[FIR] Adding a test case to show resolution of KT-29559 in K2

compiler/testData/diagnostics/tests/smartCasts/incrementAfterAssignment.fir.kt

@@ -0,0 +1,27 @@
+// WITH_STDLIB
+// SKIP_TEXT
+// ISSUE: KT-29559
+
+fun consume(i: Int) {}
+fun consume(c: Char) {}
+fun consume(a: Any?) {}
+
+fun test1() {
+    var a: Any
+
+    a = 1
+    consume(a)
+
+    a = 1
+    consume(a++)
+
+    a = 1
+    consume(++a)
+
+    a = 't'
+    consume(a++)
+
+    a = 't'
+    consume(++a)
+    consume(a++)
+}