final fields cannot be modified inside its class

plugins/groovy/src/org/jetbrains/plugins/groovy/GroovyBundle.properties

@@ -360,3 +360,4 @@ annotation.type.cannot.be.inner=Annotation type cannot be inner
 cannot.find.operator.overload.method=Cannot resolve index access with arguments {0}
 named.arguments.are.not.allowed.inside.index.operations=Named arguments are not allowed inside index operations
 expected.0.to.be.inline.constant=Expected ''{0}'' to be an inline constant
+cannot.assign.a.value.to.final.field.0=Cannot assign a value to final field ''{0}''

plugins/groovy/src/org/jetbrains/plugins/groovy/annotator/GroovyAnnotator.java

@@ -286,6 +286,7 @@ public class GroovyAnnotator extends GroovyElementVisitor {
   public void visitReferenceExpression(final GrReferenceExpression referenceExpression) {
     checkStringNameIdentifier(referenceExpression);
     checkThisOrSuperReferenceExpression(referenceExpression, myHolder);
+    checkFinalFieldAccess(referenceExpression);
     if (ResolveUtil.isKeyOfMap(referenceExpression)) {
       PsiElement nameElement = referenceExpression.getReferenceNameElement();
       LOG.assertTrue(nameElement != null);
@@ -298,6 +299,40 @@ public class GroovyAnnotator extends GroovyElementVisitor {
     }
   }
 
+  private void checkFinalFieldAccess(@NotNull GrReferenceExpression ref) {
+    final PsiElement resolved = ref.resolve();
+
+    if (resolved instanceof GrField && resolved.isPhysical() && ((GrField)resolved).hasModifierProperty(FINAL) && PsiUtil.isLValue(ref)) {
+      final GrField field = (GrField)resolved;
+
+      final PsiClass containingClass = field.getContainingClass();
+      if (containingClass != null && PsiTreeUtil.isAncestor(containingClass, ref, true)) {
+        GrMember container = findClassMemberContainer(ref, containingClass);
+
+        if (field.hasModifierProperty(STATIC)) {
+          if (container instanceof GrClassInitializer && ((GrClassInitializer)container).isStatic()) {
+            return;
+          }
+        }
+        else {
+          if (container instanceof GrMethod && ((GrMethod)container).isConstructor()) {
+            return;
+          }
+        }
+
+        myHolder.createErrorAnnotation(ref, GroovyBundle.message("cannot.assign.a.value.to.final.field.0", field.getName()));
+      }
+    }
+  }
+
+  @Nullable
+  private static GrMember findClassMemberContainer(@NotNull GrReferenceExpression ref, @NotNull PsiClass aClass) {
+    for (PsiElement parent = ref.getParent(); parent != null && parent != aClass; parent = parent.getParent()) {
+      if (parent instanceof GrMember && ((GrMember)parent).getContainingClass() == aClass) return (GrMember)parent;
+    }
+    return null;
+  }
+
   private void checkStringNameIdentifier(GrReferenceExpression ref) {
     final PsiElement nameElement = ref.getReferenceNameElement();
     if (nameElement == null) return;

plugins/groovy/src/org/jetbrains/plugins/groovy/lang/psi/impl/statements/GrClassInitializerImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2012 JetBrains s.r.o.
+ * Copyright 2000-2013 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,9 +20,9 @@ import com.intellij.lang.ASTNode;
 import com.intellij.psi.PsiClass;
 import com.intellij.psi.PsiCodeBlock;
 import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiModifier;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.plugins.groovy.lang.lexer.GroovyTokenTypes;
 import org.jetbrains.plugins.groovy.lang.psi.GroovyElementVisitor;
 import org.jetbrains.plugins.groovy.lang.psi.api.auxiliary.modifiers.GrModifier;
 import org.jetbrains.plugins.groovy.lang.psi.api.auxiliary.modifiers.GrModifierList;
@@ -56,12 +56,12 @@ public class GrClassInitializerImpl extends GroovyPsiElementImpl implements GrCl
   }
 
   public boolean isStatic() {
-    return findChildByType(GroovyTokenTypes.kSTATIC) != null;
+    return getModifierList().hasExplicitModifier(PsiModifier.STATIC);
   }
 
 
   public PsiClass getContainingClass() {
-    PsiElement parent = getParent().getParent();
+    PsiElement parent = getParent();
     if (parent instanceof GrTypeDefinitionBody) {
       final PsiElement pparent = parent.getParent();
       if (pparent instanceof PsiClass) {

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/highlighting/GroovyHighlightingTest.groovy

@@ -1368,5 +1368,48 @@ def bar
 ''')
   }
 
+ void testFinalFieldRewrite() {
+   testHighlighting('''\
+class A {
+  final foo = 1
+
+  def A() {
+    foo = 2 //no error
+  }
+
+  def foo() {
+    <error descr="Cannot assign a value to final field 'foo'">foo</error> = 2
+  }
+}
+
+new A().foo = 2 //no error
+''')
+ }
+
+  void testStaticFinalFieldRewrite() {
+    testHighlighting('''\
+class A {
+  static final foo = 1
+
+  def A() {
+    <error descr="Cannot assign a value to final field 'foo'">foo</error> = 2
+  }
+
+  static {
+    foo = 2 //no error
+  }
+
+  def foo() {
+    <error descr="Cannot assign a value to final field 'foo'">foo</error> = 2
+  }
+
+  static def bar() {
+    <error descr="Cannot assign a value to final field 'foo'">foo</error> = 2
+  }
+}
+
+A.foo = 3 //no error
+''')
+  }
 
 }