Added check for read-only files in intention actions

idea/src/org/jetbrains/jet/plugin/quickfix/JetIntentionAction.java

@@ -16,12 +16,14 @@
 
 package org.jetbrains.jet.plugin.quickfix;
 
+import com.intellij.codeInsight.CodeInsightUtilBase;
 import com.intellij.codeInsight.intention.IntentionAction;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.project.Project;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.diagnostics.Diagnostic;
@@ -39,6 +41,20 @@ public abstract class JetIntentionAction<T extends PsiElement> implements Intent
         return element.isValid() && file.getManager().isInProject(file) && (file instanceof JetFile);
     }
 
+    //Don't override this method. Use the method below instead.
+    @Deprecated
+    @Override
+    public void invoke(@NotNull Project project, Editor editor, PsiFile file) throws IncorrectOperationException {
+        if (file instanceof JetFile) {
+            if (CodeInsightUtilBase.prepareFileForWrite(element.getContainingFile())) {
+                invoke(project, editor, (JetFile) file);
+            }
+        }
+    }
+
+    protected void invoke(@NotNull Project project, Editor editor, JetFile file) throws IncorrectOperationException {
+    }
+
     @Override
     public boolean startInWriteAction() {
         return true;