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-rw-r--r--src/dotty/tools/dotc/core/Types.scala36
-rw-r--r--tests/neg/ski.scala41
2 files changed, 50 insertions, 27 deletions
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index dadb5b95e..403b49da6 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -2254,14 +2254,32 @@ object Types {
tp
}
*/
+
+ /** Create a RecType, normalizing its contents. This means:
+ *
+ * 1. Nested Rec types on the type's spine are merged with the outer one.
+ * 2. Any refinement of the form `type T = z.T` on the spine of the type
+ * where `z` refers to the created rec-type is replaced by
+ * `type T`. This avoids infinite recursons later when we
+ * try to follow these references.
+ * TODO: Figure out how to guarantee absence of cycles
+ * of length > 1
+ */
def apply(parentExp: RecType => Type)(implicit ctx: Context): RecType = {
- var rt = new RecType(parentExp)
- rt.parent match {
- case rt2: RecType =>
- rt = rt2.derivedRecType(rt2.parent.substRecThis(rt, RecThis(rt2)))
- case _ =>
+ val rt = new RecType(parentExp)
+ def normalize(tp: Type): Type = tp.stripTypeVar match {
+ case tp: RecType =>
+ normalize(tp.parent.substRecThis(tp, RecThis(rt)))
+ case tp @ RefinedType(parent, rname, rinfo) =>
+ val rinfo1 = rinfo match {
+ case TypeAlias(TypeRef(RecThis(`rt`), `rname`)) => TypeBounds.empty
+ case _ => rinfo
+ }
+ tp.derivedRefinedType(normalize(parent), rname, rinfo1)
+ case tp =>
+ tp
}
- unique(rt)
+ unique(rt.derivedRecType(normalize(rt.parent)))
}
def closeOver(parentExp: RecType => Type)(implicit ctx: Context) = {
val rt = this(parentExp)
@@ -2747,7 +2765,11 @@ object Types {
case that: RecThis => this.binder eq that.binder
case _ => false
}
- override def toString = s"RecThis(${binder.hashCode})"
+ override def toString =
+ try s"RecThis(${binder.hashCode})"
+ catch {
+ case ex: NullPointerException => s"RecThis(<under construction>)"
+ }
}
// ----- Skolem types -----------------------------------------------
diff --git a/tests/neg/ski.scala b/tests/neg/ski.scala
index b192dc9e2..3d44e77da 100644
--- a/tests/neg/ski.scala
+++ b/tests/neg/ski.scala
@@ -17,8 +17,8 @@ trait S2[x <: Term, y <: Term] extends Term {
type eval = S2[x, y]
}
trait S3[x <: Term, y <: Term, z <: Term] extends Term {
- type ap[v <: Term] = eval#ap[v] // error
- type eval = x#ap[z]#ap[y#ap[z]]#eval // error // error
+ type ap[v <: Term] = eval#ap[v] // error: not a legal path
+ type eval = x#ap[z]#ap[y#ap[z]]#eval // error: not a legal path // error: not a legal path
}
// The K combinator
@@ -31,8 +31,8 @@ trait K1[x <: Term] extends Term {
type eval = K1[x]
}
trait K2[x <: Term, y <: Term] extends Term {
- type ap[z <: Term] = eval#ap[z] // error
- type eval = x#eval // error
+ type ap[z <: Term] = eval#ap[z] // error: not a legal path
+ type eval = x#eval // error: not a legal path
}
// The I combinator
@@ -41,8 +41,8 @@ trait I extends Term {
type eval = I
}
trait I1[x <: Term] extends Term {
- type ap[y <: Term] = eval#ap[y] // error
- type eval = x#eval // error
+ type ap[y <: Term] = eval#ap[y] // error: not a legal path
+ type eval = x#eval // error: not a legal path
}
// Constants
@@ -64,9 +64,10 @@ case class Equals[A >: B <:B , B]()
object Test {
type T1 = Equals[Int, Int] // compiles fine
- type T2 = Equals[String, Int] // error
+ type T2 = Equals[String, Int] // error: Type argument String does not conform to upper bound Int
+
type T3 = Equals[I#ap[c]#eval, c]
- type T3a = Equals[I#ap[c]#eval, d] // error
+ type T3a = Equals[I#ap[c]#eval, d] // error: Type argument I1[c]#eval does not conform to upper bound d
// Ic -> c
type T4 = Equals[I#ap[c]#eval, c]
@@ -75,29 +76,29 @@ object Test {
type T5 = Equals[K#ap[c]#ap[d]#eval, c]
// KKcde -> d
- type T6 = Equals[K#ap[K]#ap[c]#ap[d]#ap[e]#eval, d]
+ type T6 = Equals[K#ap[K]#ap[c]#ap[d]#ap[e]#eval, d] // error: Type argument K2[K1[_ <: Term] @UnsafeNonvariant#x, e]#eval does not conform to upper bound d
// SIIIc -> Ic
- type T7 = Equals[S#ap[I]#ap[I]#ap[I]#ap[c]#eval, c]
+ type T7 = Equals[S#ap[I]#ap[I]#ap[I]#ap[c]#eval, c] // error: not a legal path // error: Type argument I1[_ <: Term]#eval#ap[_]#eval does not conform to upper bound c
// SKKc -> Ic
type T8 = Equals[S#ap[K]#ap[K]#ap[c]#eval, c]
// SIIKc -> KKc
- type T9 = Equals[S#ap[I]#ap[I]#ap[K]#ap[c]#eval, K#ap[K]#ap[c]#eval]
+ type T9 = Equals[S#ap[I]#ap[I]#ap[K]#ap[c]#eval, K#ap[K]#ap[c]#eval] // error: Type argument K2[K1[_ <: Term] @UnsafeNonvariant#x, _ <: Term]#eval does not conform to upper bound K2[K, c]#eval
// SIKKc -> K(KK)c
- type T10 = Equals[S#ap[I]#ap[K]#ap[K]#ap[c]#eval, K#ap[K#ap[K]]#ap[c]#eval]
+ type T10 = Equals[S#ap[I]#ap[K]#ap[K]#ap[c]#eval, K#ap[K#ap[K]]#ap[c]#eval] // error: Type argument K2[K1[_ <: Term] @UnsafeNonvariant#x, _ <: Term]#eval does not conform to upper bound K2[K1[K], c]#eval
// SIKIc -> KIc
- type T11 = Equals[S#ap[I]#ap[K]#ap[I]#ap[c]#eval, K#ap[I]#ap[c]#eval]
+ type T11 = Equals[S#ap[I]#ap[K]#ap[I]#ap[c]#eval, K#ap[I]#ap[c]#eval] // error: not a legal path // error: Type argument I1[_ <: Term]#eval#ap[_]#eval does not conform to upper bound K2[I, c]#eval
// SKIc -> Ic
type T12 = Equals[S#ap[K]#ap[I]#ap[c]#eval, c]
// R = S(K(SI))K (reverse)
type R = S#ap[K#ap[S#ap[I]]]#ap[K]
- type T13 = Equals[R#ap[c]#ap[d]#eval, d#ap[c]#eval]
+ type T13 = Equals[R#ap[c]#ap[d]#eval, d#ap[c]#eval] // error: Type argument S3[I, S2[I, _ <: Term] @UnsafeNonvariant#y, _ <: Term]#eval does not conform to upper bound d#eval
type b[a <: Term] = S#ap[K#ap[a]]#ap[S#ap[I]#ap[I]]
@@ -106,27 +107,27 @@ object Test {
type eval = A0
}
trait A1 extends Term {
- type ap[x <: Term] = x#ap[A0]#eval // error
+ type ap[x <: Term] = x#ap[A0]#eval // error: not a legal path
type eval = A1
}
trait A2 extends Term {
- type ap[x <: Term] = x#ap[A1]#eval // error
+ type ap[x <: Term] = x#ap[A1]#eval // error: not a legal path
type eval = A2
}
type NN1 = b[R]#ap[b[R]]#ap[A0]
- type T13a = Equals[NN1#eval, c]
+ type T13a = Equals[NN1#eval, c] // error: Type argument Test.NN1#eval does not conform to upper bound c
// Double iteration
type NN2 = b[R]#ap[b[R]]#ap[A1]
- type T14 = Equals[NN2#eval, c]
+ type T14 = Equals[NN2#eval, c] // error: Type argument Test.NN2#eval does not conform to upper bound c
// Triple iteration
type NN3 = b[R]#ap[b[R]]#ap[A2]
- type T15 = Equals[NN3#eval, c]
+ type T15 = Equals[NN3#eval, c] // error: Type argument Test.NN3#eval does not conform to upper bound c
trait An extends Term {
- type ap[x <: Term] = x#ap[An]#eval // error
+ type ap[x <: Term] = x#ap[An]#eval // error: not a legal path
type eval = An
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-21 20:42:13 +0000