Backport "push distributivity rule to source future" to 3.8.0

compiler/src/dotty/tools/dotc/config/SourceVersion.scala

@@ -46,7 +46,7 @@ enum SourceVersion:
   def enablesNamedTuples = isAtLeast(`3.7`)
   def enablesBetterFors(using Context) = isAtLeast(`3.8`) || (isAtLeast(`3.7`) && isPreviewEnabled)
   /** See PR #23441 and tests/neg/i23435-min */
-  def enablesDistributeAnd = !isAtLeast(`3.8`)
+  def enablesDistributeAnd = !isAtLeast(`future`)
 
   def requiresNewSyntax = isAtLeast(future)
 

tests/neg/i23435-min.scala

@@ -1,4 +1,4 @@
-//> using options -source:3.8
+//> using options -source:future
 
 type Or[+A, +B] = A | B
 

tests/neg/i23435.scala

@@ -1,4 +1,4 @@
-//> using options -source:3.8
+//> using options -source:future
 
 trait L[+A]{val a:A}
 trait R[+B]{val b: B}

tests/neg/i24096.check

@@ -1,10 +1,10 @@
--- [E007] Type Mismatch Error: tests/neg/i24096.scala:8:31 -------------------------------------------------------------
-8 |        case r: Terminal[?] => r // error
-  |                               ^
-  |                     Found:    (r : Pull.Terminal[_] & Pull[F, O, Unit])
-  |                     Required: Pull[F2, O2, Unit]
-  |
-  |                     where:    F  is a type in class StreamPullOps with bounds <: [_²] =>> Any
-  |                               F2 is a type in method flatMapOutput with bounds >: [x] =>> F[x] and <: [x] =>> Any
-  |
-  | longer explanation available when compiling with `-explain`
+-- [E007] Type Mismatch Error: tests/neg/i24096.scala:10:31 ------------------------------------------------------------
+10 |        case r: Terminal[?] => r // error
+   |                               ^
+   |                   Found:    (r : Pull.Terminal[_] & Pull[F, O, Unit])
+   |                   Required: Pull[F2, O2, Unit]
+   |
+   |                   where:    F  is a type in class StreamPullOps with bounds <: [_²] =>> Any
+   |                             F2 is a type in method flatMapOutput with bounds >: [x] =>> F[x] and <: [x] =>> Any
+   |
+   | longer explanation available when compiling with `-explain`

tests/neg/i24096.scala

@@ -1,3 +1,5 @@
+//> using options -source:future
+
 abstract class Pull[+F[_], +O, +R]
 object Pull:
   abstract class Terminal[+R] extends Pull[Nothing, Nothing, R]

tests/neg/i3989e.scala

@@ -1,4 +1,4 @@
-//> using options -source:3.8
+//> using options -source:future
 
 object Test extends App {
   trait A[+X](val x: X)

tests/neg/singletonInterval.scala

@@ -1,4 +1,4 @@
-//> using options -source:3.8
+//> using options -source:future
 
 /** Why the singletonInterval logic cannot be applied for lubArgs and glbArgs in TypeComparer. */
 

tests/pos/cb-companion-joins.scala

@@ -1,4 +1,4 @@
-//> using options -source:3.8
+//> using options -source:future
 import language.experimental.modularity
 
 trait M[Self]:

tests/pos/i10256.scala

@@ -1,4 +1,4 @@
-//> using options -source:3.8
+//> using options -source:future
 
 trait Foo[T <: Foo[T]] {
   type I <: Foo[I]

tests/pos/i11064.scala

@@ -1,12 +1,12 @@
-//> using options -source:3.8
+//> using options -source:future
 
 trait TypedArray[T, Repr]
 
-trait Ops[T <: TypedArray[_, T]] {
+trait Ops[T <: TypedArray[?, T]] {
   def typedArray(): T
 }
 
 object Test {
-  def test1(ops: Ops[_ <: TypedArray[_, _]]) = ops.typedArray()
-  def test2(ops: Ops[_ <: TypedArray[_ <: AnyRef, _]]) = ops.typedArray() // ok, was error: Recursion limit exceeded.
+  def test1(ops: Ops[? <: TypedArray[?, ?]]) = ops.typedArray()
+  def test2(ops: Ops[? <: TypedArray[? <: AnyRef, ?]]) = ops.typedArray() // ok, was error: Recursion limit exceeded.
 }

tests/pos/i24094.scala

@@ -0,0 +1,46 @@
+class TyreCompiler[IN <: Tuple, R](val context: Context[R *: IN]):
+  import context.*
+
+  private class Loop[IS <: Tuple, T](
+      val context: Context[T *: IS],
+      innerAutomaton: context.Automaton[IS]
+  ) {
+    private lazy val fixableStates: List[RefinedInitNonAcceptingState[T, IS]] =
+      innerAutomaton.initStates.map { case is: context.InitNonAcceptingState[?] =>
+        new RefinedInitNonAcceptingState[T, IS] {
+          type Tail = is.OS
+          type OS = List[T] *: Tail
+          lazy val state = new NonAcceptingState:
+            val next: List[Transition[OS]] =
+              is.state.next.flatMap(fixTransition[is.OS](fixableStates, _))
+        }
+      }
+
+    private def fixTransition[S <: Tuple](
+        initStates: List[RefinedInitNonAcceptingState[T, IS]],
+        transition: context.Transition[S]
+    ): List[Transition[List[T] *: S]] = ???
+
+    private trait RefinedInitNonAcceptingState[T, IS <: Tuple] extends InitNonAcceptingState[IS]:
+      type Tail <: Tuple
+      type OS = List[T] *: Tail
+      lazy val state: NonAcceptingState[OS]
+  }
+
+private class Context[R <: Tuple]:
+  sealed trait State[S <: Tuple]:
+    val next: List[Transition[S]]
+  trait NonAcceptingState[S <: Tuple] extends State[S]
+
+  sealed trait Transition[IS <: Tuple]:
+    def state: State[?]
+
+  sealed trait InitState[-IS <: Tuple]:
+    type OS <: Tuple
+    def state: State[?]
+
+  trait InitNonAcceptingState[-IS <: Tuple] extends InitState[IS]:
+    lazy val state: NonAcceptingState[OS]
+
+  trait Automaton[-IS <: Tuple]:
+    val initStates: List[InitState[IS]]

tests/pos/i24097-a.scala

@@ -0,0 +1,36 @@
+trait <[+A, -S]
+object `<`:
+  extension [A, S](v: A < S) def map[B, S2](f: A => B < S2): B < (S & S2) = ???
+
+def lift[A, S](v: A): A < S = ???
+
+abstract class ArrowEffect[-Input[_], +Output[_]]
+object ArrowEffect:
+  inline def handleCatching[I[_], O[_], E <: ArrowEffect[I, O], A, B, S, S2, S3](
+      v: A < (E & S)
+  ): B < (S & S2 & S3) = ???
+
+trait Result[+E, +A]
+object Result:
+  def succeed[E, A](value: A): Result[E, A] = ???
+
+abstract class Error[+E]
+
+type Const[A] = [B] =>> A
+sealed trait Abort[-E] extends ArrowEffect[Const[Error[E]], Const[Unit]]
+object Abort:
+  inline def runWith[E, A, S, ER, B, S2](v: A < (Abort[E | ER] & S)) =
+    ArrowEffect.handleCatching[
+      Const[Error[E]],
+      Const[Unit],
+      Abort[E],
+      Result[E, A],
+      B,
+      Abort[ER] & S,
+      Abort[ER] & S,
+      S2
+    ](
+      v.map: 
+        value => lift:
+          Result.succeed[E, A](value)
+    )

tests/pos/i24097-b.scala

@@ -0,0 +1,25 @@
+trait <[+A, -S]
+
+trait TypeMap[+A]:
+  def union[B](that: TypeMap[B]): TypeMap[A & B] = ???
+
+trait Tag[E]
+trait ContextEffect[+A]
+object ContextEffect:
+  def handle[A, E <: ContextEffect[A], B, S](effectTag: Tag[E], ifDefined: A => A)(
+      v: B < (E & S)
+  ): B < S = ???
+
+sealed trait Env[+R] extends ContextEffect[TypeMap[R]]
+object Env:
+  def runAll[R >: Nothing, A, S, VR](
+      env: TypeMap[R],
+      tag: Tag[Env[R]]
+  )(
+      v: A < (Env[R & VR] & S)
+  ) =
+    ContextEffect.handle(
+      tag,
+      _.union(env)
+    )(v): A < (Env[VR] & S)
+    ???