Rename swift-latest to Latest Installed Toolchain in the toolchain selection dialog (#877)

* filter out toolchain directories that don't have a Swift binary

* add a notification to clarify what Latest Installed Toolchain means

Author: matthewbastien

src/toolchain/toolchain.ts

@@ -261,13 +261,21 @@ export class SwiftToolchain {
      */
     public static async findToolchainsIn(directory: string): Promise<string[]> {
         try {
-            return (await fs.readdir(directory, { withFileTypes: true }))
-                .filter(
-                    dirent =>
-                        dirent.name.startsWith("swift-") &&
-                        (dirent.isDirectory() || dirent.isSymbolicLink())
-                )
-                .map(dirent => path.join(dirent.path, dirent.name));
+            const toolchains = await Promise.all(
+                (await fs.readdir(directory, { withFileTypes: true }))
+                    .filter(dirent => dirent.name.startsWith("swift-"))
+                    .map(async dirent => {
+                        const toolchainPath = path.join(dirent.path, dirent.name);
+                        const toolchainSwiftPath = path.join(toolchainPath, "usr", "bin", "swift");
+                        if (!(await pathExists(toolchainSwiftPath))) {
+                            return null;
+                        }
+                        return toolchainPath;
+                    })
+            );
+            return toolchains.filter(
+                (toolchain): toolchain is string => typeof toolchain === "string"
+            );
         } catch {
             // Assume that there are no installations here
             return [];

src/ui/ToolchainSelection.ts

@@ -98,6 +98,7 @@ interface SwiftToolchainItem extends vscode.QuickPickItem {
     type: "toolchain";
     toolchainPath: string;
     swiftFolderPath: string;
+    onDidSelect?(): Promise<void>;
 }
 
 /** A {@link vscode.QuickPickItem} that performs an action for the user */
@@ -150,13 +151,24 @@ async function getQuickPickItems(
         });
     const toolchains = (await SwiftToolchain.getToolchainInstalls())
         .reverse()
-        .map<SwiftToolchainItem>(toolchainPath => ({
-            type: "toolchain",
-            label: path.basename(toolchainPath, ".xctoolchain"),
-            detail: toolchainPath,
-            toolchainPath: path.join(toolchainPath, "usr"),
-            swiftFolderPath: path.join(toolchainPath, "usr", "bin"),
-        }));
+        .map<SwiftToolchainItem>(toolchainPath => {
+            const result: SwiftToolchainItem = {
+                type: "toolchain",
+                label: path.basename(toolchainPath, ".xctoolchain"),
+                detail: toolchainPath,
+                toolchainPath: path.join(toolchainPath, "usr"),
+                swiftFolderPath: path.join(toolchainPath, "usr", "bin"),
+            };
+            if (result.label === "swift-latest") {
+                result.label = "Latest Installed Toolchain";
+                result.onDidSelect = async () => {
+                    vscode.window.showInformationMessage(
+                        `The Swift extension is now configured to always use the most recently installed toolchain pointed at by the symbolic link "${toolchainPath}".`
+                    );
+                };
+            }
+            return result;
+        });
     const swiftlyToolchains = (await SwiftToolchain.getSwiftlyToolchainInstalls())
         .reverse()
         .map<SwiftToolchainItem>(toolchainPath => ({
@@ -233,7 +245,10 @@ export async function showToolchainSelectionQuickPick(activeToolchain: SwiftTool
     if (selected?.type === "action") {
         await selected.run();
     } else if (selected?.type === "toolchain") {
-        await setToolchainPath(selected.swiftFolderPath, "prompt");
+        const isUpdated = await setToolchainPath(selected.swiftFolderPath, "prompt");
+        if (isUpdated && selected.onDidSelect) {
+            await selected.onDidSelect();
+        }
     }
 }
 
@@ -249,7 +264,7 @@ async function removeToolchainPath() {
 async function setToolchainPath(
     value: string | undefined,
     target?: vscode.ConfigurationTarget | "prompt"
-): Promise<void> {
+): Promise<boolean> {
     if (target === "prompt") {
         const items: (vscode.QuickPickItem & {
             target?: vscode.ConfigurationTarget;
@@ -275,14 +290,19 @@ async function setToolchainPath(
                 canPickMany: false,
             });
             if (!selected) {
-                return;
+                return false;
             }
             target = selected.target;
         } else {
             target = vscode.ConfigurationTarget.Global; // Global scope by default
         }
     }
     await vscode.workspace.getConfiguration("swift").update("path", value, target);
+    await checkAndRemoveWorkspaceSetting(target);
+    return true;
+}
+
+async function checkAndRemoveWorkspaceSetting(target: vscode.ConfigurationTarget | undefined) {
     // Check to see if the configuration would be overridden by workspace settings
     if (target !== vscode.ConfigurationTarget.Global) {
         return;