[Node 20] ESM Loaders no longer have process.argv access

[lukeed]

Version

20.x

Platform

Darwin MacBook-Pro-2.local 21.3.0 Darwin Kernel Version 21.3.0: Wed Jan 5 21:37:58 PST 2022; root:xnu-8019.80.24~20/RELEASE_ARM64_T6000 arm64

Subsystem

No response

What steps will reproduce the bug?

// foo.mjs
console.log('argv:', process.argv);

// bar.mjs
console.log('hello from bar', process.version);

Run:

$ node --loader ./foo.mjs bar.mjs --hello=world

Output:

$ node --loader ./foo.mjs bar.mjs --hello=world
# (node:37260) ExperimentalWarning: Custom ESM Loaders is an experimental feature. This feature could change at any time
# (Use `node --trace-warnings ...` to show where the warning was created)
# argv: [
#   '/.../.volta/tools/image/node/18.12.1/bin/node',
#   '/.../bar.mjs',
#  '--hello=world'
# ]
# hello from bar v18.12.1

$ volta install node@20.2.0 # or any 20.x
$ node --loader ./foo.mjs bar.mjs --hello=world
# (node:37288) ExperimentalWarning: Custom ESM Loaders is an experimental feature and might change at any time
# (Use `node --trace-warnings ...` to show where the warning was created)
# argv: [ '/.../.volta/tools/image/node/20.2.0/bin/node' ]
# hello from bar v20.2.0

How often does it reproduce? Is there a required condition?

Every time.

What is the expected behavior? Why is that the expected behavior?

Have access to process.argv

What do you see instead?

Doesn't receive any arguments beyond node path

Additional information

This is a breaking change introduced by #44710 & it was not listed in the PR notes.

Additionally, this breaking change wasn't listed in the 20.x Changelog

As indicated by #44710 (comment), the knowledge of this impact is assumed based on the user understanding (& awareness) of loaders now being off main thread.

[tniessen]

cc @nodejs/loaders

[JakobJingleheimer]

As you are clearly aware: we are aware of the undesirable limitation and are already working to address it. This breaking change in the major release is a (known and documented) byproduct of the breaking change cited in the release for this experimental feature.

We believe we are close to resolving this. The design discussion is here: nodejs/loaders#147 and the draft implementation is here: #48439