2 files changed, 14 insertions, 10 deletions

diff --git a/editors/code/src/ctx.ts b/editors/code/src/ctx.ts
index b4e983a0c..25ef38aed 100644
--- a/editors/code/src/ctx.ts
+++ b/editors/code/src/ctx.ts
@@ -3,7 +3,7 @@ import * as lc from 'vscode-languageclient';
 
 import { Config } from './config';
 import { createClient } from './client';
-import { isRustDocument } from './util';
+import { isRustEditor, RustEditor } from './util';
 
 export class Ctx {
     private constructor(
@@ -22,17 +22,15 @@ export class Ctx {
         return res;
     }
 
-    get activeRustEditor(): vscode.TextEditor | undefined {
+    get activeRustEditor(): RustEditor | undefined {
         const editor = vscode.window.activeTextEditor;
-        return editor && isRustDocument(editor.document)
+        return editor && isRustEditor(editor)
             ? editor
             : undefined;
     }
 
-    get visibleRustEditors(): vscode.TextEditor[] {
-        return vscode.window.visibleTextEditors.filter(
-            editor => isRustDocument(editor.document),
-        );
+    get visibleRustEditors(): RustEditor[] {
+        return vscode.window.visibleTextEditors.filter(isRustEditor);
     }
 
     registerCommand(name: string, factory: (ctx: Ctx) => Cmd) {
diff --git a/editors/code/src/util.ts b/editors/code/src/util.ts
index 7c95769bb..95a5f1227 100644
--- a/editors/code/src/util.ts
+++ b/editors/code/src/util.ts
@@ -1,7 +1,6 @@
 import * as lc from "vscode-languageclient";
 import * as vscode from "vscode";
 import { strict as nativeAssert } from "assert";
-import { TextDocument } from "vscode";
 
 export function assert(condition: boolean, explanation: string): asserts condition {
     try {
@@ -67,9 +66,16 @@ function sleep(ms: number) {
     return new Promise(resolve => setTimeout(resolve, ms));
 }
 
-export function isRustDocument(document: TextDocument) {
+export type RustDocument = vscode.TextDocument & { languageId: "rust" };
+export type RustEditor = vscode.TextEditor & { document: RustDocument; id: string };
+
+export function isRustDocument(document: vscode.TextDocument): document is RustDocument {
     return document.languageId === 'rust'
         // SCM diff views have the same URI as the on-disk document but not the same content
         && document.uri.scheme !== 'git'
         && document.uri.scheme !== 'svn';
-}
\ No newline at end of file
+}
+
+export function isRustEditor(editor: vscode.TextEditor): editor is RustEditor {
+    return isRustDocument(editor.document);
+}