NI: Discard definitely not-null types inside invariant positions during inference process

^KT-36816 Fixed

compiler/testData/diagnostics/tests/inference/constraints/approximationWithDefNotNullInInvPositionDuringInference.fir.kt

@@ -0,0 +1,24 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// Issues: KT-36816
+
+interface Parent<T>
+
+class Foo<K>(x: K?): Parent<K> {}
+class Bar<T>(x: T): Parent<T> {}
+
+fun <R> select(vararg x: R) = x[0]
+
+fun <S> main(x: S) {
+    select(Foo(x), Bar(x))
+}
+
+
+
+inline fun <R> test(transform: () -> R) {}
+
+class Inv<T>(x: T?) {}
+
+fun <K> foo(x: K) {
+    test { Inv(x) }
+}

compiler/testData/diagnostics/tests/inference/constraints/approximationWithDefNotNullInInvPositionDuringInference.kt

@@ -0,0 +1,24 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// Issues: KT-36816
+
+interface Parent<T>
+
+class Foo<K>(x: K?): Parent<K> {}
+class Bar<T>(x: T): Parent<T> {}
+
+fun <R> select(vararg x: R) = x[0]
+
+fun <S> main(x: S) {
+    <!DEBUG_INFO_EXPRESSION_TYPE("Parent<S>")!>select(Foo(x), Bar(x))<!>
+}
+
+
+
+inline fun <R> test(transform: () -> R) {}
+
+class Inv<T>(x: T?) {}
+
+fun <K> foo(x: K) {
+    test { <!DEBUG_INFO_EXPRESSION_TYPE("Inv<K>")!>Inv(x)<!> }
+}

compiler/testData/diagnostics/tests/inference/constraints/approximationWithDefNotNullInInvPositionDuringInference.txt

@@ -0,0 +1,33 @@
+package
+
+public fun </*0*/ K> foo(/*0*/ x: K): kotlin.Unit
+public fun </*0*/ S> main(/*0*/ x: S): kotlin.Unit
+public fun </*0*/ R> select(/*0*/ vararg x: R /*kotlin.Array<out R>*/): R
+public inline fun </*0*/ R> test(/*0*/ transform: () -> R): kotlin.Unit
+
+public final class Bar</*0*/ T> : Parent<T> {
+    public constructor Bar</*0*/ T>(/*0*/ x: 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
+}
+
+public final class Foo</*0*/ K> : Parent<K> {
+    public constructor Foo</*0*/ K>(/*0*/ x: K?)
+    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
+}
+
+public final class Inv</*0*/ T> {
+    public constructor Inv</*0*/ T>(/*0*/ x: 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
+}
+
+public interface Parent</*0*/ 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
+}