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Fix signature caching in NamedType #4593

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Merged
merged 3 commits into from
Jun 6, 2018
Merged

Fix signature caching in NamedType #4593

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9753483
Fix signature caching in NamedType
smarter May 28, 2018
bf91347
Refactor signature caching
smarter May 28, 2018
3652d94
Signature: Fix documentation
smarter May 28, 2018
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12 changes: 9 additions & 3 deletions compiler/src/dotty/tools/dotc/core/Signature.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -87,14 +87,15 @@ case class Signature(paramsSig: List[TypeName], resSig: TypeName) {

/** Construct a signature by prepending the signature names of the given `params`
* to the parameter part of this signature.
*
* Like Signature#apply, the result is only cacheable if `isUnderDefined == false`.
*/
def prepend(params: List[Type], isJava: Boolean)(implicit ctx: Context) =
Signature(params.map(p => sigName(p, isJava)) ++ paramsSig, resSig)

/** A signature is under-defined if its paramsSig part contains at least one
* `tpnme.Uninstantiated`. Under-defined signatures arise when taking a signature
* of a type that still contains uninstantiated type variables. They are eliminated
* by `fixSignature` in `PostTyper`.
* of a type that still contains uninstantiated type variables.
*/
def isUnderDefined(implicit ctx: Context) =
paramsSig.contains(tpnme.Uninstantiated) || resSig == tpnme.Uninstantiated
Expand All @@ -116,7 +117,12 @@ object Signature {
*/
val OverloadedSignature = Signature(List(tpnme.OVERLOADED), EmptyTypeName)

/** The signature of a method with no parameters and result type `resultType`. */
/** The signature of a method with no parameters and result type `resultType`.
*
* The resulting value is only cacheable if `isUnderDefined == false`,
* otherwise the signature will change once the contained type variables have
* been instantiated.
*/
def apply(resultType: Type, isJava: Boolean)(implicit ctx: Context): Signature = {
assert(!resultType.isInstanceOf[ExprType])
apply(Nil, sigName(resultType, isJava))
Expand Down
38 changes: 17 additions & 21 deletions compiler/src/dotty/tools/dotc/core/Types.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1580,7 +1580,7 @@ object Types {

// --- NamedTypes ------------------------------------------------------------------

abstract class NamedType extends CachedProxyType with ValueType { self =>
abstract class NamedType extends CachedProxyType with ValueType with SignatureCachingType { self =>

type ThisType >: this.type <: NamedType
type ThisName <: Name
Expand All @@ -1592,7 +1592,6 @@ object Types {
assert(prefix.isValueType || (prefix eq NoPrefix), s"invalid prefix $prefix")

private[this] var myName: Name = null
private[this] var mySig: Signature = null
private[this] var lastDenotation: Denotation = null
private[this] var lastSymbol: Symbol = null
private[this] var checkedPeriod: Period = Nowhere
Expand All @@ -1601,6 +1600,7 @@ object Types {
// Invariants:
// (1) checkedPeriod != Nowhere => lastDenotation != null
// (2) lastDenotation != null => lastSymbol != null
// (3) mySigRunId != NoRunId => mySig != null

def isType = isInstanceOf[TypeRef]
def isTerm = isInstanceOf[TermRef]
Expand All @@ -1621,12 +1621,7 @@ object Types {
/** The signature of the last known denotation, or if there is none, the
* signature of the symbol
*/
final override def signature(implicit ctx: Context): Signature = {
if (mySig == null) mySig = computeSignature
mySig
}

def computeSignature(implicit ctx: Context): Signature = {
protected def computeSignature(implicit ctx: Context): Signature = {
val lastd = lastDenotation
if (lastd != null) lastd.signature
else symbol.asSeenFrom(prefix).signature
Expand All @@ -1637,7 +1632,7 @@ object Types {
* Otherwise NotAMethod.
*/
private def currentSignature(implicit ctx: Context): Signature =
if (mySig != null) mySig
if (ctx.runId == mySignatureRunId) mySignature
else {
val lastd = lastDenotation
if (lastd != null) lastd.signature
Expand Down Expand Up @@ -2584,13 +2579,22 @@ object Types {
// and therefore two different poly types would never be equal.

/** A trait that mixes in functionality for signature caching */
trait MethodicType extends TermType {

private[this] var mySignature: Signature = _
private[this] var mySignatureRunId: Int = NoRunId
trait SignatureCachingType extends TermType {
protected[this] var mySignature: Signature = _
protected[this] var mySignatureRunId: Int = NoRunId

protected def computeSignature(implicit ctx: Context): Signature

final override def signature(implicit ctx: Context): Signature = {
if (ctx.runId != mySignatureRunId) {
mySignature = computeSignature
if (!mySignature.isUnderDefined) mySignatureRunId = ctx.runId
}
mySignature
}
}

trait MethodicType extends SignatureCachingType {
protected def resultSignature(implicit ctx: Context) = try resultType match {
case rtp: MethodicType => rtp.signature
case tp =>
Expand All @@ -2602,14 +2606,6 @@ object Types {
println(i"failure while taking result signature of $this: $resultType")
throw ex
}

final override def signature(implicit ctx: Context): Signature = {
if (ctx.runId != mySignatureRunId) {
mySignature = computeSignature
if (!mySignature.isUnderDefined) mySignatureRunId = ctx.runId
}
mySignature
}
}

/** A by-name parameter type of the form `=> T`, or the type of a method with no parameter list. */
Expand Down