From bce786f070afe383d203c4d809ef69803330b340 Mon Sep 17 00:00:00 2001 From: Jason Zaugg Date: Mon, 26 Aug 2013 12:30:21 +0200 Subject: SI-7782 Derive type skolems at the ground level Rather than at the current value of `skolemizationLevel`, which could be influenced by an in-flight existential subtype computation. This method is called in `PolyTypeCompleter`, which could be constructed by the lazy type completer of the enclosing class. So currently it is closing over a mutable variable; hence the Heisenbug. This issue was exposed by the changes in b74c33eb860, which was introduced in Scala 2.10.1. --- src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'src/reflect') diff --git a/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala b/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala index 3bcb793926..2c2ed351c9 100644 --- a/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala +++ b/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala @@ -19,6 +19,9 @@ trait ExistentialsAndSkolems { * can be deskolemized to the original type parameter. (A skolem is a * representation of a bound variable when viewed inside its scope.) * !!!Adriaan: this does not work for hk types. + * + * Skolems will be created at level 0, rather than the current value + * of `skolemizationLevel`. (See SI-7782) */ def deriveFreshSkolems(tparams: List[Symbol]): List[Symbol] = { class Deskolemizer extends LazyType { @@ -30,7 +33,11 @@ trait ExistentialsAndSkolems { sym setInfo sym.deSkolemize.info.substSym(typeParams, typeSkolems) } } - (new Deskolemizer).typeSkolems + + val saved = skolemizationLevel + skolemizationLevel = 0 + try new Deskolemizer().typeSkolems + finally skolemizationLevel = saved } def isRawParameter(sym: Symbol) = // is it a type parameter leaked by a raw type? -- cgit v1.2.3