KT-1457 Subtyping doesn't work when type parameter is used indirectly in supertype declaration

compiler/frontend/src/org/jetbrains/jet/lang/types/checker/TypeCheckingProcedure.java

@@ -87,9 +87,11 @@ public class TypeCheckingProcedure {
         }
 
         for (int i = 0; i < type1Arguments.size(); i++) {
+            TypeParameterDescriptor typeParameter1 = constructor1.getParameters().get(i);
             TypeProjection typeProjection1 = type1Arguments.get(i);
+            TypeParameterDescriptor typeParameter2 = constructor2.getParameters().get(i);
             TypeProjection typeProjection2 = type2Arguments.get(i);
-            if (typeProjection1.getProjectionKind() != typeProjection2.getProjectionKind()) {
+            if (getEffectiveProjectionKind(typeParameter1, typeProjection1) != getEffectiveProjectionKind(typeParameter2, typeProjection2)) {
                 return false;
             }
 
@@ -100,6 +102,58 @@ public class TypeCheckingProcedure {
         return true;
     }
 
+    private enum EnrichedProjectionKind {
+        IN, OUT, INV, STAR;
+
+        @NotNull
+        public static EnrichedProjectionKind fromVariance(@NotNull Variance variance) {
+            switch (variance) {
+                case INVARIANT:
+                    return INV;
+                case IN_VARIANCE:
+                    return IN;
+                case OUT_VARIANCE:
+                    return OUT;
+            }
+            throw new IllegalStateException("Unknown variance");
+        }
+    }
+
+    // If class C<out T> then C<T> and C<out T> mean the same
+    // out * out = out
+    // out * in  = *
+    // out * inv = out
+    //
+    // in * out  = *
+    // in * in   = in
+    // in * inv  = in
+    //
+    // inv * out = out
+    // inv * in  = out
+    // inv * inv = inv
+    private EnrichedProjectionKind getEffectiveProjectionKind(@NotNull TypeParameterDescriptor typeParameter, @NotNull TypeProjection typeArgument) {
+        Variance a = typeParameter.getVariance();
+        Variance b = typeArgument.getProjectionKind();
+
+        // If they are not both invariant, let's make b not invariant for sure
+        if (b == INVARIANT) {
+            Variance t = a;
+            a = b;
+            b = t;
+        }
+
+        // Opposites yield STAR
+        if (a == IN_VARIANCE && b == OUT_VARIANCE) {
+            return EnrichedProjectionKind.STAR;
+        }
+        if (a == OUT_VARIANCE && b == IN_VARIANCE) {
+            return EnrichedProjectionKind.STAR;
+        }
+
+        // If they are not opposite, return b, because b is either equal to a or b is in/out and a is inv
+        return EnrichedProjectionKind.fromVariance(b);
+    }
+
     public boolean isSubtypeOf(@NotNull JetType subtype, @NotNull JetType supertype) {
         if (ErrorUtils.isErrorType(subtype) || ErrorUtils.isErrorType(supertype)) {
             return true;
@@ -127,7 +181,7 @@ public class TypeCheckingProcedure {
         List<TypeProjection> subArguments = subtype.getArguments();
         List<TypeProjection> superArguments = supertype.getArguments();
         List<TypeParameterDescriptor> parameters = constructor.getParameters();
-        for (int i = 0, parametersSize = parameters.size(); i < parametersSize; i++) {
+        for (int i = 0; i < parameters.size(); i++) {
             TypeParameterDescriptor parameter = parameters.get(i);
 
 

compiler/testData/diagnostics/tests/subtyping/kt-1457.jet

@@ -0,0 +1,8 @@
+// +JDK
+import java.util.ArrayList
+
+class MyListOfPairs<T> : ArrayList<#(T, T)>() { }
+
+fun test() {
+    MyListOfPairs<Int> : ArrayList<#(Int, Int)>
+}

compiler/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java

@@ -471,6 +471,21 @@ public class JetTypeCheckerTest extends JetLiteFixture {
         assertSupertypes("Derived1_inT<Int>", "Derived_T<Int>", "Base_T<Int>", "Any", "Base_inT<Int>");
     }
 
+    public void testEffectiveProjectionKinds() throws Exception {
+        assertSubtype("Tuple1<Int>", "Tuple1<Int>");
+        assertSubtype("Tuple1<out Int>", "Tuple1<out Int>");
+        assertSubtype("Tuple1<out Int>", "Tuple1<Int>");
+        assertSubtype("Tuple1<Int>", "Tuple1<out Int>");
+        assertSubtype("Tuple1<in Int>", "Tuple1<out Any?>");
+        assertSubtype("Tuple1<out Any?>", "Tuple1<in String>");
+        assertSubtype("Base_inT<Int>", "Base_inT<Int>");
+        assertSubtype("Base_inT<in Int>", "Base_inT<in Int>");
+        assertSubtype("Base_inT<in Int>", "Base_inT<Int>");
+        assertSubtype("Base_inT<Int>", "Base_inT<in Int>");
+        assertSubtype("Base_inT<out Int>", "Base_inT<out Any?>");
+        assertSubtype("Base_inT<out Any?>", "Base_inT<out Int>");
+    }
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
     private void assertSupertypes(String typeStr, String... supertypeStrs) {