fix(gatsby-plugin-mdx): support yarn PnP

[kevin940726]

Description

See yarnpkg/berry#689 (comment)

In order to support yarn PnP, dependencies have to be explicit listed or required from their direct parents. gatsby-plugin-mdx has required some dependencies which are not listed in package.json, but sub-dependencies of @mdx-js/mdx.

We have 2 options to fix this:

1. List the dependencies explicitly. But we have to remember to update the range whenever @mdx-js/mdx updates. It would soon become troublesome and tedious.
2. Require the packages anyways, but require them from the @mdx-js/mdx package via Module.createRequire.

This PR goes for the second approach. The createRequireFromPath util is already implemented in the core package from gatsby/src/utils/create-require-from-path.js. We can just use it here. (Now that it's used by a plugin, should we move it to gatsby-core-utils or something similar?)

Documentation

https://next.yarnpkg.com/features/pnp/, and https://next.yarnpkg.com/advanced/migration

Related Issues

Related to yarnpkg/berry#689. c.c. @arcanis

[kevin940726]

yarn 2 has now been released! Any chance we can take a look at this again 😉? @pieh? (Sorry if I pinged the wrong person)

[pieh]

Just a note - I just published gatsby-plugin-mdx@berry-mdx with changes from this (+ bunch of other packages like gatsby-core-utils, gatsby etc) and will be testing this out. But you could already start using those dist-tags if you use Yarn 2 in meantime.

[pieh]

Ok, after few bumps, I did get it to build it when using Yarn2 (see appendix :P) and I think we should get this in. @johno do you want to check changes to gatsby-plugin-mdx here? (I think they make total sense).

-- Yarn 2 appendix

• was getting:

YN0001: │ Error: fsevents@patch:fsevents@npm%3A2.0.7#builtin<compat/fsevents>::version=2.0.7&hash=e8cd9e: Cannot apply hunk #1
    at c (/Users/misiek/test/pr20638/.yarn/releases/yarn-berry.js:58:888149)
    at process._tickCallback (internal/process/next_tick.js:68:7)

which I solved with resolutions by pinning fsevents to 2.1.2 (per yarnpkg/berry#719)

• was getting:

Error: Something that got detected as your top-level application (because it doesn't seem to belong to any package) tried to access a package that is not declared in your dependencies
  Required package: minimatch (via "minimatch")
  Required by: /Users/misiek/test/pr20638/public/
  Require stack:
  - /Users/misiek/test/pr20638/public/render-page.js
  - /Users/misiek/test/pr20638/.yarn/unplugged/gatsby-virtual-1919d581a5/node_modules/gatsby/dist/utils/worker/render-html.js
  - /Users/misiek/test/pr20638/.yarn/unplugged/gatsby-virtual-1919d581a5/node_modules/gatsby/dist/utils/worker/child.js
  - /Users/misiek/test/pr20638/.yarn/cache/jest-worker-npm-24.9.0-bcd452e3a8-1.zip/node_modules/jest-worker/build/workers/processChild.js

which I hackily solved by installing minimatch in project (but that's something we will need to handle in core most likely, because this is where we generate render-page.js - tho I'm not sure if this is because of gatsby core or some other plugin that was in mdx starter that I was using as test case)

[johno]

✨ lgtm, thanks @kevin940726!

I would've leaned towards making the versions explicit in the package.json since both Gatsby and MDX core automatically bump dep versions on a quick cadence, but this will work!

[gatsbot]

Holy buckets, @kevin940726 — we just merged your PR to Gatsby! 💪💜

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[pieh]

Published gatsby-plugin-mdx@1.0.69, thanks @kevin940726 for the fixes!