Stub infrastructure for enhancing platform signatures

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/components/ExternalSignatureResolver.java

@@ -18,12 +18,14 @@ package org.jetbrains.kotlin.load.java.components;
 
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.ReadOnly;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.load.java.structure.JavaField;
 import org.jetbrains.kotlin.load.java.structure.JavaMember;
 import org.jetbrains.kotlin.load.java.structure.JavaMethod;
 import org.jetbrains.kotlin.types.JetType;
 
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
@@ -73,6 +75,11 @@ public interface ExternalSignatureResolver {
         public void reportSignatureErrors(@NotNull CallableMemberDescriptor descriptor, @NotNull List<String> signatureErrors) {
             throw new UnsupportedOperationException("Should not be called");
         }
+
+        @Override
+        public <D extends CallableMemberDescriptor> Collection<D> enhanceSignatures(@NotNull @ReadOnly Collection<D> platformSignatures) {
+            return platformSignatures;
+        }
     };
 
     abstract class MemberSignature {
@@ -201,4 +208,10 @@ public interface ExternalSignatureResolver {
     );
 
     void reportSignatureErrors(@NotNull CallableMemberDescriptor descriptor, @NotNull List<String> signatureErrors);
+
+    /**
+     * Replaces some items in the {@code platformSignatures} collection with enhanced signatures.
+     * Is called after binding overrides, so the implementation is allowed to inspect contents of getOverriddenDescriptors()
+     */
+    <D extends CallableMemberDescriptor> Collection<D> enhanceSignatures(@NotNull @ReadOnly Collection<D> platformSignatures);
 }

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaMemberScope.kt

@@ -86,14 +86,16 @@ public abstract class LazyJavaMemberScope(
 
         computeNonDeclaredFunctions(result, name)
 
+        val enhancedResult = c.externalSignatureResolver.enhanceSignatures(result)
+
         // Make sure that lazy things are computed before we release the lock
-        for (f in result) {
+        for (f in enhancedResult) {
             for (p in f.getValueParameters()) {
                 p.hasDefaultValue()
             }
         }
 
-        result.toReadOnlyList()
+        enhancedResult.toReadOnlyList()
     }
 
     protected data class MethodSignatureData(