From 0d042c5478e6ecda4bf4328960f8a632984da879 Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Tue, 5 Jun 2012 18:24:18 +0200
Subject: [PATCH] [^anima] recreate completion file copy when the previous one
 is outdated

---
 .../completion/CodeCompletionHandlerBase.java        | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/platform/lang-impl/src/com/intellij/codeInsight/completion/CodeCompletionHandlerBase.java b/platform/lang-impl/src/com/intellij/codeInsight/completion/CodeCompletionHandlerBase.java
index c5ed564d4f56..4715b4e5d53f 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/completion/CodeCompletionHandlerBase.java
+++ b/platform/lang-impl/src/com/intellij/codeInsight/completion/CodeCompletionHandlerBase.java
@@ -776,6 +776,16 @@ public class CodeCompletionHandlerBase implements CodeInsightActionHandler {
 
   public static final Key<SoftReference<Pair<PsiFile, Document>>> FILE_COPY_KEY = Key.create("CompletionFileCopy");
 
+  private static boolean isCopyUpToDate(Document document, @NotNull PsiFile file) {
+    if (!file.isValid()) {
+      return false;
+    }
+    // the psi file cache might have been cleared by some external activity,
+    // in which case PSI-document sync may stop working
+    PsiFile current = PsiDocumentManager.getInstance(file.getProject()).getPsiFile(document);
+    return current != null && current.getViewProvider().getPsi(file.getLanguage()) == file;
+  }
+
   private static PsiFile createFileCopy(PsiFile file) {
     final VirtualFile virtualFile = file.getVirtualFile();
     if (file.isPhysical() && virtualFile != null && virtualFile.getFileSystem() == LocalFileSystem.getInstance()
@@ -784,7 +794,7 @@ public class CodeCompletionHandlerBase implements CodeInsightActionHandler {
       final SoftReference<Pair<PsiFile, Document>> reference = file.getUserData(FILE_COPY_KEY);
       if (reference != null) {
         final Pair<PsiFile, Document> pair = reference.get();
-        if (pair != null && pair.first.isValid() && pair.first.getClass().equals(file.getClass())) {
+        if (pair != null && pair.first.getClass().equals(file.getClass()) && isCopyUpToDate(pair.second, pair.first)) {
           final PsiFile copy = pair.first;
           if (copy.getViewProvider().getModificationStamp() > file.getViewProvider().getModificationStamp()) {
             ((PsiModificationTrackerImpl) file.getManager().getModificationTracker()).incCounter();