Don't use reflection in JetType.getCapability

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/types/LazyJavaTypeResolver.kt

@@ -300,10 +300,11 @@ class LazyJavaTypeResolver(
         override val id: String get() = "kotlin.jvm.PlatformType"
 
         override fun <T : TypeCapability> getCapability(capabilityClass: Class<T>, jetType: JetType, flexibility: Flexibility): T? {
-            if (capabilityClass.isAssignableFrom(javaClass<Impl>()))
+            @suppress("UNCHECKED_CAST")
-                [suppress("UNCHECKED_CAST")]
+            return when (capabilityClass) {
-                return Impl(flexibility) as T
+                javaClass<CustomTypeVariable>(), javaClass<Specificity>() -> Impl(flexibility) as T
-            else return null
+                else -> null
+            }
         }
 
 

core/descriptors/src/org/jetbrains/kotlin/resolve/calls/inference/CapturedTypeConstructor.kt

@@ -16,11 +16,12 @@
 
 package org.jetbrains.kotlin.resolve.calls.inference
 
-import org.jetbrains.kotlin.types.*
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
-import org.jetbrains.kotlin.types.Variance.*
+import org.jetbrains.kotlin.types.*
-import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.types.Variance.IN_VARIANCE
+import org.jetbrains.kotlin.types.Variance.OUT_VARIANCE
 
 public class CapturedTypeConstructor(
         public val typeProjection: TypeProjection
@@ -64,6 +65,12 @@ public class CapturedType(
 
     override fun getDelegate(): JetType = delegateType
 
+    override fun <T : TypeCapability> getCapability(capabilityClass: Class<T>): T? {
+        @suppress("UNCHECKED_CAST")
+        return if (capabilityClass == javaClass<SubtypingRepresentatives>()) this as T
+        else super<DelegatingType>.getCapability(capabilityClass)
+    }
+
     override val subTypeRepresentative: JetType
         get() = representative(OUT_VARIANCE, KotlinBuiltIns.getInstance().getNullableAnyType())
 

core/descriptors/src/org/jetbrains/kotlin/types/AbstractJetType.java

@@ -29,10 +29,6 @@ public abstract class AbstractJetType implements JetType {
     @Nullable
     @Override
     public <T extends TypeCapability> T getCapability(@NotNull Class<T> capabilityClass) {
-        if (capabilityClass.isInstance(this)) {
-            //noinspection unchecked
-            return (T) this;
-        }
         return null;
     }
 

core/descriptors/src/org/jetbrains/kotlin/types/DelegatingType.java

@@ -64,10 +64,6 @@ public abstract class DelegatingType implements JetType {
     @Override
     @Nullable
     public <T extends TypeCapability> T getCapability(@NotNull Class<T> capabilityClass) {
-        if (capabilityClass.isInstance(this)) {
-            //noinspection unchecked
-            return (T) this;
-        }
         return getDelegate().getCapability(capabilityClass);
     }
 

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

@@ -17,7 +17,6 @@
 package org.jetbrains.kotlin.types
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
-import kotlin.platform.platformStatic
 
 open class DynamicTypesSettings {
     open val dynamicTypesAllowed: Boolean
@@ -29,7 +28,7 @@ class DynamicTypesAllowed: DynamicTypesSettings() {
         get() = true
 }
 
-trait Dynamicity : TypeCapability
+interface Dynamicity : TypeCapability
 
 // Object is created only for convenience here. Dynamic types may occur in the form of DelegatingFlexibleTypes,
 // which are produced by substitutions
@@ -45,14 +44,20 @@ public object DynamicTypeCapabilities : FlexibleTypeCapabilities {
     override val id: String get() = "kotlin.DynamicType"
 
     override fun <T : TypeCapability> getCapability(capabilityClass: Class<T>, jetType: JetType, flexibility: Flexibility): T? {
-        if (capabilityClass.isAssignableFrom(javaClass<Impl>()))
+        @suppress("UNCHECKED_CAST")
-            [suppress("UNCHECKED_CAST")]
+        return if (capabilityClass in Impl.capabilityClasses) Impl(flexibility) as T else null
-            return Impl(flexibility) as T
-        else return null
     }
 
-
     private class Impl(flexibility: Flexibility) : Dynamicity, Specificity, NullAwareness, FlexibleTypeDelegation {
+        companion object {
+            internal val capabilityClasses = hashSetOf(
+                    javaClass<Dynamicity>(),
+                    javaClass<Specificity>(),
+                    javaClass<NullAwareness>(),
+                    javaClass<FlexibleTypeDelegation>()
+            )
+        }
+
         override val delegateType: JetType = flexibility.upperBound
 
         override fun getSpecificityRelationTo(otherType: JetType): Specificity.Relation {

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

@@ -16,11 +16,10 @@
 
 package org.jetbrains.kotlin.types
 
-import org.jetbrains.kotlin.types.checker.JetTypeChecker
-import org.jetbrains.kotlin.types.Approximation.DataFlowExtras
-import org.jetbrains.kotlin.name.FqName
-import kotlin.platform.platformStatic
 import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.types.checker.JetTypeChecker
+import kotlin.platform.platformStatic
 
 public trait FlexibleTypeCapabilities {
     fun <T: TypeCapability> getCapability(capabilityClass: Class<T>, jetType: JetType, flexibility: Flexibility): T?
@@ -142,12 +141,20 @@ trait FlexibleTypeDelegation : TypeCapability {
     public val delegateType: JetType
 }
 
-public open class DelegatingFlexibleType protected (
+public open class DelegatingFlexibleType protected constructor(
         override val lowerBound: JetType,
         override val upperBound: JetType,
         override val extraCapabilities: FlexibleTypeCapabilities
 ) : DelegatingType(), NullAwareness, Flexibility, FlexibleTypeDelegation, Approximation {
     companion object {
+        internal val capabilityClasses = hashSetOf(
+                javaClass<NullAwareness>(),
+                javaClass<Flexibility>(),
+                javaClass<SubtypingRepresentatives>(),
+                javaClass<FlexibleTypeDelegation>(),
+                javaClass<Approximation>()
+        )
+
         platformStatic fun create(lowerBound: JetType, upperBound: JetType, extraCapabilities: FlexibleTypeCapabilities): JetType {
             if (lowerBound == upperBound) return lowerBound
             return DelegatingFlexibleType(lowerBound, upperBound, extraCapabilities)
@@ -166,7 +173,13 @@ public open class DelegatingFlexibleType protected (
     }
 
     override fun <T : TypeCapability> getCapability(capabilityClass: Class<T>): T? {
-        return extraCapabilities.getCapability(capabilityClass, this, this) ?: super<DelegatingType>.getCapability(capabilityClass)
+        val extra = extraCapabilities.getCapability(capabilityClass, this, this)
+        if (extra != null) return extra
+
+        @suppress("UNCHECKED_CAST")
+        if (capabilityClass in capabilityClasses) return this as T
+
+        return super<DelegatingType>.getCapability(capabilityClass)
     }
 
     override fun makeNullableAsSpecified(nullable: Boolean): JetType {