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[NI] Do not add useless constraints to constraint system

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Skipped constraints:
 - T <: Any, T >: Nothing
 - T <: T, T <: T?, T >: T, T <: T!, T! <: T
This commit is contained in:
Stanislav Erokhin
2017-05-22 16:24:22 +03:00
committed by Mikhail Zarechenskiy
parent 3a25405088
commit 89ac3bd5cf
1 changed files with 33 additions and 10 deletions
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compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/components/ConstraintInjector.kt
+33 -10
View File
@@ -18,12 +18,16 @@ package org.jetbrains.kotlin.resolve.calls.inference.components
import org.jetbrains.kotlin.builtins.KotlinBuiltIns
import org.jetbrains.kotlin.resolve.calls.inference.model.*
import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintKind.LOWER
import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintKind.UPPER
import org.jetbrains.kotlin.resolve.calls.model.KotlinCallDiagnostic
import org.jetbrains.kotlin.types.*
import org.jetbrains.kotlin.types.checker.CaptureStatus
import org.jetbrains.kotlin.types.checker.NewCapturedType
import org.jetbrains.kotlin.types.checker.NewKotlinTypeChecker
import org.jetbrains.kotlin.types.typeUtil.contains
import org.jetbrains.kotlin.types.typeUtil.isNothing
import org.jetbrains.kotlin.types.typeUtil.isNullableAny
import java.util.*
class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val typeApproximator: TypeApproximator) {
@@ -40,7 +44,7 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
}
fun addInitialSubtypeConstraint(c: Context, lowerType: UnwrappedType, upperType: UnwrappedType, position: ConstraintPosition) {
val initialConstraint = InitialConstraint(lowerType, upperType, ConstraintKind.UPPER, position)
val initialConstraint = InitialConstraint(lowerType, upperType, UPPER, position)
val incorporationPosition = IncorporationConstraintPosition(position, initialConstraint)
c.addInitialConstraint(initialConstraint)
updateAllowedTypeDepth(c, lowerType)
@@ -66,6 +70,8 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
while (possibleNewConstraints.isNotEmpty()) {
val (typeVariable, constraint) = possibleNewConstraints.pop()
if (c.shouldWeSkipConstraint(typeVariable, constraint)) continue
val constraints = c.notFixedTypeVariables[typeVariable.freshTypeConstructor] ?: typeCheckerContext.fixedTypeVariable(typeVariable)
// it is important, that we add constraint here(not inside TypeCheckerContext), because inside incorporation we read constraints
@@ -93,6 +99,26 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
return maxInArguments + 1
}
private fun Context.shouldWeSkipConstraint(typeVariable: NewTypeVariable, constraint: Constraint): Boolean {
assert(constraint.kind != ConstraintKind.EQUALITY)
val constraintType = constraint.type
if (!isAllowedType(constraintType)) return true
if (constraintType.constructor == typeVariable.freshTypeConstructor) {
if (constraintType.lowerIfFlexible().isMarkedNullable && constraint.kind == LOWER) return false // T? <: T
return true // T <: T(?!)
}
if (constraintType is SimpleType) {
if (constraint.kind == UPPER && constraintType.isNullableAny()) return true // T <: Any?
if (constraint.kind == LOWER && constraintType.isNothing()) return true // T >: Nothing
}
return false
}
private fun Context.isAllowedType(type: UnwrappedType) = type.typeDepth() <= maxTypeDepthFromInitialConstraints + ALLOWED_DEPTH_DELTA_FOR_INCORPORATION
private inner class TypeCheckerContext(
@@ -100,7 +126,7 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
val position: IncorporationConstraintPosition,
val baseLowerType: UnwrappedType,
val baseUpperType: UnwrappedType,
val possibleNewConstraints: MutableList<Pair<NewTypeVariable, Constraint>> = ArrayList()
val possibleNewConstraints: MutableList<Pair<NewTypeVariable, Constraint>>
) : TypeCheckerContextForConstraintSystem(), ConstraintIncorporator.Context {
fun runIsSubtypeOf(lowerType: UnwrappedType, upperType: UnwrappedType) {
@@ -115,10 +141,10 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
// from TypeCheckerContextForConstraintSystem
override fun isMyTypeVariable(type: SimpleType): Boolean = c.allTypeVariables.containsKey(type.constructor)
override fun addUpperConstraint(typeVariable: TypeConstructor, superType: UnwrappedType) =
addConstraint(typeVariable, superType, ConstraintKind.UPPER)
addConstraint(typeVariable, superType, UPPER)
override fun addLowerConstraint(typeVariable: TypeConstructor, subType: UnwrappedType) =
addConstraint(typeVariable, subType, ConstraintKind.LOWER)
addConstraint(typeVariable, subType, LOWER)
private fun isCapturedTypeFromSubtyping(type: UnwrappedType) =
when ((type as? NewCapturedType)?.captureStatus) {
@@ -135,14 +161,14 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
var targetType = type
if (type.contains(this::isCapturedTypeFromSubtyping)) {
// TypeVariable <: type -> if TypeVariable <: subType => TypeVariable <: type
if (kind == ConstraintKind.UPPER) {
if (kind == UPPER) {
val subType = typeApproximator.approximateToSubType(type, TypeApproximatorConfiguration.SubtypeCapturedTypesApproximation)
if (subType != null && !KotlinBuiltIns.isNothingOrNullableNothing(subType)) {
targetType = subType
}
}
if (kind == ConstraintKind.LOWER) {
if (kind == LOWER) {
val superType = typeApproximator.approximateToSuperType(type, TypeApproximatorConfiguration.SubtypeCapturedTypesApproximation)
if (superType != null && !KotlinBuiltIns.isAnyOrNullableAny(superType)) { // todo rethink error reporting for Any cases
targetType = superType
@@ -155,10 +181,7 @@ class ConstraintInjector(val constraintIncorporator: ConstraintIncorporator, val
}
}
if (!c.isAllowedType(targetType)) return
val newConstraint = Constraint(kind, targetType, position)
possibleNewConstraints.add(typeVariable to newConstraint)
possibleNewConstraints.add(typeVariable to Constraint(kind, targetType, position))
}
// from ConstraintIncorporator.Context