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author | Adriaan Moors <adriaan.moors@typesafe.com> | 2014-02-12 20:01:03 -0800 |
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committer | Adriaan Moors <adriaan.moors@typesafe.com> | 2014-02-12 20:01:03 -0800 |
commit | c0edf768912e07690cf904eabf1acb5b2eefbd5e (patch) | |
tree | 4e3af4441ef920bd697b4faa4511486018e9de4d | |
parent | 9c4a6e3ed7624892f46948c1c0fb57d7d5b3346e (diff) | |
parent | d5a1ea61871ad695c67a2165d0e569f304e63662 (diff) | |
download | scala-c0edf768912e07690cf904eabf1acb5b2eefbd5e.tar.gz scala-c0edf768912e07690cf904eabf1acb5b2eefbd5e.tar.bz2 scala-c0edf768912e07690cf904eabf1acb5b2eefbd5e.zip |
Merge pull request #3518 from adriaanm/t7753
SI-7753 InstantiateDependentMap narrows type of unstable args
-rw-r--r-- | src/reflect/scala/reflect/internal/tpe/TypeMaps.scala | 81 | ||||
-rw-r--r-- | test/files/neg/t3873.check | 4 | ||||
-rw-r--r-- | test/files/neg/t3873.scala | 2 | ||||
-rw-r--r-- | test/files/pos/t7753.scala | 36 | ||||
-rw-r--r-- | test/files/pos/t8223.scala | 29 |
5 files changed, 119 insertions, 33 deletions
diff --git a/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala b/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala index f427813c01..07c9242bf3 100644 --- a/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala +++ b/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala @@ -863,31 +863,24 @@ private[internal] trait TypeMaps { private val existentials = new Array[Symbol](actuals.size) def existentialsNeeded: List[Symbol] = existentials.iterator.filter(_ ne null).toList - private object StableArg { - def unapply(param: Symbol) = Arg unapply param map actuals filter (tp => - tp.isStable && (tp.typeSymbol != NothingClass) - ) - } - private object Arg { - def unapply(param: Symbol) = Some(params indexOf param) filter (_ >= 0) - } - - def apply(tp: Type): Type = mapOver(tp) match { - // unsound to replace args by unstable actual #3873 - case SingleType(NoPrefix, StableArg(arg)) => arg - // (soundly) expand type alias selections on implicit arguments, - // see depmet_implicit_oopsla* test cases -- typically, `param.isImplicit` - case tp1 @ TypeRef(SingleType(NoPrefix, Arg(pid)), sym, targs) => - val arg = actuals(pid) - val res = typeRef(arg, sym, targs) - if (res.typeSymbolDirect.isAliasType) res.dealias else tp1 - // don't return the original `tp`, which may be different from `tp1`, - // due to dropping annotations - case tp1 => tp1 + private object StableArgTp { + // type of actual arg corresponding to param -- if the type is stable + def unapply(param: Symbol): Option[Type] = (params indexOf param) match { + case -1 => None + case pid => + val tp = actuals(pid) + if (tp.isStable && (tp.typeSymbol != NothingClass)) Some(tp) + else None + } } - /* Return the type symbol for referencing a parameter inside the existential quantifier. - * (Only needed if the actual is unstable.) + /** Return the type symbol for referencing a parameter that's instantiated to an unstable actual argument. + * + * To soundly abstract over an unstable value (x: T) while retaining the most type information, + * use `x.type forSome { type x.type <: T with Singleton}` + * `typeOf[T].narrowExistentially(symbolOf[x])`. + * + * See also: captureThis in AsSeenFromMap. */ private def existentialFor(pid: Int) = { if (existentials(pid) eq null) { @@ -900,6 +893,38 @@ private[internal] trait TypeMaps { existentials(pid) } + private object UnstableArgTp { + // existential quantifier and type of corresponding actual arg with unstable type + def unapply(param: Symbol): Option[(Symbol, Type)] = (params indexOf param) match { + case -1 => None + case pid => + val sym = existentialFor(pid) + Some((sym, sym.tpe_*)) // refers to an actual value, must be kind-* + } + } + + private object StabilizedArgTp { + def unapply(param: Symbol): Option[Type] = + param match { + case StableArgTp(tp) => Some(tp) // (1) + case UnstableArgTp(_, tp) => Some(tp) // (2) + case _ => None + } + } + + /** instantiate `param.type` to the (sound approximation of the) type `T` + * of the actual argument `arg` that was passed in for `param` + * + * (1) If `T` is stable, we can just use that. + * + * (2) SI-3873: it'd be unsound to instantiate `param.type` to an unstable `T`, + * so we approximate to `X forSome {type X <: T with Singleton}` -- we can't soundly say more. + */ + def apply(tp: Type): Type = tp match { + case SingleType(NoPrefix, StabilizedArgTp(tp)) => tp + case _ => mapOver(tp) + } + //AM propagate more info to annotations -- this seems a bit ad-hoc... (based on code by spoon) override def mapOver(arg: Tree, giveup: ()=>Nothing): Tree = { // TODO: this should be simplified; in the stable case, one can @@ -922,13 +947,9 @@ private[internal] trait TypeMaps { // Both examples are from run/constrained-types.scala. object treeTrans extends Transformer { override def transform(tree: Tree): Tree = tree.symbol match { - case StableArg(actual) => - gen.mkAttributedQualifier(actual, tree.symbol) - case Arg(pid) => - val sym = existentialFor(pid) - Ident(sym) copyAttrs tree setType typeRef(NoPrefix, sym, Nil) - case _ => - super.transform(tree) + case StableArgTp(tp) => gen.mkAttributedQualifier(tp, tree.symbol) + case UnstableArgTp(quant, tp) => Ident(quant) copyAttrs tree setType tp + case _ => super.transform(tree) } } treeTrans transform arg diff --git a/test/files/neg/t3873.check b/test/files/neg/t3873.check index 54d6abdf63..f9f413aeaf 100644 --- a/test/files/neg/t3873.check +++ b/test/files/neg/t3873.check @@ -1,6 +1,6 @@ t3873.scala:11: error: type mismatch; found : Test.a.B - required: a.B - wrongf(new A)(a.b) // should not compile -- TODO: improve error message? the "a" is ambiguous + required: a.B where val a: A + wrongf(new A)(a.b) // should not compile ^ one error found diff --git a/test/files/neg/t3873.scala b/test/files/neg/t3873.scala index e7815f0937..b27b4e9c9d 100644 --- a/test/files/neg/t3873.scala +++ b/test/files/neg/t3873.scala @@ -8,5 +8,5 @@ object Test { val a = new A wrongf(a)(a.b) - wrongf(new A)(a.b) // should not compile -- TODO: improve error message? the "a" is ambiguous + wrongf(new A)(a.b) // should not compile }
\ No newline at end of file diff --git a/test/files/pos/t7753.scala b/test/files/pos/t7753.scala new file mode 100644 index 0000000000..93ad23f114 --- /dev/null +++ b/test/files/pos/t7753.scala @@ -0,0 +1,36 @@ +import scala.language.{ higherKinds, implicitConversions } + +trait Foo { type Out } + +trait SI { + val instance: Foo + type Out +} + +object Test { + def test { + def indirect(si: SI)(v: si.instance.Out) = v + + val foo: Foo { type Out = Int } = ??? + def conv(i: Foo): SI { type Out = i.Out; val instance: i.type } = ??? + + val converted = conv(foo) + + val v1: Int = indirect(converted)(23) // Okay (after refining the return type `instance` in the return type of `conv`) + /* + indirect(converted){(v: converted.instance.Out)converted.instance.Out}( + 23{Int(23)} + ){converted.instance.Out}; + */ + + val v2: Int = indirect(conv(foo))(23) // Used to fail as follows: + /* + indirect( + conv(foo){si.SI{type Out = foo.Out; val instance: si.Test.<refinement>.type}} + ){(v: si.instance.Out)si.instance.Out}( + 23{<error>} + ){<error>}; + */ + + } +} diff --git a/test/files/pos/t8223.scala b/test/files/pos/t8223.scala new file mode 100644 index 0000000000..52d6b0098e --- /dev/null +++ b/test/files/pos/t8223.scala @@ -0,0 +1,29 @@ +package p { + class ViewEnv[AIn] { + type A = AIn + class SubView { def has(x: A): Boolean = ??? } + def get: SubView = new SubView + } + + trait HasA { type A } + trait Indexable[R] extends HasA + class ArrayTC[AIn] extends Indexable[Array[AIn]] { type A = AIn } +} + +package object p { + implicit def arrayTypeClass[A] : ArrayTC[A] = new ArrayTC[A] + object intArrayTC extends ArrayTC[Int] + + type EnvAlias[W <: HasA] = ViewEnv[W#A] + type SubAlias[W <: HasA] = ViewEnv[W#A]#SubView + + def f0[R](xs: R)(implicit tc: Indexable[R]): ViewEnv[tc.A]#SubView = new ViewEnv[tc.A]() get + def f1[R](xs: R)(implicit tc: Indexable[R]): EnvAlias[tc.type]#SubView = new ViewEnv[tc.A]() get + def f2[R](xs: R)(implicit tc: Indexable[R]): SubAlias[tc.type] = new ViewEnv[tc.A]() get + + def g0 = f0(Array(1)) has 2 // ok + def g1 = f1(Array(1)) has 2 // ok + def g2 = f2(Array(1)) has 2 // "found: Int(2), required: tc.A" + def g3 = f2(Array(1))(new ArrayTC[Int]) has 2 // "found: Int(2), required: tc.A" + def g4 = f2(Array(1))(intArrayTC) has 2 // ok +} |