Notify build is preparing before progress starts

The build progress notification would only appear once the progress
values were shown in the output, i.e. [12/122]. Until progress values
appear, show a "Preparing <task>" notification. This only needs to apply
when the `showBuildStatus` value is `notification` or `progress`, since
`swiftStatus` already shows a message in the bar immediately.

This patch also only sets the `showBuildStatus` setting on a Task if it
is coming from a user defined task. Previously it was being set on
synthetic tasks which were being cached, so when the user updated the
`showBuildStatus` setting it wouldn't take effect until they restarted
the extension.

Issue: swiftlang#1322

Author: plemarquand

src/SwiftSnippets.ts

@@ -82,7 +82,6 @@ export async function debugSnippetWithOptions(
             presentationOptions: {
                 reveal: vscode.TaskRevealKind.Always,
             },
-            showBuildStatus: configuration.showBuildStatus,
         },
         ctx.toolchain
     );

src/tasks/SwiftTaskProvider.ts

@@ -155,7 +155,6 @@ export function createBuildAllTask(
                 reveal: getBuildRevealOption(),
             },
             disableTaskQueue: true,
-            showBuildStatus: configuration.showBuildStatus,
         },
         folderContext.workspaceContext.toolchain
     );
@@ -239,7 +238,6 @@ function createBuildTasks(product: Product, folderContext: FolderContext): vscod
                 },
                 disableTaskQueue: true,
                 dontTriggerTestDiscovery: true,
-                showBuildStatus: configuration.showBuildStatus,
             },
             folderContext.workspaceContext.toolchain
         );
@@ -268,7 +266,6 @@ function createBuildTasks(product: Product, folderContext: FolderContext): vscod
                 },
                 disableTaskQueue: true,
                 dontTriggerTestDiscovery: true,
-                showBuildStatus: configuration.showBuildStatus,
             },
             folderContext.workspaceContext.toolchain
         );
@@ -314,9 +311,15 @@ export function createSwiftTask(
             args: args,
             env: env,
             cwd: cwd,
-            showBuildStatus: config.showBuildStatus,
-            disableTaskQueue: config.disableTaskQueue,
-            dontTriggerTestDiscovery: config.dontTriggerTestDiscovery,
+            ...(config.showBuildStatus !== undefined
+                ? { showBuildStatus: config.showBuildStatus }
+                : {}),
+            ...(config.disableTaskQueue !== undefined
+                ? { disableTaskQueue: config.disableTaskQueue }
+                : {}),
+            ...(config.dontTriggerTestDiscovery !== undefined
+                ? { dontTriggerTestDiscovery: config.dontTriggerTestDiscovery }
+                : {}),
         },
         config?.scope ?? vscode.TaskScope.Workspace,
         name,

src/ui/SwiftBuildStatus.ts

@@ -71,9 +71,10 @@ export class SwiftBuildStatus implements vscode.Disposable {
                     disposables.forEach(d => d.dispose());
                     res();
                 };
+                const state = { started: false };
                 disposables.push(
                     execution.onDidWrite(data => {
-                        if (this.parseEvents(task, data, update)) {
+                        if (this.parseEvents(task, data, showBuildStatus, update, state)) {
                             done();
                         }
                     }),
@@ -109,7 +110,9 @@ export class SwiftBuildStatus implements vscode.Disposable {
     private parseEvents(
         task: vscode.Task,
         data: string,
-        update: (message: string) => void
+        showBuildStatus: ShowBuildStatusOptions,
+        update: (message: string) => void,
+        state: { started: boolean }
     ): boolean {
         const name = new RunningTask(task).name;
         const sanitizedData = stripAnsi(data);
@@ -124,14 +127,27 @@ export class SwiftBuildStatus implements vscode.Disposable {
             const progress = this.findBuildProgress(line);
             if (progress) {
                 update(`${name} [${progress.completed}/${progress.total}]`);
+                state.started = true;
                 return false;
             }
             if (this.checkIfFetching(line)) {
                 // this.statusItem.update(task, `Fetching dependencies "${task.name}"`);
-                update(`${name} fetching dependencies`);
+                update(`${name}: fetching dependencies`);
+                state.started = true;
                 return false;
             }
         }
+        // If we've found nothing that matches a known state then put up a temporary
+        // message that we're preparing the build, as there is sometimes a delay before
+        // building starts while the build system is preparing, especially in large projects.
+        // The status bar has a message immediately, so only show this when using a
+        // notification to show progress.
+        if (
+            !state.started &&
+            (showBuildStatus === "notification" || showBuildStatus === "progress")
+        ) {
+            update(`Preparing ${name}`);
+        }
         return false;
     }