SIP-56-extended: Simpler provablyDisjoint test.

tests/neg/6314-1.scala

@@ -1,6 +1,7 @@
 object G {
-  final class X
-  final class Y
+  trait X
+  class Y
+  class Z
 
   trait FooSig {
     type Type
@@ -13,14 +14,14 @@ object G {
   type Foo = Foo.Type
 
   type Bar[A] = A match {
-    case X & Y => String
+    case X & Z => String
     case Y => Int
   }
 
   def main(args: Array[String]): Unit = {
     val a: Bar[X & Y] = "hello" // error
     val i: Bar[Y & Foo] = Foo.apply[Bar](a)
-    val b: Int = i // error
+    val b: Int = i
     println(b + 1)
   }
 }

tests/neg/6314-6.check

@@ -0,0 +1,16 @@
+-- Error: tests/neg/6314-6.scala:26:3 ----------------------------------------------------------------------------------
+26 |  (new YY {}).boom // error: object creation impossible
+   |   ^
+   |object creation impossible, since def apply(fa: String): Int in trait XX in object Test3 is not defined 
+   |(Note that
+   | parameter String in def apply(fa: String): Int in trait XX in object Test3 does not match
+   | parameter Test3.Bar[X & Object with Test3.YY {...}#Foo] in def apply(fa: Test3.Bar[X & YY.this.Foo]): Test3.Bar[Y & YY.this.Foo] in trait YY in object Test3
+   | )
+-- Error: tests/neg/6314-6.scala:52:3 ----------------------------------------------------------------------------------
+52 |  (new YY {}).boom // error: object creation impossible
+   |   ^
+   |object creation impossible, since def apply(fa: String): Int in trait XX in object Test4 is not defined 
+   |(Note that
+   | parameter String in def apply(fa: String): Int in trait XX in object Test4 does not match
+   | parameter Test4.Bar[X & Object with Test4.YY {...}#FooAlias] in def apply(fa: Test4.Bar[X & YY.this.FooAlias]): Test4.Bar[Y & YY.this.FooAlias] in trait YY in object Test4
+   | )

tests/neg/6314-6.scala

@@ -21,11 +21,9 @@ object Test3 {
   trait YY extends XX {
     type Foo = X & Y
 
-    def apply(fa: Bar[X & Foo]): Bar[Y & Foo] = fa // error
-        // overriding method apply in trait XX of type (fa: String): Int;
-        //   method apply of type (fa: String): String has incompatible type
+    def apply(fa: Bar[X & Foo]): Bar[Y & Foo] = fa
   }
-  (new YY {}).boom
+  (new YY {}).boom // error: object creation impossible
 }
 
 object Test4 {
@@ -49,9 +47,7 @@ object Test4 {
   trait YY extends XX {
     type Foo = X & Y
 
-    def apply(fa: Bar[X & FooAlias]): Bar[Y & FooAlias] = fa // error
-        // overriding method apply in trait XX of type (fa: String): Int;
-        //   method apply of type (fa: String): String has incompatible type
+    def apply(fa: Bar[X & FooAlias]): Bar[Y & FooAlias] = fa
   }
-  (new YY {}).boom
+  (new YY {}).boom // error: object creation impossible
 }

tests/neg/6314.check

@@ -0,0 +1,44 @@
+-- [E007] Type Mismatch Error: tests/neg/6314.scala:28:27 --------------------------------------------------------------
+28 |    val i: Bar[Y | Type] = 1 // error
+   |                           ^
+   |                           Found:    (1 : Int)
+   |                           Required: Test1Bis.Bar[Test1Bis.Y | Test.this.Type]
+   |
+   |                           Note: a match type could not be fully reduced:
+   |
+   |                             trying to reduce  Test1Bis.Bar[Test1Bis.Y | Test.this.Type]
+   |                             failed since selector Test1Bis.Y | Test.this.Type
+   |                             does not match  case Test1Bis.X & Test1Bis.Y => String
+   |                             and cannot be shown to be disjoint from it either.
+   |                             Therefore, reduction cannot advance to the remaining case
+   |
+   |                               case Any => Int
+   |
+   | longer explanation available when compiling with `-explain`
+-- [E007] Type Mismatch Error: tests/neg/6314.scala:45:33 --------------------------------------------------------------
+45 |    def right(fa: Bar[L]): Int = fa // error
+   |                                 ^^
+   |                                 Found:    (fa : Wizzle.this.Bar[L])
+   |                                 Required: Int
+   |
+   |                                 where:    L is a type in trait Wizzle with bounds <: Int & Singleton
+   |
+   | longer explanation available when compiling with `-explain`
+-- [E007] Type Mismatch Error: tests/neg/6314.scala:55:33 --------------------------------------------------------------
+55 |    def right(fa: Bar[L]): Int = fa // error
+   |                                 ^^
+   |                                 Found:    (fa : Wazzlo.this.Bar[L])
+   |                                 Required: Int
+   |
+   |                                 where:    L is a type in trait Wazzlo with bounds <: Int & AnyVal
+   |
+   | longer explanation available when compiling with `-explain`
+-- [E007] Type Mismatch Error: tests/neg/6314.scala:65:33 --------------------------------------------------------------
+65 |    def right(fa: Bar[L]): Int = fa // error
+   |                                 ^^
+   |                                 Found:    (fa : Wuzzlu.this.Bar[L])
+   |                                 Required: Int
+   |
+   |                                 where:    L is a type in trait Wuzzlu with bounds <: String & AnyRef
+   |
+   | longer explanation available when compiling with `-explain`

tests/neg/6314.scala

@@ -1,20 +1,39 @@
-final class X
-final class Y
-
 object Test1 {
+  // X, Y and Z are unrelated, Y is provably disjoint from Z, but X is not provably disjoint with either
+  trait X
+  class Y
+  class Z
+
   trait Test {
     type Type
     // This is testing that both permutations of the types in a &
-    // are taken into account by the intersection test
-    val i: Bar[Y & Type] = 1 // error
+    // are taken into account by the provablyDisjoint test
+    val i: Bar[Y & Type] = 1 // ok, disjoint from X & Z because Y and Z are disjoint
   }
 
   type Bar[A] = A match {
-    case X & Y => String
+    case X & Z => String
     case Y => Int
   }
 }
 
+object Test1Bis {
+  final class X
+  final class Y
+
+  trait Test {
+    type Type
+    // This is testing that both permutations of the types in a |
+    // are taken into account by the provablyDisjoint test
+    val i: Bar[Y | Type] = 1 // error
+  }
+
+  type Bar[A] = A match {
+    case X & Y => String
+    case Any => Int
+  }
+}
+
 object Test2 {
   trait Wizzle[L <: Int with Singleton] {
     type Bar[A] = A match {

tests/neg/i13190.check

@@ -0,0 +1,15 @@
+
+-- [E172] Type Error: tests/neg/i13190/B_2.scala:14:38 -----------------------------------------------------------------
+14 |  summon[FindField[R, "B"] =:= Double] // error
+   |                                      ^
+   |                                      Cannot prove that Test.FindField[Test.R, ("B" : String)] =:= Double.
+   |
+   |                                      Note: a match type could not be fully reduced:
+   |
+   |                                        trying to reduce  Test.FindField[Test.R, ("B" : String)]
+   |                                        failed since selector Test.R
+   |                                        does not match  case Opaque.FieldType[("B" : String), f] *: t => f
+   |                                        and cannot be shown to be disjoint from it either.
+   |                                        Therefore, reduction cannot advance to the remaining case
+   |
+   |                                          case _ *: t => Test.FindField[t, ("B" : String)]

tests/pos/i13190/A_1.scala → tests/neg/i13190/A_1.scala

@@ -1,3 +1,3 @@
 object Opaque {
   opaque type FieldType[K, +V] <: V = V
-}
+}

tests/pos/i13190/B_2.scala → tests/neg/i13190/B_2.scala

@@ -11,5 +11,5 @@ object Test {
   //val f2: Int = f
 
   type R = FieldType["A", Int] *: FieldType["B", Double] *: FieldType["C", String] *: FieldType["D", Boolean] *: EmptyTuple
-  summon[FindField[R, "B"] =:= Double]
+  summon[FindField[R, "B"] =:= Double] // error
 }

tests/neg/i13190b.check

@@ -0,0 +1,14 @@
+-- [E172] Type Error: tests/neg/i13190b.scala:18:38 --------------------------------------------------------------------
+18 |  summon[FindField[R, "B"] =:= Double] // error
+   |                                      ^
+   |                                      Cannot prove that Test.FindField[Test.R, ("B" : String)] =:= Double.
+   |
+   |                                      Note: a match type could not be fully reduced:
+   |
+   |                                        trying to reduce  Test.FindField[Test.R, ("B" : String)]
+   |                                        failed since selector Test.R
+   |                                        does not match  case Opaque.FieldType[("B" : String), f] *: t => f
+   |                                        and cannot be shown to be disjoint from it either.
+   |                                        Therefore, reduction cannot advance to the remaining case
+   |
+   |                                          case _ *: t => Test.FindField[t, ("B" : String)]

tests/neg/i13190b.scala

@@ -0,0 +1,19 @@
+object Opaque {
+  opaque type FieldType[K, +V] <: V = V
+}
+
+import Opaque.*
+
+object Test {
+  type FindField[R <: scala.Tuple, K] = R match {
+    case FieldType[K, f] *: t => f
+    case _ *: t => FindField[t, K]
+  }
+
+  val f: FieldType["A", Int] = ???
+  val f1: Int = f
+  //val f2: Int = f
+
+  type R = FieldType["A", Int] *: FieldType["B", Double] *: FieldType["C", String] *: FieldType["D", Boolean] *: EmptyTuple
+  summon[FindField[R, "B"] =:= Double] // error
+}

tests/neg/i15312.check

@@ -0,0 +1,17 @@
+-- [E007] Type Mismatch Error: tests/neg/i15312.scala:7:27 -------------------------------------------------------------
+7 |val b: F[{type A = Int}] = "asd" // error
+  |                           ^^^^^
+  |                           Found:    ("asd" : String)
+  |                           Required: F[Object{type A = Int}]
+  |
+  |                           Note: a match type could not be fully reduced:
+  |
+  |                             trying to reduce  F[Object{type A = Int}]
+  |                             failed since selector Object{type A = Int}
+  |                             does not match  case Object{type A = Float} => Int
+  |                             and cannot be shown to be disjoint from it either.
+  |                             Therefore, reduction cannot advance to the remaining case
+  |
+  |                               case Object{type A = Int} => String
+  |
+  | longer explanation available when compiling with `-explain`

tests/pos/i15312.scala → tests/neg/i15312.scala

@@ -4,4 +4,4 @@ type F[t] =
     case {type A = Int} => String
 
 val a: F[{type A = Float}] = 10
-val b: F[{type A = Int}] = "asd" // Found:("asd" : String) Required: F[Object{A = Int}]
+val b: F[{type A = Int}] = "asd" // error

tests/pos/i15677.scala

@@ -1,3 +1,5 @@
+// scalac: -Yno-deep-subtypes:false
+
 class Inv[A]
 
 class Foo[B, M[_]]

tests/pos/mytest.scala

@@ -0,0 +1,16 @@
+class Parent[T](val x: T)
+
+class Child[T](x: T) extends Parent(x)
+
+type MT[X] = X match
+  case Parent[Int] => Int
+  case Parent[Boolean] => Boolean
+
+def test(): Unit =
+  summon[MT[Parent[Int]] =:= Int]
+  summon[MT[Parent[Boolean]] =:= Boolean]
+  //summon[MT[Parent[Any]] =:= Int]
+
+  summon[MT[Child[Int]] =:= Int]
+  summon[MT[Child[Boolean]] =:= Boolean]
+end test