Add variance test for nullable and function types.

compiler/testData/diagnostics/tests/variance/FunctionTypes.kt

@@ -0,0 +1,12 @@
+trait In<in T>
+fun <T> getT(): T = null!!
+
+trait Test<in I, out O, P> {
+    fun ok1(i: (O) -> I) : (I) -> O
+    fun ok2(i: (P) -> P) : (P) -> P
+    fun ok3(i: (In<I>) -> In<O>) = getT<(In<O>) -> In<I>>()
+
+    fun neOk1(i: (<!TYPE_VARIANCE_CONFLICT!>I<!>) -> <!TYPE_VARIANCE_CONFLICT!>O<!>): (<!TYPE_VARIANCE_CONFLICT!>O<!>) -> <!TYPE_VARIANCE_CONFLICT!>I<!>
+    fun neOk2(i: (In<<!TYPE_VARIANCE_CONFLICT!>O<!>>) -> In<<!TYPE_VARIANCE_CONFLICT!>I<!>>)
+    <!TYPE_VARIANCE_CONFLICT, TYPE_VARIANCE_CONFLICT!>fun neOk3()<!> = getT<(In<I>) -> In<O>>()
+}

compiler/testData/diagnostics/tests/variance/FunctionTypes.txt

@@ -0,0 +1,21 @@
+package
+
+internal fun </*0*/ T> getT(): T
+
+internal trait In</*0*/ in T> {
+    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
+}
+
+internal trait Test</*0*/ in I, /*1*/ out O, /*2*/ P> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    internal abstract fun neOk1(/*0*/ i: (I) -> O): (O) -> I
+    internal abstract fun neOk2(/*0*/ i: (In<O>) -> In<I>): kotlin.Unit
+    internal open fun neOk3(): (In<I>) -> In<O>
+    internal abstract fun ok1(/*0*/ i: (O) -> I): (I) -> O
+    internal abstract fun ok2(/*0*/ i: (P) -> P): (P) -> P
+    internal open fun ok3(/*0*/ i: (In<I>) -> In<O>): (In<O>) -> In<I>
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/variance/NullableTypes.kt

@@ -0,0 +1,16 @@
+trait In<in I>
+trait Out<out O>
+trait Inv<P>
+fun <T> getT(): T = null!!
+
+
+trait Test<in I : Any, out O : Any, P : Any> {
+    fun ok1(i: I?) : O?
+    fun ok2(i: In<O?>?) : Out<O?>?
+    fun ok3(i: Inv<in O?>) = getT<Inv<in I?>>()
+
+    fun neOk1(i: <!TYPE_VARIANCE_CONFLICT(O; out; in; O?)!>O?<!>) : <!TYPE_VARIANCE_CONFLICT(I; in; out; I?)!>I?<!>
+    fun neOk(i: Out<<!TYPE_VARIANCE_CONFLICT(O; out; in; Out<O?>?)!>O?<!>>?) : In<<!TYPE_VARIANCE_CONFLICT(O; out; in; In<O?>?)!>O?<!>>?
+    fun neOk3(i: Inv<in <!TYPE_VARIANCE_CONFLICT(I; in; out; Inv<in I?>)!>I?<!>>)
+    <!TYPE_VARIANCE_CONFLICT(O; out; in; Inv<in O?>?)!>fun neOk4()<!> = getT<Inv<in O?>?>()
+}

compiler/testData/diagnostics/tests/variance/NullableTypes.txt

@@ -0,0 +1,34 @@
+package
+
+internal fun </*0*/ T> getT(): T
+
+internal trait In</*0*/ in I> {
+    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
+}
+
+internal trait Inv</*0*/ P> {
+    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
+}
+
+internal trait Out</*0*/ out O> {
+    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
+}
+
+internal trait Test</*0*/ in I : kotlin.Any, /*1*/ out O : kotlin.Any, /*2*/ P : kotlin.Any> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    internal abstract fun neOk(/*0*/ i: Out<O?>?): In<O?>?
+    internal abstract fun neOk1(/*0*/ i: O?): I?
+    internal abstract fun neOk3(/*0*/ i: Inv<in I?>): kotlin.Unit
+    internal open fun neOk4(): Inv<in O?>?
+    internal abstract fun ok1(/*0*/ i: I?): O?
+    internal abstract fun ok2(/*0*/ i: In<O?>?): Out<O?>?
+    internal open fun ok3(/*0*/ i: Inv<in O?>): Inv<in I?>
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

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

@@ -10304,6 +10304,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("FunctionTypes.kt")
+            public void testFunctionTypes() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/variance/FunctionTypes.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("InPosition.kt")
             public void testInPosition() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/variance/InPosition.kt");
@@ -10316,6 +10322,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("NullableTypes.kt")
+            public void testNullableTypes() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/variance/NullableTypes.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("OutPosition.kt")
             public void testOutPosition() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/variance/OutPosition.kt");