KT-2422 Invalid warning "Condition is always true"

#KT-2422 fixed

compiler/testData/diagnostics/tests/smartCasts/kt2422.kt

@@ -0,0 +1,23 @@
+package bar
+
+class Test {
+    val foo: Int? = null
+    fun foo(o: Test) = foo == null && o.foo == null // ERROR warning: o.test == null is always true
+
+    fun bar(a: Test, b: Test) {
+        if (a.foo != null) {
+            useInt(<!TYPE_MISMATCH!>b.foo<!>)
+        }
+        if (a.foo != null) {
+            useInt(<!TYPE_MISMATCH!>foo<!>)
+        }
+        if (this.foo != null) {
+            useInt(foo)
+        }
+        if (foo != null) {
+            useInt(this.foo)
+        }
+    }
+
+    fun useInt(i: Int) = i
+}

compiler/testData/diagnostics/tests/smartCasts/noErrorCheckForPackageLevelVal.kt

@@ -0,0 +1,25 @@
+//FILE: bar.kt
+package bar
+
+val i: Int? = 2
+
+//FILE: foo.kt
+package foo
+
+val i: Int? = 1
+
+class A(val i: Int?) {
+    fun testUseFromClass() {
+        if (foo.i != null) {
+            useInt(<!TYPE_MISMATCH!>i<!>)
+        }
+    }
+}
+
+fun testUseFromOtherPackage() {
+    if (bar.i != null) {
+        useInt(<!TYPE_MISMATCH!>i<!>)
+    }
+}
+
+fun useInt(i: Int) = i

compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.kt

@@ -0,0 +1,36 @@
+package foo
+
+class A(val i: Int?) {
+    fun test1() {
+        if (this@A.i != null) {
+            useInt(this.i)
+            useInt(i)
+        }
+    }
+
+    inner class B {
+        fun test2() {
+            if (i != null) {
+                useInt(this@A.i)
+            }
+        }
+    }
+}
+
+fun A.foo() {
+    if (this@foo.i != null) {
+        useInt(this.i)
+        useInt(i)
+    }
+}
+
+fun test3() {
+    useFunction {
+        if(i != null) {
+            useInt(this.i)
+        }
+    }
+}
+
+fun useInt(i: Int) = i
+fun useFunction(f: A.() -> Unit) = f

compiler/testData/diagnostics/tests/smartCasts/thisWithLabelAsReceiverPart.kt

@@ -0,0 +1,39 @@
+package foo
+
+class C(val i: Int?) {}
+
+class A(val c: C) {
+    fun test1() {
+        if (this@A.c.i != null) {
+            useInt(this.c.i)
+            useInt(c.i)
+        }
+    }
+
+    inner class B {
+        fun test2() {
+            if (c.i != null) {
+                useInt(this@A.c.i)
+            }
+        }
+    }
+}
+
+fun A.foo() {
+    if (this@foo.c.i != null) {
+        useInt(this.c.i)
+        useInt(c.i)
+    }
+}
+
+fun test3() {
+    useFunction {
+        if(c.i != null) {
+            useInt(this.c.i)
+        }
+    }
+}
+
+fun useInt(i: Int) = i
+fun useFunction(f: A.() -> Unit) = f
+