Get rid of FE 1.0 classes usage in ConstraintIncorporator

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/components/ClassicConstraintSystemUtilContext.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2020 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.resolve.calls.inference.components
+
+import org.jetbrains.kotlin.resolve.calls.components.CreateFreshVariablesSubstitutor.shouldBeFlexible
+import org.jetbrains.kotlin.resolve.calls.inference.model.TypeVariableFromCallableDescriptor
+import org.jetbrains.kotlin.types.model.TypeVariableMarker
+
+object ClassicConstraintSystemUtilContext : ConstraintSystemUtilContext {
+    override fun TypeVariableMarker.shouldBeFlexible(): Boolean {
+        return this is TypeVariableFromCallableDescriptor && this.originalTypeParameter.shouldBeFlexible()
+    }
+}

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/components/ConstraintIncorporator.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.resolve.calls.inference.components
 
-import org.jetbrains.kotlin.resolve.calls.components.CreateFreshVariablesSubstitutor.shouldBeFlexible
 import org.jetbrains.kotlin.resolve.calls.inference.model.*
 import org.jetbrains.kotlin.types.AbstractTypeApproximator
 import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
@@ -19,7 +18,8 @@ import java.util.*
 // todo problem: intersection types in constrains: A <: Number, B <: Inv<A & Any> =>? B <: Inv<out Number & Any>
 class ConstraintIncorporator(
     val typeApproximator: AbstractTypeApproximator,
-    val trivialConstraintTypeInferenceOracle: TrivialConstraintTypeInferenceOracle
+    val trivialConstraintTypeInferenceOracle: TrivialConstraintTypeInferenceOracle,
+    val utilContext: ConstraintSystemUtilContext
 ) {
 
     interface Context : TypeSystemInferenceExtensionContext {
@@ -66,8 +66,7 @@ class ConstraintIncorporator(
         typeVariable: TypeVariableMarker,
         constraint: Constraint
     ) {
-        val shouldBeTypeVariableFlexible =
-            typeVariable is TypeVariableFromCallableDescriptor && typeVariable.originalTypeParameter.shouldBeFlexible()
+        val shouldBeTypeVariableFlexible = with(utilContext) { typeVariable.shouldBeFlexible() }
 
         // \alpha <: constraint.type
         if (constraint.kind != ConstraintKind.LOWER) {
@@ -83,7 +82,7 @@ class ConstraintIncorporator(
             getConstraintsForVariable(typeVariable).forEach {
                 if (it.kind != ConstraintKind.LOWER) {
                     val isFromDeclaredUpperBound =
-                        it.position.from is DeclaredUpperBoundConstraintPosition<*> && it.type.typeConstructor() !is TypeVariableTypeConstructor
+                        it.position.from is DeclaredUpperBoundConstraintPosition<*> && !it.type.typeConstructor().isTypeVariable()
 
                     addNewIncorporatedConstraint(
                         constraint.type,

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/components/ConstraintSystemUtilContext.kt

@@ -0,0 +1,17 @@
+/*
+ * Copyright 2010-2020 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.resolve.calls.inference.components
+
+import org.jetbrains.kotlin.types.model.TypeVariableMarker
+
+/*
+ * Functions from this context can not be moved to TypeSystemInferenceExtensionContext, because
+ *   it's classic implementation, ClassicTypeSystemContext lays in :core:descriptors,
+ *   but we need access classes from :compiler:resolution for this function implementation
+ */
+interface ConstraintSystemUtilContext {
+    fun TypeVariableMarker.shouldBeFlexible(): Boolean
+}