fix(dev-infra): formatting errors not reported with failure message (#42202)

Currently if formatting for a file fails due a formatter error,
the `ng-dev` tool reports that formatting failed, but no actual
error (or involved file) is printed out. This commit prints out
the failed files with their error message.

PR Close #42202

dev-infra/format/format.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {error, info, promptConfirm} from '../utils/console';
+import {error, info, promptConfirm, red} from '../utils/console';
 
 import {runFormatterInParallel} from './run-commands-parallel';
 
@@ -24,7 +24,11 @@ export async function formatFiles(files: string[]) {
 
   // The process should exit as a failure if any of the files failed to format.
   if (failures.length !== 0) {
-    error(`Formatting failed, see errors above for more information.`);
+    error(red(`The following files could not be formatted:`));
+    failures.forEach(({filePath, message}) => {
+      info(`  • ${filePath}: ${message}`);
+    });
+    error(red(`Formatting failed, see errors above for more information.`));
     process.exit(1);
   }
   info(`√  Formatting complete.`);
@@ -46,8 +50,8 @@ export async function checkFiles(files: string[]) {
   if (failures.length) {
     // Provide output expressing which files are failing formatting.
     info.group('\nThe following files are out of format:');
-    for (const file of failures) {
+    for (const {filePath} of failures) {
-      info(`  - ${file}`);
+      info(`  • ${filePath}`);
     }
     info.groupEnd();
     info();
@@ -60,7 +64,7 @@ export async function checkFiles(files: string[]) {
 
     if (runFormatter) {
       // Format the failing files as requested.
-      await formatFiles(failures);
+      await formatFiles(failures.map(f => f.filePath));
       process.exit(0);
     } else {
       // Inform user how to format files in the future.

dev-infra/format/run-commands-parallel.ts

@@ -17,6 +17,14 @@ import {Formatter, FormatterAction, getActiveFormatters} from './formatters/inde
 
 const AVAILABLE_THREADS = Math.max(cpus().length - 1, 1);
 
+/** Interface describing a failure occurred during formatting of a file. */
+export interface FormatFailure {
+  /** Path to the file that failed. */
+  filePath: string;
+  /** Error message reported by the formatter. */
+  message: string;
+}
+
 /**
  * Run the provided commands in parallel for each provided file.
  *
@@ -30,9 +38,9 @@ const AVAILABLE_THREADS = Math.max(cpus().length - 1, 1);
  * The promise resolves with a list of failures, or `false` if no formatters have matched.
  */
 export function runFormatterInParallel(allFiles: string[], action: FormatterAction) {
-  return new Promise<false|string[]>((resolve) => {
+  return new Promise<false|FormatFailure[]>((resolve) => {
     const formatters = getActiveFormatters();
-    const failures: string[] = [];
+    const failures: FormatFailure[] = [];
     const pendingCommands: {formatter: Formatter, file: string}[] = [];
 
     for (const formatter of formatters) {
@@ -85,7 +93,7 @@ export function runFormatterInParallel(allFiles: string[], action: FormatterActi
             // Run the provided callback function.
             const failed = formatter.callbackFor(action)(file, code, stdout, stderr);
             if (failed) {
-              failures.push(file);
+              failures.push({filePath: file, message: stderr});
             }
             // Note in the progress bar another file being completed.
             progressBar.increment(1);

dev-infra/ng-dev.js

@@ -2591,7 +2591,7 @@ function runFormatterInParallel(allFiles, action) {
                 // Run the provided callback function.
                 const failed = formatter.callbackFor(action)(file, code, stdout, stderr);
                 if (failed) {
-                    failures.push(file);
+                    failures.push({ filePath: file, message: stderr });
                 }
                 // Note in the progress bar another file being completed.
                 progressBar.increment(1);
@@ -2639,7 +2639,11 @@ function formatFiles(files) {
         }
         // The process should exit as a failure if any of the files failed to format.
         if (failures.length !== 0) {
-            error(`Formatting failed, see errors above for more information.`);
+            error(red(`The following files could not be formatted:`));
+            failures.forEach(({ filePath, message }) => {
+                info(`  • ${filePath}: ${message}`);
+            });
+            error(red(`Formatting failed, see errors above for more information.`));
             process.exit(1);
         }
         info(`√  Formatting complete.`);
@@ -2660,8 +2664,8 @@ function checkFiles(files) {
         if (failures.length) {
             // Provide output expressing which files are failing formatting.
             info.group('\nThe following files are out of format:');
-            for (const file of failures) {
+            for (const { filePath } of failures) {
-                info(`  - ${file}`);
+                info(`  • ${filePath}`);
             }
             info.groupEnd();
             info();
@@ -2672,7 +2676,7 @@ function checkFiles(files) {
             }
             if (runFormatter) {
                 // Format the failing files as requested.
-                yield formatFiles(failures);
+                yield formatFiles(failures.map(f => f.filePath));
                 process.exit(0);
             }
             else {