From 42b60a7769f18b77ce6c5a76b3dc27dd10aca616 Mon Sep 17 00:00:00 2001
From: Dennis Ushakov <dennis.ushakov@gmail.com>
Date: Tue, 24 Feb 2015 12:48:37 +0300
Subject: [PATCH] diagnostics for EA-64904

---
 .../editorActions/XmlTagNameSynchronizer.java  | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java b/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java
index ce58b9311c18..8cf80b20178f 100644
--- a/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java
+++ b/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java
@@ -30,6 +30,8 @@ import com.intellij.openapi.command.CommandAdapter;
 import com.intellij.openapi.command.CommandEvent;
 import com.intellij.openapi.command.CommandProcessor;
 import com.intellij.openapi.components.ApplicationComponent;
+import com.intellij.openapi.diagnostic.Attachment;
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.*;
 import com.intellij.openapi.editor.event.DocumentAdapter;
 import com.intellij.openapi.editor.event.DocumentEvent;
@@ -58,6 +60,7 @@ import java.util.Set;
  * @author Dennis.Ushakov
  */
 public class XmlTagNameSynchronizer extends CommandAdapter implements ApplicationComponent {
+  private static final Logger LOG = Logger.getInstance(XmlTagNameSynchronizer.class);
   private static final Set<String> SUPPORTED_LANGUAGES = ContainerUtil.set(HTMLLanguage.INSTANCE.getID(),
                                                                            XMLLanguage.INSTANCE.getID(),
                                                                            XHTMLLanguage.INSTANCE.getID(),
@@ -265,12 +268,17 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
       int start = -1;
       int end = -1;
       for (int i = offset - 1; i >= Math.max(0, offset - 50); i--) {
-        final char c = sequence.charAt(i);
-        if (c == '<' || (c == '/' && i > 0 && sequence.charAt(i - 1) == '<')) {
-          start = i + 1;
-          break;
+        try {
+          final char c = sequence.charAt(i);
+          if (c == '<' || (c == '/' && i > 0 && sequence.charAt(i - 1) == '<')) {
+            start = i + 1;
+            break;
+          }
+          if (!XmlUtil.isValidTagNameChar(c)) break;
+        } catch (IndexOutOfBoundsException e) {
+          LOG.error("incorrect offset:" + i + ", initial: " + offset, new Attachment("document.txt", sequence.toString()));
+          return null;
         }
-        if (!XmlUtil.isValidTagNameChar(c)) break;
       }
       if (start < 0) return null;
       for (int i = offset; i < Math.min(document.getTextLength(), offset + 50); i++) {