[FIR] Unbound aliased variables in DFA more carefully

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt

@@ -610,10 +610,16 @@ abstract class FirDataFlowAnalyzer<FLOW : Flow>(
     }
 
     private fun exitVariableInitialization(node: CFGNode<*>, initializer: FirExpression, variable: FirProperty, isVariableDeclaration: Boolean) {
-        val propertyVariable = variableStorage.getOrCreateRealVariable(variable.symbol, variable)
+        var propertyVariable = variableStorage.getOrCreateRealVariable(variable.symbol, variable)
         if (!isVariableDeclaration) {
-            node.flow.removeAllAboutVariable(propertyVariable)
-            variableStorage.unboundPossiblyAliasedVariable(variable.symbol)
+            // Don't remove statements for variable under alias
+            if (propertyVariable.identifier.symbol == variable.symbol) {
+                node.flow.removeAllAboutVariable(propertyVariable)
+            } else {
+                variableStorage.unboundPossiblyAliasedVariable(variable.symbol)
+                // We should create new dataFlowVariable for local variable without alias
+                propertyVariable = variableStorage.getOrCreateRealVariable(variable.symbol, variable)
+            }
         }
 
         variableStorage[initializer]?.safeAs<SyntheticVariable>()?.let { initializerVariable ->

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

@@ -41,7 +41,7 @@ fun f(a: SomeClass?) {
     if (aa as? SomeSubClass != null) {
         aa = null
         // 'aa' cannot be cast to SomeSubClass
-        aa.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        aa.<!UNRESOLVED_REFERENCE!>hashCode<!>()
         aa.<!UNRESOLVED_REFERENCE!>foo<!>
         (aa as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
         (aa as SomeSubClass).foo

compiler/testData/diagnostics/tests/smartCasts/level_1_0.fir.kt

@@ -17,7 +17,7 @@ fun foo(arg: Int?) {
     var z = arg
     z = z?.let { 42 }
     if (z != null) {
-        arg.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        arg.hashCode()
     }
 }
 

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

@@ -9,5 +9,5 @@ fun foo(arg: Int?) {
     }
     if (x != null) x = 42
     // Unsafe because of lambda
-    x.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    x.<!UNRESOLVED_REFERENCE!>hashCode<!>()
 }

compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializer.fir.kt

@@ -15,6 +15,6 @@ fun foo(arg: Int?) {
     var z = arg
     z = z?.let { 42 }
     if (z != null) {
-        arg.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        arg.hashCode()
     }
 }

compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.fir.kt

@@ -23,7 +23,7 @@ fun bar(s: String?) {
     val hashCode = ss?.hashCode()
     ss = null
     if (hashCode != null) {
-        ss.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        ss.<!UNRESOLVED_REFERENCE!>hashCode<!>()
     }
 }
 

compiler/testData/diagnostics/tests/smartCasts/varnotnull/plusplusMinusminus.fir.kt

@@ -2,7 +2,7 @@
 fun foo(arg: Int?): Int {
     var i = arg
     if (i != null && i++ == 5) {
-        return i<!INAPPLICABLE_CANDIDATE!>--<!> + i
+        return i-- + i
     }
     return 0
 }