jodersky/p/bug/macro2.scala after phase inlinedPositions
checking /home/jodersky/p/bug/macro2.scala after phase posttyper
checking /home/jodersky/p/bug/macro2.scala after phase pickler
checking /home/jodersky/p/bug/macro2.scala after phase inlining
checking /home/jodersky/p/bug/macro2.scala after phase postInlining
checking /home/jodersky/p/bug/macro2.scala after phase staging
checking /home/jodersky/p/bug/macro2.scala after phase splicing
java.lang.AssertionError: assertion failed: unresolved symbols: type t$given1$_$3 (line 32) #18110 when pickling /home/jodersky/p/bug/macro2.scala while running pickleQuotes on /home/jodersky/p/bug/macro2.scala
exception occurred while compiling /home/jodersky/p/bug/macro2.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: unresolved symbols: type t$given1$_$3 (line 32) #18110 when pickling /home/jodersky/p/bug/macro2.scala while compiling /home/jodersky/p/bug/macro2.scala
java.lang.AssertionError: assertion failed: unresolved symbols: type t$given1$_$3 (line 32) #18110 when pickling /home/jodersky/p/bug/macro2.scala
	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
	at dotty.tools.dotc.core.tasty.TreePickler.pickle(TreePickler.scala:812)
	at dotty.tools.dotc.quoted.PickledQuotes$.pickle(PickledQuotes.scala:221)
	at dotty.tools.dotc.quoted.PickledQuotes$.pickleQuote(PickledQuotes.scala:33)
	at dotty.tools.dotc.transform.PickleQuotes$.pickleAsTasty$1(PickleQuotes.scala:292)
	at dotty.tools.dotc.transform.PickleQuotes$.apply(PickleQuotes.scala:378)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:106)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformBlock$$anonfun$1$$anonfun$1(tpd.scala:1230)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.loop$2(tpd.scala:1212)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformStats(tpd.scala:1225)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformBlock(tpd.scala:1230)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1424)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:49)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1432)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:49)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform$$anonfun$1(Trees.scala:1505)
	at scala.collection.immutable.List.mapConserve(List.scala:472)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1505)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transformSub(Trees.scala:1509)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1430)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:49)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformBlock$$anonfun$1$$anonfun$1(tpd.scala:1230)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.loop$2(tpd.scala:1212)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformStats(tpd.scala:1225)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformBlock(tpd.scala:1230)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1424)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:49)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1476)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:40)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.loop$2(tpd.scala:1225)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformStats(tpd.scala:1225)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformStats(tpd.scala:1227)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:47)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1478)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:40)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.loop$2(tpd.scala:1225)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformStats(tpd.scala:1225)
	at dotty.tools.dotc.ast.tpd$TreeMapWithPreciseStatContexts.transformStats(tpd.scala:1227)
	at dotty.tools.dotc.ast.Trees$Instance$TreeMap.transform(Trees.scala:1486)
	at dotty.tools.dotc.transform.MacroTransform$Transformer.transform(MacroTransform.scala:40)
	at dotty.tools.dotc.transform.PickleQuotes$$anon$1.transform(PickleQuotes.scala:121)
	at dotty.tools.dotc.transform.MacroTransform.run(MacroTransform.scala:18)
	at dotty.tools.dotc.transform.PickleQuotes.run(PickleQuotes.scala:96)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:324)
	at scala.collection.immutable.List.map(List.scala:246)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:328)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:244)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:260)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:268)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:277)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:277)
	at dotty.tools.dotc.Run.compileSources(Run.scala:195)
	at dotty.tools.dotc.Run.compile(Run.scala:179)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:35)
	at dotty.tools.dotc.Driver.process(Driver.scala:195)
	at dotty.tools.dotc.Driver.process(Driver.scala:163)
	at dotty.tools.dotc.Driver.process(Driver.scala:175)
	at dotty.tools.dotc.Driver.main(Driver.scala:205)
	at dotty.tools.dotc.Main.main(Main.scala)

Expectation

I would think that both path-dependent and non-dependent types can be accessed the same way within splices.

[nicolasstucki]

Minimized

import scala.quoted.*

trait Api:
  type Reader[E]

def bugImpl[T: Type](using Quotes) =
  '{
    val p: Api = ???
    ${
      Type.of[p.Reader[T]]
      Expr(1)
    }
  }

[nicolasstucki]

After the splicing phase we get

 def bugImpl[T >: Nothing <: Any](implicit evidence$1: quoted.Type[T],
      x$1: quoted.Quotes): quoted.Expr[Int] =
      '{
        {
          val p: Api = ???
          {{{ 0 | Int | p.Reader[evidence$1$_$1] |
            {
              def $anonfun(Type$1: scala.quoted.Type[p.Reader[evidence$1$_$1]])
                : (quoted.Quotes) ?=> quoted.Expr[Int] =
                {
                  def $anonfun(using evidence$2: quoted.Quotes):
                    quoted.Expr[Int] =
                    {
                      Type$1
                      quoted.Expr.apply[Int](1)(quoted.ToExpr.IntToExpr[Int])(
                        evidence$2)
                    }
                  closure($anonfun)
                }
              closure($anonfun:
                scala.quoted.Type[p.Reader[evidence$1$_$1]] => (quoted.Quotes)
                  ?=> quoted.Expr[Int]
              )
            }
           }}}
        }
      }.apply(x$1)

Having evidence$1$_$1 in {{{ 0 | Int | p.Reader[evidence$1$_$1] | is wrong.

Instead, we should probably have

 def bugImpl[T >: Nothing <: Any](implicit evidence$1: quoted.Type[T],
      x$1: quoted.Quotes): quoted.Expr[Int] =
      '{
        {
          val p: Api = ???
          {{{ 0 | Int | p.Reader |
            {
              def $anonfun(Type$1: scala.quoted.Type[p.Reader])
                : (quoted.Quotes) ?=> quoted.Expr[Int] =
                {
                  def $anonfun(using evidence$2: quoted.Quotes):
                    quoted.Expr[Int] =
                    {
                      quoted.Type.of[{
                        @SplicedType type evidence$1$_$1 = [[[ 0 | evidence$1.Underlying | | evidence$1 ]]]
                        @SplicedType type evidence$1$_$2 = [[[ 1 | Type$1.Underlying | | Type$1 ]]]
                         evidence$1$_$2[evidence$1$_$1]
                      }
                      quoted.Expr.apply[Int](1)(quoted.ToExpr.IntToExpr[Int])(
                        evidence$2)
                    }
                  closure($anonfun)
                }
              closure($anonfun:
                scala.quoted.Type[p.Reader] => (quoted.Quotes)
                  ?=> quoted.Expr[Int]
              )
            }
           }}}
        }
      }.apply(x$1)