[Bug] SyntaxError when running a "bin" file that isn't authored in JS

• I’d be willing to implement a fix

Describe the bug

Yarn 2.0 fails with a SyntaxError when running a bin file that isn’t authored in JS. For example, the bin file may be an executable file with a shebang #!/usr/bin/env sh.

Example bin file:

#!/usr/bin/env sh
echo 'Hello world!'

To Reproduce

See sample package (@cameronhunter/berry-bin-bug) that defines a bin that is an executable file with a shebang.

const { promises: { writeFile, chmod } } = require('fs');

await writeFile('./hello-world', '#!/usr/bin/env sh\necho "Hello world!"');
await chmod('./hello-world', 0o765);

await packageJsonAndInstall({
  bin: { 'hello-world': './hello-world' }
});

await expect(yarn('hello-world')).resolves.toContain('Hello world!');

Example of failure:

$ yarn berry-bin-bug
/Users/chunter/workspace/github/cameronhunter/berry-bin-bug/bin/berry-bin-bug:3
echo "Hello world!"
     ^^^^^^^^^^^^^^

SyntaxError: Unexpected string
    at Module._compile (internal/modules/cjs/loader.js:895:18)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:995:10)
    at Module.load (internal/modules/cjs/loader.js:815:32)
    at Function.module_1.Module._load (/Users/chunter/workspace/github/cameronhunter/berry-bin-bug/.pnp.js:13519:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10)
    at internal/main/run_main_module.js:17:11

Environment if relevant (please complete the following information):

• OS: MacOS Mojave (10.14.5)
• Node version: 12.14.0
• Yarn version: 2.0.0-rc.28

[cameronhunter]

Thanks for your response, @arcanis. Cross-platform isn’t a goal for many of our (internal) tools so it’s a shame that we have to spin up node to execute a shebang executable. I can certainly work around this using your suggestion though.

Perhaps this ticket could be changed to focus on improving the error message so that other users don’t fall into the same confusion.

Side-question: Is cross-platform portability a goal of berry or is it more the implementation detail of not being able to run them from zip archives?

[ti1024]

Some NPM packages (e.g., https://www.npmjs.com/package/elm) are meant to provide a native binary executable for various platforms and expose it so that it can be found via PATH when run from a script specified in package.json (often indirectly, e.g., via a specific loader for webpack). These packages cannot be used with Yarn Berry, even with yarn unplug (or even without Plug’n’Play altogether).

Can Yarn provide a configuration option to skip the shell script shim for a particular executable?