KT-3159 Disallow overriding var with different type #KT-3159 fixed

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java

@@ -221,6 +221,8 @@ public interface Errors {
             DiagnosticFactory3.create(ERROR, VISIBILITY_MODIFIER);
     DiagnosticFactory2<JetNamedDeclaration, CallableMemberDescriptor, CallableMemberDescriptor> RETURN_TYPE_MISMATCH_ON_OVERRIDE =
             DiagnosticFactory2.create(ERROR, DECLARATION_RETURN_TYPE);
+    DiagnosticFactory2<JetNamedDeclaration, CallableMemberDescriptor, CallableMemberDescriptor> PROPERTY_TYPE_MISMATCH_ON_OVERRIDE =
+            DiagnosticFactory2.create(ERROR, DECLARATION_RETURN_TYPE);
 
     DiagnosticFactory2<PsiElement, JetClassOrObject, CallableMemberDescriptor> ABSTRACT_MEMBER_NOT_IMPLEMENTED =
             DiagnosticFactory2.create(ERROR);

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java

@@ -358,6 +358,9 @@ public class DefaultErrorMessages {
         MAP.put(RETURN_TYPE_MISMATCH_ON_OVERRIDE, "Return type of ''{0}'' is not a subtype of the return type of overridden member {1}",
                 NAME, DescriptorRenderer.TEXT);
 
+        MAP.put(PROPERTY_TYPE_MISMATCH_ON_OVERRIDE, "Type of ''{0}'' doesn't match to the type of overridden var-property {1}",
+                NAME, DescriptorRenderer.TEXT);
+
         MAP.put(VAR_OVERRIDDEN_BY_VAL, "Var-property {0} cannot be overridden by val-property {1}", DescriptorRenderer.TEXT,
                 DescriptorRenderer.TEXT);
 

compiler/frontend/src/org/jetbrains/jet/lang/resolve/OverrideResolver.java

@@ -585,6 +585,8 @@ public class OverrideResolver {
 
         void returnTypeMismatchOnOverride(@NotNull CallableMemberDescriptor overridden);
 
+        void propertyTypeMismatchOnOverride(@NotNull CallableMemberDescriptor overridden);
+
         void varOverriddenByVal(@NotNull CallableMemberDescriptor overridden);
 
         void cannotOverrideInvisibleMember(@NotNull CallableMemberDescriptor invisibleOverridden);
@@ -636,6 +638,14 @@ public class OverrideResolver {
                     }
                 }
 
+                @Override
+                public void propertyTypeMismatchOnOverride(@NotNull CallableMemberDescriptor overridden) {
+                    if (!typeMismatchError) {
+                        typeMismatchError = true;
+                        trace.report(PROPERTY_TYPE_MISMATCH_ON_OVERRIDE.on(member, declared, overridden));
+                    }
+                }
+
                 @Override
                 public void varOverriddenByVal(@NotNull CallableMemberDescriptor overridden) {
                     if (!kindMismatchError) {
@@ -674,7 +684,11 @@ public class OverrideResolver {
                     reportError.overridingFinalMember(overridden);
                 }
 
-                if (!OverridingUtil.isReturnTypeOkForOverride(JetTypeChecker.INSTANCE, overridden, declared)) {
+                if (declared instanceof PropertyDescriptor && !OverridingUtil.isPropertyTypeOkForOverride(
+                        JetTypeChecker.INSTANCE, (PropertyDescriptor) overridden, (PropertyDescriptor) declared)) {
+                    reportError.propertyTypeMismatchOnOverride(overridden);
+                }
+                else if (!OverridingUtil.isReturnTypeOkForOverride(JetTypeChecker.INSTANCE, overridden, declared)) {
                     reportError.returnTypeMismatchOnOverride(overridden);
                 }
 
@@ -721,6 +735,11 @@ public class OverrideResolver {
                 }
             }
 
+            @Override
+            public void propertyTypeMismatchOnOverride(@NotNull CallableMemberDescriptor overridden) {
+                throw new IllegalStateException("Component functions are not properties");
+            }
+
             @Override
             public void varOverriddenByVal(@NotNull CallableMemberDescriptor overridden) {
                 throw new IllegalStateException("Component functions are not properties");

compiler/frontend/src/org/jetbrains/jet/lang/resolve/OverridingUtil.java

@@ -221,6 +221,21 @@ public class OverridingUtil {
     }
 
     public static boolean isReturnTypeOkForOverride(@NotNull JetTypeChecker typeChecker, @NotNull CallableDescriptor superDescriptor, @NotNull CallableDescriptor subDescriptor) {
+        TypeSubstitutor typeSubstitutor = prepareTypeSubstitutor(superDescriptor, subDescriptor);
+
+        JetType superReturnType = superDescriptor.getReturnType();
+        assert superReturnType != null;
+
+        JetType subReturnType = subDescriptor.getReturnType();
+        assert subReturnType != null;
+
+        JetType substitutedSuperReturnType = typeSubstitutor.substitute(superReturnType, Variance.OUT_VARIANCE);
+        assert substitutedSuperReturnType != null;
+
+        return typeChecker.isSubtypeOf(subReturnType, substitutedSuperReturnType);
+    }
+
+    private static TypeSubstitutor prepareTypeSubstitutor(@NotNull CallableDescriptor superDescriptor, @NotNull CallableDescriptor subDescriptor) {
         List<TypeParameterDescriptor> superTypeParameters = superDescriptor.getTypeParameters();
         List<TypeParameterDescriptor> subTypeParameters = subDescriptor.getTypeParameters();
         Map<TypeConstructor, TypeProjection> substitutionContext = Maps.newHashMap();
@@ -231,12 +246,14 @@ public class OverridingUtil {
                     superTypeParameter.getTypeConstructor(),
                     new TypeProjection(subTypeParameter.getDefaultType()));
         }
+        return TypeSubstitutor.create(substitutionContext);
+    }
 
-        // This code compares return types, but they are not a part of the signature, so this code does not belong here
-        TypeSubstitutor typeSubstitutor = TypeSubstitutor.create(substitutionContext);
+    public static boolean isPropertyTypeOkForOverride(@NotNull JetTypeChecker typeChecker, @NotNull PropertyDescriptor superDescriptor, @NotNull PropertyDescriptor subDescriptor) {
+        TypeSubstitutor typeSubstitutor = prepareTypeSubstitutor(superDescriptor, subDescriptor);
         JetType substitutedSuperReturnType = typeSubstitutor.substitute(superDescriptor.getReturnType(), Variance.OUT_VARIANCE);
         assert substitutedSuperReturnType != null;
-        if (!typeChecker.isSubtypeOf(subDescriptor.getReturnType(), substitutedSuperReturnType)) {
+        if (superDescriptor.isVar() && !typeChecker.equalTypes(subDescriptor.getReturnType(), substitutedSuperReturnType)) {
             return false;
         }
 

compiler/testData/diagnostics/tests/subtyping/kt3159.kt

@@ -0,0 +1,9 @@
+trait Super {
+    var v: CharSequence
+    val v2: CharSequence
+}
+
+class Sub: Super {
+    override var v: <!PROPERTY_TYPE_MISMATCH_ON_OVERRIDE!>String<!> = "fail"
+    override val v2: String = "ok"
+}

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -4105,6 +4105,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
             public void testKt2744() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/subtyping/kt2744.kt");
             }
+
+            @TestMetadata("kt3159.kt")
+            public void testKt3159() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/subtyping/kt3159.kt");
+            }
             
             @TestMetadata("kt304.kt")
             public void testKt304() throws Exception {