fix(@angular/cli): add message update updating from non LTS versions of the CLI

Author: alan-agius4

packages/angular/cli/commands/update-impl.ts

@@ -40,8 +40,6 @@ const pickManifest = require('npm-pick-manifest') as (
   selector: string,
 ) => PackageManifest;
 
-const oldConfigFileNames = ['.angular-cli.json', 'angular-cli.json'];
-
 const NG_VERSION_9_POST_MSG = colors.cyan(
   '\nYour project has been updated to Angular version 9!\n' +
   'For more info, please see: https://v9.angular.io/guide/updating-to-version-9',
@@ -367,20 +365,6 @@ export class UpdateCommand extends Command<UpdateCommandSchema> {
     }
 
     this.logger.info(`Using package manager: '${this.packageManager}'`);
-
-    // Special handling for Angular CLI 1.x migrations
-    if (
-      options.migrateOnly === undefined &&
-      options.from === undefined &&
-      packages.length === 1 &&
-      packages[0].name === '@angular/cli' &&
-      this.workspace &&
-      oldConfigFileNames.includes(path.basename(this.workspace.filePath))
-    ) {
-      options.migrateOnly = true;
-      options.from = '1.0.0';
-    }
-
     this.logger.info('Collecting installed dependencies...');
 
     const rootDependencies = await getProjectDependencies(this.context.root);
@@ -623,6 +607,28 @@ export class UpdateCommand extends Command<UpdateCommandSchema> {
         return 1;
       }
 
+      if (node.package?.name === '@angular/cli') {
+        // Migrations for non LTS versions of Angular CLI are no longer included in @schematics/angular v12.
+        const toBeInstalledMajorVersion = +manifest.version.split('.')[0];
+        const currentMajorVersion = +node.package.version.split('.')[0];
+        if (currentMajorVersion < 9 && toBeInstalledMajorVersion >= 12) {
+          const updateVersions: Record<number, number> = {
+            1: 6,
+            6: 7,
+            7: 8,
+            8: 9,
+          };
+
+          const updateTo = updateVersions[currentMajorVersion];
+          this.logger.error('Updating multiple major versions at once is not recommended. ' +
+            `Run 'ng update @angular/cli@${updateTo}' in your workspace directory ` +
+            `to update to latest '${updateTo}.x' version of '@angular/cli'.\n\n` +
+            'For more information about the update process, see https://update.angular.io/.');
+
+          return 1;
+        }
+      }
+
       if (manifest.version === node.package?.version) {
         this.logger.info(`Package '${packageName}' is already up to date.`);
         continue;