acorn-walk does not work with injected plugins

[kristoferbaxter]

Hello,

I've been attempting to use acorn-walk with the acorn-dynamic-import plugin both before and after the version 6 update. So far, have been quite unsuccessful with even the most basic examples.

I created a repo demonstrating the issue: https://github.com/kristoferbaxter/dynamic-walk

Essentially it appears that extensions to base are not leveraged within the simple or ancestor methods.

ampproject/rollup-plugin-closure-compiler#48 was the start of this issue – trying to add support for dynamic import to a rollup plugin for minification with closure compiler.

[marijnh]

Good point. I don't think this worked pre-6.0 either. The problem appears to be that the functions exported from acorn-walk default to the base visitor that they close over, which will not be the modified one produced by the inject function exported by acorn-dynamic-import. You can work around it by passing walk.base as a third argument to walk.simple, so that it'll use that one rather than the one it closed over.

I'm not sure how we can work around this in a backwards-compatible way (apart from fragile hacks which depend on this being bound to the module). I think the premise of that inject function is kind of wrong, and it should just take and return a base visitor object, to make it obvious that the user is responsible for passing that to the walker functions.

[kristoferbaxter]

Thanks for the followup, this issue did exist pre-6.0 as well in my tests. I delayed reporting it since the migration to 6.0 was just beginning when I first encountered it. In retrospect, I should have filed it then.

I think the premise of that inject function is kind of wrong, and it should just take and return a base visitor object, to make it obvious that the user is responsible for passing that to the walker functions.

That seems like a viable path forward to me. Will use the workaround you suggest until an official path forward is created.