Supported cases with two superclasses when they have different variances.

compiler/testData/loadJava/kotlinSignature/propagation/return/TwoSuperclassesInvariantAndCovariantInferMutability.java

@@ -0,0 +1,22 @@
+package test;
+
+import org.jetbrains.annotations.NotNull;
+import jet.runtime.typeinfo.KotlinSignature;
+import java.util.*;
+
+public interface TwoSuperclassesInvariantAndCovariantInferMutability {
+
+    public interface Super1 {
+        @KotlinSignature("fun foo(): List<List<String>>")
+        public List<List<String>> foo();
+    }
+
+    public interface Super2 {
+        @KotlinSignature("fun foo(): MutableList<MutableList<String>>")
+        public List<List<String>> foo();
+    }
+
+    public interface Sub extends Super1, Super2 {
+        public List<List<String>> foo();
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/TwoSuperclassesInvariantAndCovariantInferMutability.kt

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+package test
+
+public trait TwoSuperclassesInvariantAndCovariantInferMutability: Object {
+
+    public trait Super1: Object {
+        public fun foo(): List<List<String>>
+    }
+
+    public trait Super2: Object {
+        public fun foo(): MutableList<MutableList<String>>
+    }
+
+    public trait Sub: Super1, Super2 {
+        override fun foo(): MutableList<MutableList<String>>
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/TwoSuperclassesInvariantAndCovariantInferMutability.txt

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+namespace test
+
+public abstract trait test.TwoSuperclassesInvariantAndCovariantInferMutability : java.lang.Object {
+    public abstract trait test.TwoSuperclassesInvariantAndCovariantInferMutability.Sub : test.TwoSuperclassesInvariantAndCovariantInferMutability.Super1, test.TwoSuperclassesInvariantAndCovariantInferMutability.Super2 {
+        public abstract override /*2*/ fun foo(): jet.MutableList<jet.MutableList<jet.String>>
+    }
+    public abstract trait test.TwoSuperclassesInvariantAndCovariantInferMutability.Super1 : java.lang.Object {
+        public abstract fun foo(): jet.List<jet.List<jet.String>>
+    }
+    public abstract trait test.TwoSuperclassesInvariantAndCovariantInferMutability.Super2 : java.lang.Object {
+        public abstract fun foo(): jet.MutableList<jet.MutableList<jet.String>>
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/TwoSuperclassesInvariantAndCovariantInferNullability.java

@@ -0,0 +1,22 @@
+package test;
+
+import org.jetbrains.annotations.NotNull;
+import jet.runtime.typeinfo.KotlinSignature;
+import java.util.*;
+
+public interface TwoSuperclassesInvariantAndCovariantInferNullability {
+
+    public interface Super1 {
+        @KotlinSignature("fun foo(): List<String?>")
+        public List<String> foo();
+    }
+
+    public interface Super2 {
+        @KotlinSignature("fun foo(): MutableList<String>")
+        public List<String> foo();
+    }
+
+    public interface Sub extends Super1, Super2 {
+        public List<String> foo();
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/TwoSuperclassesInvariantAndCovariantInferNullability.kt

@@ -0,0 +1,16 @@
+package test
+
+public trait TwoSuperclassesInvariantAndCovariantInferNullability: Object {
+
+    public trait Super1: Object {
+        public fun foo(): List<String?>
+    }
+
+    public trait Super2: Object {
+        public fun foo(): MutableList<String>
+    }
+
+    public trait Sub: Super1, Super2 {
+        override fun foo(): MutableList<String>
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/TwoSuperclassesInvariantAndCovariantInferNullability.txt

@@ -0,0 +1,13 @@
+namespace test
+
+public abstract trait test.TwoSuperclassesInvariantAndCovariantInferNullability : java.lang.Object {
+    public abstract trait test.TwoSuperclassesInvariantAndCovariantInferNullability.Sub : test.TwoSuperclassesInvariantAndCovariantInferNullability.Super1, test.TwoSuperclassesInvariantAndCovariantInferNullability.Super2 {
+        public abstract override /*2*/ fun foo(): jet.MutableList<jet.String>
+    }
+    public abstract trait test.TwoSuperclassesInvariantAndCovariantInferNullability.Super1 : java.lang.Object {
+        public abstract fun foo(): jet.List<jet.String?>
+    }
+    public abstract trait test.TwoSuperclassesInvariantAndCovariantInferNullability.Super2 : java.lang.Object {
+        public abstract fun foo(): jet.MutableList<jet.String>
+    }
+}