Allow packageManager to be specified by name alone

sources/commands/Base.ts

@@ -14,7 +14,7 @@ export abstract class BaseCommand extends Command<Context> {
 
     const resolvedSpecs = all
       ? await this.context.engine.getDefaultDescriptors()
-      : patterns.map(pattern => specUtils.parseSpec(pattern, `CLI arguments`, {enforceExactVersion: false}));
+      : patterns.map(pattern => specUtils.parseSpec(pattern, `CLI arguments`));
 
     if (resolvedSpecs.length === 0) {
       const lookup = await specUtils.loadSpec(this.context.cwd);

sources/commands/InstallGlobal.ts

@@ -52,7 +52,7 @@ export class InstallGlobalCommand extends BaseCommand {
         if (arg.endsWith(`.tgz`)) {
           await this.installFromTarball(path.resolve(this.context.cwd, arg));
         } else {
-          await this.installFromDescriptor(specUtils.parseSpec(arg, `CLI arguments`, {enforceExactVersion: false}));
+          await this.installFromDescriptor(specUtils.parseSpec(arg, `CLI arguments`));
         }
       }
     } else {

sources/commands/Use.ts

@@ -15,8 +15,14 @@ export class UseCommand extends BaseCommand {
       automatically perform an install.
     `,
     examples: [[
-      `Configure the project to use the latest Yarn release`,
-      `corepack use 'yarn@*'`,
+      `Configure the project to use the latest pnpm release`,
+      `corepack use pnpm`,
+    ], [
+      `Use a tagged version`,
+      `corepack use yarn@stable`,
+    ], [
+      `Use a partial version number`,
+      `corepack use 'yarn@3'`,
     ]],
   });
 

sources/commands/deprecated/Prepare.ts

@@ -58,7 +58,7 @@ export class PrepareCommand extends Command<Context> {
 
     for (const request of specs) {
       const spec = typeof request === `string`
-        ? specUtils.parseSpec(request, `CLI arguments`, {enforceExactVersion: false})
+        ? specUtils.parseSpec(request, `CLI arguments`)
         : request;
 
       const resolved = await this.context.engine.resolveDescriptor(spec, {allowTags: true});

sources/specUtils.ts

@@ -1,27 +1,29 @@
 import {UsageError}                                     from 'clipanion';
 import fs                                               from 'fs';
 import path                                             from 'path';
-import semver                                           from 'semver';
 
 import {Descriptor, Locator, isSupportedPackageManager} from './types';
 
 const nodeModulesRegExp = /[\\/]node_modules[\\/](@[^\\/]*[\\/])?([^@\\/][^\\/]*)$/;
 
-export function parseSpec(raw: unknown, source: string, {enforceExactVersion = true} = {}): Descriptor {
+export function parseSpec(raw: unknown, source: string): Descriptor {
   if (typeof raw !== `string`)
     throw new UsageError(`Invalid package manager specification in ${source}; expected a string`);
 
-  const match = raw.match(/^(?!_)(.+)@(.+)$/);
-  if (match === null || (enforceExactVersion && !semver.valid(match[2])))
-    throw new UsageError(`Invalid package manager specification in ${source}; expected a semver version${enforceExactVersion ? `` : `, range, or tag`}`);
+  const match = /^(@?[^@]+)(?:@(.+))?$/.exec(raw);
+  const name = match?.[1];
+  const range = match?.[2] ?? `*`;
 
-  if (!isSupportedPackageManager(match[1]))
+  if (!name) {
+    throw new UsageError(
+      `Invalid package manager specification in ${source}. Could not determine package manager name`,
+    );
+  }
+
+  if (!isSupportedPackageManager(name))
     throw new UsageError(`Unsupported package manager specification (${match})`);
 
-  return {
-    name: match[1],
-    range: match[2],
-  };
+  return {name, range};
 }
 
 /**