diff options
| -rw-r--r-- | src/dotty/tools/dotc/core/Types.scala | 6 | ||||
| -rw-r--r-- | src/dotty/tools/dotc/typer/Inferencing.scala | 14 | ||||
| -rw-r--r-- | src/dotty/tools/dotc/typer/ProtoTypes.scala | 2 | ||||
| -rw-r--r-- | src/dotty/tools/dotc/typer/Typer.scala | 4 |
4 files changed, 19 insertions, 7 deletions
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala index 5f30f484e..f113307ef 100644 --- a/src/dotty/tools/dotc/core/Types.scala +++ b/src/dotty/tools/dotc/core/Types.scala @@ -2269,8 +2269,12 @@ object Types { * @param creatorState The typer state in which the variable was created. * @param owningTree The function part of the TypeApply tree tree that introduces * the type variable. + * @paran owner The current owner if the context where the variable was created. + * + * `owningTree` and `owner` are used to determine whether a type-variable can be instantiated + * at some given point. See `Inferencing#interpolateUndetVars`. */ - final class TypeVar(val origin: PolyParam, creatorState: TyperState, val owningTree: untpd.Tree) extends CachedProxyType with ValueType { + final class TypeVar(val origin: PolyParam, creatorState: TyperState, val owningTree: untpd.Tree, val owner: Symbol) extends CachedProxyType with ValueType { /** The permanent instance type of the the variable, or NoType is none is given yet */ private[core] var inst: Type = NoType diff --git a/src/dotty/tools/dotc/typer/Inferencing.scala b/src/dotty/tools/dotc/typer/Inferencing.scala index 38c1e49c5..753125e6a 100644 --- a/src/dotty/tools/dotc/typer/Inferencing.scala +++ b/src/dotty/tools/dotc/typer/Inferencing.scala @@ -163,10 +163,18 @@ trait Inferencing { this: Checking => * If such a variable appears covariantly in type `tp` or does not appear at all, * approximate it by its lower bound. Otherwise, if it appears contravariantly * in type `tp` approximate it by its upper bound. + * @param ownedBy if it is different from NoSymbol, all type variables owned by + * `ownedBy` qualify, independent of position. + * Without that second condition, it can be that certain variables escape + * interpolation, for instance when their tree was eta-lifted, so + * the typechecked tree is no longer the tree in which the variable + * was declared. A concrete example of this phenomenon can be + * observed when compiling core.TypeOps#asSeenFrom. */ - def interpolateUndetVars(tree: Tree)(implicit ctx: Context): Unit = { + def interpolateUndetVars(tree: Tree, ownedBy: Symbol)(implicit ctx: Context): Unit = { val constraint = ctx.typerState.constraint - val qualifies = (tvar: TypeVar) => tree contains tvar.owningTree + val qualifies = (tvar: TypeVar) => + (tree contains tvar.owningTree) || ownedBy.exists && tvar.owner == ownedBy def interpolate() = Stats.track("interpolateUndetVars") { val tp = tree.tpe.widen constr.println(s"interpolate undet vars in ${tp.show}, pos = ${tree.pos}, mode = ${ctx.mode}, undets = ${constraint.uninstVars map (tvar => s"${tvar.show}@${tvar.owningTree.pos}")}") @@ -182,7 +190,7 @@ trait Inferencing { this: Checking => } } if (changed) // instantiations might have uncovered new typevars to interpolate - interpolateUndetVars(tree) + interpolateUndetVars(tree, ownedBy) else for (tvar <- constraint.uninstVars) if (!(vs contains tvar) && qualifies(tvar)) { diff --git a/src/dotty/tools/dotc/typer/ProtoTypes.scala b/src/dotty/tools/dotc/typer/ProtoTypes.scala index c0e30b12e..f646f7ecd 100644 --- a/src/dotty/tools/dotc/typer/ProtoTypes.scala +++ b/src/dotty/tools/dotc/typer/ProtoTypes.scala @@ -326,7 +326,7 @@ object ProtoTypes { def newTypeVars(pt: PolyType): List[TypeVar] = for (n <- (0 until pt.paramNames.length).toList) - yield new TypeVar(PolyParam(pt, n), state, owningTree) + yield new TypeVar(PolyParam(pt, n), state, owningTree, ctx.owner) val added = if (state.constraint contains pt) pt.duplicate(pt.paramNames, pt.paramBounds, pt.resultType) diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala index e98b73cae..d194ccaae 100644 --- a/src/dotty/tools/dotc/typer/Typer.scala +++ b/src/dotty/tools/dotc/typer/Typer.scala @@ -1174,8 +1174,8 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit def adapt(tree: Tree, pt: Type, original: untpd.Tree = untpd.EmptyTree)(implicit ctx: Context) = /*>|>*/ track("adapt") /*<|<*/ { /*>|>*/ ctx.traceIndented(i"adapting $tree of type ${tree.tpe} to $pt", typr, show = true) /*<|<*/ { - interpolateUndetVars(tree) - tree overwriteType tree.tpe.simplified + interpolateUndetVars(tree, if (tree.isDef) tree.symbol else NoSymbol) + tree.overwriteType(tree.tpe.simplified) adaptInterpolated(tree, pt, original) } } |