diff options
| -rw-r--r-- | src/reflect/scala/reflect/internal/Types.scala | 7 | ||||
| -rw-r--r-- | test/files/pos/t7517.scala | 22 |
2 files changed, 25 insertions, 4 deletions
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala index ee584bed2c..0cc2b91a44 100644 --- a/src/reflect/scala/reflect/internal/Types.scala +++ b/src/reflect/scala/reflect/internal/Types.scala @@ -3218,10 +3218,9 @@ trait Types extends api.Types { self: SymbolTable => sameLength(typeArgs, tp.typeArgs) && { val lhs = if (isLowerBound) tp.typeArgs else typeArgs val rhs = if (isLowerBound) typeArgs else tp.typeArgs - // this is a higher-kinded type var with same arity as tp. - // side effect: adds the type constructor itself as a bound - addBound(tp.typeConstructor) - isSubArgs(lhs, rhs, params, AnyDepth) + // This is a higher-kinded type var with same arity as tp. + // If so (see SI-7517), side effect: adds the type constructor itself as a bound. + isSubArgs(lhs, rhs, params, AnyDepth) && { addBound(tp.typeConstructor); true } } } // The type with which we can successfully unify can be hidden diff --git a/test/files/pos/t7517.scala b/test/files/pos/t7517.scala new file mode 100644 index 0000000000..7ce4c6b13e --- /dev/null +++ b/test/files/pos/t7517.scala @@ -0,0 +1,22 @@ +trait Box[ K[A[x]] ] + +object Box { + // type constructor composition + sealed trait ∙[A[_], B[_]] { type l[T] = A[B[T]] } + + // composes type constructors inside K + type SplitBox[K[A[x]], B[x]] = Box[ ({ type l[A[x]] = K[ (A ∙ B)#l] })#l ] + + def split[ K[A[x]], B[x] ](base: Box[K]): SplitBox[K,B] = ??? + + class Composed[B[_], L[A[x]] ] { + val box: Box[L] = ??? + + type Split[ A[x] ] = L[ (A ∙ B)#l ] + val a: Box[Split] = Box.split(box) + + //Either of these work: + val a1: Box[Split] = Box.split[L,B](box) + val a2: Box[ ({ type l[A[x]] = L[ (A ∙ B)#l ] })#l ] = Box.split(box) + } +}
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