mdx: plugin.resolve doesn't actually resolve anymore; throws error on build

[davwheat]

Preliminary Checks

• This issue is not a duplicate. Before opening a new issue, please search existing issues: https://github.com/gatsbyjs/gatsby/issues
• This issue is not a question, feature request, RFC, or anything other than a bug report directly related to Gatsby. Please post those things in GitHub Discussions: https://github.com/gatsbyjs/gatsby/discussions

Description

During the patches for Gatsby v4, it seems that plugin.resolve has stopped being resolved to a module in the MDX plugin.

https://github.com/gatsbyjs/gatsby/blame/58d30fd9a5d85a31a29a404ce01b74fb5e7dbb7b/packages/gatsby-plugin-mdx/gatsby/create-schema-customization.js#L76-L77

Previous to #33170, plugin.resolve used to get required inside the MDX plugin. If this has been deprecated, it wasn't mentioned anywhere, and should be added to the v4 upgrade guide,

I don't think this is intentional, as it also breaks the short-hand plugin syntax where we only give the plugin name as a string, rather than a JS object.

Reproduction Link

https://github.com/davwheat/gatsby-issue-reproduction-1

Steps to Reproduce

1. Add gatsbyPlugins to MDX config
2. Use { resolve: 'my-plugin-name' } or 'my-plugin-name'
3. Attempt build

Expected Result

Site should build with plugins used

Actual Result

Build fails as plugin.module is undefined and not resolved from plugin.resolve.

Environment

System:
    OS: Windows 10 10.0.22471
    CPU: (12) x64 AMD Ryzen 5 4600H with Radeon Graphics
  Binaries:
    Node: 15.1.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.5 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 7.6.1 - ~\AppData\Roaming\npm\npm.CMD
  Languages:
    Python: 3.10.0 - /c/Python310/python
  Browsers:
    Edge: Spartan (44.22471.1000.0), Chromium (94.0.992.38)
  npmGlobalPackages:
    gatsby-cli: 3.7.1

Config Flags

No response

[pieh]

Your reproduction is using gatsby@3 (at least to package-lock.json) with mdx package for gatsby@4. You need to either upgrade gatsby or "downgrade" plugins to be compatible.

[LekoArts]

Hi!

Since we didn't receive an answer for 7 days or more about the ask of a reproduction I'm going to close this now, as we can't do much to help without a reproduction. If you are able to create a minimal reproduction for this then please do answer here or open a new issue with a reproduction. Thanks!