Added captured types and approximation

CapturedType captures type projection while solving the constraint system.
During the substitution type containing captured types is approximated
to get rid of captured types and (for simple cases) replace them with corresponding type projections.

Note that Array<Array< CapturedType(out Int) >> is (over)approximated by Array<out<Array<out Int>>

See 'Mixed-site variance' by Ross Tate for details.

 #KT-2570 Fixed
 #KT-2872 Fixed
 #KT-3213 Fixed

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintsUtil.java

@@ -47,7 +47,7 @@ public class ConstraintsUtil {
 
         Collection<JetType> conflictingTypes = constraintSystem.getTypeBounds(firstConflictingParameter).getValues();
 
-        ArrayList<Map<TypeConstructor, TypeProjection>> substitutionContexts = Lists.newArrayList();
+        List<Map<TypeConstructor, TypeProjection>> substitutionContexts = Lists.newArrayList();
         for (JetType type : conflictingTypes) {
             Map<TypeConstructor, TypeProjection> context = Maps.newLinkedHashMap();
             context.put(firstConflictingParameter.getTypeConstructor(), new TypeProjectionImpl(type));

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/tasks/AbstractTracingStrategy.java

@@ -226,6 +226,9 @@ public abstract class AbstractTracingStrategy implements TracingStrategy {
             assert !noExpectedType(data.expectedType) : "Expected type doesn't exist, but there is an expected type mismatch error";
             trace.report(TYPE_INFERENCE_EXPECTED_TYPE_MISMATCH.on(reference, data.expectedType, substitutedReturnType));
         }
+        //else if (status.hasConflictWithCapturedType()) {
+        //    trace.report(TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS.on(reference, data));
+        //}
         else if (status.hasViolatedUpperBound()) {
             trace.report(TYPE_INFERENCE_UPPER_BOUND_VIOLATED.on(reference, data));
         }

compiler/testData/capturedTypeApproximation/contravariant.kt

@@ -0,0 +1,11 @@
+class Contr<in T>
+
+fun foo<T>(a: Contr<T>) {}
+
+// T captures 'in Int'
+// lower: Contr<Any?>
+// upper: Contr<Int>
+
+// T captures 'out Int'
+// lower: Contr<Int>
+// upper: Contr<out Any?>

compiler/testData/capturedTypeApproximation/covariant.kt

@@ -0,0 +1,11 @@
+class Cov<out T>
+
+fun foo<T>(a: Cov<T>) {}
+
+// T captures 'in Int'
+// lower: Cov<Int>
+// upper: Cov<Any?>
+
+// T captures 'out Int'
+// lower: Cov<Nothing>
+// upper: Cov<Int>

compiler/testData/capturedTypeApproximation/invariant.kt

@@ -0,0 +1,11 @@
+class Inv<T>
+
+fun foo<T>(a: Inv<T>) {}
+
+// T captures 'in Int'
+// lower: Nothing
+// upper: Inv<in Int>
+
+// T captures 'out Int'
+// lower: Nothing
+// upper: Inv<out Int>

compiler/testData/capturedTypeApproximation/nestedCov.kt

@@ -0,0 +1,12 @@
+class Cov<out T>
+class Inv<T>
+
+fun foo<T>(a: Cov<Inv<T>>) {}
+
+// T captures 'in Int'
+// lower: Cov<Nothing>
+// upper: Cov<Inv<in Int>>
+
+// T captures 'out Int'
+// lower: Cov<Nothing>
+// upper: Cov<Inv<out Int>>

compiler/testData/capturedTypeApproximation/nestedInv.kt

@@ -0,0 +1,11 @@
+class Inv<T>
+
+fun foo<T>(a: Inv<Inv<T>>) {}
+
+// T captures 'in Int'
+// lower: Nothing
+// upper: Inv<out Inv<in Int>>
+
+// T captures 'out Int'
+// lower: Nothing
+// upper: Inv<out Inv<out Int>>

compiler/testData/capturedTypeApproximation/nestedInvLevel2.kt

@@ -0,0 +1,11 @@
+class Inv<T>
+
+fun foo<T>(a: Inv<Inv<Inv<T>>>) {}
+
+// T captures 'in Int'
+// lower: Nothing
+// upper: Inv<out Inv<out Inv<in Int>>>
+
+// T captures 'out Int'
+// lower: Nothing
+// upper: Inv<out Inv<out Inv<out Int>>>

compiler/testData/capturedTypeApproximation/useSiteVarianceIn.kt

@@ -0,0 +1,11 @@
+class Inv<T>
+
+fun foo<T>(a: Inv<in T>) {}
+
+// T captures 'in Int'
+// lower: Inv<Any?>
+// upper: Inv<in Int>
+
+// T captures 'out Int'
+// lower: Inv<in Int>
+// upper: Inv<out Any?>

compiler/testData/capturedTypeApproximation/useSiteVarianceOut.kt

@@ -0,0 +1,11 @@
+class Inv<T>
+
+fun foo<T>(a: Inv<out T>) {}
+
+// T captures 'in Int'
+// lower: Inv<out Int>
+// upper: Inv<out Any?>
+
+// T captures 'out Int'
+// lower: Inv<Nothing>
+// upper: Inv<out Int>

compiler/testData/diagnostics/tests/MergePackagesWithJava.txt

@@ -14280,15 +14280,15 @@ package java {
 
             private final inner class EntryIterator : java.util.HashMap.HashIterator<kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!> {
                 private constructor EntryIterator()
-                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K!, V!>!
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                 public/*package*/ final override /*1*/ /*fake_override*/ var index: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -14342,15 +14342,15 @@ package java {
 
             private final inner class KeyIterator : java.util.HashMap.HashIterator<K!> {
                 private constructor KeyIterator()
-                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K!, V!>!
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                 public/*package*/ final override /*1*/ /*fake_override*/ var index: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): K!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -14377,15 +14377,15 @@ package java {
 
             private final inner class ValueIterator : java.util.HashMap.HashIterator<V!> {
                 private constructor ValueIterator()
-                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K!, V!>!
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                 public/*package*/ final override /*1*/ /*fake_override*/ var index: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): V!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15376,14 +15376,14 @@ package java {
             public/*package*/ final inner class DescendingKeyIterator : java.util.TreeMap.PrivateEntryIterator<K!> {
                 public/*package*/ constructor DescendingKeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): K!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15510,14 +15510,14 @@ package java {
             public/*package*/ final inner class EntryIterator : java.util.TreeMap.PrivateEntryIterator<kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!> {
                 public/*package*/ constructor EntryIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15545,14 +15545,14 @@ package java {
             public/*package*/ final inner class KeyIterator : java.util.TreeMap.PrivateEntryIterator<K!> {
                 public/*package*/ constructor KeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): K!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15670,14 +15670,14 @@ package java {
                     public/*package*/ constructor DescendingSubMapEntryIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15688,14 +15688,14 @@ package java {
                     public/*package*/ constructor DescendingSubMapKeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): K!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15728,14 +15728,14 @@ package java {
                     public/*package*/ constructor SubMapEntryIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15764,14 +15764,14 @@ package java {
                     public/*package*/ constructor SubMapKeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): K!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15833,14 +15833,14 @@ package java {
             public/*package*/ final inner class ValueIterator : java.util.TreeMap.PrivateEntryIterator<V!> {
                 public/*package*/ constructor ValueIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): V!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }

compiler/testData/diagnostics/tests/inference/capturedTypes/captureForPlatformTypes.kt

@@ -0,0 +1,29 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    public static <T> Class<T> foo(Class<T> clazz) {
+        return clazz;
+    }
+
+    public static <T> Class<Class<T>> bar(Class<T> clazz) {
+        throw new Exception();
+    }
+}
+
+// FILE: b.kt
+fun test1(clazz: Class<out Int>) {
+    val foo0: Class<out Int> = A.foo(clazz)
+    val foo1 = A.foo(clazz)
+    foo1 checkType { it: _< Class<out Int> > }
+//    should be ok
+    foo1 checkType { <!TYPE_MISMATCH!>it<!>: _< Class<out Int?> > }
+}
+
+fun tes2t(clazz: Class<in Int>) {
+    val foo0: Class<out Class<in Int>> = A.bar(clazz)
+    val foo1 = A.bar(clazz)
+    foo1 checkType { it: _< Class<out Class<in Int>> > }
+//    should be ok
+    foo1 checkType { <!TYPE_MISMATCH!>it<!>: _< Class<out Class<in Int?>> > }
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/captureForPlatformTypes.txt

@@ -0,0 +1,15 @@
+package
+
+internal fun tes2t(/*0*/ clazz: java.lang.Class<in kotlin.Int>): kotlin.Unit
+internal fun test1(/*0*/ clazz: java.lang.Class<out kotlin.Int>): kotlin.Unit
+
+public open class A {
+    public constructor A()
+    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> bar(/*0*/ clazz: java.lang.Class<T!>!): java.lang.Class<java.lang.Class<T!>!>!
+    public open fun </*0*/ T> foo(/*0*/ clazz: java.lang.Class<T!>!): java.lang.Class<T!>!
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/capturedType.kt

@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo(array: Array<T>): Array<T> = array
+
+fun test1(a1: Array<out Int>) {
+    val b1: Array<out Int> = foo(a1)
+    val c1 = foo(a1)
+    c1 checkType { it : _<Array<out Int>> }
+}
+
+fun test2(a2: Array<in Int>) {
+    val b2: Array<in Int> = foo(a2)
+    val c2 = foo(a2)
+    c2 checkType { it : _<Array<in Int>> }
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/capturedType.txt

@@ -0,0 +1,5 @@
+package
+
+internal fun </*0*/ T> foo(/*0*/ array: kotlin.Array<T>): kotlin.Array<T>
+internal fun test1(/*0*/ a1: kotlin.Array<out kotlin.Int>): kotlin.Unit
+internal fun test2(/*0*/ a2: kotlin.Array<in kotlin.Int>): kotlin.Unit

compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeAndApproximation.kt

@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo(a: Array<T>): Array<Array<T>> = throw Exception()
+
+fun test1(a1: Array<out Int>) {
+    val b1: Array<out Array<out Int>> = foo(a1)
+    val c1 = foo(a1)
+    c1 checkType { it : _<Array<out Array<out Int>>> }
+}
+
+fun test2(a2: Array<in Int>) {
+    val b2: Array<out Array<in Int>> = foo(a2)
+    val c2 = foo(a2)
+    c2 checkType { it : _<Array<out Array<in Int>>> }
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeAndApproximation.txt

@@ -0,0 +1,5 @@
+package
+
+internal fun </*0*/ T> foo(/*0*/ a: kotlin.Array<T>): kotlin.Array<kotlin.Array<T>>
+internal fun test1(/*0*/ a1: kotlin.Array<out kotlin.Int>): kotlin.Unit
+internal fun test2(/*0*/ a2: kotlin.Array<in kotlin.Int>): kotlin.Unit

compiler/testData/diagnostics/tests/inference/capturedTypes/kt2570.kt

@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun <T> foo(l: MutableList<T>): MutableList<T> = l
+fun test(l: MutableList<out Int>) {
+    val a: MutableList<out Int> = foo(l)
+    val b = foo(l)
+    b checkType { it: _< MutableList<out Int> > }
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/kt2570.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun </*0*/ T> foo(/*0*/ l: kotlin.MutableList<T>): kotlin.MutableList<T>
+internal fun test(/*0*/ l: kotlin.MutableList<out kotlin.Int>): kotlin.Unit

compiler/testData/diagnostics/tests/inference/capturedTypes/kt2872.kt

@@ -0,0 +1,6 @@
+fun <T> Array<T>.foo() {}
+
+fun test(array: Array<out Int>) {
+    array.foo()
+    <!TYPE_MISMATCH!>array<!>.foo<<!PROJECTION_ON_NON_CLASS_TYPE_ARGUMENT!>out<!> Int>()
+}

compiler/testData/diagnostics/tests/inference/capturedTypes/kt2872.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun test(/*0*/ array: kotlin.Array<out kotlin.Int>): kotlin.Unit
+internal fun </*0*/ T> kotlin.Array<T>.foo(): kotlin.Unit

compiler/testData/diagnostics/tests/scopes/kt955.txt

@@ -14286,15 +14286,15 @@ package java {
 
             private final inner class EntryIterator : java.util.HashMap.HashIterator<kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!> {
                 private constructor EntryIterator()
-                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K!, V!>!
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                 public/*package*/ final override /*1*/ /*fake_override*/ var index: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -14348,15 +14348,15 @@ package java {
 
             private final inner class KeyIterator : java.util.HashMap.HashIterator<K!> {
                 private constructor KeyIterator()
-                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K!, V!>!
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                 public/*package*/ final override /*1*/ /*fake_override*/ var index: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): K!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -14383,15 +14383,15 @@ package java {
 
             private final inner class ValueIterator : java.util.HashMap.HashIterator<V!> {
                 private constructor ValueIterator()
-                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var current: java.util.HashMap.Entry<K!, V!>!
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                 public/*package*/ final override /*1*/ /*fake_override*/ var index: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): V!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.HashMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15382,14 +15382,14 @@ package java {
             public/*package*/ final inner class DescendingKeyIterator : java.util.TreeMap.PrivateEntryIterator<K!> {
                 public/*package*/ constructor DescendingKeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): K!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15516,14 +15516,14 @@ package java {
             public/*package*/ final inner class EntryIterator : java.util.TreeMap.PrivateEntryIterator<kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!> {
                 public/*package*/ constructor EntryIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15551,14 +15551,14 @@ package java {
             public/*package*/ final inner class KeyIterator : java.util.TreeMap.PrivateEntryIterator<K!> {
                 public/*package*/ constructor KeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): K!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
@@ -15676,14 +15676,14 @@ package java {
                     public/*package*/ constructor DescendingSubMapEntryIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15694,14 +15694,14 @@ package java {
                     public/*package*/ constructor DescendingSubMapKeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): K!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15734,14 +15734,14 @@ package java {
                     public/*package*/ constructor SubMapEntryIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15770,14 +15770,14 @@ package java {
                     public/*package*/ constructor SubMapKeyIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!, /*1*/ p1: java.util.TreeMap.Entry<K!, V!>!)
                     public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
                     public/*package*/ final override /*1*/ /*fake_override*/ val fenceKey: kotlin.Any!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                     public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                     public open override /*1*/ fun next(): K!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                    public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                     public open override /*1*/ fun remove(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeAscending(): kotlin.Unit
                     public/*package*/ final override /*1*/ /*fake_override*/ fun removeDescending(): kotlin.Unit
@@ -15839,14 +15839,14 @@ package java {
             public/*package*/ final inner class ValueIterator : java.util.TreeMap.PrivateEntryIterator<V!> {
                 public/*package*/ constructor ValueIterator(/*0*/ p0: java.util.TreeMap.Entry<K!, V!>!)
                 public/*package*/ final override /*1*/ /*fake_override*/ var expectedModCount: kotlin.Int
-                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var lastReturned: java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ var next: java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public final override /*1*/ /*fake_override*/ fun hasNext(): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
                 public open override /*1*/ fun next(): V!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun nextEntry(): java.util.TreeMap.Entry<K!, V!>!
-                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K, V>!
+                public/*package*/ final override /*1*/ /*fake_override*/ fun prevEntry(): java.util.TreeMap.Entry<K!, V!>!
                 public open override /*1*/ /*fake_override*/ fun remove(): kotlin.Unit
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }

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

@@ -4899,7 +4899,7 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
 
         @TestMetadata("compiler/testData/diagnostics/tests/inference")
         @TestDataPath("$PROJECT_ROOT")
-        @InnerTestClasses({Inference.Constraints.class, Inference.NestedCalls.class, Inference.Regressions.class, Inference.ReportingImprovements.class, Inference.Substitutions.class, Inference.UpperBounds.class, Inference.Varargs.class})
+        @InnerTestClasses({Inference.CapturedTypes.class, Inference.Constraints.class, Inference.NestedCalls.class, Inference.Regressions.class, Inference.ReportingImprovements.class, Inference.Substitutions.class, Inference.UpperBounds.class, Inference.Varargs.class})
         @RunWith(JUnit3RunnerWithInners.class)
         public static class Inference extends AbstractJetDiagnosticsTest {
             public void testAllFilesPresentInInference() throws Exception {
@@ -5086,6 +5086,45 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes")
+            @TestDataPath("$PROJECT_ROOT")
+            @RunWith(JUnit3RunnerWithInners.class)
+            public static class CapturedTypes extends AbstractJetDiagnosticsTest {
+                public void testAllFilesPresentInCapturedTypes() throws Exception {
+                    JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/inference/capturedTypes"), Pattern.compile("^(.+)\\.kt$"), true);
+                }
+
+                @TestMetadata("captureForPlatformTypes.kt")
+                public void testCaptureForPlatformTypes() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/captureForPlatformTypes.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("capturedType.kt")
+                public void testCapturedType() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/capturedType.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("capturedTypeAndApproximation.kt")
+                public void testCapturedTypeAndApproximation() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeAndApproximation.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("kt2570.kt")
+                public void testKt2570() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/kt2570.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("kt2872.kt")
+                public void testKt2872() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/kt2872.kt");
+                    doTest(fileName);
+                }
+            }
+
             @TestMetadata("compiler/testData/diagnostics/tests/inference/constraints")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)

compiler/tests/org/jetbrains/jet/resolve/typeApproximation/AbstractCapturedTypeApproximationTest.kt

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.resolve.typeApproximation
+
+import org.jetbrains.jet.JetLiteFixture
+import org.jetbrains.jet.cli.jvm.compiler.JetCoreEnvironment
+import org.jetbrains.jet.ConfigurationKind
+import java.io.File
+import org.jetbrains.jet.lang.resolve.lazy.JvmResolveUtil
+import org.jetbrains.jet.lang.resolve.BindingContext
+import org.jetbrains.jet.lang.descriptors.FunctionDescriptor
+import org.jetbrains.jet.lang.types.TypeSubstitutor
+import org.jetbrains.jet.lang.types.TypeProjectionImpl
+import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns
+import org.jetbrains.jet.lang.types.Variance
+import org.jetbrains.jet.lang.types.typesApproximation.approximateCapturedTypes
+import org.jetbrains.jet.JetTestUtils
+import org.jetbrains.jet.lang.psi.JetPsiFactory
+import org.jetbrains.jet.lang.resolve.calls.inference.CapturedTypeConstructor
+import org.jetbrains.jet.lang.types.JetTypeImpl
+import org.jetbrains.jet.lang.resolve.calls.inference.createCapturedType
+
+abstract public class AbstractCapturedTypeApproximationTest() : JetLiteFixture() {
+    override fun createEnvironment(): JetCoreEnvironment = createEnvironmentWithMockJdk(ConfigurationKind.ALL)
+
+    public fun doTest(filePath: String) {
+        val file = File(filePath)
+        val text = JetTestUtils.doLoadFile(file)!!
+
+        val jetFile = JetPsiFactory(getProject()).createFile(text)
+        val bindingContext = JvmResolveUtil.analyzeOneFileWithJavaIntegration(jetFile).bindingContext
+
+        val functions = bindingContext.getSliceContents(BindingContext.FUNCTION)
+        val functionFoo = functions.values().firstOrNull { it.getName().asString() == "foo" } ?:
+                          throw AssertionError("Function 'foo' is not declared")
+        val typeParameter = functionFoo.getTypeParameters().first()
+        val parameter = functionFoo.getValueParameters().first().getType()
+
+        val result = StringBuilder {
+            val endIndex = text.indexOf("// T captures")
+            appendln(if (endIndex == -1) text else text.substring(0, endIndex).trimTrailing())
+
+            for (variance in listOf(Variance.IN_VARIANCE, Variance.OUT_VARIANCE)) {
+
+                val captured = createCapturedType(TypeProjectionImpl(variance, KotlinBuiltIns.getInstance().getIntType()))
+                val typeSubstitutor = TypeSubstitutor.create(mapOf(typeParameter.getTypeConstructor() to TypeProjectionImpl(captured)))
+                val typeWithCapturedType = typeSubstitutor.substituteWithoutApproximation(
+                        TypeProjectionImpl(Variance.INVARIANT, parameter))!!.getType()
+
+                val (lower, upper) = approximateCapturedTypes(typeWithCapturedType)
+
+                appendln()
+                appendln("// T captures '${(captured.getConstructor() as CapturedTypeConstructor).typeProjection}'")
+                appendln("// lower: $lower")
+                appendln("// upper: $upper")
+            }
+        }.toString()
+
+        JetTestUtils.assertEqualsToFile(file, result)
+    }
+}

compiler/tests/org/jetbrains/jet/resolve/typeApproximation/CapturedTypeApproximationTestGenerated.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.resolve.typeApproximation;
+
+import com.intellij.testFramework.TestDataPath;
+import org.jetbrains.jet.JUnit3RunnerWithInners;
+import org.jetbrains.jet.JetTestUtils;
+import org.jetbrains.jet.test.InnerTestClasses;
+import org.jetbrains.jet.test.TestMetadata;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.util.regex.Pattern;
+
+/** This class is generated by {@link org.jetbrains.jet.generators.tests.TestsPackage}. DO NOT MODIFY MANUALLY */
+@SuppressWarnings("all")
+@TestMetadata("compiler/testData/capturedTypeApproximation")
+@TestDataPath("$PROJECT_ROOT")
+@RunWith(JUnit3RunnerWithInners.class)
+public class CapturedTypeApproximationTestGenerated extends AbstractCapturedTypeApproximationTest {
+    public void testAllFilesPresentInCapturedTypeApproximation() throws Exception {
+        JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/capturedTypeApproximation"), Pattern.compile("^(.+)\\.kt$"), true);
+    }
+
+    @TestMetadata("contravariant.kt")
+    public void testContravariant() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/contravariant.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("covariant.kt")
+    public void testCovariant() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/covariant.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("invariant.kt")
+    public void testInvariant() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/invariant.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("nestedCov.kt")
+    public void testNestedCov() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/nestedCov.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("nestedInv.kt")
+    public void testNestedInv() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/nestedInv.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("nestedInvLevel2.kt")
+    public void testNestedInvLevel2() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/nestedInvLevel2.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("useSiteVarianceIn.kt")
+    public void testUseSiteVarianceIn() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/useSiteVarianceIn.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("useSiteVarianceOut.kt")
+    public void testUseSiteVarianceOut() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/capturedTypeApproximation/useSiteVarianceOut.kt");
+        doTest(fileName);
+    }
+}

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

@@ -235,7 +235,7 @@ public class TypeSubstitutorTest extends KotlinTestWithEnvironment {
 
     public void testOutInProjection() throws Exception {
         doTest(
-                "C<out Any>",
+                "C<out Any?>",
                 "C<out T>",
                 map("T", "in String")
         );

core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/CapturedTypeConstructor.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.resolve.calls.inference
+
+import org.jetbrains.jet.lang.types.JetType
+import org.jetbrains.jet.lang.types.TypeProjection
+import org.jetbrains.jet.lang.types.TypeConstructor
+import org.jetbrains.jet.lang.descriptors.TypeParameterDescriptor
+import org.jetbrains.jet.lang.descriptors.annotations.Annotations
+import org.jetbrains.jet.lang.types.Variance
+import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns
+import org.jetbrains.jet.lang.types.JetTypeImpl
+import org.jetbrains.jet.lang.types.ErrorUtils
+
+public class CapturedTypeConstructor(
+        public val typeProjection: TypeProjection
+): TypeConstructor {
+    {
+        assert(typeProjection.getProjectionKind() != Variance.INVARIANT) {
+            "Only nontrivial projections can be captured, not: $typeProjection"
+        }
+    }
+
+    override fun getParameters(): List<TypeParameterDescriptor> = listOf()
+
+    override fun getSupertypes(): Collection<JetType> {
+        val superType = if (typeProjection.getProjectionKind() == Variance.OUT_VARIANCE)
+            typeProjection.getType()
+        else
+            KotlinBuiltIns.getInstance().getNullableAnyType()
+        return listOf(superType)
+    }
+
+    override fun isFinal() = true
+
+    override fun isDenotable() = false
+
+    override fun getDeclarationDescriptor() = null
+
+    override fun getAnnotations() = Annotations.EMPTY
+
+    override fun toString() = "Captured($typeProjection)"
+}
+
+public fun createCapturedType(typeProjection: TypeProjection): JetType {
+    val scope = ErrorUtils.createErrorScope("No member resolution should be done on captured type, " +
+                                            "it used only during constraint system resolution", true)
+    return JetTypeImpl(Annotations.EMPTY, CapturedTypeConstructor(typeProjection), false, listOf(), scope)
+}
+
+public fun JetType.isCaptured(): Boolean = getConstructor() is CapturedTypeConstructor

core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintPosition.kt

@@ -43,6 +43,8 @@ public trait ConstraintPosition {
     val kind: ConstraintPositionKind
 
     fun isStrong(): Boolean = kind != TYPE_BOUND_POSITION
+
+    fun isCaptureAllowed(): Boolean = kind in setOf(VALUE_PARAMETER_POSITION, RECEIVER_POSITION)
 }
 
 private open data class ConstraintPositionImpl(override val kind: ConstraintPositionKind) : ConstraintPosition {
@@ -53,14 +55,11 @@ private data class ConstraintPositionWithIndex(override val kind: ConstraintPosi
 }
 
 class CompoundConstraintPosition(
-        val positions: Collection<ConstraintPosition>
+        vararg positions: ConstraintPosition
 ) : ConstraintPositionImpl(ConstraintPositionKind.COMPOUND_CONSTRAINT_POSITION) {
+    val positions: Collection<ConstraintPosition> = positions.toList()
 
     override fun isStrong() = positions.any { it.isStrong() }
 
     override fun toString() = "$kind(${positions.joinToString()}"
 }
-
-public fun getCompoundConstraintPosition(vararg positions: ConstraintPosition): ConstraintPosition {
-    return CompoundConstraintPosition(positions.toList())
-}

core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintSystemImpl.kt

@@ -41,7 +41,6 @@ import org.jetbrains.jet.lang.resolve.calls.inference.constraintPosition.Constra
 import org.jetbrains.jet.lang.resolve.calls.inference.constraintPosition.ConstraintPositionKind
 import org.jetbrains.jet.lang.resolve.calls.inference.constraintPosition.ConstraintPositionKind.*
 import org.jetbrains.jet.lang.resolve.calls.inference.constraintPosition.CompoundConstraintPosition
-import org.jetbrains.jet.lang.resolve.calls.inference.constraintPosition.getCompoundConstraintPosition
 import org.jetbrains.jet.lang.types.CustomTypeVariable
 import org.jetbrains.jet.lang.types.getCustomTypeVariable
 import org.jetbrains.jet.lang.types.isFlexible
@@ -226,6 +225,14 @@ public class ConstraintSystemImpl : ConstraintSystem {
                 return true
             }
 
+            override fun capture(typeVariable: JetType, typeProjection: TypeProjection): Boolean {
+                if (isMyTypeVariable(typeVariable) && constraintPosition.isCaptureAllowed()) {
+                    generateTypeParameterCaptureConstraint(typeVariable, typeProjection, constraintPosition)
+                    return true
+                }
+                return false
+            }
+
             override fun noCorrespondingSupertype(subtype: JetType, supertype: JetType): Boolean {
                 errorConstraintPositions.add(constraintPosition)
                 return true
@@ -303,9 +310,16 @@ public class ConstraintSystemImpl : ConstraintSystem {
                 generateTypeParameterConstraint(superType, subType, boundKind, constraintPosition)
                 return
             }
-            // if superType is nullable and subType is not nullable, unsafe call error will be generated later,
+            // if superType is nullable and subType is not nullable, unsafe call or type mismatch error will be generated later,
             // but constraint system should be solved anyway
-            typeCheckingProcedure.isSubtypeOf(TypeUtils.makeNotNullable(subType), TypeUtils.makeNotNullable(superType))
+            val subTypeNotNullable = TypeUtils.makeNotNullable(subType)
+            val superTypeNotNullable = TypeUtils.makeNotNullable(superType)
+            if (constraintKind == EQUAL) {
+                typeCheckingProcedure.equalTypes(subTypeNotNullable, superTypeNotNullable)
+            }
+            else {
+                typeCheckingProcedure.isSubtypeOf(subTypeNotNullable, superTypeNotNullable)
+            }
         }
         simplifyConstraint(newSubType, superType)
     }
@@ -352,6 +366,16 @@ public class ConstraintSystemImpl : ConstraintSystem {
         }
     }
 
+    private fun generateTypeParameterCaptureConstraint(
+            parameterType: JetType,
+            constrainingTypeProjection: TypeProjection,
+            constraintPosition: ConstraintPosition
+    ) {
+        val typeBounds = getTypeBounds(parameterType)
+        val capturedType = createCapturedType(constrainingTypeProjection)
+        typeBounds.addBound(EXACT_BOUND, capturedType, constraintPosition)
+    }
+
     public fun processDeclaredBoundConstraints() {
         for ((typeParameterDescriptor, typeBounds) in typeParameterBounds) {
             for (declaredUpperBound in typeParameterDescriptor.getUpperBounds()) {
@@ -359,7 +383,7 @@ public class ConstraintSystemImpl : ConstraintSystem {
                 val bounds = ArrayList(typeBounds.bounds)
                 for (bound in bounds) {
                     if (bound.kind == LOWER_BOUND || bound.kind == EXACT_BOUND) {
-                        val position = getCompoundConstraintPosition(
+                        val position = CompoundConstraintPosition(
                                 TYPE_BOUND_POSITION.position(typeParameterDescriptor.getIndex()), bound.position)
                         addSubtypeConstraint(bound.constrainingType, declaredUpperBound, position)
                     }
@@ -368,7 +392,7 @@ public class ConstraintSystemImpl : ConstraintSystem {
                     val typeBoundsForUpperBound = getTypeBounds(declaredUpperBound)
                     for (bound in typeBoundsForUpperBound.bounds) {
                         if (bound.kind == UPPER_BOUND || bound.kind == EXACT_BOUND) {
-                            val position = getCompoundConstraintPosition(
+                            val position = CompoundConstraintPosition(
                                     TYPE_BOUND_POSITION.position(typeParameterDescriptor.getIndex()), bound.position)
                             typeBounds.addBound(UPPER_BOUND, bound.constrainingType, position)
                         }

core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/TypeBoundsImpl.kt

@@ -156,7 +156,8 @@ public class TypeBoundsImpl(
 
     private fun tryPossibleAnswer(possibleAnswer: JetType?): Boolean {
         if (possibleAnswer == null) return false
-        if (!possibleAnswer.getConstructor().isDenotable()) return false
+        // a captured type might be an answer
+        if (!possibleAnswer.getConstructor().isDenotable() && !possibleAnswer.isCaptured()) return false
 
         for (bound in bounds) {
             when (bound.kind) {

core/descriptors/src/org/jetbrains/jet/lang/types/CapturedTypeApproximation.kt

@@ -0,0 +1,136 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.types.typesApproximation
+
+import org.jetbrains.jet.lang.types.JetType
+import org.jetbrains.jet.lang.types.checker.JetTypeChecker
+import org.jetbrains.jet.lang.types.TypeProjection
+import org.jetbrains.jet.lang.types.TypeProjectionImpl
+import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns
+import org.jetbrains.jet.lang.types.Variance
+import java.util.ArrayList
+import org.jetbrains.jet.lang.types.JetTypeImpl
+import org.jetbrains.jet.lang.types.TypeUtils
+import org.jetbrains.jet.lang.resolve.calls.inference.CapturedTypeConstructor
+import org.jetbrains.jet.lang.types.TypeSubstitutor
+import org.jetbrains.jet.lang.types.TypeSubstitution
+import org.jetbrains.jet.lang.types.TypeConstructor
+import org.jetbrains.jet.lang.descriptors.TypeParameterDescriptor
+import org.jetbrains.jet.lang.types.LazyType
+import org.jetbrains.jet.lang.resolve.calls.inference.isCaptured
+
+public data class ApproximationBounds<T>(
+        public val lower: T,
+        public val upper: T
+)
+
+private class TypeArgument(
+        val typeParameter: TypeParameterDescriptor,
+        val inProjection: JetType,
+        val outProjection: JetType
+) {
+    val isConsistent: Boolean
+        get() = JetTypeChecker.DEFAULT.isSubtypeOf(inProjection, outProjection)
+}
+
+private val NULLABLE_ANY = KotlinBuiltIns.getInstance().getNullableAnyType()
+
+private val NOTHING = KotlinBuiltIns.getInstance().getNothingType()
+
+private fun TypeArgument.toTypeProjection(): TypeProjection {
+    assert(isConsistent) { "Only consistent enhanced type propection can be converted to type projection" }
+    fun removeProjectionIfRedundant(variance: Variance) = if (variance == typeParameter.getVariance()) Variance.INVARIANT else variance
+    return when {
+        inProjection == outProjection -> TypeProjectionImpl(inProjection)
+        inProjection == NOTHING -> TypeProjectionImpl(removeProjectionIfRedundant(Variance.OUT_VARIANCE), outProjection)
+        outProjection == NULLABLE_ANY -> TypeProjectionImpl(removeProjectionIfRedundant(Variance.IN_VARIANCE), inProjection)
+        else -> throw AssertionError("Enhanced type projection can't be converted to type projection: $this")
+    }
+}
+
+private fun TypeProjection.toTypeArgument(typeParameter: TypeParameterDescriptor) =
+        when (TypeSubstitutor.combine(typeParameter.getVariance(), getProjectionKind()) : Variance) {
+            Variance.INVARIANT -> TypeArgument(typeParameter, getType(), getType())
+            Variance.IN_VARIANCE -> TypeArgument(typeParameter, getType(), NULLABLE_ANY)
+            Variance.OUT_VARIANCE -> TypeArgument(typeParameter, NOTHING, getType())
+        }
+
+public fun approximateCapturedTypesIfNecessary(typeProjection: TypeProjection?): TypeProjection? {
+    if (typeProjection == null) return null
+
+    val type = typeProjection.getType()
+    if (!TypeUtils.containsSpecialType(type, { it.isCaptured() })) {
+        return typeProjection
+    }
+    val howThisTypeIsUsed = typeProjection.getProjectionKind()
+    if (howThisTypeIsUsed == Variance.OUT_VARIANCE) {
+        // only 'return' type containing captured types should be over-approximated
+        val approximation = approximateCapturedTypes(type)
+        return TypeProjectionImpl(howThisTypeIsUsed, approximation.upper)
+    }
+    return substituteCapturedTypes(typeProjection)
+}
+
+private fun substituteCapturedTypes(typeProjection: TypeProjection): TypeProjection? {
+    val typeSubstitutor = TypeSubstitutor.create(object : TypeSubstitution {
+        override fun get(typeConstructor: TypeConstructor?): TypeProjection? {
+            return (typeConstructor as? CapturedTypeConstructor)?.typeProjection
+        }
+        override fun isEmpty() = false
+    })
+    return typeSubstitutor.substituteWithoutApproximation(typeProjection)
+}
+
+public fun approximateCapturedTypes(type: JetType): ApproximationBounds<JetType> {
+    val typeConstructor = type.getConstructor()
+    if (type.isCaptured()) {
+        val typeProjection = (typeConstructor as CapturedTypeConstructor).typeProjection
+
+        return when (typeProjection.getProjectionKind()) {
+            Variance.IN_VARIANCE -> ApproximationBounds(typeProjection.getType(), NULLABLE_ANY)
+            Variance.OUT_VARIANCE -> ApproximationBounds(NOTHING, typeProjection.getType())
+            else -> throw AssertionError("Only nontrivial projections should have been captured, not: $typeProjection")
+        }
+    }
+    if (type.getArguments().isEmpty()) {
+        return ApproximationBounds(type, type)
+    }
+    val lowerBoundArguments = ArrayList<TypeArgument>()
+    val upperBoundArguments = ArrayList<TypeArgument>()
+    for ((typeProjection, typeParameter) in type.getArguments().zip(typeConstructor.getParameters())) {
+        val (lower, upper) = approximateProjection(typeProjection.toTypeArgument(typeParameter))
+        lowerBoundArguments.add(lower)
+        upperBoundArguments.add(upper)
+    }
+    val lowerBoundIsTrivial = lowerBoundArguments.any { !it.isConsistent }
+    return ApproximationBounds(
+            if (lowerBoundIsTrivial) NOTHING else type.replaceTypeArguments(lowerBoundArguments),
+            type.replaceTypeArguments(upperBoundArguments))
+}
+
+private fun JetType.replaceTypeArguments(newTypeArguments: List<TypeArgument>): JetType {
+    assert(getArguments().size() == newTypeArguments.size()) { "Incorrect type arguments $newTypeArguments" }
+    return JetTypeImpl(getAnnotations(), getConstructor(), isMarkedNullable(), newTypeArguments.map { it.toTypeProjection() }, getMemberScope())
+}
+
+private fun approximateProjection(typeArgument: TypeArgument): ApproximationBounds<TypeArgument> {
+    val (inLower, inUpper) = approximateCapturedTypes(typeArgument.inProjection)
+    val (outLower, outUpper) = approximateCapturedTypes(typeArgument.outProjection)
+    return ApproximationBounds(
+            lower = TypeArgument(typeArgument.typeParameter, inUpper, outLower),
+            upper = TypeArgument(typeArgument.typeParameter, inLower, outUpper))
+}

core/descriptors/src/org/jetbrains/jet/lang/types/TypeSubstitutor.java

@@ -22,6 +22,7 @@ import org.jetbrains.jet.lang.descriptors.TypeParameterDescriptor;
 import org.jetbrains.jet.lang.resolve.scopes.SubstitutingScope;
 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
 import org.jetbrains.jet.lang.types.typeUtil.TypeUtilPackage;
+import org.jetbrains.jet.lang.types.typesApproximation.TypesApproximationPackage;
 
 import java.util.*;
 
@@ -60,18 +61,22 @@ public class TypeSubstitutor {
         }
     }
 
+    @NotNull
     public static TypeSubstitutor create(@NotNull TypeSubstitution substitution) {
         return new TypeSubstitutor(substitution);
     }
 
+    @NotNull
     public static TypeSubstitutor create(@NotNull TypeSubstitution... substitutions) {
         return create(new CompositeTypeSubstitution(substitutions));
     }
 
+    @NotNull
     public static TypeSubstitutor create(@NotNull Map<TypeConstructor, TypeProjection> substitutionContext) {
         return create(new MapToTypeSubstitutionAdapter(substitutionContext));
     }
 
+    @NotNull
     public static TypeSubstitutor create(@NotNull JetType context) {
         return create(buildSubstitutionContext(context.getConstructor().getParameters(), context.getArguments()));
     }
@@ -135,6 +140,12 @@ public class TypeSubstitutor {
 
     @Nullable
     public TypeProjection substitute(@NotNull TypeProjection typeProjection) {
+        TypeProjection substitutedTypeProjection = substituteWithoutApproximation(typeProjection);
+        return TypesApproximationPackage.approximateCapturedTypesIfNecessary(substitutedTypeProjection);
+    }
+
+    @Nullable
+    public TypeProjection substituteWithoutApproximation(@NotNull TypeProjection typeProjection) {
         if (isEmpty()) {
             return typeProjection;
         }
@@ -159,14 +170,15 @@ public class TypeSubstitutor {
                     unsafeSubstitute(new TypeProjectionImpl(originalProjectionKind, flexibility.getLowerBound()), recursionDepth + 1);
             TypeProjection substitutedUpper =
                     unsafeSubstitute(new TypeProjectionImpl(originalProjectionKind, flexibility.getUpperBound()), recursionDepth + 1);
-            // todo: projection kind is neglected
+
-            return new TypeProjectionImpl(originalProjectionKind,
+            Variance substitutedProjectionKind = substitutedLower.getProjectionKind();
-                                          DelegatingFlexibleType.create(
+            assert (substitutedProjectionKind == substitutedUpper.getProjectionKind()) &&
-                                                  substitutedLower.getType(),
+                   originalProjectionKind == Variance.INVARIANT || originalProjectionKind == substitutedProjectionKind :
-                                                  substitutedUpper.getType(),
+                    "Unexpected substituted projection kind: " + substitutedProjectionKind + "; original: " + originalProjectionKind;
-                                                  flexibility.getExtraCapabilities()
+
-                                          )
+            JetType substitutedFlexibleType = DelegatingFlexibleType.create(
-            );
+                    substitutedLower.getType(), substitutedUpper.getType(), flexibility.getExtraCapabilities());
+            return new TypeProjectionImpl(substitutedProjectionKind, substitutedFlexibleType);
         }
 
         if (KotlinBuiltIns.isNothing(type) || type.isError()) return originalProjection;
@@ -174,15 +186,12 @@ public class TypeSubstitutor {
         TypeProjection replacement = substitution.get(type.getConstructor());
 
         if (replacement != null) {
-            // It must be a type parameter: only they can be directly substituted for
-            TypeParameterDescriptor typeParameter = (TypeParameterDescriptor) type.getConstructor().getDeclarationDescriptor();
-
             switch (conflictType(originalProjectionKind, replacement.getProjectionKind())) {
                 case OUT_IN_IN_POSITION:
                     throw new SubstitutionException("Out-projection in in-position");
                 case IN_IN_OUT_POSITION:
-                    //noinspection ConstantConditions
+                    // todo use the right type parameter variance and upper bound
-                    return TypeUtils.makeStarProjection(typeParameter);
+                    return new TypeProjectionImpl(Variance.OUT_VARIANCE, KotlinBuiltIns.getInstance().getNullableAnyType());
                 case NO_CONFLICT:
                     JetType substitutedType;
                     CustomTypeVariable typeVariable = TypesPackage.getCustomTypeVariable(type);
@@ -191,7 +200,7 @@ public class TypeSubstitutor {
                     }
                     else {
                         // this is a simple type T or T?: if it's T, we should just take replacement, if T? - we make replacement nullable
-                        substitutedType = type.isMarkedNullable() ? TypeUtils.makeNullable(replacement.getType()) : replacement.getType();
+                        substitutedType = TypeUtils.makeNullableIfNeeded(replacement.getType(), type.isMarkedNullable());
                     }
 
                     Variance resultingProjectionKind = combine(originalProjectionKind, replacement.getProjectionKind());
@@ -201,14 +210,21 @@ public class TypeSubstitutor {
             }
         }
         // The type is not within the substitution range, i.e. Foo, Bar<T> etc.
-        return substituteCompoundType(type, originalProjectionKind, recursionDepth);
+        return substituteCompoundType(originalProjection, recursionDepth);
     }
 
     private TypeProjection substituteCompoundType(
-            final JetType type,
+            TypeProjection originalProjection,
-            Variance projectionKind,
             int recursionDepth
     ) throws SubstitutionException {
+        final JetType type = originalProjection.getType();
+        Variance projectionKind = originalProjection.getProjectionKind();
+        if (type.getConstructor().getDeclarationDescriptor() instanceof TypeParameterDescriptor) {
+            // substitution can't change type parameter
+            // todo substitute bounds
+            return originalProjection;
+        }
+
         List<TypeProjection> substitutedArguments = substituteTypeArguments(
                 type.getConstructor().getParameters(), type.getArguments(), recursionDepth);
 
@@ -265,10 +281,12 @@ public class TypeSubstitutor {
         return substitutedArguments;
     }
 
-    private static Variance combine(Variance typeParameterVariance, Variance projectionKind) {
+    @NotNull
+    public static Variance combine(@NotNull Variance typeParameterVariance, @NotNull Variance projectionKind) {
         if (typeParameterVariance == Variance.INVARIANT) return projectionKind;
         if (projectionKind == Variance.INVARIANT) return typeParameterVariance;
         if (typeParameterVariance == projectionKind) return projectionKind;
+        //todo ask why?
         return Variance.IN_VARIANCE;
     }
 

core/descriptors/src/org/jetbrains/jet/lang/types/checker/TypeCheckerTypingConstraints.java

@@ -19,6 +19,7 @@ package org.jetbrains.jet.lang.types.checker;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.TypeConstructor;
+import org.jetbrains.jet.lang.types.TypeProjection;
 
 class TypeCheckerTypingConstraints implements TypingConstraints {
     @Override
@@ -36,6 +37,11 @@ class TypeCheckerTypingConstraints implements TypingConstraints {
         return typeCheckingProcedure.isSubtypeOf(subtype, supertype);
     }
 
+    @Override
+    public boolean capture(@NotNull JetType type, @NotNull TypeProjection typeProjection) {
+        return false;
+    }
+
     @Override
     public boolean noCorrespondingSupertype(@NotNull JetType subtype, @NotNull JetType supertype) {
         return false; // type checking fails

core/descriptors/src/org/jetbrains/jet/lang/types/checker/TypeCheckingProcedure.java

@@ -106,6 +106,9 @@ public class TypeCheckingProcedure {
             TypeProjection typeProjection1 = type1Arguments.get(i);
             TypeParameterDescriptor typeParameter2 = constructor2.getParameters().get(i);
             TypeProjection typeProjection2 = type2Arguments.get(i);
+            if (capture(typeProjection1, typeProjection2, typeParameter1)) {
+                continue;
+            }
             if (getEffectiveProjectionKind(typeParameter1, typeProjection1) != getEffectiveProjectionKind(typeParameter2, typeProjection2)) {
                 return false;
             }
@@ -225,6 +228,8 @@ public class TypeCheckingProcedure {
             JetType superIn = getInType(parameter, superArgument);
             JetType superOut = getOutType(parameter, superArgument);
 
+            if (capture(subArgument, superArgument, parameter)) continue;
+
             boolean argumentIsErrorType = subArgument.getType().isError() || superArgument.getType().isError();
             if (!argumentIsErrorType && parameter.getVariance() == INVARIANT
                     && subArgument.getProjectionKind() == INVARIANT && superArgument.getProjectionKind() == INVARIANT) {
@@ -237,4 +242,25 @@ public class TypeCheckingProcedure {
         }
         return true;
     }
+
+    private boolean capture(
+            @NotNull TypeProjection firstProjection,
+            @NotNull TypeProjection secondProjection,
+            @NotNull TypeParameterDescriptor parameter
+    ) {
+        // Capturing makes sense only for invariant classes
+        if (parameter.getVariance() != INVARIANT) return false;
+
+        // Now, both subtype and supertype relations transform to equality constraints on type arguments:
+        // Array<T> is a subtype, supertype or equal to Array<out Int> then T captures a type that extends Int: 'Captured(out Int)'
+        // Array<T> is a subtype, supertype or equal to Array<in Int> then T captures a type that extends Int: 'Captured(in Int)'
+
+        if (firstProjection.getProjectionKind() == INVARIANT && secondProjection.getProjectionKind() != INVARIANT) {
+            return constraints.capture(firstProjection.getType(), secondProjection);
+        }
+        if (firstProjection.getProjectionKind() != INVARIANT && secondProjection.getProjectionKind() == INVARIANT) {
+            return constraints.capture(secondProjection.getType(), firstProjection);
+        }
+        return false;
+    }
 }

core/descriptors/src/org/jetbrains/jet/lang/types/checker/TypingConstraints.java

@@ -19,6 +19,7 @@ package org.jetbrains.jet.lang.types.checker;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.TypeConstructor;
+import org.jetbrains.jet.lang.types.TypeProjection;
 
 /**
  * Methods of this class return true to continue type checking and false to fail
@@ -30,5 +31,7 @@ public interface TypingConstraints {
 
     boolean assertSubtype(@NotNull JetType subtype, @NotNull JetType supertype, @NotNull TypeCheckingProcedure typeCheckingProcedure);
 
+    boolean capture(@NotNull JetType type, @NotNull TypeProjection typeProjection);
+
     boolean noCorrespondingSupertype(@NotNull JetType subtype, @NotNull JetType supertype);
 }

generators/src/org/jetbrains/jet/generators/tests/GenerateTests.kt

@@ -116,6 +116,7 @@ import org.jetbrains.jet.lang.resolve.java.AbstractJavaTypeSubstitutorTest
 import org.jetbrains.jet.plugin.intentions.declarations.AbstractJoinLinesTest
 import org.jetbrains.jet.codegen.AbstractScriptCodegenTest
 import org.jetbrains.jet.plugin.parameterInfo.AbstractFunctionParameterInfoTest
+import org.jetbrains.jet.resolve.typeApproximation.AbstractCapturedTypeApproximationTest
 import org.jetbrains.jet.psi.patternMatching.AbstractJetPsiUnifierTest
 import org.jetbrains.jet.completion.weighers.AbstractBasicCompletionWeigherTest
 import org.jetbrains.jet.completion.weighers.AbstractSmartCompletionWeigherTest
@@ -167,6 +168,10 @@ fun main(args: Array<String>) {
             model("constraintSystem", extension = "bounds")
         }
 
+        testClass(javaClass<AbstractCapturedTypeApproximationTest>()) {
+            model("capturedTypeApproximation")
+        }
+
         testClass(javaClass<AbstractJetParsingTest>()) {
             model("psi", testMethod = "doParsingTest", pattern = "^(.*)\\.kts?$")
             model("parseCodeFragment/expression", testMethod = "doExpressionCodeFragmentParsingTest", extension = "kt")