fix(@angular/cli): ensure full process exit with older local CLI versions

packages/angular/cli/lib/init.ts

@@ -10,12 +10,20 @@ import 'symbol-observable';
 // symbol polyfill must go first
 import { promises as fs } from 'fs';
 import * as path from 'path';
-import { SemVer } from 'semver';
+import { SemVer, major } from 'semver';
 import { colors } from '../src/utilities/color';
 import { isWarningEnabled } from '../src/utilities/config';
 import { disableVersionCheck } from '../src/utilities/environment-options';
 import { VERSION } from '../src/utilities/version';
 
+/**
+ * Angular CLI versions prior to v14 may not exit correctly if not forcibly exited
+ * via `process.exit()`. When bootstrapping, `forceExit` will be set to `true`
+ * if the local CLI version is less than v14 to prevent the CLI from hanging on
+ * exit in those cases.
+ */
+let forceExit = false;
+
 (async () => {
   /**
    * Disable Browserslist old data warning as otherwise with every release we'd need to update this dependency
@@ -57,6 +65,11 @@ import { VERSION } from '../src/utilities/version';
       }
     }
 
+    // Ensure older versions of the CLI fully exit
+    if (major(localVersion) < 14) {
+      forceExit = true;
+    }
+
     let isGlobalGreater = false;
     try {
       isGlobalGreater = !!localVersion && globalVersion.compare(localVersion) > 0;
@@ -107,6 +120,9 @@ import { VERSION } from '../src/utilities/version';
     });
   })
   .then((exitCode: number) => {
+    if (forceExit) {
+      process.exit(exitCode);
+    }
     process.exitCode = exitCode;
   })
   .catch((err: Error) => {

tests/legacy-cli/e2e/tests/misc/cli-exit-interop.ts

@@ -0,0 +1,34 @@
+import { createProjectFromAsset } from '../../utils/assets';
+import { moveFile, replaceInFile } from '../../utils/fs';
+import { setRegistry } from '../../utils/packages';
+import { noSilentNg } from '../../utils/process';
+import { useCIChrome } from '../../utils/project';
+import { expectToFail } from '../../utils/utils';
+
+/**
+ * @fileoverview This tests that using the latest version of the CLI globally does not cause older (< 14)
+ * versions of the CLI to never exit after completing certain commands.
+ * This test will timeout in a failure condition.
+ */
+
+export default async function () {
+  try {
+    // We need to use the public registry because in the local NPM server we don't have
+    // older versions @angular/cli packages which would cause `npm install` during `ng update` to fail.
+    await setRegistry(false);
+    await createProjectFromAsset('12.0-project', true);
+
+    // A missing stylesheet error will trigger the stuck process issue with v12 when building
+    await moveFile('src/styles.css', 'src/styles.scss');
+    await expectToFail(() => noSilentNg('build'));
+
+    // Setup a SCSS global stylesheet
+    // Simulates issue https://github.com/angular/angular-cli/issues/23289
+    await replaceInFile('angular.json', /styles\.css/g, 'styles.scss');
+
+    await useCIChrome();
+    await noSilentNg('test', '--watch=false');
+  } finally {
+    await setRegistry(true);
+  }
+}