[FIR] Introduce ConeTypeApproximator

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/CallAndReferenceGenerator.kt

@@ -41,7 +41,6 @@ import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.psi2ir.generators.hasNoSideEffects
-import org.jetbrains.kotlin.types.AbstractTypeApproximator
 import org.jetbrains.kotlin.types.AbstractTypeChecker
 
 class CallAndReferenceGenerator(
@@ -50,7 +49,7 @@ class CallAndReferenceGenerator(
     private val conversionScope: Fir2IrConversionScope
 ) : Fir2IrComponents by components {
 
-    private val approximator = object : AbstractTypeApproximator(session.typeContext) {}
+    private val approximator = ConeTypeApproximator(session.typeContext)
     private val adapterGenerator = AdapterGenerator(components, conversionScope)
     private val samResolver = FirSamResolverImpl(session, scopeSession)
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirCallCompleter.kt

@@ -243,5 +243,5 @@ class FirCallCompleter(
     private fun ConeKotlinType.approximateLambdaInputType(): ConeKotlinType =
         session.inferenceComponents.approximator.approximateToSuperType(
             this, TypeApproximatorConfiguration.FinalApproximationAfterResolutionAndInference
-        ) as ConeKotlinType? ?: this
+        ) ?: this
 }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/InferenceComponents.kt

@@ -7,9 +7,9 @@ package org.jetbrains.kotlin.fir.resolve.inference
 
 import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.types.ConeInferenceContext
+import org.jetbrains.kotlin.fir.types.ConeTypeApproximator
 import org.jetbrains.kotlin.resolve.calls.inference.components.*
 import org.jetbrains.kotlin.resolve.calls.inference.model.NewConstraintSystemImpl
-import org.jetbrains.kotlin.types.AbstractTypeApproximator
 
 @NoMutableState
 class InferenceComponents(val session: FirSession) : FirSessionComponent {
@@ -18,7 +18,7 @@ class InferenceComponents(val session: FirSession) : FirSessionComponent {
             get() = this@InferenceComponents.session
     }
 
-    val approximator: AbstractTypeApproximator = object : AbstractTypeApproximator(ctx) {}
+    val approximator: ConeTypeApproximator = ConeTypeApproximator(ctx)
     val trivialConstraintTypeInferenceOracle = TrivialConstraintTypeInferenceOracle.create(ctx)
     private val incorporator = ConstraintIncorporator(approximator, trivialConstraintTypeInferenceOracle, ConeConstraintSystemUtilContext)
     private val injector = ConstraintInjector(

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/substitution/Substitutors.kt

@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
 import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
-import org.jetbrains.kotlin.types.model.KotlinTypeMarker
 import org.jetbrains.kotlin.types.model.TypeConstructorMarker
 import org.jetbrains.kotlin.types.model.TypeSubstitutorMarker
 import org.jetbrains.kotlin.types.model.typeConstructor
@@ -161,7 +160,7 @@ data class ConeSubstitutorByMap(val substitution: Map<FirTypeParameterSymbol, Co
         if (type.isUnsafeVarianceType(session)) {
             return session.inferenceComponents.approximator.approximateToSuperType(
                 result, TypeApproximatorConfiguration.FinalApproximationAfterResolutionAndInference
-            ) as? ConeKotlinType ?: result
+            ) ?: result
         }
         return result
     }

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

@@ -971,7 +971,7 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
         access.resultType = typeFromCallee.withReplacedConeType(
             session.inferenceComponents.approximator.approximateToSuperType(
                 typeFromCallee.type, TypeApproximatorConfiguration.FinalApproximationAfterResolutionAndInference
-            ) as ConeKotlinType?
+            )
         )
     }
 }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/types/ConeTypeApproximator.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2021 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.types
+
+import org.jetbrains.kotlin.types.AbstractTypeApproximator
+import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
+
+class ConeTypeApproximator(inferenceContext: ConeInferenceContext) : AbstractTypeApproximator(inferenceContext) {
+    fun approximateToSuperType(type: ConeKotlinType, conf: TypeApproximatorConfiguration): ConeKotlinType? {
+        return super.approximateToSuperType(type, conf) as ConeKotlinType?
+    }
+
+    fun approximateToSubType(type: ConeKotlinType, conf: TypeApproximatorConfiguration): ConeKotlinType? {
+        return super.approximateToSubType(type, conf) as ConeKotlinType?
+    }
+}

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/types/TypeUtils.kt

@@ -22,7 +22,6 @@ import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
 import org.jetbrains.kotlin.fir.types.impl.ConeTypeParameterTypeImpl
 import org.jetbrains.kotlin.resolve.calls.NewCommonSuperTypeCalculator
 import org.jetbrains.kotlin.types.AbstractStrictEqualityTypeChecker
-import org.jetbrains.kotlin.types.AbstractTypeApproximator
 import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
 import org.jetbrains.kotlin.types.model.*
@@ -250,7 +249,7 @@ fun FirTypeRef.withReplacedConeType(
 }
 
 fun FirTypeRef.approximated(
-    typeApproximator: AbstractTypeApproximator,
+    typeApproximator: ConeTypeApproximator,
     toSuper: Boolean,
     conf: TypeApproximatorConfiguration = TypeApproximatorConfiguration.PublicDeclaration
 ): FirTypeRef {
@@ -258,11 +257,11 @@ fun FirTypeRef.approximated(
         typeApproximator.approximateToSuperType(coneType, conf)
     else
         typeApproximator.approximateToSubType(coneType, conf)
-    return withReplacedConeType(approximatedType as? ConeKotlinType)
+    return withReplacedConeType(approximatedType)
 }
 
 fun FirTypeRef.approximatedIfNeededOrSelf(
-    approximator: AbstractTypeApproximator,
+    approximator: ConeTypeApproximator,
     containingCallableVisibility: Visibility?,
     isInlineFunction: Boolean = false
 ): FirTypeRef {
@@ -273,7 +272,7 @@ fun FirTypeRef.approximatedIfNeededOrSelf(
     return approximated.hideLocalTypeIfNeeded(containingCallableVisibility, isInlineFunction).withoutEnhancedNullability()
 }
 
-fun FirTypeRef.approximatedForPublicPosition(approximator: AbstractTypeApproximator): FirTypeRef =
+fun FirTypeRef.approximatedForPublicPosition(approximator: ConeTypeApproximator): FirTypeRef =
     if (this is FirResolvedTypeRef && type.requiresApproximationInPublicPosition())
         this.approximated(approximator, toSuper = true)
     else