Monorepo with Yarn PnP in the root and standalone project with esbuild in a subdir

[JanVoracek]

We have a repository with the following structure:

.
├── .pnp.cjs
├── package.json // { "workspaces": ["packages/*"] } - notice that `prototypes` are not part of the workspaces
├── packages
│   ├── package-a/
│   ├── package-b/
│   └── ...
└── prototypes
    ├── esbuild-prototype // uses npm
    │   ├── package.json
    │   └── package-lock.json
    ├── some-other-prototype // can use pnpm, yarn + node_modules linker, etc.
    └── ...

In this case, the esbuild bundler doesn't work correctly because it finds the .pnp.cjs file in the repository root and tries to resolve dependencies using the PnP strategy - even though the esbuild project is not part of the Yarn workspaces and doesn't even use Yarn at all.

[merceyz]

This is working as intended, if you want a directory to not be part of the project you need to tell Yarn about it using pnpIgnorePatterns.

pnpIgnorePatterns:
    - "./prototypes/**"

[evanw]

Closing because it sounds like this is working as intended, and there is an easy workaround available.

[JanVoracek]

I'm not sure it works as intended. Here's a demo repository that reproduces the problem: https://github.com/JanVoracek/esbuild-yarn-demo. There is also a GH Action demonstrating the failure: https://github.com/JanVoracek/esbuild-yarn-demo/actions/runs/2998205785

Also, it seems that Yarn can resolve the import but esbuild crashes on Could not resolve "react" anyway:

$ echo "[\"react\", \"$PWD/prototypes/esbuild-prototype/src/app.tsx\"]" | node .pnp.cjs
[null,".../prototypes/esbuild-prototype/node_modules/react/index.js"]

[evanw]

Thank you for providing a way to reproduce this. It looks like the problem is that Yarn's regular expression for ignorePatternData uses regular expression features that work in JavaScript but not in Go. Specifically this is not a valid Go regular expression:

(^(?:\.yarn\/sdks(?:\/(?!\.{1,2}(?:\/|$))(?:(?:(?!(?:^|\/)\.{1,2}(?:\/|$)).)*?)|$))$)|(^(?:prototypes(?:\/(?!\.{1,2}(?:\/|$))(?:(?:(?!(?:^|\/)\.{1,2}(?:\/|$)).)*?)|$))$)

I'm not sure what to do about this.

Edit: Pretty-printed:

(
  ^(
    ?:\.yarn\/sdks(
      ?:\/(
        ?!\.{1,2}(
          ?:\/|$
        )
      )(
        ?:(
          ?:(
            ?!(
              ?:^|\/
            )\.{1,2}(
              ?:\/|$
            )
          ).
        )*?
      )|$
    )
  )$
)|(
  ^(
    ?:prototypes(
      ?:\/(
        ?!\.{1,2}(
          ?:\/|$
        )
      )(
        ?:(
          ?:(
            ?!(
              ?:^|\/
            )\.{1,2}(
              ?:\/|$
            )
          ).
        )*?
      )|$
    )
  )$
)

The problematic part is the use of (?! which Go doesn't support.

[evanw]

Perhaps I can just manually strip (?!\.{1,2}(?:\/|$)) and (?!(?:^|\/)\.{1,2}(?:\/|$)) from this regular expression. They seem to be used by Yarn to guard against the . and .. path segments in the middle of a relative URL. But esbuild will never generate such path segments, so I don't think these cases will ever be hit? In any case, stripping these means these regular expression has a better chance of working which is better than what's happening now. Stripping these fixes this issue, for example.