KT-10939 CANNOT_COMPLETE_RESOLVE for inherited generic interface method

'original' for value parameters of fake override is not a value parameter of unsubstituted fake override.
Match value parameters by index.

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/results/CandidateCallWithArgumentMapping.kt

@@ -69,6 +69,7 @@ class CandidateCallWithArgumentMapping<D : CallableDescriptor, K> private constr
             val argumentsToParameters = hashMapOf<K, ValueParameterDescriptor>()
             var parametersWithDefaultValuesCount = 0
 
+            val unsubstitutedValueParameters = call.candidateDescriptor.original.valueParameters
             for ((valueParameterDescriptor, resolvedValueArgument) in call.unsubstitutedValueArguments.entries) {
                 if (resolvedValueArgument is DefaultValueArgument) {
                     parametersWithDefaultValuesCount++
@@ -76,7 +77,10 @@ class CandidateCallWithArgumentMapping<D : CallableDescriptor, K> private constr
                 else {
                     val keys = resolvedArgumentToKeys(resolvedValueArgument)
                     for (argumentKey in keys) {
-                        argumentsToParameters[argumentKey] = valueParameterDescriptor.original
+                        // TODO fix 'original' for value parameters of Java generic descriptors.
+                        // Should be able to use just 'valueParameterDescriptor' below.
+                        // Doesn't work for Java generic descriptors. See also KT-10939.
+                        argumentsToParameters[argumentKey] = unsubstitutedValueParameters[valueParameterDescriptor.index]
                     }
                 }
             }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/results/OverloadingConflictResolver.kt

@@ -326,9 +326,6 @@ class OverloadingConflictResolver(private val builtIns: KotlinBuiltIns) {
     private fun getVarargElementTypeOrType(parameterDescriptor: ValueParameterDescriptor): KotlinType =
             parameterDescriptor.varargElementType ?: parameterDescriptor.type
 
-    private val CallableDescriptor.hasVarargs: Boolean get() =
-            this.valueParameters.any { it.varargElementType != null }
-
     private fun typeNotLessSpecific(specific: KotlinType, general: KotlinType): Boolean {
         val isSubtype = KotlinTypeChecker.DEFAULT.isSubtypeOf(specific, general) || numericTypeMoreSpecific(specific, general)
 

compiler/testData/diagnostics/tests/overload/UnsubstitutedJavaGenetics.kt

@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// FILE: Base.java
+public interface Base {
+    <T> String foo(T a);
+    <T> int foo(T a, Object... args);
+}
+
+// FILE: Derived.java
+public interface Derived extends Base {
+}
+
+// FILE: test.kt
+fun testDerived(base: Base, derived: Derived) {
+    val test1: String = base.foo("")
+    val test2: String = derived.foo("")
+}

compiler/testData/diagnostics/tests/overload/UnsubstitutedJavaGenetics.txt

@@ -0,0 +1,19 @@
+package
+
+public fun testDerived(/*0*/ base: Base, /*1*/ derived: Derived): kotlin.Unit
+
+public interface Base {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun </*0*/ T : kotlin.Any!> foo(/*0*/ a: T!): kotlin.String!
+    public abstract fun </*0*/ T : kotlin.Any!> foo(/*0*/ a: T!, /*1*/ vararg args: kotlin.Any! /*kotlin.Array<(out) kotlin.Any!>!*/): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface Derived : Base {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> foo(/*0*/ a: T!): kotlin.String!
+    public abstract override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> foo(/*0*/ a: T!, /*1*/ vararg args: kotlin.Any! /*kotlin.Array<(out) kotlin.Any!>!*/): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/overload/kt10939.kt

@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+object X1
+object X2
+
+interface Base {
+    fun <T1> foo(a: T1): X1
+    fun <T2> foo(a: T2, vararg args: Any): X2
+}
+
+interface Derived : Base
+
+fun testDerived(base: Base, derived: Derived) {
+    val test1: X1 = base.foo("")
+    val test2: X1 = derived.foo("")
+}
+
+interface GenericBase<T> {
+    fun <T1> foo(x: T, a: T1): X1
+}
+
+interface SpecializedDerived : GenericBase<String> {
+    fun <T2> foo(x: String, a: T2, vararg args: Any): X2
+}
+
+fun testSpecializedDerived(derived: SpecializedDerived) {
+    val test1: X1 = derived.foo("", "")
+}

compiler/testData/diagnostics/tests/overload/kt10939.txt

@@ -0,0 +1,49 @@
+package
+
+public fun testDerived(/*0*/ base: Base, /*1*/ derived: Derived): kotlin.Unit
+public fun testSpecializedDerived(/*0*/ derived: SpecializedDerived): kotlin.Unit
+
+public interface Base {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun </*0*/ T1> foo(/*0*/ a: T1): X1
+    public abstract fun </*0*/ T2> foo(/*0*/ a: T2, /*1*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): X2
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface Derived : Base {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ /*fake_override*/ fun </*0*/ T1> foo(/*0*/ a: T1): X1
+    public abstract override /*1*/ /*fake_override*/ fun </*0*/ T2> foo(/*0*/ a: T2, /*1*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): X2
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface GenericBase</*0*/ T> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun </*0*/ T1> foo(/*0*/ x: T, /*1*/ a: T1): X1
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface SpecializedDerived : GenericBase<kotlin.String> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract override /*1*/ /*fake_override*/ fun </*0*/ T1> foo(/*0*/ x: kotlin.String, /*1*/ a: T1): X1
+    public abstract fun </*0*/ T2> foo(/*0*/ x: kotlin.String, /*1*/ a: T2, /*2*/ vararg args: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): X2
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public object X1 {
+    private constructor X1()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public object X2 {
+    private constructor X2()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -11715,6 +11715,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("kt10939.kt")
+            public void testKt10939() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/overload/kt10939.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("kt1998.kt")
             public void testKt1998() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/overload/kt1998.kt");
@@ -11768,6 +11774,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/overload/TypeParameterMultipleBounds.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("UnsubstitutedJavaGenetics.kt")
+            public void testUnsubstitutedJavaGenetics() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/overload/UnsubstitutedJavaGenetics.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/diagnostics/tests/override")