org.jetbrains.kotlin.fir.resolve.inference.PostponedArgumentsAnalyzer.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.expressions.FirExpression
import org.jetbrains.kotlin.fir.lookupTracker
import org.jetbrains.kotlin.fir.recordTypeResolveAsLookup
import org.jetbrains.kotlin.fir.references.builder.buildErrorNamedReference
import org.jetbrains.kotlin.fir.resolve.calls.*
import org.jetbrains.kotlin.fir.resolve.calls.candidate.*
import org.jetbrains.kotlin.fir.resolve.calls.stages.ArgumentCheckingProcessor
import org.jetbrains.kotlin.fir.resolve.dfa.cfg.lastStatement
import org.jetbrains.kotlin.fir.resolve.diagnostics.ConeUnresolvedReferenceError
import org.jetbrains.kotlin.fir.resolve.inference.model.ConeLambdaArgumentConstraintPosition
import org.jetbrains.kotlin.fir.resolve.isImplicitUnitForEmptyLambda
import org.jetbrains.kotlin.fir.resolve.shouldReturnUnit
import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
import org.jetbrains.kotlin.fir.resolvedTypeFromPrototype
import org.jetbrains.kotlin.fir.types.*
import org.jetbrains.kotlin.resolve.calls.components.PostponedArgumentsAnalyzerContext
import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilder
import org.jetbrains.kotlin.resolve.calls.inference.addSubtypeConstraintIfCompatible
import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintStorage
import org.jetbrains.kotlin.types.model.KotlinTypeMarker
import org.jetbrains.kotlin.types.model.TypeConstructorMarker
import org.jetbrains.kotlin.types.model.freshTypeConstructor
import org.jetbrains.kotlin.types.model.safeSubstitute
data class ReturnArgumentsAnalysisResult(
val returnArguments: Collection,
val additionalConstraints: ConstraintStorage?,
)
interface LambdaAnalyzer {
fun analyzeAndGetLambdaReturnArguments(
lambdaAtom: ConeResolvedLambdaAtom,
receiverType: ConeKotlinType?,
contextReceivers: List,
parameters: List,
expectedReturnType: ConeKotlinType?, // null means, that return type is not proper i.e. it depends on some type variables
candidate: Candidate,
withPCLASession: Boolean,
forOverloadByLambdaReturnType: Boolean,
): ReturnArgumentsAnalysisResult
}
class PostponedArgumentsAnalyzer(
private val resolutionContext: ResolutionContext,
private val lambdaAnalyzer: LambdaAnalyzer,
private val components: InferenceComponents,
private val callResolver: FirCallResolver,
) {
fun analyze(
c: PostponedArgumentsAnalyzerContext,
argument: ConePostponedResolvedAtom,
candidate: Candidate,
withPCLASession: Boolean,
) {
when (argument) {
is ConeResolvedLambdaAtom ->
analyzeLambda(c, argument, candidate, forOverloadByLambdaReturnType = false, withPCLASession)
is ConeLambdaWithTypeVariableAsExpectedTypeAtom ->
analyzeLambda(
c,
argument.transformToResolvedLambda(c.getBuilder(), resolutionContext),
candidate, forOverloadByLambdaReturnType = false, withPCLASession
)
is ConeResolvedCallableReferenceAtom -> processCallableReference(argument, candidate)
}
}
private fun processCallableReference(atom: ConeResolvedCallableReferenceAtom, candidate: Candidate) {
if (atom.mightNeedAdditionalResolution) {
callResolver.resolveCallableReference(candidate, atom, hasSyntheticOuterCall = false)
}
val callableReferenceAccess = atom.expression
atom.analyzed = true
resolutionContext.bodyResolveContext.dropCallableReferenceContext(callableReferenceAccess)
val namedReference = atom.resultingReference ?: buildErrorNamedReference {
source = callableReferenceAccess.source
diagnostic = ConeUnresolvedReferenceError(callableReferenceAccess.calleeReference.name)
}
callableReferenceAccess.apply {
replaceCalleeReference(namedReference)
val typeForCallableReference = atom.resultingTypeForCallableReference
val resolvedType = when {
typeForCallableReference != null -> typeForCallableReference
namedReference is FirErrorReferenceWithCandidate -> ConeErrorType(namedReference.diagnostic)
else -> ConeErrorType(ConeUnresolvedReferenceError(callableReferenceAccess.calleeReference.name))
}
replaceConeTypeOrNull(resolvedType)
resolutionContext.session.lookupTracker?.recordTypeResolveAsLookup(
resolvedType, source, resolutionContext.bodyResolveComponents.file.source
)
}
}
fun analyzeLambda(
c: PostponedArgumentsAnalyzerContext,
lambda: ConeResolvedLambdaAtom,
candidate: Candidate,
forOverloadByLambdaReturnType: Boolean,
withPCLASession: Boolean,
//diagnosticHolder: KotlinDiagnosticsHolder
): ReturnArgumentsAnalysisResult {
// TODO: replace with `require(!lambda.analyzed)` when KT-54767 will be fixed
if (lambda.analyzed) {
return ReturnArgumentsAnalysisResult(lambda.returnStatements, additionalConstraints = null)
}
val additionalBinding: Pair? =
(resolutionContext.bodyResolveContext.inferenceSession as? FirPCLAInferenceSession)?.let { pclaInferenceSession ->
// TODO: Fix variables for context receivers, too (KT-64859)
lambda.receiverType
?.let { pclaInferenceSession.semiFixCurrentResultIfTypeVariableAndReturnBinding(it, candidate.system) }
}
val unitType = components.session.builtinTypes.unitType.coneType
val currentSubstitutor = c.buildCurrentSubstitutor(additionalBinding) as ConeSubstitutor
fun substitute(type: ConeKotlinType) = currentSubstitutor.safeSubstitute(c, type) as ConeKotlinType
val receiver = lambda.receiverType?.let(::substitute)
val contextReceivers = lambda.contextReceiverTypes.map(::substitute)
val parameters = lambda.parameterTypes.map(::substitute)
val rawReturnType = lambda.returnType
val expectedTypeForReturnArguments = when {
c.canBeProper(rawReturnType) -> substitute(rawReturnType)
// For Unit-coercion
!rawReturnType.isMarkedNullable && c.hasUpperOrEqualUnitConstraint(rawReturnType) -> unitType
else -> null
}
val results = lambdaAnalyzer.analyzeAndGetLambdaReturnArguments(
lambda,
receiver,
contextReceivers,
parameters,
expectedTypeForReturnArguments,
candidate,
withPCLASession,
forOverloadByLambdaReturnType,
)
applyResultsOfAnalyzedLambdaToCandidateSystem(
c,
lambda,
candidate,
results,
::substitute
)
return results
}
fun applyResultsOfAnalyzedLambdaToCandidateSystem(
c: PostponedArgumentsAnalyzerContext,
lambda: ConeResolvedLambdaAtom,
candidate: Candidate,
results: ReturnArgumentsAnalysisResult,
substituteAlreadyFixedVariables: (ConeKotlinType) -> ConeKotlinType = c.createSubstituteFunctorForLambdaAnalysis(),
) {
val (returnAtoms, additionalConstraintStorage) = results
val returnArguments = returnAtoms.map { it.expression }
if (additionalConstraintStorage != null) {
c.addOtherSystem(additionalConstraintStorage)
}
val checkerSink: CheckerSink = CheckerSinkImpl(candidate)
val builder = c.getBuilder()
val lastExpression = lambda.anonymousFunction.lastStatement() as? FirExpression
var hasExpressionInReturnArguments = false
val returnTypeRef = lambda.anonymousFunction.returnTypeRef.let {
it as? FirResolvedTypeRef ?: it.resolvedTypeFromPrototype(substituteAlreadyFixedVariables(lambda.returnType))
}
val isUnitLambda = returnTypeRef.coneType.isUnitOrFlexibleUnit || lambda.anonymousFunction.shouldReturnUnit(returnArguments)
for (atom in returnAtoms) {
val expression = atom.expression
if (expression.isImplicitUnitForEmptyLambda()) continue
// If the lambda returns Unit, the last expression is not returned and should not be constrained.
val isLastExpression = expression == lastExpression
// TODO (KT-55837) questionable moment inherited from FE1.0 (the `haveSubsystem` case):
// fun foo(): T
// run {
// if (p) return@run
// foo() // T = Unit, even though there is no implicit return
// }
// Things get even weirder if T has an upper bound incompatible with Unit.
val haveSubsystem = c.addSubsystemFromExpression(expression)
if (isLastExpression && isUnitLambda) {
// That "if" is necessary because otherwise we would force a lambda return type
// to be inferred from completed last expression.
// See `test1` at testData/diagnostics/tests/inference/coercionToUnit/afterBareReturn.kt
if (haveSubsystem) {
// We don't force it because of the cases like
// buildMap {
// put("a", 1) // While `put` returns V, we should not enforce the latter to be a subtype of Unit
// }
// See KT-63602 for details.
builder.addSubtypeConstraintIfCompatible(
expression.resolvedType, returnTypeRef.coneType,
ConeLambdaArgumentConstraintPosition(lambda.anonymousFunction)
)
}
continue
}
hasExpressionInReturnArguments = true
// Nested lambdas need to be resolved even when we have a contradiction.
if (!builder.hasContradiction || atom is ConeResolutionAtomWithPostponedChild) {
ArgumentCheckingProcessor.resolveArgumentExpression(
candidate,
atom,
substituteAlreadyFixedVariables(lambda.returnType),
checkerSink,
context = resolutionContext,
isReceiver = false,
isDispatch = false
)
}
}
if (!hasExpressionInReturnArguments) {
addLambdaReturnTypeUnitConstraintOrReportError(c, builder, lambda, checkerSink, substituteAlreadyFixedVariables)
}
lambda.analyzed = true
lambda.returnStatements = returnAtoms
}
private fun addLambdaReturnTypeUnitConstraintOrReportError(
c: PostponedArgumentsAnalyzerContext,
builder: ConstraintSystemBuilder,
lambda: ConeResolvedLambdaAtom,
checkerSink: CheckerSink,
substituteAlreadyFixedVariables: (ConeKotlinType) -> ConeKotlinType,
) {
val lambdaReturnType = substituteAlreadyFixedVariables(lambda.returnType)
// If we've got some errors already, no new constraints or diagnostics are required
if (with(c) { lambdaReturnType.isError() } || builder.hasContradiction) return
val position = ConeLambdaArgumentConstraintPosition(lambda.anonymousFunction)
val unitType = components.session.builtinTypes.unitType.coneType
if (!builder.addSubtypeConstraintIfCompatible(
unitType,
lambdaReturnType,
position
)
) {
val wholeLambdaExpectedType =
lambda.expectedType?.let { substituteAlreadyFixedVariables(it) }
if (wholeLambdaExpectedType != null) {
checkerSink.reportDiagnostic(
// TODO: Consider replacement with ArgumentTypeMismatch once KT-67961 is fixed
// Currently, ArgumentTypeMismatch only allows expressions and we don't have it here
UnitReturnTypeLambdaContradictsExpectedType(
lambda.anonymousFunction,
wholeLambdaExpectedType,
lambda.sourceForFunctionExpression,
)
)
} else {
// Fallback situation, probably quite rare or even impossible, though it's hard to proof that.
// But we're still forcing some constraint error, not to leave the candidate falsely successful.
builder.addSubtypeConstraint(
unitType,
lambdaReturnType,
position,
)
}
}
}
private fun PostponedArgumentsAnalyzerContext.createSubstituteFunctorForLambdaAnalysis(): (ConeKotlinType) -> ConeKotlinType {
val stubsForPostponedVariables = bindingStubsForPostponedVariables()
val currentSubstitutor = buildCurrentSubstitutor(stubsForPostponedVariables.mapKeys { it.key.freshTypeConstructor(this) })
return { currentSubstitutor.safeSubstitute(this, it) as ConeKotlinType }
}
}
fun ConeLambdaWithTypeVariableAsExpectedTypeAtom.transformToResolvedLambda(
csBuilder: ConstraintSystemBuilder,
context: ResolutionContext,
expectedType: ConeKotlinType? = null,
returnTypeVariable: ConeTypeVariableForLambdaReturnType? = null,
): ConeResolvedLambdaAtom {
val fixedExpectedType = (csBuilder.buildCurrentSubstitutor() as ConeSubstitutor)
.substituteOrSelf(expectedType ?: this.expectedType)
val resolvedAtom = ArgumentCheckingProcessor.createResolvedLambdaAtomDuringCompletion(
candidateOfOuterCall, csBuilder, ConeResolutionAtomWithPostponedChild(expression), fixedExpectedType,
context, returnTypeVariable = returnTypeVariable
)
subAtom = resolvedAtom
analyzed = true
return resolvedAtom
}