Support overrides of generic methods with erased version in Java

core/descriptor.loader.java/src/META-INF/services/org.jetbrains.kotlin.resolve.ExternalOverridabilityCondition

@@ -1 +1,2 @@
-org.jetbrains.kotlin.load.java.FieldOverridabilityCondition
+org.jetbrains.kotlin.load.java.FieldOverridabilityCondition
+org.jetbrains.kotlin.load.java.ErasedOverridabilityCondition

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/ErasedOverridabilityCondition.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.load.java
+
+import org.jetbrains.kotlin.descriptors.CallableDescriptor
+import org.jetbrains.kotlin.descriptors.SimpleFunctionDescriptor
+import org.jetbrains.kotlin.load.java.descriptors.JavaMethodDescriptor
+import org.jetbrains.kotlin.load.java.lazy.types.RawSubstitution
+import org.jetbrains.kotlin.resolve.ExternalOverridabilityCondition
+import org.jetbrains.kotlin.resolve.ExternalOverridabilityCondition.Result
+import org.jetbrains.kotlin.resolve.OverridingUtil
+
+class ErasedOverridabilityCondition : ExternalOverridabilityCondition {
+    override fun isOverridable(superDescriptor: CallableDescriptor, subDescriptor: CallableDescriptor): Result {
+        if (subDescriptor !is JavaMethodDescriptor) return Result.UNKNOWN
+
+        var erasedSuper = superDescriptor.substitute(RawSubstitution.buildSubstitutor()) ?: return Result.UNKNOWN
+
+        if (erasedSuper is SimpleFunctionDescriptor && erasedSuper.typeParameters.isNotEmpty()) {
+            // Only simple functions are supported now for erased overrides
+            erasedSuper = erasedSuper.createCopyWithNewTypeParameters(emptyList())
+        }
+
+        val overridabilityResult =
+                OverridingUtil.DEFAULT.isOverridableByWithoutExternalConditions(erasedSuper, subDescriptor, false).result
+        return when (overridabilityResult) {
+            OverridingUtil.OverrideCompatibilityInfo.Result.OVERRIDABLE -> Result.OVERRIDABLE
+            else ->  Result.UNKNOWN
+        }
+    }
+}

core/descriptors/src/org/jetbrains/kotlin/descriptors/SimpleFunctionDescriptor.java

@@ -35,6 +35,9 @@ public interface SimpleFunctionDescriptor extends FunctionDescriptor {
     @NotNull
     SimpleFunctionDescriptor createCopyWithNewValueParameters(@NotNull List<ValueParameterDescriptor> valueParameters);
 
+    @NotNull
+    SimpleFunctionDescriptor createCopyWithNewTypeParameters(@NotNull List<TypeParameterDescriptor> typeParameters);
+
     @NotNull
     @Override
     SimpleFunctionDescriptor getOriginal();

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/FunctionDescriptorImpl.java

@@ -283,6 +283,7 @@ public abstract class FunctionDescriptorImpl extends DeclarationDescriptorNonRoo
         protected @Nullable Name name;
         protected boolean copyOverrides;
         protected boolean signatureChange;
+        private List<TypeParameterDescriptor> newTypeParameters = null;
 
         public CopyConfiguration(
                 @NotNull TypeSubstitutor originalSubstitutor,
@@ -412,11 +413,21 @@ public abstract class FunctionDescriptorImpl extends DeclarationDescriptorNonRoo
                 configuration.newOwner, configuration.original, configuration.kind, configuration.name,
                 /* preserveSource = */ configuration.signatureChange);
 
-        List<TypeParameterDescriptor> originalTypeParameters = getTypeParameters();
-        List<TypeParameterDescriptor> substitutedTypeParameters = new ArrayList<TypeParameterDescriptor>(originalTypeParameters.size());
-        TypeSubstitutor substitutor = DescriptorSubstitutor.substituteTypeParameters(
-                originalTypeParameters, configuration.originalSubstitutor.getSubstitution(), substitutedDescriptor, substitutedTypeParameters
-        );
+        List<TypeParameterDescriptor> substitutedTypeParameters;
+        TypeSubstitutor substitutor;
+
+        if (configuration.newTypeParameters == null) {
+            List<TypeParameterDescriptor> originalTypeParameters = getTypeParameters();
+            substitutedTypeParameters = new ArrayList<TypeParameterDescriptor>(originalTypeParameters.size());
+            substitutor = DescriptorSubstitutor.substituteTypeParameters(
+                    originalTypeParameters, configuration.originalSubstitutor.getSubstitution(), substitutedDescriptor, substitutedTypeParameters
+            );
+        }
+        else {
+            // They should be already substituted
+            substitutedTypeParameters = configuration.newTypeParameters;
+            substitutor = configuration.originalSubstitutor;
+        }
 
         KotlinType substitutedReceiverParameterType = null;
         if (configuration.newExtensionReceiverParameterType != null) {

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/SimpleFunctionDescriptorImpl.java

@@ -122,4 +122,11 @@ public class SimpleFunctionDescriptorImpl extends FunctionDescriptorImpl impleme
         //noinspection ConstantConditions
         return (SimpleFunctionDescriptor) newCopyBuilder().setValueParameters(valueParameters).setSignatureChange().build();
     }
+
+    @NotNull
+    @Override
+    public SimpleFunctionDescriptor createCopyWithNewTypeParameters(@NotNull List<TypeParameterDescriptor> typeParameters) {
+        //noinspection ConstantConditions
+        return (SimpleFunctionDescriptor) newCopyBuilder().setTypeParameters(typeParameters).build();
+    }
 }

core/descriptors/src/org/jetbrains/kotlin/types/error/ErrorSimpleFunctionDescriptorImpl.java

@@ -67,6 +67,12 @@ public class ErrorSimpleFunctionDescriptorImpl extends SimpleFunctionDescriptorI
         return this;
     }
 
+    @NotNull
+    @Override
+    public SimpleFunctionDescriptor createCopyWithNewTypeParameters(@NotNull List<TypeParameterDescriptor> typeParameters) {
+        return this;
+    }
+
     @Override
     public void addOverriddenDescriptor(@NotNull CallableMemberDescriptor overriddenFunction) {
         // nop