Simplify implementation of TypeSystemCommonSuperTypesContext.typeDepth

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

@@ -91,7 +91,8 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext,
                 || this is ConeTypeParameterType
     }
 
-    fun ConeKotlinType.typeDepthSimple(): Int {
+    override fun SimpleTypeMarker.typeDepth(): Int {
+        require(this is ConeKotlinType)
         // if (this is TypeUtils.SpecialType) return 0 // TODO: WTF?
 
         val maxInArguments = this.typeArguments.asSequence().map {
@@ -101,21 +102,6 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext,
         return maxInArguments + 1
     }
 
-    override fun SimpleTypeMarker.typeDepth(): Int {
-        require(this is ConeKotlinType)
-        return this.typeDepthSimple()
-    }
-
-    override fun KotlinTypeMarker.typeDepth(): Int {
-        require(this is ConeKotlinType) {
-            "Incorrect type of class ${this::class.java}: $this"
-        }
-        return when (this) {
-            is ConeFlexibleType -> Math.max(lowerBound.typeDepthSimple(), upperBound.typeDepthSimple())
-            else -> typeDepthSimple()
-        }
-    }
-
     override fun KotlinTypeMarker.contains(predicate: (KotlinTypeMarker) -> Boolean): Boolean {
         return this.containsInternal(predicate)
     }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeSystemContext.kt

@@ -217,8 +217,6 @@ interface IrTypeSystemContext : TypeSystemInferenceExtensionContext {
 
     override fun SimpleTypeMarker.typeDepth() = 2
 
-    override fun KotlinTypeMarker.typeDepth() = if (this is IrStarProjection) 1 else 0
-
     override fun findCommonIntegerLiteralTypesSuperType(explicitSupertypes: List<SimpleTypeMarker>): SimpleTypeMarker? =
         irBuiltIns.intType as IrSimpleType
 

core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt

@@ -21,7 +21,6 @@ import org.jetbrains.kotlin.types.typeUtil.asTypeProjection
 import org.jetbrains.kotlin.types.typeUtil.contains
 import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.contract
-import kotlin.math.max
 
 interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext {
     override fun TypeConstructorMarker.isDenotable(): Boolean {
@@ -268,12 +267,13 @@ interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext {
 
     override fun SimpleTypeMarker.typeDepth(): Int {
         require(this is SimpleType, this::errorMessage)
-        return this.typeDepthInternal()
+        if (this is TypeUtils.SpecialType) return 0
-    }
 
-    override fun KotlinTypeMarker.typeDepth(): Int {
+        val maxInArguments = arguments.asSequence().map {
-        require(this is UnwrappedType, this::errorMessage)
+            if (it.isStarProjection) 1 else it.type.unwrap().typeDepth()
-        return this.typeDepthInternal()
+        }.max() ?: 0
+
+        return maxInArguments + 1
     }
 
     override fun intersectTypes(types: List<KotlinTypeMarker>): KotlinTypeMarker {
@@ -514,23 +514,6 @@ private fun containsInternal(type: KotlinType, predicate: (KotlinTypeMarker) ->
 
 private fun singleBestRepresentative(collection: Collection<KotlinType>) = collection.singleBestRepresentative()
 
-internal fun UnwrappedType.typeDepthInternal() =
-    when (this) {
-        is SimpleType -> typeDepthInternal()
-        is FlexibleType -> max(lowerBound.typeDepthInternal(), upperBound.typeDepthInternal())
-    }
-
-internal fun SimpleType.typeDepthInternal(): Int {
-    if (this is TypeUtils.SpecialType) return 0
-
-    val maxInArguments = arguments.asSequence().map {
-        if (it.isStarProjection) 1 else it.type.unwrap().typeDepthInternal()
-    }.max() ?: 0
-
-    return maxInArguments + 1
-}
-
-
 @Suppress("NOTHING_TO_INLINE")
 private inline fun Any.errorMessage(): String {
     return "ClassicTypeSystemContext couldn't handle: $this, ${this::class}"

core/type-system/src/org/jetbrains/kotlin/types/model/TypeSystemContext.kt

@@ -76,7 +76,12 @@ interface TypeSystemCommonSuperTypesContext : TypeSystemContext, TypeSystemTypeF
     fun KotlinTypeMarker.canHaveUndefinedNullability(): Boolean
 
     fun SimpleTypeMarker.typeDepth(): Int
-    fun KotlinTypeMarker.typeDepth(): Int
+
+    fun KotlinTypeMarker.typeDepth(): Int = when (this) {
+        is SimpleTypeMarker -> typeDepth()
+        is FlexibleTypeMarker -> maxOf(lowerBound().typeDepth(), upperBound().typeDepth())
+        else -> error("Type should be simple or flexible: $this")
+    }
 
     fun findCommonIntegerLiteralTypesSuperType(explicitSupertypes: List<SimpleTypeMarker>): SimpleTypeMarker?
 }