Typer regression in `purplekingdomgames/ultraviolet`

[WojciechMazur]

Based on OpenCB failure in purplekingdomgames/ultraviolet - build logs

Compiler version

3.7.1-RC1
Last good release: 3.7.0-RC1-bin-20250222-4dc4668-NIGHTLY
First bad release: 3.7.0-RC1-bin-20250225-a25fe5e-NIGHTLY
Bisect points to 32ac2e6

3.7.0 is not affected

Minimized code

object types{
  final case class vec2(x: Float, y: Float)
  final case class vec4(x: Float, y: Float, z: Float, w: Float)
  object vec4:
    def apply(xy: vec2, z: Float, w: Float): vec4 = vec4(xy.x, xy.y, z, w)

  opaque type Shader[In, Out] = In => Out
  object Shader:
    inline def apply[In, Out](f: In => Out): Shader[In, Out] = f
    inline def apply[In](f: In => Unit): Shader[In, Unit]    = f
    inline def apply(body: => Any): Shader[Unit, Unit] = (_: Unit) => body
}
import types.*

class GLSLEnvTests {
  case class FragEnv(UV: vec2)

  inline def fragment: Shader[FragEnv, vec4] =
    Shader { env =>
      val x = env.UV
      vec4(env.UV, 0.0f, 1.0f)
    }
}

Output

Compiling project (Scala 3.7.2-RC1-bin-20250520-baac46c-NIGHTLY, JVM (21))
[error] ./example.scala:49:15
[error] value UV is not a member of Any
[error]       val x = env.UV
[error]               ^^^^^^
[error] ./example.scala:50:12
[error] value UV is not a member of Any
[error]       vec4(env.UV, 0.0f, 1.0f)
[error]            ^^^^^^

Expectation

[WojciechMazur]

Another reproducer based on unibas-gravis/scalismo

sealed trait Dim
trait _2D extends Dim
trait _3D extends Dim

sealed abstract class IntVector[D]
object IntVector{
  def apply[D](d: Array[Int]): IntVector[D] = ???
  def apply(x: Int, y: Int): IntVector2D = IntVector2D(x, y)
  def apply(x: Int, y: Int, z: Int): IntVector3D = IntVector3D(x, y, z)
}
case class IntVector2D(i: Int, j: Int) extends IntVector[_2D]
case class IntVector3D(i: Int, j: Int, k: Int) extends IntVector[_3D]

type DiscreteImage[D, A] = DiscreteField[D, DiscreteImageDomain, A]
class DiscreteField[D, DDomain[D] <: DiscreteDomain[D], A](val domain: DDomain[D], val data: IndexedSeq[A])  extends PartialFunction[PointId, A] {
  override def apply(v1: PointId) = ???
  override def isDefinedAt(ptId: PointId) = ???
}
object DiscreteField{
    implicit class DiscreteImageOps[D, A](discreteField: DiscreteField[D, DiscreteImageDomain, A]) {
      def apply(idx: IntVector[D]): A = ???
      def isDefinedAt(idx: IntVector[D]): Boolean = ???
  }
}
trait DiscreteDomain[D] 
trait DiscreteImageDomain[D] extends DiscreteDomain[D] 
final case class PointId(id: Int) extends AnyVal

def test[S](img: DiscreteImage[_3D, S]) = img(IntVector(1, 2, 3))

-- [E007] Type Mismatch Error: /Users/wmazur/projects/scala/sandbox/example.scala:58:56 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
58 |def test[S](img: DiscreteImage[_3D, S]) = img(IntVector(1, 2, 3))
   |                                                        ^^^^^^^
   |                                                        Found:    (Int, Int, Int)
   |                                                        Required: Array[Int]
   |
   | longer explanation available when compiling with `-explain` 

[Gedochao]

cc @smarter

[WojciechMazur]

No longer present in main, after revert of #21744 in #23331