FIR: Simplify callable references resolution

Also that fixes some bugs

compiler/fir/analysis-tests/testData/resolveWithStdlib/callableReferences/companions.kt

@@ -34,9 +34,9 @@ fun main() {
     <!AMBIGUITY!>foo3<!>(KotlinClass::baz)
 
     // Type mismatch
-    foo1(KotlinClass::bar)
+    <!INAPPLICABLE_CANDIDATE!>foo1<!>(<!UNRESOLVED_REFERENCE!>KotlinClass::bar<!>)
     foo2(KotlinClass::bar)
-    <!AMBIGUITY!>foo3<!>(KotlinClass::bar)
+    foo3(KotlinClass::bar)
 
     foo1(KotlinClass2::bar)
     // Type mismatch

compiler/fir/analysis-tests/testData/resolveWithStdlib/callableReferences/companions.txt

@@ -50,13 +50,13 @@ FILE: main.kt
     public final fun foo3(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
-        R|/foo1|(Q|KotlinClass|::R|/KotlinClass.baz|)
+        R|/foo1|(Q|KotlinClass|::R|/KotlinClass.Companion.baz|)
         R|/foo2|(Q|KotlinClass|::R|/KotlinClass.baz|)
         <Ambiguity: foo3, [/foo3, /foo3]>#(Q|KotlinClass|::R|/KotlinClass.baz|)
-        R|/foo1|(Q|KotlinClass|::R|/JavaClass.bar|)
+        <Inapplicable(INAPPLICABLE): /foo1>#(Q|KotlinClass|::<Unresolved reference: bar>#)
         R|/foo2|(Q|KotlinClass|::R|/JavaClass.bar|)
-        <Ambiguity: foo3, [/foo3, /foo3]>#(Q|KotlinClass|::R|/JavaClass.bar|)
+        R|/foo3|(Q|KotlinClass|::R|/JavaClass.bar|)
-        R|/foo1|(Q|KotlinClass2|::R|/KotlinClass2.bar|)
+        R|/foo1|(Q|KotlinClass2|::R|/KotlinClass2.Companion.bar|)
         <Inapplicable(INAPPLICABLE): /foo2>#(Q|KotlinClass2|::<Unresolved reference: bar>#)
-        R|/foo3|(Q|KotlinClass2|::R|/KotlinClass2.bar|)
+        R|/foo3|(Q|KotlinClass2|::R|/KotlinClass2.Companion.bar|)
     }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt

@@ -9,7 +9,6 @@ import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
 import org.jetbrains.kotlin.fir.expressions.*
-import org.jetbrains.kotlin.fir.expressions.builder.buildExpressionStub
 import org.jetbrains.kotlin.fir.expressions.builder.buildResolvedReifiedParameterReference
 import org.jetbrains.kotlin.fir.references.*
 import org.jetbrains.kotlin.fir.references.builder.buildBackingFieldReference
@@ -400,7 +399,9 @@ class FirCallResolver(
             }
         }
         if (constructorSymbol == null) return null
-        val candidate = CandidateFactory(transformer.resolutionContext, callInfo).createCandidate(
+        val candidateFactory = CandidateFactory(transformer.resolutionContext, callInfo)
+        val candidate = candidateFactory.createCandidate(
+            callInfo,
             constructorSymbol!!,
             ExplicitReceiverKind.NO_EXPLICIT_RECEIVER,
             scope = null
@@ -471,12 +472,6 @@ class FirCallResolver(
             expectedType,
             outerConstraintSystemBuilder,
             lhs,
-            stubReceiver = if (lhs !is DoubleColonLHS.Type) null else buildExpressionStub {
-                source = callableReferenceAccess.source
-                typeRef = buildResolvedTypeRef {
-                    type = lhs.type
-                }
-            },
         )
     }
 
@@ -547,7 +542,7 @@ class FirCallResolver(
         source: FirSourceElement?,
         name: Name
     ): FirErrorReferenceWithCandidate {
-        val candidate = CandidateFactory(transformer.resolutionContext, callInfo).createErrorCandidate(diagnostic)
+        val candidate = CandidateFactory(transformer.resolutionContext, callInfo).createErrorCandidate(callInfo, diagnostic)
         components.resolutionStageRunner.processCandidate(candidate, transformer.resolutionContext, stopOnFirstError = false)
         return FirErrorReferenceWithCandidate(source, name, candidate, diagnostic)
     }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Candidate.kt

@@ -52,16 +52,12 @@ data class CallInfo(
     // Four properties for callable references only
     val expectedType: ConeKotlinType? = null,
     val outerCSBuilder: ConstraintSystemBuilder? = null,
-    val lhs: DoubleColonLHS? = null,
+    val lhs: DoubleColonLHS? = null
-    val stubReceiver: FirExpression? = null
 ) {
     val arguments: List<FirExpression> get() = argumentList.arguments
 
     val argumentCount get() = arguments.size
 
-    fun noStubReceiver(): CallInfo =
-        if (stubReceiver == null) this else copy(stubReceiver = null)
-
     fun replaceWithVariableAccess(): CallInfo =
         copy(callKind = CallKind.VariableAccess, typeArguments = emptyList(), argumentList = FirEmptyArgumentList)
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CandidateFactory.kt

@@ -22,7 +22,6 @@ import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
 
 class CandidateFactory private constructor(
     val context: ResolutionContext,
-    val callInfo: CallInfo,
     private val baseSystem: ConstraintStorage
 ) {
 
@@ -37,17 +36,10 @@ class CandidateFactory private constructor(
         }
     }
 
-    constructor(context: ResolutionContext, callInfo: CallInfo) :
+    constructor(context: ResolutionContext, callInfo: CallInfo) : this(context, buildBaseSystem(context, callInfo))
-            this(context, callInfo, buildBaseSystem(context, callInfo))
-
-    fun replaceCallInfo(callInfo: CallInfo): CandidateFactory {
-        if (this.callInfo.arguments.size != callInfo.arguments.size) {
-            throw AssertionError("Incorrect replacement of call info in CandidateFactory")
-        }
-        return CandidateFactory(context, callInfo, baseSystem)
-    }
 
     fun createCandidate(
+        callInfo: CallInfo,
         symbol: AbstractFirBasedSymbol<*>,
         explicitReceiverKind: ExplicitReceiverKind,
         scope: FirScope?,
@@ -65,7 +57,7 @@ class CandidateFactory private constructor(
         )
     }
 
-    fun createErrorCandidate(diagnostic: ConeDiagnostic): Candidate {
+    fun createErrorCandidate(callInfo: CallInfo, diagnostic: ConeDiagnostic): Candidate {
         val symbol: AbstractFirBasedSymbol<*> = when (callInfo.callKind) {
             is CallKind.VariableAccess -> createErrorPropertySymbol(diagnostic)
             is CallKind.Function,

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/tower/FirInvokeResolveTowerExtension.kt

@@ -245,7 +245,6 @@ internal class FirInvokeResolveTowerExtension(
         receiverGroup,
         candidateFactoriesAndCollectors.resultCollector,
         candidateFactory,
-        candidateFactoriesAndCollectors.stubReceiverCandidateFactory
     )
 }
 
@@ -307,7 +306,6 @@ private class InvokeReceiverResolveTask(
     towerDataElementsForName,
     collector,
     candidateFactory,
-    stubReceiverCandidateFactory = null
 ) {
     override fun interceptTowerGroup(towerGroup: TowerGroup): TowerGroup =
         towerGroup.InvokeResolvePriority(InvokeResolvePriority.INVOKE_RECEIVER)
@@ -324,14 +322,12 @@ private class InvokeFunctionResolveTask(
     private val receiverGroup: TowerGroup,
     collector: CandidateCollector,
     candidateFactory: CandidateFactory,
-    stubReceiverCandidateFactory: CandidateFactory? = null
 ) : FirBaseTowerResolveTask(
     components,
     manager,
     towerDataElementsForName,
     collector,
     candidateFactory,
-    stubReceiverCandidateFactory
 ) {
 
     override fun interceptTowerGroup(towerGroup: TowerGroup): TowerGroup =

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/tower/FirTowerResolveTask.kt

@@ -9,12 +9,15 @@ import org.jetbrains.kotlin.fir.asReversedFrozen
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
 import org.jetbrains.kotlin.fir.expressions.FirResolvedQualifier
+import org.jetbrains.kotlin.fir.expressions.builder.buildExpressionStub
 import org.jetbrains.kotlin.fir.resolve.BodyResolveComponents
+import org.jetbrains.kotlin.fir.resolve.DoubleColonLHS
 import org.jetbrains.kotlin.fir.resolve.FirTowerDataContext
 import org.jetbrains.kotlin.fir.resolve.calls.*
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.ProcessorAction
 import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitBuiltinTypeRef
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
@@ -53,8 +56,7 @@ internal abstract class FirBaseTowerResolveTask(
     private val manager: TowerResolveManager,
     protected val towerDataElementsForName: TowerDataElementsForName,
     private val collector: CandidateCollector,
-    private val candidateFactory: CandidateFactory,
+    private val candidateFactory: CandidateFactory
-    private val stubReceiverCandidateFactory: CandidateFactory? = null
 ) {
     protected val session get() = components.session
 
@@ -131,7 +133,6 @@ internal abstract class FirBaseTowerResolveTask(
         val result = handler.handleLevel(
             collector,
             candidateFactory,
-            stubReceiverCandidateFactory,
             callInfo,
             explicitReceiverKind,
             finalGroup,
@@ -149,14 +150,12 @@ internal open class FirTowerResolveTask(
     towerDataElementsForName: TowerDataElementsForName,
     collector: CandidateCollector,
     candidateFactory: CandidateFactory,
-    stubReceiverCandidateFactory: CandidateFactory? = null
 ) : FirBaseTowerResolveTask(
     components,
     manager,
     towerDataElementsForName,
     collector,
     candidateFactory,
-    stubReceiverCandidateFactory
 ) {
 
     suspend fun runResolverForQualifierReceiver(
@@ -178,8 +177,17 @@ internal open class FirTowerResolveTask(
 
         if (resolvedQualifier.symbol != null) {
             val typeRef = resolvedQualifier.typeRef
-            if (info.callKind == CallKind.CallableReference && info.stubReceiver != null ) {
+            if (info.callKind == CallKind.CallableReference && info.lhs is DoubleColonLHS.Type) {
-                runResolverForExpressionReceiver(info, info.stubReceiver, parentGroup = TowerGroup.QualifierValue)
+                val stubReceiver = buildExpressionStub {
+                    source = info.explicitReceiver?.source
+                    this.typeRef = buildResolvedTypeRef {
+                        type = info.lhs.type
+                    }
+                }
+
+                val stubReceiverInfo = info.replaceExplicitReceiver(stubReceiver)
+
+                runResolverForExpressionReceiver(stubReceiverInfo, stubReceiver, parentGroup = TowerGroup.QualifierValue)
             }
 
             // NB: yet built-in Unit is used for "no-value" type
@@ -197,7 +205,7 @@ internal open class FirTowerResolveTask(
         val callableScope = qualifierReceiver.callableScope() ?: return
         processLevel(
             callableScope.toScopeTowerLevel(includeInnerConstructors = false),
-            info.noStubReceiver(), TowerGroup.Qualifier
+            info, TowerGroup.Qualifier
         )
     }
 
@@ -212,7 +220,7 @@ internal open class FirTowerResolveTask(
         val scope = qualifierReceiver.classifierScope() ?: return
         val group = if (prioritized) TowerGroup.ClassifierPrioritized else TowerGroup.Classifier
         processLevel(
-            scope.toScopeTowerLevel(includeInnerConstructors = false), info.noStubReceiver(),
+            scope.toScopeTowerLevel(includeInnerConstructors = false), info,
             group
         )
     }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/tower/FirTowerResolver.kt

@@ -52,7 +52,6 @@ class FirTowerResolver(
             TowerDataElementsForName(info.name, components.towerDataContext),
             candidateFactoriesAndCollectors.resultCollector,
             candidateFactoriesAndCollectors.candidateFactory,
-            candidateFactoriesAndCollectors.stubReceiverCandidateFactory
         )
         when (val receiver = info.explicitReceiver) {
             is FirResolvedQualifier -> {
@@ -103,6 +102,7 @@ class FirTowerResolver(
             resultCollector.consumeCandidate(
                 TowerGroup.Member,
                 candidateFactory.createCandidate(
+                    info,
                     it,
                     ExplicitReceiverKind.NO_EXPLICIT_RECEIVER,
                     scope,
@@ -123,16 +123,10 @@ class FirTowerResolver(
         context: ResolutionContext
     ): CandidateFactoriesAndCollectors {
         val candidateFactory = CandidateFactory(context, info)
-        val stubReceiverCandidateFactory =
-            if (info.callKind == CallKind.CallableReference && info.stubReceiver != null)
-                candidateFactory.replaceCallInfo(info.replaceExplicitReceiver(info.stubReceiver))
-            else
-                null
 
         return CandidateFactoriesAndCollectors(
             candidateFactory,
-            collector,
+            collector
-            stubReceiverCandidateFactory
         )
     }
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/tower/TowerLevelHandler.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.fir.resolve.calls.tower
 
-import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.expressions.FirResolvedQualifier
 import org.jetbrains.kotlin.fir.resolve.calls.*
 import org.jetbrains.kotlin.fir.scopes.FirScope
@@ -18,7 +17,6 @@ import org.jetbrains.kotlin.fir.types.ConeClassLikeType
 import org.jetbrains.kotlin.fir.types.ConeStarProjection
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.fir.types.constructClassType
-import org.jetbrains.kotlin.fir.types.impl.FirImplicitBuiltinTypeRef
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
 import org.jetbrains.kotlin.types.AbstractTypeChecker
@@ -27,9 +25,6 @@ internal class CandidateFactoriesAndCollectors(
     // Common calls
     val candidateFactory: CandidateFactory,
     val resultCollector: CandidateCollector,
-
-    // Callable references
-    val stubReceiverCandidateFactory: CandidateFactory?,
 )
 
 
@@ -41,7 +36,6 @@ internal class TowerLevelHandler {
     fun handleLevel(
         collector: CandidateCollector,
         candidateFactory: CandidateFactory,
-        stubReceiverCandidateFactory: CandidateFactory? = null,
         info: CallInfo,
         explicitReceiverKind: ExplicitReceiverKind,
         group: TowerGroup,
@@ -50,7 +44,7 @@ internal class TowerLevelHandler {
         processResult = ProcessorAction.NONE
         val processor =
             TowerScopeLevelProcessor(
-                info.explicitReceiver,
+                info,
                 explicitReceiverKind,
                 collector,
                 candidateFactory,
@@ -69,22 +63,7 @@ internal class TowerLevelHandler {
                 towerLevel.processFunctions(info.name, processor)
             }
             CallKind.CallableReference -> {
-                val stubReceiver = info.stubReceiver
+                towerLevel.processFunctionsAndProperties(info.name, processor)
-                if (stubReceiver != null) {
-                    val stubProcessor = TowerScopeLevelProcessor(
-                        info.explicitReceiver,
-                        explicitReceiverKind,
-                        collector,
-                        stubReceiverCandidateFactory!!, group
-                    )
-                    towerLevel.processFunctionsAndProperties(info.name, stubProcessor)
-                    // NB: we don't perform this for implicit Unit
-                    if (!collector.isSuccess() && info.explicitReceiver?.typeRef !is FirImplicitBuiltinTypeRef) {
-                        towerLevel.processFunctionsAndProperties(info.name, processor)
-                    }
-                } else {
-                    towerLevel.processFunctionsAndProperties(info.name, processor)
-                }
             }
             else -> {
                 throw AssertionError("Unsupported call kind in tower resolver: ${info.callKind}")
@@ -135,7 +114,7 @@ internal class TowerLevelHandler {
 }
 
 private class TowerScopeLevelProcessor(
-    val explicitReceiver: FirExpression?,
+    val callInfo: CallInfo,
     val explicitReceiverKind: ExplicitReceiverKind,
     val resultCollector: CandidateCollector,
     val candidateFactory: CandidateFactory,
@@ -151,7 +130,7 @@ private class TowerScopeLevelProcessor(
         // Check explicit extension receiver for default package members
         if (symbol is FirNamedFunctionSymbol && dispatchReceiverValue == null &&
             extensionReceiverValue != null &&
-            explicitReceiver !is FirResolvedQualifier &&
+            callInfo.explicitReceiver !is FirResolvedQualifier &&
             symbol.callableId.packageName.startsWith(defaultPackage)
         ) {
             val extensionReceiverType = extensionReceiverValue.type as? ConeClassLikeType
@@ -175,6 +154,7 @@ private class TowerScopeLevelProcessor(
         // ---
         resultCollector.consumeCandidate(
             group, candidateFactory.createCandidate(
+                callInfo,
                 symbol,
                 explicitReceiverKind,
                 scope,

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirSyntheticCallGenerator.kt

@@ -172,12 +172,15 @@ class FirSyntheticCallGenerator(
         return FirNamedReferenceWithCandidate(null, name, candidate)
     }
 
-    private fun generateCandidate(callInfo: CallInfo, function: FirSimpleFunction, context: ResolutionContext): Candidate =
+    private fun generateCandidate(callInfo: CallInfo, function: FirSimpleFunction, context: ResolutionContext): Candidate {
-        CandidateFactory(context, callInfo).createCandidate(
+        val candidateFactory = CandidateFactory(context, callInfo)
+        return candidateFactory.createCandidate(
+            callInfo,
             symbol = function.symbol,
             explicitReceiverKind = ExplicitReceiverKind.NO_EXPLICIT_RECEIVER,
             scope = null
         )
+    }
 
     private fun generateCallInfo(name: Name, argumentList: FirArgumentList, callKind: CallKind) = CallInfo(
         callKind = callKind,

compiler/testData/codegen/box/callableReference/function/referenceToCompanionMember.kt

@@ -1,7 +1,6 @@
 // DONT_TARGET_EXACT_BACKEND: WASM
 // WASM_MUTE_REASON: BINDING_RECEIVERS
 // WITH_RUNTIME
-// IGNORE_BACKEND_FIR: JVM_IR
 // IGNORE_BACKEND: JS
 
 class A {

compiler/testData/diagnostics/tests/callableReference/referenceToCompanionObjectMemberViaClassName.kt

@@ -27,7 +27,7 @@ fun testA(a: A) {
 
 fun testB(b: B) {
     val call1 = call(B::foo)
-    <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.String")!>call1<!>
+    <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int")!>call1<!>
 
     val call2 = call(B()::foo)
     <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.String")!>call2<!>

compiler/testData/diagnostics/tests/inference/completion/postponedArgumentsAnalysis/basic.fir.kt

@@ -186,7 +186,7 @@ fun main() {
     // Should be error as `A3::foo1` is `KFunction2`, but the remaining arguments are `KFuncion1` or `Function1`
     <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Function<kotlin.Any>")!>select(A3(), <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.reflect.KFunction2<A3, kotlin.Int, kotlin.Unit>")!>A3::foo1<!>, { a -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>a<!> }, { it -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>it<!> })<!>
     // It's OK because `A3::foo2` is from companion of `A3`
-    <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Function<kotlin.Any>")!>select(A3(), <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.reflect.KFunction2<A3, kotlin.Int, kotlin.Unit>")!>A3::foo2<!>, { a -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>a<!> }, { it -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>it<!> })<!>
+    <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Function1<kotlin.Int, kotlin.Any>")!>select(A3(), <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.reflect.KFunction1<kotlin.Int, kotlin.Unit>")!>A3::foo2<!>, { a -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>a<!> }, { it -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>it<!> })<!>
     <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Function1<kotlin.Int, kotlin.Comparable<*> & java.io.Serializable>")!>select(A4(), { x: Number -> "" })<!>
     <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Function2<kotlin.Int, kotlin.Int, kotlin.Comparable<*> & java.io.Serializable>")!>select(A5<Int, Int>(), { x: Number, y: Int -> "" })<!>
     <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Function3<kotlin.Int, kotlin.String, kotlin.Float, kotlin.Float>")!>select(A2(), id { a, b, c -> <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int")!>a<!>; <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.String")!>b<!>; <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing")!>c<!> })<!>

compiler/tests-spec/testData/diagnostics/linked/overload-resolution/resolving-callable-references/resolving-callable-references-not-used-as-arguments-to-a-call/p-1/pos/1.2.fir.kt

@@ -11,7 +11,7 @@ import libCase1.*
 import kotlin.text.format
 
 fun case1() {
-    val y2 : () ->String =(String)::format
+    val y2 : () ->String =<!UNRESOLVED_REFERENCE!>(String)::format<!>
 }
 
 // FILE: LibCase1.kt

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/resolver/SingleCandidateResolver.kt

@@ -65,6 +65,7 @@ class SingleCandidateResolver(
         val resolutionContext = stubBodyResolveTransformer.resolutionContext
 
         val candidate = CandidateFactory(resolutionContext, callInfo).createCandidate(
+            callInfo,
             resolutionParameters.callableSymbol,
             explicitReceiverKind = explicitReceiverKind,
             dispatchReceiverValue = dispatchReceiverValue,