FIR: Support type aliases to function types in resolution

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

@@ -12,6 +12,8 @@ import org.jetbrains.kotlin.fir.declarations.FirValueParameter
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.inferenceContext
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
+import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
+import org.jetbrains.kotlin.fir.resolve.toSymbol
 import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.firUnsafe
 import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.resultType
 import org.jetbrains.kotlin.fir.resolve.withNullability
@@ -19,11 +21,13 @@ import org.jetbrains.kotlin.fir.returnExpressions
 import org.jetbrains.kotlin.fir.scopes.impl.FirILTTypeRefPlaceHolder
 import org.jetbrains.kotlin.fir.scopes.impl.FirIntegerOperator
 import org.jetbrains.kotlin.fir.scopes.impl.FirIntegerOperatorCall
+import org.jetbrains.kotlin.fir.symbols.impl.FirTypeAliasSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilder
 import org.jetbrains.kotlin.resolve.calls.inference.addSubtypeConstraintIfCompatible
 import org.jetbrains.kotlin.resolve.calls.inference.model.SimpleConstraintSystemConstraintPosition
 import org.jetbrains.kotlin.types.model.CaptureStatus
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 
 fun Candidate.resolveArgumentExpression(
@@ -299,14 +303,14 @@ private fun Candidate.getExpectedTypeWithSAMConversion(
     argument: FirExpression,
     candidateExpectedType: ConeKotlinType
 ): ConeKotlinType? {
-    if (candidateExpectedType.isBuiltinFunctionalType) return null
+    if (candidateExpectedType.isBuiltinFunctionalType(session)) return null
     // TODO: if (!callComponents.languageVersionSettings.supportsFeature(LanguageFeature.SamConversionPerArgument)) return null
     val firNamedFunction = symbol.fir as? FirSimpleFunction ?: return null
     if (!samResolver.shouldRunSamConversionForFunction(firNamedFunction)) return null
 
     val argumentIsFunctional = when ((argument as? FirWrappedArgumentExpression)?.expression ?: argument) {
         is FirAnonymousFunction, is FirCallableReferenceAccess -> true
-        else -> argument.typeRef.coneTypeSafe<ConeKotlinType>()?.isBuiltinFunctionalType == true
+        else -> argument.typeRef.coneTypeSafe<ConeKotlinType>()?.isBuiltinFunctionalType(session) == true
     }
     if (!argumentIsFunctional) return null
 
@@ -335,3 +339,19 @@ internal fun FirExpression.getExpectedType(
 private fun ConeKotlinType.varargElementType(session: FirSession): ConeKotlinType {
     return this.arrayElementType(session) ?: error("Failed to extract! ${this.render()}!")
 }
+
+fun FirTypeRef.isExtensionFunctionType(session: FirSession): Boolean {
+    if (annotations.any(FirAnnotationCall::isExtensionFunctionAnnotationCall)) return true
+
+    if (this !is FirResolvedTypeRef) return false
+    val type = type as? ConeClassLikeType ?: return false
+    if (type.fullyExpandedType(session) === type) return false
+
+    val typeAlias = type.lookupTag
+        .toSymbol(session)
+        ?.safeAs<FirTypeAliasSymbol>()?.fir ?: return false
+
+    if (typeAlias.expandedTypeRef.annotations.any(FirAnnotationCall::isExtensionFunctionAnnotationCall)) return true
+
+    return false
+}

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

@@ -5,11 +5,13 @@
 
 package org.jetbrains.kotlin.fir.resolve.calls
 
+import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.FirAnonymousFunction
 import org.jetbrains.kotlin.fir.expressions.FirCallableReferenceAccess
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.resolve.DoubleColonLHS
 import org.jetbrains.kotlin.fir.resolve.createFunctionalType
+import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
 import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.symbols.impl.ConeClassLikeLookupTagImpl
 import org.jetbrains.kotlin.fir.types.*
@@ -31,8 +33,8 @@ fun Candidate.preprocessLambdaArgument(
     }
 
     val resolvedArgument =
-        extractLambdaInfoFromFunctionalType(expectedType, expectedTypeRef, argument)
-            ?: extraLambdaInfo(expectedType, expectedTypeRef, argument, csBuilder)
+        extractLambdaInfoFromFunctionalType(expectedType, expectedTypeRef, argument, bodyResolveComponents.session)
+            ?: extraLambdaInfo(expectedType, expectedTypeRef, argument, csBuilder, bodyResolveComponents.session)
 
     if (expectedType != null) {
         // TODO: add SAM conversion processing
@@ -53,51 +55,45 @@ fun Candidate.preprocessCallableReference(
     expectedType: ConeKotlinType
 ) {
     val lhs = bodyResolveComponents.doubleColonExpressionResolver.resolveDoubleColonLHS(argument)
-    postponedAtoms += ResolvedCallableReferenceAtom(argument, expectedType, lhs)
+    postponedAtoms += ResolvedCallableReferenceAtom(argument, expectedType, lhs, bodyResolveComponents.session)
 }
 
-val ConeKotlinType.isBuiltinFunctionalType: Boolean
-    get() {
-        return when (this) {
-            is ConeClassLikeType -> this.lookupTag.classId.asString().startsWith("kotlin/Function")
-            else -> false
-        }
+fun ConeKotlinType.isBuiltinFunctionalType(session: FirSession): Boolean {
+    return when (this) {
+        is ConeClassLikeType -> fullyExpandedType(session).lookupTag.classId.asString().startsWith("kotlin/Function")
+        else -> false
     }
+}
 
-
-private val ConeKotlinType.isSuspendFunctionType: Boolean
-    get() {
-        val type = this
-        return when (type) {
-            is ConeClassLikeType -> {
-                val classId = type.lookupTag.classId
-                classId.packageFqName.asString() == "kotlin" && classId.relativeClassName.asString().startsWith("SuspendFunction")
-            }
-            else -> false
+fun ConeKotlinType.isSuspendFunctionType(session: FirSession): Boolean {
+    return when (val type = this) {
+        is ConeClassLikeType -> {
+            val classId = type.fullyExpandedType(session).lookupTag.classId
+            classId.packageFqName.asString() == "kotlin" && classId.relativeClassName.asString().startsWith("SuspendFunction")
         }
+        else -> false
     }
+}
 
-private fun ConeKotlinType.receiverType(expectedTypeRef: FirTypeRef): ConeKotlinType? {
-    if (expectedTypeRef.isExtensionFunctionType()) {
-        return (this.typeArguments.first() as ConeTypedProjection).type
+fun ConeKotlinType.receiverType(expectedTypeRef: FirTypeRef, session: FirSession): ConeKotlinType? {
+    if (isBuiltinFunctionalType(session) && expectedTypeRef.isExtensionFunctionType(session)) {
+        return ((this as ConeClassLikeType).fullyExpandedType(session).typeArguments.first() as ConeTypedProjection).type
     }
     return null
 }
 
-val ConeKotlinType.returnType: ConeKotlinType?
-    get() {
-        require(this is ConeClassLikeType)
-        val projection = typeArguments.last()
-        return (projection as? ConeTypedProjection)?.type
-    }
+fun ConeKotlinType.returnType(session: FirSession): ConeKotlinType? {
+    require(this is ConeClassLikeType)
+    val projection = fullyExpandedType(session).typeArguments.last()
+    return (projection as? ConeTypedProjection)?.type
+}
 
-val ConeKotlinType.valueParameterTypes: List<ConeKotlinType?>
-    get() {
-        require(this is ConeClassLikeType)
-        return typeArguments.dropLast(1).map {
-            (it as? ConeTypedProjection)?.type
-        }
+private fun ConeKotlinType.valueParameterTypes(session: FirSession): List<ConeKotlinType?> {
+    require(this is ConeClassLikeType)
+    return fullyExpandedType(session).typeArguments.dropLast(1).map {
+        (it as? ConeTypedProjection)?.type
     }
+}
 
 private val FirAnonymousFunction.returnType get() = returnTypeRef.coneTypeSafe<ConeKotlinType>()
 private val FirAnonymousFunction.receiverType get() = receiverTypeRef?.coneTypeSafe<ConeKotlinType>()
@@ -107,13 +103,15 @@ private fun extraLambdaInfo(
     expectedType: ConeKotlinType?,
     expectedTypeRef: FirTypeRef,
     argument: FirAnonymousFunction,
-    csBuilder: ConstraintSystemBuilder
+    csBuilder: ConstraintSystemBuilder,
+    session: FirSession
 ): ResolvedLambdaAtom {
 //    val builtIns = csBuilder.builtIns
-    val isSuspend = expectedType?.isSuspendFunctionType ?: false
+    val isSuspend = expectedType?.isSuspendFunctionType(session) ?: false
 
     val isFunctionSupertype =
-        expectedType != null && expectedType.lowerBoundIfFlexible().isBuiltinFunctionalType//isNotNullOrNullableFunctionSupertype(expectedType)
+        expectedType != null && expectedType.lowerBoundIfFlexible()
+            .isBuiltinFunctionalType(session)//isNotNullOrNullableFunctionSupertype(expectedType)
     val argumentAsFunctionExpression = argument//.safeAs<FunctionExpression>()
 
     val typeVariable = TypeVariableForLambdaReturnType(argument, "_L")
@@ -124,7 +122,8 @@ private fun extraLambdaInfo(
             ?: expectedType?.typeArguments?.singleOrNull()?.safeAs<ConeTypedProjection>()?.type?.takeIf { isFunctionSupertype }
             ?: typeVariable.defaultType
 
-    val nothingType = argument.session.builtinTypes.nothingType.type //StandardClassIds.Nothing(argument.session.firSymbolProvider).constructType(emptyArray(), false)
+    val nothingType = argument.session.builtinTypes.nothingType
+        .type //StandardClassIds.Nothing(argument.session.firSymbolProvider).constructType(emptyArray(), false)
     val parameters = argument.valueParameters?.map {
         it.returnTypeRef.coneTypeSafe<ConeKotlinType>() ?: nothingType
     } ?: emptyList()
@@ -138,20 +137,23 @@ private fun extraLambdaInfo(
 internal fun extractLambdaInfoFromFunctionalType(
     expectedType: ConeKotlinType?,
     expectedTypeRef: FirTypeRef,
-    argument: FirAnonymousFunction
+    argument: FirAnonymousFunction,
+    session: FirSession
 ): ResolvedLambdaAtom? {
     if (expectedType == null) return null
-    if (expectedType is ConeFlexibleType) return extractLambdaInfoFromFunctionalType(expectedType.lowerBound, expectedTypeRef, argument)
-    if (!expectedType.isBuiltinFunctionalType) return null
+    if (expectedType is ConeFlexibleType) {
+        return extractLambdaInfoFromFunctionalType(expectedType.lowerBound, expectedTypeRef, argument, session)
+    }
+    if (!expectedType.isBuiltinFunctionalType(session)) return null
 
     val argumentAsFunctionExpression = argument//.safeAs<FunctionExpression>()
-    val receiverType = argumentAsFunctionExpression.receiverType ?: expectedType.receiverType(expectedTypeRef)
-    val returnType = argumentAsFunctionExpression.returnType ?: expectedType.returnType ?: return null
-    val parameters = extractLambdaParameters(expectedType, argument, expectedTypeRef.isExtensionFunctionType())
+    val receiverType = argumentAsFunctionExpression.receiverType ?: expectedType.receiverType(expectedTypeRef, session)
+    val returnType = argumentAsFunctionExpression.returnType ?: expectedType.returnType(session) ?: return null
+    val parameters = extractLambdaParameters(expectedType, argument, expectedTypeRef.isExtensionFunctionType(session), session)
 
     return ResolvedLambdaAtom(
         argument,
-        expectedType.isSuspendFunctionType,
+        expectedType.isSuspendFunctionType(session),
         receiverType,
         parameters,
         returnType,
@@ -159,12 +161,16 @@ internal fun extractLambdaInfoFromFunctionalType(
     )
 }
 
-private fun extractLambdaParameters(expectedType: ConeKotlinType, argument: FirAnonymousFunction, expectedTypeIsExtensionFunctionType: Boolean): List<ConeKotlinType> {
+private fun extractLambdaParameters(
+    expectedType: ConeKotlinType,
+    argument: FirAnonymousFunction,
+    expectedTypeIsExtensionFunctionType: Boolean,
+    session: FirSession
+): List<ConeKotlinType> {
     val parameters = argument.valueParameters
-    val expectedParameters = expectedType.extractParametersForFunctionalType(expectedTypeIsExtensionFunctionType)
-
-    val nullableAnyType = argument.session.builtinTypes.nullableAnyType.type //StandardClassIds.Any(argument.session.firSymbolProvider).constructType(emptyArray(), true)
+    val expectedParameters = expectedType.extractParametersForFunctionalType(expectedTypeIsExtensionFunctionType, session)
 
+    val nullableAnyType = argument.session.builtinTypes.nullableAnyType.type
     if (parameters.isEmpty()) {
         return expectedParameters.map { it?.type ?: nullableAnyType }
     }
@@ -175,8 +181,11 @@ private fun extractLambdaParameters(expectedType: ConeKotlinType, argument: FirA
     }
 }
 
-private fun ConeKotlinType.extractParametersForFunctionalType(isExtensionFunctionType: Boolean): List<ConeKotlinType?> {
-    return valueParameterTypes.let {
+private fun ConeKotlinType.extractParametersForFunctionalType(
+    isExtensionFunctionType: Boolean,
+    session: FirSession
+): List<ConeKotlinType?> {
+    return valueParameterTypes(session).let {
         if (isExtensionFunctionType) {
             it.drop(1)
         } else {
@@ -217,7 +226,8 @@ class ResolvedLambdaAtom(
 class ResolvedCallableReferenceAtom(
     val reference: FirCallableReferenceAccess,
     val expectedType: ConeKotlinType?,
-    val lhs: DoubleColonLHS?
+    val lhs: DoubleColonLHS?,
+    private val session: FirSession
 ) : PostponedResolvedAtomMarker {
     override var analyzed: Boolean = false
     var postponed: Boolean = false
@@ -227,23 +237,27 @@ class ResolvedCallableReferenceAtom(
     override val inputTypes: Collection<ConeKotlinType>
         get() {
             if (!postponed) return emptyList()
-            return extractInputOutputTypesFromCallableReferenceExpectedType(expectedType)?.inputTypes ?: listOfNotNull(expectedType)
+            return extractInputOutputTypesFromCallableReferenceExpectedType(expectedType, session)?.inputTypes
+                ?: listOfNotNull(expectedType)
         }
     override val outputType: ConeKotlinType?
         get() {
             if (!postponed) return null
-            return extractInputOutputTypesFromCallableReferenceExpectedType(expectedType)?.outputType
+            return extractInputOutputTypesFromCallableReferenceExpectedType(expectedType, session)?.outputType
         }
 }
 
 private data class InputOutputTypes(val inputTypes: List<ConeKotlinType>, val outputType: ConeKotlinType)
 
-private fun extractInputOutputTypesFromCallableReferenceExpectedType(expectedType: ConeKotlinType?): InputOutputTypes? {
+private fun extractInputOutputTypesFromCallableReferenceExpectedType(
+    expectedType: ConeKotlinType?,
+    session: FirSession
+): InputOutputTypes? {
     if (expectedType == null) return null
 
     return when {
-        expectedType.isBuiltinFunctionalType || expectedType.isSuspendFunctionType ->
-            extractInputOutputTypesFromFunctionType(expectedType)
+        expectedType.isBuiltinFunctionalType(session) || expectedType.isSuspendFunctionType(session) ->
+            extractInputOutputTypesFromFunctionType(expectedType, session)
 
 //        ReflectionTypes.isBaseTypeForNumberedReferenceTypes(expectedType) ->
 //            InputOutputTypes(emptyList(), expectedType.arguments.single().type.unwrap())
@@ -267,9 +281,12 @@ private fun extractInputOutputTypesFromCallableReferenceExpectedType(expectedTyp
     }
 }
 
-private fun extractInputOutputTypesFromFunctionType(functionType: ConeKotlinType): InputOutputTypes {
+private fun extractInputOutputTypesFromFunctionType(
+    functionType: ConeKotlinType,
+    session: FirSession
+): InputOutputTypes {
     val receiver = null// TODO: functionType.receiverType()
-    val parameters = functionType.valueParameterTypes.map {
+    val parameters = functionType.valueParameterTypes(session).map {
         it ?: ConeClassLikeTypeImpl(
             ConeClassLikeLookupTagImpl(StandardClassIds.Nothing), emptyArray(),
             isNullable = false
@@ -277,7 +294,7 @@ private fun extractInputOutputTypesFromFunctionType(functionType: ConeKotlinType
     }
 
     val inputTypes = /*listOfNotNull(receiver) +*/ parameters
-    val outputType = functionType.returnType ?: ConeClassLikeTypeImpl(
+    val outputType = functionType.returnType(session) ?: ConeClassLikeTypeImpl(
         ConeClassLikeLookupTagImpl(StandardClassIds.Any), emptyArray(),
         isNullable = true
     )

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

@@ -99,8 +99,7 @@ internal sealed class CheckReceivers : ResolutionStage() {
             val receiverType = (callable.receiverTypeRef as FirResolvedTypeRef?)?.type
             if (receiverType != null) return receiverType
             val returnTypeRef = callable.returnTypeRef as? FirResolvedTypeRef ?: return null
-            if (!returnTypeRef.isExtensionFunctionType()) return null
-            return (returnTypeRef.type.typeArguments.firstOrNull() as? ConeTypedProjection)?.type
+            return returnTypeRef.type.receiverType(returnTypeRef, bodyResolveComponents.session)
         }
     }
 

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

@@ -168,7 +168,7 @@ class TowerResolveManager internal constructor(private val towerResolver: FirTow
                         for (invokeReceiverCandidate in invokeReceiverCollector.bestCandidates()) {
 
                             val symbol = invokeReceiverCandidate.symbol as FirCallableSymbol<*>
-                            val isExtensionFunctionType = symbol.fir.returnTypeRef.isExtensionFunctionType()
+                            val isExtensionFunctionType = symbol.fir.returnTypeRef.isExtensionFunctionType(towerResolver.components.session)
                             if (invokeBuiltinExtensionMode && !isExtensionFunctionType) {
                                 continue
                             }
@@ -303,4 +303,4 @@ class TowerResolveManager internal constructor(private val towerResolver: FirTow
             }
         }
     }
-}
+}

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

@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.fir.references.impl.FirResolvedNamedReferenceImpl
 import org.jetbrains.kotlin.fir.resolve.calls.Candidate
 import org.jetbrains.kotlin.fir.resolve.calls.FirNamedReferenceWithCandidate
 import org.jetbrains.kotlin.fir.resolve.calls.isBuiltinFunctionalType
+import org.jetbrains.kotlin.fir.resolve.calls.returnType
 import org.jetbrains.kotlin.fir.resolve.constructFunctionalTypeRef
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.substitution.substituteOrNull
@@ -187,7 +188,8 @@ class FirCallCompletionResultsWriterTransformer(
         result = when (result) {
             is FirIntegerOperatorCall -> {
                 val expectedType = data?.getExpectedType(functionCall)
-                resultType = typeRef.resolvedTypeFromPrototype(typeRef.coneTypeUnsafe<ConeIntegerLiteralType>().getApproximatedType(expectedType))
+                resultType =
+                    typeRef.resolvedTypeFromPrototype(typeRef.coneTypeUnsafe<ConeIntegerLiteralType>().getApproximatedType(expectedType))
                 result.transformArguments(this, expectedType?.toExpectedType()).transformSingle(integerApproximator, expectedType)
             }
             else -> {
@@ -238,9 +240,9 @@ class FirCallCompletionResultsWriterTransformer(
 
     private fun Candidate.createArgumentsMapping(): ExpectedArgumentType? {
         return argumentMapping?.map { (argument, valueParameter) ->
-            val expectedType = valueParameter.returnTypeRef.substitute(this)
-            argument.unwrapArgument() to expectedType
-        }
+                val expectedType = valueParameter.returnTypeRef.substitute(this)
+                argument.unwrapArgument() to expectedType
+            }
             ?.toMap()?.toExpectedType()
     }
 
@@ -248,7 +250,8 @@ class FirCallCompletionResultsWriterTransformer(
         delegatedConstructorCall: FirDelegatedConstructorCall,
         data: ExpectedArgumentType?
     ): CompositeTransformResult<FirStatement> {
-        val calleeReference = delegatedConstructorCall.calleeReference as? FirNamedReferenceWithCandidate ?: return delegatedConstructorCall.compose()
+        val calleeReference =
+            delegatedConstructorCall.calleeReference as? FirNamedReferenceWithCandidate ?: return delegatedConstructorCall.compose()
 
         val result = delegatedConstructorCall.transformArguments(this, calleeReference.candidate.createArgumentsMapping())
         return result.transformCalleeReference(
@@ -276,8 +279,8 @@ class FirCallCompletionResultsWriterTransformer(
         data: ExpectedArgumentType?
     ): CompositeTransformResult<FirStatement> {
         val expectedReturnType = data?.getExpectedType(anonymousFunction)
-            ?.takeIf { it.isBuiltinFunctionalType }
-            ?.let { it.typeArguments.last() as? ConeClassLikeType }
+            ?.takeIf { it.isBuiltinFunctionalType(session) }
+            ?.returnType(session) as? ConeClassLikeType
 
         val initialType = anonymousFunction.returnTypeRef.coneTypeSafe<ConeKotlinType>()
         if (initialType != null) {
@@ -373,4 +376,4 @@ private fun ConeKotlinType.approximateIfPossible(expectedType: ConeKotlinType?)
     getApproximatedType(expectedType)
 } else {
     this
-}
+}

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirDeclarationsResolveTransformer.kt

@@ -416,7 +416,7 @@ class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransformer)
                 val expectedTypeRef = (data as? ResolutionMode.WithExpectedType)?.expectedTypeRef ?: FirImplicitTypeRefImpl(null)
                 val resolvedLambdaAtom = (expectedTypeRef as? FirResolvedTypeRef)?.let {
                     extractLambdaInfoFromFunctionalType(
-                        it.type, it, anonymousFunction
+                        it.type, it, anonymousFunction, session
                     )
                 }
                 var af = anonymousFunction

compiler/fir/resolve/testData/resolve/functionTypeAlias.kt

@@ -0,0 +1,11 @@
+private typealias A = String.(Int) -> Int
+
+private fun b(a: A) {
+    "b".a(1)
+}
+
+fun main() {
+    b {
+        length + it
+    }
+}

compiler/fir/resolve/testData/resolve/functionTypeAlias.txt

@@ -0,0 +1,11 @@
+FILE: functionTypeAlias.kt
+    private final typealias A = R|kotlin/String.(kotlin/Int) -> kotlin/Int|
+    private final fun b(a: R|A|): R|kotlin/Unit| {
+        R|<local>/a|.R|FakeOverride<kotlin/Function2.invoke: R|kotlin/Int|>|(String(b), Int(1))
+    }
+    public final fun main(): R|kotlin/Unit| {
+        R|/b|(<L> = b@fun R|kotlin/String|.<anonymous>(it: R|kotlin/Int|): R|kotlin/Int| {
+            this@R|special/anonymous|.R|kotlin/String.length|.R|kotlin/Int.plus|(R|<local>/it|)
+        }
+        )
+    }

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsTestGenerated.java

@@ -128,6 +128,11 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
         runTest("compiler/fir/resolve/testData/resolve/ft.kt");
     }
 
+    @TestMetadata("functionTypeAlias.kt")
+    public void testFunctionTypeAlias() throws Exception {
+        runTest("compiler/fir/resolve/testData/resolve/functionTypeAlias.kt");
+    }
+
     @TestMetadata("functionTypes.kt")
     public void testFunctionTypes() throws Exception {
         runTest("compiler/fir/resolve/testData/resolve/functionTypes.kt");

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsWithLightTreeTestGenerated.java

@@ -128,6 +128,11 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
         runTest("compiler/fir/resolve/testData/resolve/ft.kt");
     }
 
+    @TestMetadata("functionTypeAlias.kt")
+    public void testFunctionTypeAlias() throws Exception {
+        runTest("compiler/fir/resolve/testData/resolve/functionTypeAlias.kt");
+    }
+
     @TestMetadata("functionTypes.kt")
     public void testFunctionTypes() throws Exception {
         runTest("compiler/fir/resolve/testData/resolve/functionTypes.kt");

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -769,7 +769,9 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
         annotations.renderAnnotations()
         print("R|")
         val coneType = resolvedTypeRef.type
-        print(coneType.renderFunctionType(kind, resolvedTypeRef.isExtensionFunctionType()))
+        print(coneType.renderFunctionType(kind, resolvedTypeRef.annotations.any {
+            it.isExtensionFunctionAnnotationCall
+        }))
         print("|")
     }
 

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/FirTypeUtils.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.types
 
+import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.expressions.FirConstKind
 import org.jetbrains.kotlin.fir.symbols.StandardClassIds
@@ -38,12 +39,6 @@ val FirFunctionTypeRef.parametersCount: Int
 
 const val EXTENSION_FUNCTION_ANNOTATION = "kotlin/ExtensionFunctionType"
 
-fun FirTypeRef.isExtensionFunctionType(): Boolean {
-    return annotations.any {
-        it.isExtensionFunctionAnnotationCall
-    }
-}
-
 val FirAnnotationCall.isExtensionFunctionAnnotationCall: Boolean
     get() = (this as? FirAnnotationCall)?.let {
         (it.annotationTypeRef as? FirResolvedTypeRef)?.let {
@@ -64,4 +59,4 @@ fun ConeClassLikeType.toConstKind(): FirConstKind<*>? = when (lookupTag.classId)
     StandardClassIds.Int -> FirConstKind.Int
     StandardClassIds.Long -> FirConstKind.Long
     else -> null
-}
+}

compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitution.fir.kt

@@ -16,9 +16,9 @@ fun buildB() {
     val a2 = applyRestrictions2()
     val a3 = applyRestrictions3("foo")
 
-    B.Builder().<!UNRESOLVED_REFERENCE!>a1<!>()
-    B.Builder().<!UNRESOLVED_REFERENCE!>a2<!>()
-    B.Builder().<!UNRESOLVED_REFERENCE!>a3<!>()
+    B.Builder().a1()
+    B.Builder().a2()
+    B.Builder().a3()
 }
 
 // additional example from #KT-34820

compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitutionOldInference.fir.kt

@@ -16,7 +16,7 @@ fun buildB() {
     val a2 = applyRestrictions2()
     val a3 = applyRestrictions3("foo")
 
-    B.Builder().<!UNRESOLVED_REFERENCE!>a1<!>()
-    B.Builder().<!UNRESOLVED_REFERENCE!>a2<!>()
-    B.Builder().<!UNRESOLVED_REFERENCE!>a3<!>()
+    B.Builder().a1()
+    B.Builder().a2()
+    B.Builder().a3()
 }

compiler/testData/diagnostics/tests/regressions/kt30245.fir.kt

@@ -36,13 +36,13 @@ class W4(val f: L2) {
 }
 
 fun test1() { // to extension lambda 0
-    val w10 = <!INAPPLICABLE_CANDIDATE!>W1<!> { this } // oi+ ni+
+    val w10 = W1 { this } // oi+ ni+
     val i10: E0 = id { this } // o1- ni+
     val j10 = <!INAPPLICABLE_CANDIDATE!>id<!><E0> { this } // oi+ ni+
     val f10 = W1(fun Int.(): Int = this) // oi+ ni+
     val g10: E0 = id(fun Int.(): Int = this) // oi+ ni+
 
-    val w11 = W1 { i: Int -> i } // oi- ni-
+    val w11 = <!INAPPLICABLE_CANDIDATE!>W1<!> { i: Int -> i } // oi- ni-
     val i11: E0 = id { i: Int -> i } // o1+ ni+
     val w12 = <!INAPPLICABLE_CANDIDATE!>W1<!> { i -> i } // oi- ni-
     val i12: E0 = id { i -> i } // oi- ni-
@@ -53,23 +53,23 @@ fun test1() { // to extension lambda 0
 //    val i13: E0 = id { it } // this or it: oi- ni-
 //    val j13 = id<E0> { it } // this or it: oi- ni-
 
-    val o14 = <!INAPPLICABLE_CANDIDATE!>W1<!> { -> 0 } // oi+ ni+
+    val o14 = W1 { -> 0 } // oi+ ni+
 }
 
 fun test2() { // to extension lambda 1
-    val w20 = <!INAPPLICABLE_CANDIDATE!>W2<!> { this + <!UNRESOLVED_REFERENCE!>it<!>.<!UNRESOLVED_REFERENCE!>length<!> } // oi+ ni+
+    val w20 = W2 { this + it.length } // oi+ ni+
     val i20: E1 = id { this + <!UNRESOLVED_REFERENCE!>it<!>.<!UNRESOLVED_REFERENCE!>length<!> } // oi- ni+
-    val w21 = <!INAPPLICABLE_CANDIDATE!>W2<!> { this } // oi+ ni+
+    val w21 = W2 { this } // oi+ ni+
     val i21: E1 = id { this } // oi- ni+
-    val f21 = <!INAPPLICABLE_CANDIDATE!>W2<!>(fun Int.(String): Int = this) // oi+ ni+
+    val f21 = W2(fun Int.(String): Int = this) // oi+ ni+
     val g21: E1 = id(fun Int.(String): Int = this) // oi+ ni+
-    val w22 = <!INAPPLICABLE_CANDIDATE!>W2<!> { s -> this + s.<!UNRESOLVED_REFERENCE!>length<!> } // oi+ ni+
+    val w22 = W2 { s -> this + s.length } // oi+ ni+
     val i22: E1 = id { s -> this + s.<!UNRESOLVED_REFERENCE!>length<!> } // oi+ ni+
-    val w23 = <!INAPPLICABLE_CANDIDATE!>W2<!> { s -> s.<!UNRESOLVED_REFERENCE!>length<!> } // oi+ ni+
+    val w23 = W2 { s -> s.length } // oi+ ni+
     val i23: E1 = id { s -> s.<!UNRESOLVED_REFERENCE!>length<!> } // oi+ ni+
-    val w24 = <!INAPPLICABLE_CANDIDATE!>W2<!> { s: String -> this + s.length } // oi+ ni+
+    val w24 = W2 { s: String -> this + s.length } // oi+ ni+
 //    val i24: E1 = id { s: String -> this + s.length } //oi- ni-
-    val w25 = <!INAPPLICABLE_CANDIDATE!>W2<!> { s: String -> s.length } // oi+ ni+
+    val w25 = W2 { s: String -> s.length } // oi+ ni+
 //    val i25: E1 = id { s: String -> s.length } // oi- ni-
 
     // yet unsupported cases with ambiguity for the lambda conversion (commented constructors in wrappers above)
@@ -80,7 +80,7 @@ fun test2() { // to extension lambda 1
 
     val w28 = <!INAPPLICABLE_CANDIDATE!>W2<!> { i: Int, s -> i <!AMBIGUITY!>+<!> s.<!UNRESOLVED_REFERENCE!>length<!> } // oi- ni-
     val i28: E1 = id { i: Int, s -> i <!AMBIGUITY!>+<!> s.<!UNRESOLVED_REFERENCE!>length<!> } // oi- ni-
-    val w29 = W2 { i: Int, s: String -> i + s.length } // oi- ni-
+    val w29 = <!INAPPLICABLE_CANDIDATE!>W2<!> { i: Int, s: String -> i + s.length } // oi- ni-
     val i29: E1 = id { i: Int, s: String -> i + s.length } // oi+ ni+
 
     // yet unsupported cases with ambiguity for the lambda conversion (commented constructors in wrappers above)
@@ -89,9 +89,9 @@ fun test2() { // to extension lambda 1
 }
 
 fun test3() { // to non-extension lambda 1
-    val w30 = <!INAPPLICABLE_CANDIDATE!>W3<!> { i -> i } // oi+ ni+
+    val w30 = W3 { i -> i } // oi+ ni+
     val i30: L1 = id { i -> i } // oi+ ni+
-    val w31 = <!INAPPLICABLE_CANDIDATE!>W3<!> { <!UNRESOLVED_REFERENCE!>it<!> } // oi+ ni+
+    val w31 = W3 { it } // oi+ ni+
     val i31: L1 = id { <!UNRESOLVED_REFERENCE!>it<!> } // oi- ni+
     val j31 = <!INAPPLICABLE_CANDIDATE!>id<!><L1> { <!UNRESOLVED_REFERENCE!>it<!> } // oi+ ni+
 
@@ -100,7 +100,7 @@ fun test3() { // to non-extension lambda 1
 //    val i32: L1 = id { this } // this or it: oi- ni-
 //    val j32 = id<L1> { this } // this or it: oi- ni-
 
-    val w33 = W3(fun Int.(): Int = this) // oi- ni+
+    val w33 = <!INAPPLICABLE_CANDIDATE!>W3<!>(fun Int.(): Int = this) // oi- ni+
     val i33: L1 = id(fun Int.(): Int = this) // oi+ ni+
 
     // yet unsupported cases with ambiguity for the lambda conversion (commented constructors in wrappers above)
@@ -108,7 +108,7 @@ fun test3() { // to non-extension lambda 1
 }
 
 fun test4() { // to non-extension lambda 2
-    val w30 = <!INAPPLICABLE_CANDIDATE!>W4<!> { i, s -> i } // oi+ ni+
+    val w30 = W4 { i, s -> i } // oi+ ni+
     val i30: L2 = id { i, s -> i } // oi+ ni+
 
     // yet unsupported cases with ambiguity for the lambda conversion (commented constructors in wrappers above)