org.jetbrains.kotlin.fir.resolve.inference.FirPCLAInferenceSession.kt Maven / Gradle / Ivy
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/*
* Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package org.jetbrains.kotlin.fir.resolve.inference
import org.jetbrains.kotlin.fir.FirElement
import org.jetbrains.kotlin.fir.expressions.*
import org.jetbrains.kotlin.fir.resolve.ResolutionMode
import org.jetbrains.kotlin.fir.resolve.calls.candidate.Candidate
import org.jetbrains.kotlin.fir.resolve.calls.candidate.candidate
import org.jetbrains.kotlin.fir.resolve.inference.model.ConeExpectedTypeConstraintPosition
import org.jetbrains.kotlin.fir.resolve.inference.model.ConeSemiFixVariableConstraintPosition
import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
import org.jetbrains.kotlin.fir.resolve.transformers.ReturnTypeCalculator
import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.BodyResolveContext
import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
import org.jetbrains.kotlin.fir.types.*
import org.jetbrains.kotlin.fir.visitors.FirDefaultTransformer
import org.jetbrains.kotlin.resolve.calls.inference.addSubtypeConstraintIfCompatible
import org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintSystemCompletionContext
import org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintSystemCompletionMode
import org.jetbrains.kotlin.resolve.calls.inference.components.TypeVariableDirectionCalculator
import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintStorage
import org.jetbrains.kotlin.resolve.calls.inference.model.NewConstraintSystemImpl
import org.jetbrains.kotlin.types.model.TypeConstructorMarker
import org.jetbrains.kotlin.types.model.defaultType
/**
* @see [docs/fir/pcla.md]
*/
class FirPCLAInferenceSession(
private val outerCandidate: Candidate,
private val inferenceComponents: InferenceComponents,
) : FirInferenceSession() {
var currentCommonSystem: NewConstraintSystemImpl = prepareSharedBaseSystem(outerCandidate.system, inferenceComponents)
private set
override fun baseConstraintStorageForCandidate(candidate: Candidate, bodyResolveContext: BodyResolveContext): ConstraintStorage? {
if (candidate.mightBeAnalyzedAndCompletedIndependently(bodyResolveContext.returnTypeCalculator)) return null
return currentCommonSystem.currentStorage()
}
override fun customCompletionModeInsteadOfFull(
call: FirResolvable,
): ConstraintSystemCompletionMode? = when {
call.candidate()?.usedOuterCs == true -> ConstraintSystemCompletionMode.PCLA_POSTPONED_CALL
else -> null
}
override fun processPartiallyResolvedCall(
call: T,
resolutionMode: ResolutionMode,
completionMode: ConstraintSystemCompletionMode,
) where T : FirResolvable, T : FirStatement {
if (call is FirExpression) {
call.updateReturnTypeWithCurrentSubstitutor(resolutionMode)
}
val candidate = call.candidate()
if (candidate?.usedOuterCs != true) return
// Integrating back would happen at FirDelegatedPropertyInferenceSession.completeSessionOrPostponeIfNonRoot
// after all other delegation-related calls are being analyzed
if (resolutionMode == ResolutionMode.Delegate) return
currentCommonSystem.replaceContentWith(candidate.system.currentStorage())
if (completionMode == ConstraintSystemCompletionMode.PCLA_POSTPONED_CALL) {
outerCandidate.postponedPCLACalls += call
}
}
override fun runLambdaCompletion(candidate: Candidate, forOverloadByLambdaReturnType: Boolean, block: () -> Unit): ConstraintStorage? {
if (forOverloadByLambdaReturnType) {
val constraintAccumulatorForLambda =
inferenceComponents.createConstraintSystem().apply {
setBaseSystem(currentCommonSystem.currentStorage())
}
runWithSpecifiedCurrentCommonSystem(constraintAccumulatorForLambda, block)
return constraintAccumulatorForLambda.currentStorage()
}
runWithSpecifiedCurrentCommonSystem(candidate.system, block)
return null
}
override fun runCallableReferenceResolution(candidate: Candidate, block: () -> T): T {
candidate.system.apply {
// It's necessary because otherwise when we create CS for a child, it would simplify constraints
// (see 3rd constructor of MutableVariableWithConstraints)
// and merging it back might become a problem for transaction logic because the latter literally remembers
// the number of constraints for each variable and then restores it back.
// But since the constraints are simplified in the child, their number might become even fewer, leading to incorrect behavior
// or runtime exceptions.
// See callableReferenceAsArgumentForTransaction.kt test data
notFixedTypeVariables.values.forEach { it.runConstraintsSimplification() }
}
return runWithSpecifiedCurrentCommonSystem(candidate.system, block)
}
private fun runWithSpecifiedCurrentCommonSystem(newSystem: NewConstraintSystemImpl, block: () -> T): T {
val previous = currentCommonSystem
return try {
currentCommonSystem = newSystem
block()
} finally {
currentCommonSystem = previous
}
}
fun applyResultsToMainCandidate() {
outerCandidate.system.replaceContentWith(currentCommonSystem.currentStorage())
}
fun integrateChildSession(
childCalls: Collection,
childStorage: ConstraintStorage,
onCompletionResultsWriting: (ConeSubstitutor) -> Unit,
) {
outerCandidate.postponedPCLACalls += childCalls
currentCommonSystem.addOtherSystem(childStorage)
outerCandidate.onPCLACompletionResultsWritingCallbacks += onCompletionResultsWriting
}
@OptIn(TemporaryInferenceSessionHook::class) // Needed to override
override fun updateExpressionReturnTypeWithCurrentSubstitutorInPCLA(expression: FirExpression, resolutionMode: ResolutionMode) {
expression.updateReturnTypeWithCurrentSubstitutor(resolutionMode)
}
private fun FirExpression.updateReturnTypeWithCurrentSubstitutor(
resolutionMode: ResolutionMode,
) {
val additionalBindings = mutableMapOf()
val system = (this as? FirResolvable)?.candidate()?.system ?: currentCommonSystem
if (resolutionMode is ResolutionMode.ReceiverResolution) {
fixCurrentResultIfTypeVariableAndReturnBinding(resolvedType, system)?.let { additionalBindings += it }
}
val substitutor = system.buildCurrentSubstitutor(additionalBindings) as ConeSubstitutor
val updatedType = substitutor.substituteOrNull(resolvedType)
if (updatedType != null) {
replaceConeTypeOrNull(updatedType)
}
}
override fun getAndSemiFixCurrentResultIfTypeVariable(type: ConeKotlinType): ConeKotlinType? =
fixCurrentResultIfTypeVariableAndReturnBinding(type, currentCommonSystem)?.second
fun fixCurrentResultIfTypeVariableAndReturnBinding(
type: ConeKotlinType,
myCs: NewConstraintSystemImpl,
): Pair? {
return when (type) {
is ConeFlexibleType -> fixCurrentResultIfTypeVariableAndReturnBinding(type.lowerBound, myCs)
is ConeDefinitelyNotNullType -> fixCurrentResultIfTypeVariableAndReturnBinding(type.original, myCs)
is ConeTypeVariableType -> fixCurrentResultForNestedTypeVariable(type, myCs)
else -> null
}
}
private fun fixCurrentResultForNestedTypeVariable(
type: ConeTypeVariableType,
myCs: NewConstraintSystemImpl,
): Pair? {
val coneTypeVariableTypeConstructor = type.typeConstructor
require(coneTypeVariableTypeConstructor in myCs.allTypeVariables) {
"$coneTypeVariableTypeConstructor not found"
}
val variableWithConstraints = myCs.notFixedTypeVariables[coneTypeVariableTypeConstructor] ?: return null
val c = myCs.getBuilder()
if (coneTypeVariableTypeConstructor in myCs.outerTypeVariables.orEmpty()) {
// For outer TV, we don't allow semi-fixing them (adding the new equality constraints),
// but if there's already some proper EQ constraint, it's safe & sound to use it as a representative
c.prepareContextForTypeVariableForSemiFixation(coneTypeVariableTypeConstructor) {
inferenceComponents.resultTypeResolver.findResultIfThereIsEqualsConstraint(
c,
variableWithConstraints,
isStrictMode = true,
) as ConeKotlinType?
}?.let { appropriateResultType ->
return Pair(coneTypeVariableTypeConstructor, appropriateResultType)
}
return null
}
val resultType = c.prepareContextForTypeVariableForSemiFixation(coneTypeVariableTypeConstructor) {
inferenceComponents.resultTypeResolver.findResultType(
c,
variableWithConstraints,
TypeVariableDirectionCalculator.ResolveDirection.UNKNOWN
) as ConeKotlinType
} ?: return null
val variable = variableWithConstraints.typeVariable
c.addEqualityConstraint(variable.defaultType(c), resultType, ConeSemiFixVariableConstraintPosition(variable))
return Pair(coneTypeVariableTypeConstructor, resultType)
}
private fun ConstraintSystemCompletionContext.prepareContextForTypeVariableForSemiFixation(
coneTypeVariableTypeConstructor: ConeTypeVariableTypeConstructor,
resultTypeCallback: () -> ConeKotlinType?,
): ConeKotlinType? = withTypeVariablesThatAreCountedAsProperTypes(outerTypeVariables.orEmpty()) {
if (!inferenceComponents.variableFixationFinder.isTypeVariableHasProperConstraint(this, coneTypeVariableTypeConstructor)) {
return@withTypeVariablesThatAreCountedAsProperTypes null
}
resultTypeCallback()
}
/**
* This function returns true only when it's safe & sound to analyze and complete the candidate outside the PCLA context,
* i.e., independently of outer CS.
*
* That might be some plain variable accesses that do not contain type variables or regular function calls with only trivial arguments.
*
* The basic purpose of that function is performance enhancement because resolving all the calls inside PCLA lambda in the outer context
* might be too much.
*
* Mostly, that means that this function might always return false and it should be correct.
* TODO: Currently, making it always returning "false" leads to few test failures
* TODO: due to some corner cases like annotations calls (KT-65465)
*/
private fun Candidate.mightBeAnalyzedAndCompletedIndependently(returnTypeCalculator: ReturnTypeCalculator): Boolean {
when (callInfo.resolutionMode) {
// Currently, we handle delegates specifically, not completing them even if they are trivial function calls
// Thus they are being resolved in the context of outer CS
is ResolutionMode.Delegate -> return false
is ResolutionMode.WithExpectedType -> when {
// For assignments like myVarContainingTV = SomeCallWithNonTrivialInference(...)
// We should integrate even simple calls into the PCLA tree, too
callInfo.resolutionMode.expectedTypeRef.type.containsNotFixedTypeVariables() -> return false
}
is ResolutionMode.WithStatus, is ResolutionMode.LambdaResolution ->
error("$this call should not be analyzed in ${callInfo.resolutionMode}")
is ResolutionMode.AssignmentLValue,
is ResolutionMode.ContextDependent,
is ResolutionMode.ContextIndependent,
is ResolutionMode.ReceiverResolution,
-> {
// Regular cases, just continue execution.
// Enumerating all the cases just to make sure we don't forget to handle some mode.
}
}
val callSite = callInfo.callSite
// Annotation calls and collection literals (allowed only inside annotations)
// should be completed independently since that can't somehow affect PCLA
if (callSite is FirAnnotationCall || callSite is FirArrayLiteral) return true
// I'd say that this might be an assertion, but let's do an early return
if (callSite !is FirResolvable && callSite !is FirVariableAssignment) return false
// We can't analyze independently the calls which have postponed receivers
// Even if the calls themselves are trivial
if (dispatchReceiver?.isReceiverPostponed() == true) return false
if (givenExtensionReceiverOptions.any { it.isReceiverPostponed() }) return false
// At the step of candidate's system creation, there are no chosen context receiver values, yet
// (see org.jetbrains.kotlin.fir.resolve.calls.CheckContextReceivers)
// Thus, we just postpone everything with symbols requiring some context receivers
if ((symbol as? FirCallableSymbol)?.resolvedContextReceivers?.isNotEmpty() == true) return false
// Accesses to local variables or local functions which return types contain not fixed TVs
val returnType = (symbol as? FirCallableSymbol)?.let(returnTypeCalculator::tryCalculateReturnType)
if (returnType?.type?.containsNotFixedTypeVariables() == true) return false
// Now, we've got some sort of call/variable access/callable reference/synthetic call (see hierarchy of FirResolvable)
// It has regular independent receivers and trivial return type
// The only thing we need to check if it has only trivial arguments
if (callInfo.arguments.any { !it.isTrivialArgument() }) return false
return true
}
private fun FirExpression.isTrivialArgument(): Boolean =
when (this) {
// Callable references might be unresolved at this stage, so obtaining `resolvedType` would lead to exceptions
// Anyway, they should lead to integrated resolution of containing call
is FirCallableReferenceAccess -> false
is FirResolvable -> when (val candidate = candidate()) {
null -> !resolvedType.containsNotFixedTypeVariables()
else -> !candidate.usedOuterCs
}
is FirWrappedExpression -> expression.isTrivialArgument()
is FirSamConversionExpression -> expression.isTrivialArgument()
is FirSmartCastExpression -> originalExpression.isTrivialArgument()
is FirCall -> argumentList.arguments.all { it.isTrivialArgument() }
is FirBinaryLogicExpression -> leftOperand.isTrivialArgument() && rightOperand.isTrivialArgument()
is FirComparisonExpression -> compareToCall.isTrivialArgument()
is FirCheckedSafeCallSubject -> originalReceiverRef.value.isTrivialArgument()
is FirSafeCallExpression -> receiver.isTrivialArgument() && (selector as? FirExpression)?.isTrivialArgument() == true
is FirVarargArgumentsExpression -> arguments.all { it.isTrivialArgument() }
is FirLiteralExpression, is FirResolvedQualifier, is FirResolvedReifiedParameterReference -> true
// Be default, we consider all the unknown cases as unsafe to resolve independently
else -> false
}
private fun FirExpression.isReceiverPostponed(): Boolean {
return when {
resolvedType.containsNotFixedTypeVariables() -> true
(this as? FirResolvable)?.candidate()?.usedOuterCs == true -> true
else -> false
}
}
private fun ConeKotlinType.containsNotFixedTypeVariables(): Boolean =
contains {
// TODO: Investigate why using `notFixedTypeVariables` instead of `allTypeVariables` leads to failure of the test (KT-64861)
// org.jetbrains.kotlin.test.runners.codegen.FirPsiBlackBoxCodegenTestGenerated.BuilderInference.OneParameter.OneTypeVariable.
// OneTypeInfoOrigin.SourceSinkFeedContexts.testThroughDelegatedLocalVariableYieldCase
it is ConeTypeVariableType && it.typeConstructor in currentCommonSystem.allTypeVariables
}
override fun addSubtypeConstraintIfCompatible(lowerType: ConeKotlinType, upperType: ConeKotlinType, element: FirElement) {
currentCommonSystem.addSubtypeConstraintIfCompatible(lowerType, upperType, ConeExpectedTypeConstraintPosition)
}
}
class FirTypeVariablesAfterPCLATransformer(private val substitutor: ConeSubstitutor) : FirDefaultTransformer() {
override fun transformElement(element: E, data: Nothing?): E {
// All resolvable nodes should be implemented separately to cover substitution of receivers in the candidate
if (element is FirResolvable) {
element.candidate()?.let { processCandidate(it) }
}
// Since FirExpressions don't have typeRefs, they need to be updated separately.
// FirAnonymousFunctionExpression doesn't support replacing the type
// since it delegates the getter to the underlying FirAnonymousFunction.
if (element is FirExpression && element !is FirAnonymousFunctionExpression) {
element.resolvedType
.let(substitutor::substituteOrNull)
?.let { element.replaceConeTypeOrNull(it) }
}
@Suppress("UNCHECKED_CAST")
return element.transformChildren(this, data = null) as E
}
override fun transformResolvedTypeRef(resolvedTypeRef: FirResolvedTypeRef, data: Nothing?): FirTypeRef =
substitutor.substituteOrNull(resolvedTypeRef.type)?.let {
resolvedTypeRef.withReplacedConeType(it)
} ?: resolvedTypeRef
/*
* We should manually update all receivers in the all not completed candidates, because not all calls with candidates
* contained in partiallyResolvedCalls and candidate stores not receiver values, which are updated, (TODO: remove this comment after removal of updating values)
* and receivers of candidates are not direct FIR children of calls, so they won't be visited during regular transformChildren
*/
private fun processCandidate(candidate: Candidate) {
candidate.dispatchReceiver = candidate.dispatchReceiver?.transform(this, data = null)
candidate.chosenExtensionReceiver = candidate.chosenExtensionReceiver?.transform(this, data = null)
candidate.contextReceiverArguments = candidate.contextReceiverArguments?.map { it.transform(this, data = null) }
}
}