Split stub types into stub type for subtyping and for builder inference and use them in the proper way

core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt

@@ -249,7 +249,7 @@ internal class DescriptorRendererImpl(
                 }
                 append(renderTypeArguments(type.arguments))
             }
-            type is StubType -> append(type.originalTypeVariable.toString())
+            type is StubTypeForBuilderInference -> append(type.originalTypeVariable.toString())
             else -> renderTypeConstructorAndArguments(type)
         }
 
@@ -290,7 +290,7 @@ internal class DescriptorRendererImpl(
         is TypeParameterDescriptor, is ClassDescriptor, is TypeAliasDescriptor -> renderClassifierName(cd)
         null -> {
             if (typeConstructor is IntersectionTypeConstructor) {
-                typeConstructor.makeDebugNameForIntersectionType { if (it is StubType) it.originalTypeVariable else it }
+                typeConstructor.makeDebugNameForIntersectionType { if (it is StubTypeForBuilderInference) it.originalTypeVariable else it }
             } else typeConstructor.toString()
         }
         else -> error("Unexpected classifier: " + cd::class.java)

core/descriptors/src/org/jetbrains/kotlin/types/StubType.kt

@@ -1,75 +0,0 @@
-/*
- * Copyright 2010-2018 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.types
-
-import org.jetbrains.kotlin.descriptors.annotations.Annotations
-import org.jetbrains.kotlin.resolve.scopes.MemberScope
-import org.jetbrains.kotlin.types.checker.KotlinTypeRefiner
-import org.jetbrains.kotlin.types.model.StubTypeMarker
-import org.jetbrains.kotlin.types.refinement.TypeRefinement
-
-// This type is used as a stub for postponed type variables, which are important for coroutine inference
-class StubType(
-    originalTypeVariable: TypeConstructor,
-    isMarkedNullable: Boolean,
-    constructor: TypeConstructor = ErrorUtils.createErrorTypeConstructor("Constructor for non fixed type: $originalTypeVariable"),
-    memberScope: MemberScope = ErrorUtils.createErrorScope("Scope for non fixed type: $originalTypeVariable")
-) : AbstractStubType(originalTypeVariable, isMarkedNullable, constructor, memberScope), StubTypeMarker {
-    override fun materialize(newNullability: Boolean): AbstractStubType {
-        return StubType(originalTypeVariable, newNullability, constructor, memberScope)
-    }
-}
-
-class StubTypeForTypeVariablesInSubtyping(
-    originalTypeVariable: TypeConstructor,
-    isMarkedNullable: Boolean,
-    constructor: TypeConstructor = ErrorUtils.createErrorTypeConstructor("Constructor for non fixed type: $originalTypeVariable"),
-    memberScope: MemberScope = ErrorUtils.createErrorScope("Scope for non fixed type: $originalTypeVariable")
-) : AbstractStubType(originalTypeVariable, isMarkedNullable, constructor, memberScope), StubTypeMarker {
-    override fun materialize(newNullability: Boolean): AbstractStubType {
-        return StubTypeForTypeVariablesInSubtyping(originalTypeVariable, newNullability, constructor, memberScope)
-    }
-}
-
-// This type is used as a replacement of type variables for provideDelegate resolve
-class StubTypeForProvideDelegateReceiver(
-    originalTypeVariable: TypeConstructor,
-    isMarkedNullable: Boolean,
-    constructor: TypeConstructor = ErrorUtils.createErrorTypeConstructor("Constructor for non fixed type: $originalTypeVariable"),
-    memberScope: MemberScope = ErrorUtils.createErrorScope("Scope for non fixed type: $originalTypeVariable")
-) : AbstractStubType(originalTypeVariable, isMarkedNullable, constructor, memberScope) {
-    override fun materialize(newNullability: Boolean): StubTypeForProvideDelegateReceiver {
-        return StubTypeForProvideDelegateReceiver(originalTypeVariable, newNullability, constructor, memberScope)
-    }
-}
-
-abstract class AbstractStubType(
-    val originalTypeVariable: TypeConstructor,
-    override val isMarkedNullable: Boolean,
-    override val constructor: TypeConstructor,
-    override val memberScope: MemberScope
-) : SimpleType() {
-    override val arguments: List<TypeProjection>
-        get() = emptyList()
-
-    override val annotations: Annotations
-        get() = Annotations.EMPTY
-
-    override fun replaceAnnotations(newAnnotations: Annotations): SimpleType = this
-
-    override fun makeNullableAsSpecified(newNullability: Boolean): SimpleType {
-        return if (newNullability == isMarkedNullable) this else materialize(newNullability)
-    }
-
-    override fun toString(): String {
-        return "NonFixed: $originalTypeVariable${if (isMarkedNullable) "?" else ""}"
-    }
-
-    @TypeRefinement
-    override fun refine(kotlinTypeRefiner: KotlinTypeRefiner) = this
-
-    abstract fun materialize(newNullability: Boolean): AbstractStubType
-}

core/descriptors/src/org/jetbrains/kotlin/types/StubTypes.kt

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2010-2018 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.types
+
+import org.jetbrains.kotlin.descriptors.annotations.Annotations
+import org.jetbrains.kotlin.types.checker.KotlinTypeRefiner
+import org.jetbrains.kotlin.types.model.StubTypeMarker
+import org.jetbrains.kotlin.types.refinement.TypeRefinement
+
+class StubTypeForBuilderInference(
+    originalTypeVariable: TypeConstructor,
+    isMarkedNullable: Boolean,
+) : AbstractStubType(originalTypeVariable, isMarkedNullable), StubTypeMarker {
+    override fun materialize(newNullability: Boolean): AbstractStubType =
+        StubTypeForBuilderInference(originalTypeVariable, newNullability)
+
+    override fun toString(): String {
+        // BI means builder inference
+        return "Stub (BI): $originalTypeVariable${if (isMarkedNullable) "?" else ""}"
+    }
+}
+
+class StubTypeForTypeVariablesInSubtyping(originalTypeVariable: TypeConstructor, isMarkedNullable: Boolean) :
+    AbstractStubType(originalTypeVariable, isMarkedNullable), StubTypeMarker {
+    override fun materialize(newNullability: Boolean): AbstractStubType =
+        StubTypeForTypeVariablesInSubtyping(originalTypeVariable, newNullability)
+
+    override fun toString(): String {
+        return "Stub (subtyping): $originalTypeVariable${if (isMarkedNullable) "?" else ""}"
+    }
+}
+
+// This type is used as a replacement of type variables for provideDelegate resolve
+class StubTypeForProvideDelegateReceiver(originalTypeVariable: TypeConstructor, isMarkedNullable: Boolean) :
+    AbstractStubType(originalTypeVariable, isMarkedNullable) {
+    override fun materialize(newNullability: Boolean): StubTypeForProvideDelegateReceiver =
+        StubTypeForProvideDelegateReceiver(originalTypeVariable, newNullability)
+
+    override fun toString(): String {
+        return "Stub (delegation): $originalTypeVariable${if (isMarkedNullable) "?" else ""}"
+    }
+}
+
+abstract class AbstractStubType(val originalTypeVariable: TypeConstructor, override val isMarkedNullable: Boolean) : SimpleType() {
+    override val memberScope = ErrorUtils.createErrorScope("Scope for stub type: $originalTypeVariable")
+    override val constructor = ErrorUtils.createErrorTypeConstructor("Constructor for stub type: $originalTypeVariable")
+
+    override val arguments: List<TypeProjection>
+        get() = emptyList()
+
+    override val annotations: Annotations
+        get() = Annotations.EMPTY
+
+    override fun replaceAnnotations(newAnnotations: Annotations): SimpleType = this
+
+    override fun makeNullableAsSpecified(newNullability: Boolean): SimpleType {
+        return if (newNullability == isMarkedNullable) this else materialize(newNullability)
+    }
+
+    @TypeRefinement
+    override fun refine(kotlinTypeRefiner: KotlinTypeRefiner) = this
+
+    abstract fun materialize(newNullability: Boolean): AbstractStubType
+}

core/descriptors/src/org/jetbrains/kotlin/types/TypeUtils.kt

@@ -375,4 +375,4 @@ private fun NewCapturedType.unCaptureTopLevelType(): UnwrappedType {
     return constructor.projection.type.unwrap()
 }
 
-fun KotlinType.shouldBeUpdated() = contains { it is StubType || it.constructor is TypeVariableTypeConstructorMarker || it.isError }
+fun KotlinType.shouldBeUpdated() = contains { it is StubTypeForBuilderInference || it.constructor is TypeVariableTypeConstructorMarker || it.isError }

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

@@ -81,7 +81,7 @@ interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext, TypeSy
 
     override fun SimpleTypeMarker.isStubType(): Boolean {
         require(this is SimpleType, this::errorMessage)
-        return this is StubType || this is StubTypeForProvideDelegateReceiver
+        return this is StubTypeForBuilderInference || this is StubTypeForProvideDelegateReceiver
     }
 
     override fun SimpleTypeMarker.isStubTypeForVariableInSubtyping(): Boolean {
@@ -544,7 +544,7 @@ interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext, TypeSy
         errorSupportedOnlyInTypeInference()
     }
 
-    override fun createStubType(typeVariable: TypeVariableMarker): StubTypeMarker {
+    override fun createStubTypeForBuilderInference(typeVariable: TypeVariableMarker): StubTypeMarker {
         errorSupportedOnlyInTypeInference()
     }