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Merged
merged 2 commits into from
Mar 26, 2018
Merged

Optimize findRef #4156

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e7a5438
Optimize findRef
odersky Mar 22, 2018
1e34d2d
Don't crash when taking the signature of NoType
odersky Mar 22, 2018
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/core/TypeErasure.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -549,7 +549,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
if (inst.exists) sigName(inst) else tpnme.Uninstantiated
case tp: TypeProxy =>
sigName(tp.underlying)
case _: ErrorType | WildcardType =>
case _: ErrorType | WildcardType | NoType =>
tpnme.WILDCARD
case tp: WildcardType =>
sigName(tp.optBounds)
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@Blaisorblade Blaisorblade Mar 22, 2018 •
edited
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Does this code match twice against WildcardType? I don't get it. In fact, the latter matches appear to be erased away:

scala> def foo: Any => Any = { case _: String | Int => 1; case _: Int => 2 }
def foo: Any => Any
scala> foo(1)
val res0: Any = 2
scala> def foo: Any => Any = { case _: String | AnyRef => 1; case _: AnyRef => 2 }
def foo: Any => Any
scala> foo(new AnyRef())
val res1: Any = 2

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It first matches against the object WildcardType, then the case below matches against any instance of the class WildcardType.

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Yeah sorry, Allan explained me what's going on. But do we really know that the only instance of WildcardType(NoType) is the WildcardType object?

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31 changes: 19 additions & 12 deletions compiler/src/dotty/tools/dotc/core/Types.scala
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Expand Up @@ -508,10 +508,20 @@ object Types {
case tp1 => tp1
})
case tp: TypeRef =>
tp.denot.findMember(name, pre, excluded)
tp.denot match {
case d: ClassDenotation => d.findMember(name, pre, excluded)
case d => go(d.info)
}
case tp: AppliedType =>
goApplied(tp)
case tp: ThisType =>
tp.tycon match {
case tc: TypeRef if tc.symbol.isClass =>
go(tc)
case tc: HKTypeLambda =>
goApplied(tp, tc)
case _ =>
go(tp.superType)
}
case tp: ThisType => // ??? inline
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Stray comment?

goThis(tp)
case tp: RefinedType =>
if (name eq tp.refinedName) goRefined(tp) else go(tp.parent)
Expand Down Expand Up @@ -598,15 +608,9 @@ object Types {
}
}

def goApplied(tp: AppliedType) = tp.tycon match {
case tl: HKTypeLambda =>
go(tl.resType).mapInfo(info =>
tl.derivedLambdaAbstraction(tl.paramNames, tl.paramInfos, info).appliedTo(tp.args))
case tc: TypeRef if tc.symbol.isClass =>
go(tc)
case _ =>
go(tp.superType)
}
def goApplied(tp: AppliedType, tycon: HKTypeLambda) =
go(tycon.resType).mapInfo(info =>
tycon.derivedLambdaAbstraction(tycon.paramNames, tycon.paramInfos, info).appliedTo(tp.args))

def goThis(tp: ThisType) = {
val d = go(tp.underlying)
Expand All @@ -623,6 +627,7 @@ object Types {
// loadClassWithPrivateInnerAndSubSelf in ShowClassTests
go(tp.cls.typeRef) orElse d
}

def goParam(tp: TypeParamRef) = {
val next = tp.underlying
ctx.typerState.constraint.entry(tp) match {
Expand All @@ -632,12 +637,14 @@ object Types {
go(next)
}
}

def goSuper(tp: SuperType) = go(tp.underlying) match {
case d: JointRefDenotation =>
typr.println(i"redirecting super.$name from $tp to ${d.symbol.showLocated}")
new UniqueRefDenotation(d.symbol, tp.memberInfo(d.symbol), d.validFor)
case d => d
}

def goAnd(l: Type, r: Type) = {
go(l) & (go(r), pre, safeIntersection = ctx.pendingMemberSearches.contains(name))
}
Expand Down