[NI] Approximate captured types when we resolve type variable TO_SUPER.

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/components/ResultTypeResolver.kt

@@ -58,7 +58,6 @@ class ResultTypeResolver(
                  *
                  * To fix this problem when we fix variable, we will approximate captured types before fixation.
                  *
-                 * todo: may be for TO_SUPER direction we should do the same
                  */
 
                 return typeApproximator.approximateToSuperType(commonSupertype, TypeApproximatorConfiguration.CapturedTypesApproximation) ?: commonSupertype
@@ -68,7 +67,9 @@ class ResultTypeResolver(
         // direction == TO_SUPER or there is no LOWER bounds
         val upperConstraints = variableWithConstraints.constraints.filter { it.kind == ConstraintKind.UPPER && c.isProperType(it.type) }
         if (upperConstraints.isNotEmpty()) {
-            return intersectTypes(upperConstraints.map { it.type })
+            val upperType = intersectTypes(upperConstraints.map { it.type })
+
+            return typeApproximator.approximateToSubType(upperType, TypeApproximatorConfiguration.CapturedTypesApproximation) ?: upperType
         }
 
         return null

compiler/testData/diagnostics/tests/inference/flexibleTypesAsUpperBound.kt

@@ -0,0 +1,13 @@
+// FILE: 1.kt
+fun <S> Array<S>.plus(): Array<S> {
+    val result = Arrays.copyOf(this, 3)
+    // result type is Array<(out) (S&Any)!>!
+    return result
+}
+
+// FILE: Arrays.java
+public class Arrays {
+    public static <T> T[] copyOf(T[] original, int newLength) {
+        return (T[]) null;
+    }
+}

compiler/testData/diagnostics/tests/inference/flexibleTypesAsUpperBound.txt

@@ -0,0 +1,13 @@
+package
+
+public fun </*0*/ S> kotlin.Array<S>.plus(): kotlin.Array<S>
+
+public open class Arrays {
+    public constructor Arrays()
+    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
+
+    // Static members
+    public open fun </*0*/ T : kotlin.Any!> copyOf(/*0*/ original: kotlin.Array<(out) T!>!, /*1*/ newLength: kotlin.Int): kotlin.Array<(out) T!>!
+}

compiler/testData/diagnostics/tests/inference/nullableTypeArgumentWithNotNullUpperBound.kt

@@ -0,0 +1,11 @@
+fun <S : Any> foo(x: Array<out S?>, y: Array<in S?>) {
+    val xo = outA(x)
+    val yo = inA(y)
+
+    var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>f<!>: Array<S> = xo
+    <!UNUSED_VALUE!>f =<!> yo
+}
+
+
+fun <X : Any> outA(<!UNUSED_PARAMETER!>x<!>: Array<out X?>): Array<X> = TODO()
+fun <Y : Any> inA(<!UNUSED_PARAMETER!>x<!>: Array<in Y?>): Array<Y> = TODO()

compiler/testData/diagnostics/tests/inference/nullableTypeArgumentWithNotNullUpperBound.txt

@@ -0,0 +1,5 @@
+package
+
+public fun </*0*/ S : kotlin.Any> foo(/*0*/ x: kotlin.Array<out S?>, /*1*/ y: kotlin.Array<in S?>): kotlin.Unit
+public fun </*0*/ Y : kotlin.Any> inA(/*0*/ x: kotlin.Array<in Y?>): kotlin.Array<Y>
+public fun </*0*/ X : kotlin.Any> outA(/*0*/ x: kotlin.Array<out X?>): kotlin.Array<X>

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

@@ -10048,6 +10048,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("flexibleTypesAsUpperBound.kt")
+            public void testFlexibleTypesAsUpperBound() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/flexibleTypesAsUpperBound.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("functionPlaceholderError.kt")
             public void testFunctionPlaceholderError() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/functionPlaceholderError.kt");
@@ -10162,6 +10168,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("nullableTypeArgumentWithNotNullUpperBound.kt")
+            public void testNullableTypeArgumentWithNotNullUpperBound() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/nullableTypeArgumentWithNotNullUpperBound.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("nullableUpperBound.kt")
             public void testNullableUpperBound() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/nullableUpperBound.kt");