(1.1 only) Var can be val: correct handling of delegated local variables #KT-14409 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/CanBeValInspection.kt

@@ -49,7 +49,10 @@ class CanBeValInspection : AbstractKotlinInspection() {
 
                 when (declaration) {
                     is KtProperty -> {
-                        if (declaration.isVar && declaration.isLocal && canBeVal(declaration, declaration.hasInitializer(), listOf(declaration))) {
+                        if (declaration.isVar && declaration.isLocal &&
+                            canBeVal(declaration,
+                                     declaration.hasInitializer() || declaration.hasDelegateExpression(),
+                                     listOf(declaration))) {
                             reportCanBeVal(declaration)
                         }
                     }
@@ -63,13 +66,17 @@ class CanBeValInspection : AbstractKotlinInspection() {
                 }
             }
 
-            private fun canBeVal(declaration: KtVariableDeclaration, hasInitializer: Boolean, allDeclarations: Collection<KtVariableDeclaration>): Boolean {
+            private fun canBeVal(
+                    declaration: KtVariableDeclaration,
+                    hasInitializerOrDelegate: Boolean,
+                    allDeclarations: Collection<KtVariableDeclaration>
+            ): Boolean {
                 if (allDeclarations.all { ReferencesSearch.search(it, it.useScope).none() }) {
                     // do not report for unused var's (otherwise we'll get it highlighted immediately after typing the declaration
                     return false
                 }
 
-                if (hasInitializer) {
+                if (hasInitializerOrDelegate) {
                     val hasWriteUsages = ReferencesSearch.search(declaration, declaration.useScope).any {
                         (it as? KtSimpleNameReference)?.element?.readWriteAccess(useResolveForReadWrite = true)?.isWrite == true
                     }

idea/testData/inspections/canBeVal/inspectionData/expected.xml

@@ -79,4 +79,13 @@
         <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' is never modified and can be declared as 'val'</problem_class>
         <description>Variable is never modified and can be declared immutable using 'val'</description>
     </problem>
+
+    <problem>
+        <file>withReadOnlyDelegate.kt</file>
+        <line>4</line>
+        <module>light_idea_test_case</module>
+        <entry_point TYPE="file" FQNAME="withReadOnlyDelegate.kt" />
+        <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' is never modified and can be declared as 'val'</problem_class>
+        <description>Variable is never modified and can be declared immutable using 'val'</description>
+    </problem>
 </problems>

idea/testData/inspections/canBeVal/withDelegate.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+
+fun foo() {
+    var s: String by Delegates.notNull()
+    s = ""
+}

idea/testData/inspections/canBeVal/withReadOnlyDelegate.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+
+fun foo() {
+    var s: String by lazy { "Hello!" }
+    s.hashCode()
+}