Merge pull request #5263 from retronym/review/5041

SI-5294 SI-6161 Hard graft in asSeenFrom, refinements, and existentials [ci: last-only]

11 files changed, 206 insertions, 7 deletions

diff --git a/test/files/neg/lub-from-hell-2.check b/test/files/neg/lub-from-hell-2.check
new file mode 100644
index 0000000000..3ef935f93b
--- /dev/null
+++ b/test/files/neg/lub-from-hell-2.check
@@ -0,0 +1,7 @@
+lub-from-hell-2.scala:3: error: type arguments [Any,Iterable[Any] with Int => Any with scala.collection.generic.Subtractable[Any,Iterable[Any] with Int => Any with scala.collection.generic.Subtractable[Any,Iterable[Any] with Int => Any]{def seq: Iterable[Any] with Int => Any}]{def seq: Iterable[Any] with Int => Any{def seq: Iterable[Any] with Int => Any}}] do not conform to trait Subtractable's type parameter bounds [A,+Repr <: scala.collection.generic.Subtractable[A,Repr]]
+  def foo(a: Boolean, b: collection.mutable.Set[Any], c: collection.mutable.ListBuffer[Any]) = if (a) b else c
+      ^
+lub-from-hell-2.scala:4: error: type arguments [Any,scala.collection.mutable.Iterable[Any] with scala.collection.mutable.Cloneable[scala.collection.mutable.Iterable[Any] with scala.collection.mutable.Cloneable[scala.collection.mutable.Iterable[Any] with Cloneable with Int => Any] with Int => Any{def seq: scala.collection.mutable.Iterable[Any] with Cloneable with Int => Any}] with scala.collection.generic.Growable[Any] with Int => Any with scala.collection.generic.Shrinkable[Any] with scala.collection.generic.Subtractable[Any,Iterable[Any] with Int => Any with scala.collection.generic.Subtractable[Any,Iterable[Any] with Int => Any]{def seq: Iterable[Any] with Int => Any}] with scala.collection.script.Scriptable[Any]] do not conform to trait Subtractable's type parameter bounds [A,+Repr <: scala.collection.generic.Subtractable[A,Repr]]
+  def bar(a: Boolean, b: scala.collection.mutable.SetLike[Any,scala.collection.mutable.Set[Any]], c: scala.collection.mutable.Buffer[Any]) = if (a) b else c
+      ^
+two errors found
diff --git a/test/files/neg/lub-from-hell-2.scala b/test/files/neg/lub-from-hell-2.scala
new file mode 100644
index 0000000000..18c99dfada
--- /dev/null
+++ b/test/files/neg/lub-from-hell-2.scala
@@ -0,0 +1,13 @@
+class Test {
+  trait Tree
+  def foo(a: Boolean, b: collection.mutable.Set[Any], c: collection.mutable.ListBuffer[Any]) = if (a) b else c
+  def bar(a: Boolean, b: scala.collection.mutable.SetLike[Any,scala.collection.mutable.Set[Any]], c: scala.collection.mutable.Buffer[Any]) = if (a) b else c
+  // bar produces an ill-bounded LUB in 2.11.8. After this commit, which fixes a bug in existential+refinement lubs, foo also fails.
+}
+// This test case minimizes a case that stated to fail compile after my fixes in SI-5294.
+// `foo` used to compile for the wrong reason, `mergePrefixAndArgs` failed to transpose a
+// ragged matrix and skipped to the next level of the base type sequences to find a common type symbol.
+//
+// My changes fixed the root cause of the ragged matrix, which uncovered the latent bug.
+// For comparison, `bar` failed to compile before _and_ after my changes for the same reason:
+// f-bounded types involved in LUBs can sometimes produce an ill-bounded LUB.
diff --git a/test/files/pos/lub-from-hell.scala b/test/files/pos/lub-from-hell.scala
new file mode 100644
index 0000000000..cb4b1733c7
--- /dev/null
+++ b/test/files/pos/lub-from-hell.scala
@@ -0,0 +1,6 @@
+class Test {
+  trait Tree
+  def foo(b: Boolean, buf: collection.mutable.ArrayBuffer[Any], acc: StringBuilder) = if (b) buf else acc
+}
+// This test case minimizes a case that failed to compile due to a bug in my work on
+// SI-5294. After refining my patches, it compiles again, as expected.
\ No newline at end of file
diff --git a/test/files/pos/t5294b.scala b/test/files/pos/t5294b.scala
new file mode 100644
index 0000000000..038d2ff806
--- /dev/null
+++ b/test/files/pos/t5294b.scala
@@ -0,0 +1,36 @@
+class Test {
+  def test = {
+
+    val l1 = null: Int #: String #: Boolean #: String #: HNil.type
+
+    type _2 = Succ[Succ[Zero.type]]
+
+    val t1: Boolean = null.asInstanceOf[ l1.type#Drop[_2]#Head ]
+
+    val t2: Boolean = null.asInstanceOf[ l1.type#Apply[_2] ]
+  }
+}
+
+
+sealed trait Nat {
+  type Fold[U, F[_ <: U] <: U, Z <: U] <: U
+}
+
+final object Zero extends Nat {
+  type Fold[U, F[_ <: U] <: U, Z <: U] = Z
+}
+
+final class Succ[N <: Nat] extends Nat {
+  type Fold[U, F[_ <: U] <: U, Z <: U] = F[N#Fold[U, F, Z]]
+}
+
+trait HList {
+  type Head
+  type Tail <: HList
+  type Drop[N <: Nat] = N#Fold[HList, ({ type L[X <: HList] = X#Tail })#L, this.type]
+  type Apply[N <: Nat] = Drop[N]#Head
+}
+
+class #: [H, T <: HList] extends HList { type Head = H; type Tail = T }
+
+object HNil extends HList { type Head = Nothing;  type Tail = Nothing }
diff --git a/test/files/pos/t5294c.scala b/test/files/pos/t5294c.scala
new file mode 100644
index 0000000000..2709098988
--- /dev/null
+++ b/test/files/pos/t5294c.scala
@@ -0,0 +1,30 @@
+sealed trait Nat {
+  type IsZero[U, A <: U, B <: U] <: U
+}
+
+final object Zero extends Nat {
+  type IsZero[U, T <: U, F <: U] = T
+}
+
+final class Succ[N <: Nat] extends Nat {
+  type IsZero[U, T <: U, F <: U] = F
+}
+
+trait HList {
+  type Head
+  type Tail <: HList
+  type Drop[N <: Nat] = N#IsZero[HList, this.type, Tail]
+  type Apply[N <: Nat] = Drop[N]#Head // typechecks as HList.this.Head
+}
+
+object Test {
+  type ::[H, T <: HList] = HList { type Head = H; type Tail = T}
+  type HNil <: HList
+  type T = Int :: String :: HNil
+
+  type U = T#Drop[Succ[Zero.type]]#Head
+  type V = T#Apply[Succ[Zero.type]]
+  var u: U = ???
+  var v: V = ???
+  u = v
+}
diff --git a/test/pending/pos/t6161.scala b/test/files/pos/t6161b.scala
index 5783cc85f2..5783cc85f2 100644
--- a/test/pending/pos/t6161.scala
+++ b/test/files/pos/t6161b.scala
diff --git a/test/files/pos/typevar-in-prefix.scala b/test/files/pos/typevar-in-prefix.scala
new file mode 100644
index 0000000000..929648b789
--- /dev/null
+++ b/test/files/pos/typevar-in-prefix.scala
@@ -0,0 +1,9 @@
+trait Test1 {
+  abstract class Setting
+  def Bool: Setting
+
+  class C[T <: Setting](val s: T)
+  val setting1 = null.asInstanceOf[_1.s.type forSome { val _1: C[Setting] }]
+  // the derived accessor for this val was not using an inferred type, as was
+  // the intention of the implementation in MethodSynthesis.
+}
diff --git a/test/files/presentation/callcc-interpreter/Runner.scala b/test/files/presentation/callcc-interpreter/Runner.scala
index a5698be5c2..1c03e3d5ba 100644
--- a/test/files/presentation/callcc-interpreter/Runner.scala
+++ b/test/files/presentation/callcc-interpreter/Runner.scala
@@ -1,6 +1,3 @@
 import scala.tools.nsc.interactive.tests._
 
-object Test extends InteractiveTest {
-  // Normalize ordering of LUB
-  override def normalize(s: String) = s.replace("Serializable with Product", "Product with Serializable")
-}
+object Test extends InteractiveTest
diff --git a/test/files/run/t5294.scala b/test/files/run/t5294.scala
new file mode 100644
index 0000000000..2551ae89a6
--- /dev/null
+++ b/test/files/run/t5294.scala
@@ -0,0 +1,22 @@
+import scala.language.higherKinds
+
+package p {
+  trait T[+A, +CC] {
+    def t: CC
+  }
+  class C {
+    def test[CC[X] <: T[X,String] with T[X,Int]](from: CC[_]): Unit = ()
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val symtab = reflect.runtime.universe.asInstanceOf[reflect.internal.SymbolTable]
+    val CTpe = reflect.runtime.universe.typeOf[p.C].asInstanceOf[symtab.Type]
+    val TClass = reflect.runtime.universe.symbolOf[p.T[_, _]].asInstanceOf[symtab.Symbol]
+    import symtab._
+    val from = CTpe.member(TermName("test")).paramss.head.head
+    assert(from.baseClasses contains TClass)
+    assert(from.info.baseTypeIndex(TClass) != -1) // was failing!
+  }
+}
diff --git a/test/files/run/t7747-repl.scala b/test/files/run/t7747-repl.scala
index 0094d3ba98..8203f4c802 100644
--- a/test/files/run/t7747-repl.scala
+++ b/test/files/run/t7747-repl.scala
@@ -10,9 +10,7 @@ object Test extends ReplTest {
 
   override def normalize(s: String) = {
     // replace indylambda function names by <function0>
-    val s2 = """\$Lambda.*""".r.replaceAllIn(s, "<function0>")
-    // Normalize ordering of LUB
-    s2.replace("Serializable with Product", "Product with Serializable")
+    """\$Lambda.*""".r.replaceAllIn(s, "<function0>")
   }
 
   def code = """
diff --git a/test/junit/scala/reflect/internal/TypesTest.scala b/test/junit/scala/reflect/internal/TypesTest.scala
index 05a77cfb47..585493280b 100644
--- a/test/junit/scala/reflect/internal/TypesTest.scala
+++ b/test/junit/scala/reflect/internal/TypesTest.scala
@@ -58,4 +58,85 @@ class TypesTest {
         Assert.fail(xs.mkString("\n"))
     }
   }
+
+  @Test
+  def testRefinementContains(): Unit = {
+    val refinement = typeOf[{def foo: Int}]
+    assert(refinement.isInstanceOf[RefinedType])
+    assert(refinement.contains(IntClass))
+    val elem0 = refinement.baseTypeSeq(0)
+    assert(elem0.isInstanceOf[RefinementTypeRef])
+    assert(elem0.contains(IntClass))
+  }
+
+  @Test
+  def testRefinedLubs(): Unit = {
+    // https://github.com/scala/scala-dev/issues/168
+    assertEquals(typeOf[Option[AnyVal]], lub(typeOf[Option[Int] with Option[Char]] :: typeOf[Option[Boolean] with Option[Short]] :: Nil))
+    assertEquals(typeOf[Option[AnyVal]], lub(typeOf[Option[Int] with Option[Char]] :: typeOf[Option[Boolean]] :: Nil))
+    assertEquals(typeOf[Option[AnyVal]], lub((typeOf[Option[Int] with Option[Char]] :: typeOf[Option[Boolean] with Option[Short]] :: Nil).reverse))
+    assertEquals(typeOf[Option[AnyVal]], lub((typeOf[Option[Int] with Option[Char]] :: typeOf[Option[Boolean]] :: Nil).reverse))
+  }
+
+  @Test
+  def testExistentialRefinement(): Unit = {
+    import rootMirror.EmptyPackageClass
+
+    // class M[A]
+    val MClass = EmptyPackageClass.newClass("M")
+    val A = MClass.newTypeParameter("A").setInfo(TypeBounds.empty)
+    MClass.setInfo(PolyType(A :: Nil, ClassInfoType(ObjectClass.tpeHK :: Nil, newScopeWith(), MClass)))
+
+    // (M[Int] with M[X] { def m: Any }) forSome { type X }
+    val X = NoSymbol.newExistential("X").setInfo(TypeBounds.empty)
+    val T: Type = {
+      val decls = newScopeWith(MClass.newMethod("m").setInfo(NullaryMethodType(AnyClass.tpeHK)))
+      val refined = refinedType(appliedType(MClass, IntClass.tpeHK) :: appliedType(MClass, X.tpeHK) :: Nil, NoSymbol, decls, NoPosition)
+      newExistentialType(X :: Nil, refined)
+    }
+
+    val RefinementClass = T.underlying.typeSymbol
+    assertTrue(RefinementClass.isRefinementClass)
+    TypeRef(NoPrefix, RefinementClass, Nil) match {
+      case rtr : RefinementTypeRef =>
+        // ContainsCollector needs to look inside the info of symbols of RefinementTypeRefs
+        assert(rtr.contains(X))
+    }
+
+    val underlying = T.underlying
+    val baseTypeSeqIndices = T.baseTypeSeq.toList.indices
+    for (i <- baseTypeSeqIndices) {
+      // Elements of the existential type should have the same type symbol as underlying
+      assertEquals(T.baseTypeSeq.typeSymbol(i), underlying.baseTypeSeq.typeSymbol(i))
+    }
+
+    // Type symbols should be distinct
+    def checkDistinctTypeSyms(bts: BaseTypeSeq): Unit = {
+      val syms = baseTypeSeqIndices.map(T.baseTypeSeq.typeSymbol)
+      assertEquals(syms, syms.distinct)
+    }
+    checkDistinctTypeSyms(T.baseTypeSeq)
+    checkDistinctTypeSyms(T.underlying.baseTypeSeq)
+
+    // This is the entry for the refinement class
+    assertTrue(T.baseTypeSeq.typeSymbol(0).isRefinementClass)
+    assertEquals("M[Int] with M[X]{def m: Any} forSome { type X }", T.baseTypeSeq.rawElem(0).toString)
+
+    // This is the entry for M. The raw entry is an existential over a RefinedType which encodes a lazily computed base type
+    assertEquals(T.baseTypeSeq.typeSymbol(1), MClass)
+    assertEquals("M[X] with M[Int] forSome { type X }", T.baseTypeSeq.rawElem(1).toString)
+    // calling `apply` merges the prefix/args of the elements ot the RefinedType and rewraps in the existential
+    assertEquals("M[_1] forSome { type X; type _1 >: X with Int }", T.baseTypeSeq.apply(1).toString)
+  }
+
+  @Test
+  def testExistentialMerge(): Unit = {
+    val ts = typeOf[Set[Any]] :: typeOf[Set[X] forSome { type X <: Y; type Y <: Int}] :: Nil
+    def merge(ts: List[Type]) = mergePrefixAndArgs(ts, Variance.Contravariant, lubDepth(ts))
+    val merged1 = merge(ts)
+    val merged2 = merge(ts.reverse)
+    assert(ts.forall(_ <:< merged1)) // use to fail before fix to mergePrefixAndArgs for existentials
+    assert(ts.forall(_ <:< merged2))
+    assert(merged1 =:= merged2)
+  }
 }