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Fix parameterized typedefs with lambdas as rhs #1409

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Merged
merged 3 commits into from
Jul 25, 2016
Merged

Fix parameterized typedefs with lambdas as rhs #1409

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5968e9f
Fix parameterized typedefs with lambdas as rhs
odersky Jul 21, 2016
013101d
Take curried type lambdas into account
odersky Jul 22, 2016
006748d
Simplify abstracted
odersky Jul 22, 2016
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14 changes: 6 additions & 8 deletions src/dotty/tools/dotc/typer/Namer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -934,15 +934,11 @@ class Namer { typer: Typer =>
}

def typeDefSig(tdef: TypeDef, sym: Symbol, tparamSyms: List[TypeSymbol])(implicit ctx: Context): Type = {
val isDerived = tdef.rhs.isInstanceOf[untpd.DerivedTypeTree]
//val toParameterize = tparamSyms.nonEmpty && !isDerived
//val needsLambda = sym.allOverriddenSymbols.exists(_ is HigherKinded) && !isDerived
def abstracted(tp: Type): Type =
if (tparamSyms.nonEmpty && !tp.isHK) tp.LambdaAbstract(tparamSyms)
//else if (toParameterize) tp.parameterizeWith(tparamSyms)
def abstracted(tp: Type, canAbstract: Boolean): Type =
if (tparamSyms.nonEmpty && canAbstract) tp.LambdaAbstract(tparamSyms)
else tp

val dummyInfo = abstracted(TypeBounds.empty)
val dummyInfo = abstracted(TypeBounds.empty, canAbstract = true)
sym.info = dummyInfo
// Temporarily set info of defined type T to ` >: Nothing <: Any.
// This is done to avoid cyclic reference errors for F-bounds.
Expand All @@ -954,7 +950,9 @@ class Namer { typer: Typer =>
//
// The scheme critically relies on an implementation detail of isRef, which
// inspects a TypeRef's info, instead of simply dealiasing alias types.
val rhsType = abstracted(typedAheadType(tdef.rhs).tpe)

val isDerived = tdef.rhs.isInstanceOf[untpd.DerivedTypeTree]
val rhsType = abstracted(typedAheadType(tdef.rhs).tpe, canAbstract = !isDerived)
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Having a boolean parameter that changes the behavior of a method to become the identity seems weird to me, I would just write:

val rhsType0 = typedAheadType(tdef.rhs).tpe
val rhsType = if (!isDerived) abstracted(rhsType0) else rhsType0

val unsafeInfo = rhsType match {
case bounds: TypeBounds => bounds
case alias => TypeAlias(alias, if (sym is Local) sym.variance else 0)
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9 changes: 9 additions & 0 deletions tests/pos/nestedLambdas.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
class Test {

type T = [X] -> [Y] -> (X, Y)

type A[X] = [Y] -> (X, Y)

type B[X] = (X, X)

}