Update the type system when files get removed from the project.

src/Main/Base/Project/Parser/IParserService.cs

@@ -262,13 +262,20 @@ namespace ICSharpCode.SharpDevelop.Parser
 		/// The parser services tries to use the project that contains the file directly (non-linked)
 		/// as the primary parent project.
 		/// </param>
+		/// <remarks>
+		/// If the file was already parsed (e.g. because it also belongs to another project),
+		/// this method invokes <c>project.UpdateParseInformation(null, existingUnresolvedFile);</c>.
+		/// Otherwise, the project will be notified of the new file the next time it is parsed.
+		/// </remarks>
 		void AddOwnerProject(FileName fileName, IProject project, bool startAsyncParse, bool isLinkedFile);
 		
 		/// <summary>
 		/// Removes a project from the owners of the file.
+		/// </summary>
+		/// <remarks>
 		/// This method invokes <c>project.UpdateParseInformation(existingUnresolvedFile, null);</c>.
 		/// (unless existingUnresolvedFile==null)
-		/// </summary>
+		/// </remarks>
 		void RemoveOwnerProject(FileName fileName, IProject project);
 		
 		/// <summary>

src/Main/SharpDevelop/Parser/ParserService.cs

@@ -194,7 +194,10 @@ namespace ICSharpCode.SharpDevelop.Parser
 		{
 			if (project == null)
 				throw new ArgumentNullException("project");
-			GetFileEntry(fileName, true).AddOwnerProject(project, isLinkedFile);
+			var entry = GetFileEntry(fileName, true);
+			entry.AddOwnerProject(project, isLinkedFile);
+			if (startAsyncParse)
+				entry.ParseFileAsync(null, project, CancellationToken.None).FireAndForget();
 		}
 		
 		public void RemoveOwnerProject(FileName fileName, IProject project)

src/Main/SharpDevelop/Parser/ParserServiceEntry.cs

@@ -83,16 +83,27 @@ namespace ICSharpCode.SharpDevelop.Parser
 		public void RemoveOwnerProject(IProject project)
 		{
 			Debug.Assert(project != null);
+			ProjectEntry oldEntry;
+			bool removedLastOwner = false;
 			lock (this) {
 				int index = FindIndexForProject(project);
 				if (index < 0)
 					throw new InvalidOperationException("The project does not own the file");
+				oldEntry = entries[index];
 				if (entries.Count == 1) {
 					entries[0] = default(ProjectEntry);
+					removedLastOwner = true;
 				} else {
 					entries.RemoveAt(index);
 				}
 			}
+			if (oldEntry.UnresolvedFile != null) {
+				project.OnParseInformationUpdated(new ParseInformationEventArgs(project, oldEntry.UnresolvedFile, null));
+			}
+			if (removedLastOwner) {
+				// allow the parser service to forget this entry
+				parserService.RegisterForCacheExpiry(this);
+			}
 		}
 		#endregion