KT-6118 Redundant type cast can be not redundant?

#KT-6118 Fixed

compiler/testData/diagnostics/tests/dataFlow/assignment/assignToNewVal.kt

@@ -0,0 +1,10 @@
+fun test(a: Any?) {
+    if (a == null) return
+    <!DEBUG_INFO_SMARTCAST!>a<!>.hashCode()
+
+    val b = a
+    <!DEBUG_INFO_SMARTCAST!>b<!>.hashCode()
+
+    val c: Any? = a
+    c<!UNSAFE_CALL!>.<!>hashCode()
+}

compiler/testData/diagnostics/tests/dataFlow/assignment/assignToNewVal.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(/*0*/ a: kotlin.Any?): kotlin.Unit

compiler/testData/diagnostics/tests/dataFlow/assignment/kt6118.kt

@@ -0,0 +1,16 @@
+// KT-6118 Redundant type cast can be not redundant?
+
+fun foo(o: Any) {
+    if (o is String) {
+        val s = o <!USELESS_CAST_STATIC_ASSERT_IS_FINE!>as String<!>
+        s.length()
+    }
+}
+
+fun foo1(o: Any) {
+    if (o is String) {
+        <!DEBUG_INFO_SMARTCAST!>o<!>.length()
+        val s = o
+        <!DEBUG_INFO_SMARTCAST!>s<!>.length()
+    }
+}

compiler/testData/diagnostics/tests/dataFlow/assignment/kt6118.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun foo(/*0*/ o: kotlin.Any): kotlin.Unit
+internal fun foo1(/*0*/ o: kotlin.Any): kotlin.Unit

compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValIsCheck.kt

@@ -0,0 +1,15 @@
+fun test(a: Any?, flag: Boolean, x: Any?) {
+    if (a !is String) return
+    <!DEBUG_INFO_SMARTCAST!>a<!>.length()
+
+    val b: Any?
+
+    if (flag) {
+        b = a
+        <!DEBUG_INFO_SMARTCAST!>b<!>.length()
+    }
+    else {
+        b = x
+        b.<!UNRESOLVED_REFERENCE!>length<!>()
+    }
+}

compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValIsCheck.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(/*0*/ a: kotlin.Any?, /*1*/ flag: kotlin.Boolean, /*2*/ x: kotlin.Any?): kotlin.Unit

compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValNullability.kt

@@ -0,0 +1,15 @@
+fun test(a: Any?, flag: Boolean, x: Any?) {
+    if (a == null) return
+    <!DEBUG_INFO_SMARTCAST!>a<!>.hashCode()
+
+    val b: Any?
+
+    if (flag) {
+        b = a
+        <!DEBUG_INFO_SMARTCAST!>b<!>.hashCode()
+    }
+    else {
+        b = x
+        b<!UNSAFE_CALL!>.<!>hashCode()
+    }
+}

compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValNullability.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(/*0*/ a: kotlin.Any?, /*1*/ flag: kotlin.Boolean, /*2*/ x: kotlin.Any?): kotlin.Unit

compiler/testData/diagnostics/tests/dataFlow/assignment/when.kt

@@ -0,0 +1,12 @@
+fun test(a: Any?) {
+    when (a) {
+        is String -> {
+            val s = a
+            <!DEBUG_INFO_SMARTCAST!>s<!>.length()
+        }
+        "" -> {
+            val s = a
+            <!DEBUG_INFO_SMARTCAST!>s<!>.hashCode()
+        }
+    }
+}

compiler/testData/diagnostics/tests/dataFlow/assignment/when.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(/*0*/ a: kotlin.Any?): kotlin.Unit