IDEA-71379 Throwable at org.zmlx.hg4idea.execution.HgCommandExecutor.executeInCurrentThread

also, report when files just edited, but not changed

platform/platform-impl/src/com/intellij/openapi/progress/BackgroundSynchronousInvisibleComputable.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2000-2011 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.progress;
+
+import com.intellij.openapi.application.ApplicationManager;
+import com.intellij.util.concurrency.Semaphore;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * @author irengrig
+ *         Date: 6/24/11
+ *         Time: 7:34 PM
+ */
+public abstract class BackgroundSynchronousInvisibleComputable<T> {
+  protected abstract T runImpl();
+
+  public T compute() {
+    final Semaphore semaphore = new Semaphore();
+    semaphore.down();
+    final AtomicReference<T> reference = new AtomicReference<T>();
+    ApplicationManager.getApplication().executeOnPooledThread(new Runnable() {
+      @Override
+      public void run() {
+        try {
+          reference.set(runImpl());
+        }
+        finally {
+          semaphore.up();
+        }
+      }
+    });
+    semaphore.waitFor();
+    return reference.get();
+  }
+}

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/FragmentedDiffRequestFromChange.java

@@ -25,8 +25,10 @@ import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.editor.impl.DocumentImpl;
 import com.intellij.openapi.fileEditor.FileDocumentManager;
 import com.intellij.openapi.fileTypes.FileType;
+import com.intellij.openapi.progress.BackgroundSynchronousInvisibleComputable;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Pair;
+import com.intellij.openapi.util.Ref;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vcs.FilePath;
@@ -220,7 +222,23 @@ public class FragmentedDiffRequestFromChange implements DiffRequestFromChange<Sh
     }
 
     private String notNullContentRevision(final ContentRevision cr) throws VcsException {
-      final String s = cr == null ? "" : cr.getContent();
+      if (cr == null) return "";
+      final Ref<VcsException> ref = new Ref<VcsException>();
+      final String s = new BackgroundSynchronousInvisibleComputable<String>() {
+        @Override
+        protected String runImpl() {
+          try {
+            return cr.getContent();
+          }
+          catch (VcsException e) {
+            ref.set(e);
+            return null;
+          }
+        }
+      }.compute();
+      if (! ref.isNull()) {
+        throw ref.get();
+      }
       return s == null ? "" : s;
     }
   }

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/VcsChangeDetailsManager.java

@@ -16,6 +16,7 @@
 package com.intellij.openapi.vcs.changes;
 
 import com.intellij.openapi.Disposable;
+import com.intellij.openapi.diff.DiffBundle;
 import com.intellij.openapi.diff.DiffContent;
 import com.intellij.openapi.diff.DiffPanel;
 import com.intellij.openapi.diff.ShiftedSimpleContent;
@@ -148,7 +149,11 @@ public class VcsChangeDetailsManager {
     public Pair<JPanel, Disposable> convert(Change o) {
       try {
         final List<BeforeAfter<ShiftedSimpleContent>> requestForChange = myRequestFromChange.createRequestForChange(o, extraLines);
-        if (requestForChange == null || requestForChange.isEmpty()) return null;
+        if (requestForChange == null) return null;
+        if (requestForChange.isEmpty()) {
+          return new Pair<JPanel, Disposable>(
+            errorPanel(DiffBundle.message("diff.contents.have.differences.only.in.line.separators.message.text"), false), null);
+        }
         final ChangesFragmentedDiffPanel panel =
           new ChangesFragmentedDiffPanel(myProject, requestForChange, myDiffPanelCache, changeDescription(o));
         return new Pair<JPanel, Disposable>(panel.getPanel(), panel);