Merge "Merge remote-tracking branch 'aosp/upstream-master' into merge"

1 files changed, 16 insertions, 1 deletions

diff --git a/platform/core-impl/src/com/intellij/pom/core/impl/PomModelImpl.java b/platform/core-impl/src/com/intellij/pom/core/impl/PomModelImpl.java
index ba5858c52993..2ca35e4227e9 100644
--- a/platform/core-impl/src/com/intellij/pom/core/impl/PomModelImpl.java
+++ b/platform/core-impl/src/com/intellij/pom/core/impl/PomModelImpl.java
@@ -301,15 +301,30 @@ public class PomModelImpl extends UserDataHolderBase implements PomModel {
     final PsiToDocumentSynchronizer synchronizer = manager.getSynchronizer();
     final PsiElement changeScope = transaction.getChangeScope();
     LOG.assertTrue(changeScope != null);
-    BlockSupportImpl.sendBeforeChildrenChangeEvent((PsiManagerImpl)PsiManager.getInstance(myProject), changeScope, true);
+
     final PsiFile containingFileByTree = getContainingFileByTree(changeScope);
+    if (changeScope.isPhysical() && synchronizer.toProcessPsiEvent() && isDocumentUncommitted(containingFileByTree)) {
+      // fail-fast to prevent any psi modifications that would cause psi/document text mismatch
+      // PsiToDocumentSynchronizer assertions happen inside event processing and are logged by PsiManagerImpl.fireEvent instead of being rethrown
+      // so it's important to throw something outside event processing
+      throw new IllegalStateException("Attempt to modify PSI for non-committed Document!");
+    }
 
+    BlockSupportImpl.sendBeforeChildrenChangeEvent((PsiManagerImpl)PsiManager.getInstance(myProject), changeScope, true);
     Document document = containingFileByTree == null ? null : manager.getCachedDocument(containingFileByTree);
     if(document != null) {
       synchronizer.startTransaction(myProject, document, changeScope);
     }
   }
 
+  private boolean isDocumentUncommitted(@Nullable PsiFile file) {
+    if (file == null) return false;
+
+    PsiDocumentManager manager = PsiDocumentManager.getInstance(myProject);
+    Document cachedDocument = manager.getCachedDocument(file);
+    return cachedDocument != null && manager.isUncommited(cachedDocument);
+  }
+
   @Nullable
   private static PsiFile getContainingFileByTree(@NotNull final PsiElement changeScope) {
     // there could be pseudo physical trees (JSPX/JSP/etc.) which must not translate