From fd6f8c6eaac5e379c98424dd3648a7046a9cd7ef Mon Sep 17 00:00:00 2001
From: Kirill Likhodedov <kirill.likhodedov@jetbrains.com>
Date: Fri, 8 Apr 2011 17:27:51 +0400
Subject: [PATCH] IDEA-64883 Don't save document if it is null.

---
 .../intellij/openapi/fileEditor/FileDocumentManager.java    | 1 +
 .../openapi/fileEditor/impl/FileDocumentManagerImpl.java    | 1 +
 .../openapi/vcs/actions/AbstractShowDiffAction.java         | 6 +++++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/platform/platform-api/src/com/intellij/openapi/fileEditor/FileDocumentManager.java b/platform/platform-api/src/com/intellij/openapi/fileEditor/FileDocumentManager.java
index f0181c23c35a..243ad6dd4cfd 100644
--- a/platform/platform-api/src/com/intellij/openapi/fileEditor/FileDocumentManager.java
+++ b/platform/platform-api/src/com/intellij/openapi/fileEditor/FileDocumentManager.java
@@ -27,6 +27,7 @@ public abstract class FileDocumentManager {
     return ApplicationManager.getApplication().getComponent(FileDocumentManager.class);
   }
 
+  @Nullable
   public abstract Document getDocument(@NotNull VirtualFile file);
 
   @Nullable
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/FileDocumentManagerImpl.java b/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/FileDocumentManagerImpl.java
index e4dae40553d6..294f15809460 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/FileDocumentManagerImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/FileDocumentManagerImpl.java
@@ -107,6 +107,7 @@ public class FileDocumentManagerImpl extends FileDocumentManager implements Appl
   public void disposeComponent() {
   }
 
+  @Nullable
   public Document getDocument(@NotNull final VirtualFile file) {
     DocumentEx document = (DocumentEx)getCachedDocument(file);
     if (document == null) {
diff --git a/platform/vcs-impl/src/com/intellij/openapi/vcs/actions/AbstractShowDiffAction.java b/platform/vcs-impl/src/com/intellij/openapi/vcs/actions/AbstractShowDiffAction.java
index 1f1ba9523d02..392f1112fdac 100644
--- a/platform/vcs-impl/src/com/intellij/openapi/vcs/actions/AbstractShowDiffAction.java
+++ b/platform/vcs-impl/src/com/intellij/openapi/vcs/actions/AbstractShowDiffAction.java
@@ -17,6 +17,7 @@ package com.intellij.openapi.vcs.actions;
 
 import com.intellij.openapi.actionSystem.AnActionEvent;
 import com.intellij.openapi.actionSystem.Presentation;
+import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.fileEditor.FileDocumentManager;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vcs.AbstractVcs;
@@ -89,7 +90,10 @@ public abstract class AbstractShowDiffAction extends AbstractVcsAction{
     final Project project = vcsContext.getProject();
     final VirtualFile selectedFile = vcsContext.getSelectedFiles()[0];
     final FileDocumentManager fileDocumentManager = FileDocumentManager.getInstance();
-    fileDocumentManager.saveDocument(fileDocumentManager.getDocument(selectedFile));
+    final Document document = fileDocumentManager.getDocument(selectedFile);
+    if (document != null) {
+      fileDocumentManager.saveDocument(document);
+    }
 
     final ProjectLevelVcsManager vcsManager = ProjectLevelVcsManager.getInstance(project);
     final AbstractVcs vcs = vcsManager.getVcsFor(selectedFile);