From 7ea2d6d175c9379d39b4aca2566dfdb741a6dc6f Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Wed, 1 Jul 2015 22:21:31 +0200
Subject: [PATCH] IG: check fields with initializers correctly in "Field may be
 final" inspection

---
 .../src/com/siyeh/ig/psiutils/FinalUtils.java |  6 ++++-
 .../ig/psiutils/VariableAccessUtils.java      | 27 +++++++++++++++++++
 .../style/field_final/FieldMayBeFinal.java    | 12 +++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/FinalUtils.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/FinalUtils.java
index 1155a1083906..e320e35b1c2f 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/FinalUtils.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/FinalUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2013 Bas Leijdekkers
+ * Copyright 2009-2015 Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,10 @@ public class FinalUtils {
   private FinalUtils() {}
 
   public static boolean canBeFinal(@NotNull PsiVariable variable) {
+    if (variable.getInitializer() != null || variable instanceof PsiParameter) {
+      // parameters hava implicit initializer
+      return !VariableAccessUtils.variableIsAssigned(variable);
+    }
     final FinalDefiniteAssignment definiteAssignment = new FinalDefiniteAssignment(variable);
     DefiniteAssignmentUtil.checkVariable(variable, definiteAssignment);
     return definiteAssignment.isDefinitelyAssigned() &&
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/VariableAccessUtils.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/VariableAccessUtils.java
index 03bf5937d44f..a6639f51d1e8 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/VariableAccessUtils.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/VariableAccessUtils.java
@@ -16,7 +16,10 @@
 package com.siyeh.ig.psiutils;
 
 import com.intellij.psi.*;
+import com.intellij.psi.search.searches.ReferencesSearch;
 import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.Processor;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -79,6 +82,30 @@ public class VariableAccessUtils {
     return visitor.isPassed();
   }
 
+  public static boolean variableIsAssigned(@NotNull PsiVariable variable) {
+    if (variable instanceof PsiField) {
+      if (variable.hasModifierProperty(PsiModifier.PRIVATE)) {
+        final PsiClass aClass = PsiUtil.getTopLevelClass(variable);
+        return variableIsAssigned(variable, aClass);
+      }
+      return !ReferencesSearch.search(variable, variable.getUseScope()).forEach(new Processor<PsiReference>() {
+        @Override
+        public boolean process(PsiReference reference) {
+          final PsiElement element = reference.getElement();
+          if (!(element instanceof PsiExpression)) {
+            return true;
+          }
+          final PsiExpression expression = (PsiExpression)element;
+          return !PsiUtil.isAccessedForWriting(expression);
+        }
+      });
+    }
+    final PsiElement context =
+      PsiTreeUtil.getParentOfType(variable, PsiCodeBlock.class, PsiMethod.class, PsiLambdaExpression.class,
+                                  PsiCatchSection.class, PsiForStatement.class, PsiForeachStatement.class);
+    return variableIsAssigned(variable, context);
+  }
+
   public static boolean variableIsAssigned(
     @NotNull PsiVariable variable, @Nullable PsiElement context) {
     if (context == null) {
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/style/field_final/FieldMayBeFinal.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/style/field_final/FieldMayBeFinal.java
index e532626bfd39..299549b239ed 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/style/field_final/FieldMayBeFinal.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/style/field_final/FieldMayBeFinal.java
@@ -886,6 +886,18 @@ class T58 {
     x = 3;
   }
 }
+class T59 {
+  private int i = 0;
+  {
+    assert true : i++;
+  }
+}
+class T60 {
+  private int i = 1;
+  {
+    if (false) i = 2;
+  }
+}
 class Foo {
 
   public interface Accessor<T> {