Remove WorkspaceDocument.IsCurrent.

This was a rather poor API that wasn't particularly helpful for users as it's
inherently racey.

Author: alexrp

src/language/tooling/Workspaces/Workspace.cs

@@ -78,8 +78,6 @@ internal void AddOrEditDocument(string path)
 
             Documents = Documents.SetItem(path, editedOldDoc);
 
-            oldDoc.IsCurrent = false;
-
             _documentEdited.Raise(oldDoc, editedOldDoc);
         }
 
@@ -103,8 +101,6 @@ internal void MoveDocument(string oldPath, string newPath)
 
                 Documents = Documents.Remove(oldPath).Add(newPath, movedOldDoc);
 
-                oldDoc.IsCurrent = false;
-
                 _documentRenamed.Raise(oldDoc, movedOldDoc);
 
                 break;
@@ -116,8 +112,6 @@ internal void MoveDocument(string oldPath, string newPath)
 
                 Documents = Documents.SetItem(newPath, editedNewDoc);
 
-                newDoc.IsCurrent = false;
-
                 _documentEdited.Raise(newDoc, editedNewDoc);
 
                 break;
@@ -130,9 +124,6 @@ internal void MoveDocument(string oldPath, string newPath)
 
                 Documents = Documents.SetItem(oldPath, editedOldDoc).SetItem(newPath, editedNewDoc);
 
-                oldDoc.IsCurrent = false;
-                newDoc.IsCurrent = false;
-
                 _documentEdited.Raise(oldDoc, editedOldDoc);
                 _documentEdited.Raise(newDoc, editedNewDoc);
 
@@ -148,18 +139,11 @@ internal void DeleteDocument(string path)
 
         Documents = Documents.Remove(path);
 
-        doc.IsCurrent = false;
-
         _documentRemoved.Raise(doc);
     }
 
     internal void ClearDocuments()
     {
-        var docs = Documents;
-
-        Documents = ImmutableDictionary<string, WorkspaceDocument>.Empty;
-
-        foreach (var (_, doc) in docs)
-            doc.IsCurrent = false;
+        Documents = Documents.Clear();
     }
 }

src/language/tooling/Workspaces/WorkspaceDocument.cs

@@ -18,14 +18,6 @@ public sealed class WorkspaceDocument
         var path => Unsafe.As<string>(path),
     };
 
-    public bool IsCurrent
-    {
-        get => _current;
-        internal set => _current = value;
-    }
-
-    private volatile bool _current = true;
-
     // This starts out as a string (path). As callers access text, syntax, and semantic information, it gets promoted to
     // SourceText, SyntaxTree, and SemanticTree, respectively. SemanticTree links back to SyntaxTree which in turn
     // soft-links back to SourceText. The SourceText can always be reconstructed from the SyntaxTree (and by extension
@@ -49,8 +41,6 @@ internal WorkspaceDocument(Workspace workspace, WorkspaceDocumentAttributes attr
 
     public ValueTask<SourceText> GetTextAsync(CancellationToken cancellationToken = default)
     {
-        Check.Operation((_state, IsCurrent) is not (string, false));
-
         return GetTextAsync();
 
         [AsyncMethodBuilder(typeof(PoolingAsyncValueTaskMethodBuilder<>))]