feat(builder): add --metafile flag (#6212)

**What's the problem this PR addresses?**
<!-- Describe the rationale of your PR. -->
<!-- Link all issues that it closes. (Closes/Resolves #xxxx.) -->

resolves #6211

...

**How did you fix it?**

- added a boolean CLI switch to `builder build {bundle,plugin}` called
`--metafile`, defaults to `false`
- if CLI switch 
  - is `false`,  then the `esbuild` in instructed to NOT emit `metafile`
  - is `true`, then ...
    - the `esbuild` in instructed to emit `metafile`
- the `metafile` data is written to target file
`bundles/${name}.meta.json`
    - the target file is announced in the summary  
      example ourput:   
      ```shellSession
      $ builder build plugin --metafile 
      ➤ YN0000: ┌ Building @yarnpkg/plugin-cyclonedx
      ➤ YN0000: └ Completed in 8s 619ms
      
      ➤ YN0000: ✓ Done building @yarnpkg/plugin-cyclonedx!
➤ YN0000: ? Bundle path:
/.../cyclonedx-node-yarn/bundles/@yarnpkg/plugin-cyclonedx.js
      ➤ YN0000: ? Bundle size: 771.52 KiB
➤ YN0000: ? Bundle meta:
/.../cyclonedx-node-yarn/bundles/@yarnpkg/plugin-cyclonedx.meta.json
      ```
 
<!-- A detailed description of your implementation. -->

...

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---------

Signed-off-by: Jan Kowalleck <jan.kowalleck@gmail.com>
Co-authored-by: merceyz <merceyz@users.noreply.github.com>

.yarn/versions/7ec9c2c1.yml

@@ -0,0 +1,12 @@
+releases:
+  "@yarnpkg/builder": minor
+
+declined:
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/cli"

packages/yarnpkg-builder/sources/commands/build/bundle.ts

@@ -70,6 +70,10 @@ export default class BuildBundleCommand extends Command {
     description: `Includes a source map in the bundle`,
   });
 
+  metafile = Option.Boolean(`--metafile`, false, {
+    description: `Emit a metafile next to the bundle`,
+  });
+
   async execute() {
     const basedir = process.cwd();
     const portableBaseDir = npath.toPortablePath(basedir);
@@ -79,6 +83,7 @@ export default class BuildBundleCommand extends Command {
     const plugins = findPlugins({basedir, profile: this.profile, plugins: this.plugins.map(plugin => path.resolve(plugin))});
     const modules = [...getDynamicLibs().keys()].concat(plugins);
     const output = ppath.join(portableBaseDir, `bundles/yarn.js`);
+    const metafile = this.metafile ? ppath.join(portableBaseDir, `bundles/yarn.meta.json`) : false;
 
     let version = pkgJsonVersion(basedir);
 
@@ -132,6 +137,7 @@ export default class BuildBundleCommand extends Command {
             }),
           },
           outfile: npath.fromPortablePath(output),
+          metafile: metafile !== false,
           // Default extensions + .mjs
           resolveExtensions: [`.tsx`, `.ts`, `.jsx`, `.mjs`, `.js`, `.css`, `.json`],
           logLevel: `silent`,
@@ -160,6 +166,10 @@ export default class BuildBundleCommand extends Command {
         }
 
         await xfs.chmodPromise(output, 0o755);
+
+        if (metafile) {
+          await xfs.writeFilePromise(metafile, JSON.stringify(res.metafile));
+        }
       });
     });
 
@@ -174,6 +184,8 @@ export default class BuildBundleCommand extends Command {
       report.reportInfo(null, `${Mark.Question} Bundle path: ${formatUtils.pretty(configuration, output, formatUtils.Type.PATH)}`);
       report.reportInfo(null, `${Mark.Question} Bundle size: ${formatUtils.pretty(configuration, (await xfs.statPromise(output)).size, formatUtils.Type.SIZE)}`);
       report.reportInfo(null, `${Mark.Question} Bundle version: ${formatUtils.pretty(configuration, version, formatUtils.Type.REFERENCE)}`);
+      if (metafile)
+        report.reportInfo(null, `${Mark.Question} Bundle meta: ${formatUtils.pretty(configuration, metafile, formatUtils.Type.PATH)}`);
 
       report.reportSeparator();
 

packages/yarnpkg-builder/sources/commands/build/plugin.ts

@@ -54,6 +54,10 @@ export default class BuildPluginCommand extends Command {
     description: `Includes a source map in the bundle`,
   });
 
+  metafile = Option.Boolean(`--metafile`, false, {
+    description: `Emit a metafile next to the bundle`,
+  });
+
   async execute() {
     const basedir = process.cwd();
     const portableBaseDir = npath.toPortablePath(basedir);
@@ -63,6 +67,7 @@ export default class BuildPluginCommand extends Command {
     const name = getNormalizedName(rawName);
     const prettyName = structUtils.prettyIdent(configuration, structUtils.parseIdent(name));
     const output = ppath.join(portableBaseDir, `bundles/${name}.js`);
+    const metafile = this.metafile ? ppath.join(portableBaseDir, `bundles/${name}.meta.json`) : false;
 
     await xfs.mkdirPromise(ppath.dirname(output), {recursive: true});
 
@@ -113,6 +118,7 @@ export default class BuildPluginCommand extends Command {
           entryPoints: [path.resolve(basedir, main ?? `sources/index`)],
           bundle: true,
           outfile: npath.fromPortablePath(output),
+          metafile: metafile !== false,
           // Default extensions + .mjs
           resolveExtensions: [`.tsx`, `.ts`, `.jsx`, `.mjs`, `.js`, `.css`, `.json`],
           logLevel: `silent`,
@@ -139,6 +145,10 @@ export default class BuildPluginCommand extends Command {
           report.reportWarning(MessageName.UNNAMED, `${warning.location.file}:${warning.location.line}:${warning.location.column}`);
           report.reportWarning(MessageName.UNNAMED, `   ↳ ${warning.text}`);
         }
+
+        if (metafile) {
+          await xfs.writeFilePromise(metafile, JSON.stringify(res.metafile));
+        }
       });
     });
 
@@ -152,6 +162,9 @@ export default class BuildPluginCommand extends Command {
       report.reportInfo(null, `${Mark.Check} Done building ${prettyName}!`);
       report.reportInfo(null, `${Mark.Question} Bundle path: ${formatUtils.pretty(configuration, output, formatUtils.Type.PATH)}`);
       report.reportInfo(null, `${Mark.Question} Bundle size: ${formatUtils.pretty(configuration, (await xfs.statPromise(output)).size, formatUtils.Type.SIZE)}`);
+      if (metafile) {
+        report.reportInfo(null, `${Mark.Question} Bundle meta: ${formatUtils.pretty(configuration, metafile, formatUtils.Type.PATH)}`);
+      }
     }
 
     return report.exitCode();