Fix Swiftly toolchain selection

Author: roulpriya

src/toolchain/swiftly.ts

@@ -101,9 +101,7 @@ export class Swiftly {
             return response.toolchains.map(t => t.version.name);
         } catch (error) {
             outputChannel?.appendLine(`Failed to retrieve Swiftly installations: ${error}`);
-            throw new Error(
-                `Failed to retrieve Swiftly installations from disk: ${(error as Error).message}`
-            );
+            return [];
         }
     }
 
@@ -143,6 +141,13 @@ export class Swiftly {
         return inUse.trimEnd();
     }
 
+    public static async use(version: string): Promise<void> {
+        if (!this.isSupported()) {
+            throw new Error("Swiftly is not supported on this platform");
+        }
+        await execFile("swiftly", ["use", version]);
+    }
+
     /**
      * Determine if Swiftly is being used to manage the active toolchain and if so, return
      * the path to the active toolchain.

src/ui/ToolchainSelection.ts

@@ -304,7 +304,22 @@ export async function showToolchainSelectionQuickPick(activeToolchain: SwiftTool
             }
         }
         // Update the toolchain path
-        const isUpdated = await setToolchainPath(selected.swiftFolderPath, developerDir);
+        let swiftPath = selected.swiftFolderPath;
+
+        // Handle Swiftly toolchains specially
+        if (selected.category === "swiftly") {
+            try {
+                // Run swiftly use <version> and get the path to the toolchain
+                await Swiftly.use(selected.label);
+                const inUseLocation = await Swiftly.inUseLocation("swiftly");
+                swiftPath = path.join(inUseLocation, "usr", "bin");
+            } catch (error) {
+                void vscode.window.showErrorMessage(`Failed to switch Swiftly toolchain: ${error}`);
+                return;
+            }
+        }
+
+        const isUpdated = await setToolchainPath(swiftPath, developerDir);
         if (isUpdated && selected.onDidSelect) {
             await selected.onDidSelect();
         }

test/unit-tests/toolchain/swiftly.test.ts

@@ -38,50 +38,45 @@ suite("Swiftly Unit Tests", () => {
                 toolchains: [
                     {
                         inUse: true,
-                        installed: true,
                         isDefault: true,
-                        name: "swift-5.9.0-RELEASE",
                         version: {
                             major: 5,
                             minor: 9,
                             patch: 0,
+                            name: "swift-5.9.0-RELEASE",
                             type: "stable",
                         },
                     },
                     {
                         inUse: false,
-                        installed: true,
                         isDefault: false,
-                        name: "swift-5.8.0-RELEASE",
                         version: {
                             major: 5,
                             minor: 8,
                             patch: 0,
+                            name: "swift-5.8.0-RELEASE",
                             type: "stable",
                         },
                     },
                     {
                         inUse: false,
-                        installed: false,
                         isDefault: false,
-                        name: "swift-DEVELOPMENT-SNAPSHOT-2023-10-15-a",
                         version: {
                             major: 5,
                             minor: 10,
                             branch: "development",
                             date: "2023-10-15",
+                            name: "swift-DEVELOPMENT-SNAPSHOT-2023-10-15-a",
                             type: "snapshot",
                         },
                     },
                 ],
             };
 
-            mockUtilities.execFile
-                .withArgs("swiftly", ["list-available", "--format=json"])
-                .resolves({
-                    stdout: JSON.stringify(jsonOutput),
-                    stderr: "",
-                });
+            mockUtilities.execFile.withArgs("swiftly", ["list", "--format=json"]).resolves({
+                stdout: JSON.stringify(jsonOutput),
+                stderr: "",
+            });
 
             const result = await Swiftly.listAvailableToolchains();
 
@@ -93,7 +88,7 @@ suite("Swiftly Unit Tests", () => {
 
             expect(mockUtilities.execFile).to.have.been.calledWith("swiftly", ["--version"]);
             expect(mockUtilities.execFile).to.have.been.calledWith("swiftly", [
-                "list-available",
+                "list",
                 "--format=json",
             ]);
         });