Add more variable aliasing tests

compiler/testData/diagnostics/tests/smartCasts/variables/aliasing.fir.kt

@@ -1,3 +1,5 @@
+// SKIP_TXT
+
 fun test() {
     var a: Any? = null
     var b = a
@@ -63,3 +65,20 @@ fun test2() {
     b.length // OK
     b.<!UNRESOLVED_REFERENCE!>unaryPlus<!>() // error
 }
+
+fun test3() {
+    var a: Any? = null
+    val b = a
+    val c = a
+    if (a is String) {
+        a.length // ok
+        b.length // ok
+        c.length // ok
+    }
+    a = null // b and c are still aliases to the same old value
+    if (b is String) {
+        a.<!UNRESOLVED_REFERENCE!>length<!> // error
+        b.length // ok
+        c.<!UNRESOLVED_REFERENCE!>length<!> // ok
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/aliasing.kt

@@ -1,3 +1,5 @@
+// SKIP_TXT
+
 fun test() {
     var a: Any? = null
     var b = a
@@ -63,3 +65,20 @@ fun test2() {
     <!DEBUG_INFO_SMARTCAST!>b<!>.length // OK
     b.<!UNRESOLVED_REFERENCE!>unaryPlus<!>() // error
 }
+
+fun test3() {
+    var a: Any? = null
+    val b = a
+    val c = a
+    if (a is String) {
+        <!DEBUG_INFO_SMARTCAST!>a<!>.length // ok
+        b.<!UNRESOLVED_REFERENCE!>length<!> // ok
+        c.<!UNRESOLVED_REFERENCE!>length<!> // ok
+    }
+    a = null // b and c are still aliases to the same old value
+    if (b is String) {
+        a.<!UNRESOLVED_REFERENCE!>length<!> // error
+        <!DEBUG_INFO_SMARTCAST!>b<!>.length // ok
+        c.<!UNRESOLVED_REFERENCE!>length<!> // ok
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/aliasing.txt

@@ -1,4 +0,0 @@
-package
-
-public fun test(): kotlin.Unit
-public fun test2(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/reassignedDependency.fir.kt

@@ -61,3 +61,17 @@ fun test4(p: Boolean, q: Boolean) {
     x.length // ok
     c.x<!UNSAFE_CALL!>.<!>length // bad
 }
+
+fun test5() {
+    var c = C("...")
+    val d = c
+    val x = d.x
+    if (x == null) return
+    x.length // ok
+    c.x.length // ok
+    d.x.length // ok
+    c = C(null)
+    x.length // ok
+    c.x<!UNSAFE_CALL!>.<!>length // bad
+    d.x<!UNSAFE_CALL!>.<!>length // ok
+}

compiler/testData/diagnostics/tests/smartCasts/variables/reassignedDependency.kt

@@ -61,3 +61,17 @@ fun test4(p: Boolean, q: Boolean) {
     <!DEBUG_INFO_SMARTCAST!>x<!>.length // ok
     c.x<!UNSAFE_CALL!>.<!>length // bad
 }
+
+fun test5() {
+    var c = C("...")
+    val d = c
+    val x = d.x
+    if (x == null) return
+    <!DEBUG_INFO_SMARTCAST!>x<!>.length // ok
+    c.x<!UNSAFE_CALL!>.<!>length // ok
+    <!DEBUG_INFO_SMARTCAST!>d.x<!>.length // ok
+    c = C(null)
+    <!DEBUG_INFO_SMARTCAST!>x<!>.length // ok
+    c.x<!UNSAFE_CALL!>.<!>length // bad
+    <!DEBUG_INFO_SMARTCAST!>d.x<!>.length // ok
+}