Incremental build not working with React.lazy loaded component when a gatsby-config file exists

[joiglifberg]

Preliminary Checks

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Description

Gatsby does not update a page with Incremental build when a change in a component imported with React.lazy AND a gatsby-config file exists.

The first video displays when a gatsby-config exist and therefore it's not working.
In the second video, the gatsby-config file is deleted and the change in the React.lazy loaded component is detected and the page updated.

Screen.Recording.2023-02-27.at.14.28.31.mp4

Screen.Recording.2023-02-27.at.14.30.45.mp4

Reproduction Link

https://github.com/joiglifberg/gatsby-incremental-build-react-lazy-gatsby-config-reproduction

Steps to Reproduce

1. Download the repo
2. Run npx gatsby build --log-pages.
   Updated page: / is displayed.
3. Make a change in the component src/MyComponent.js
4. Run npx gatsby build --log-pages.
   There are no new or changed html files to build. is displayed.

Expected Result

I expect the page / to have been updated and the console output to be Updated page: /

Actual Result

The page / has not been updated and the console output is There are no new or changed html files to build.

Environment

System:
    OS: macOS 13.2
    CPU: (10) arm64 Apple M1 Pro
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 18.14.2 - ~/.nvm/versions/node/v18.14.2/bin/node
    npm: 9.5.0 - ~/.nvm/versions/node/v18.14.2/bin/npm
  Browsers:
    Safari: 16.3
  npmPackages:
    gatsby: ^5.7.0 => 5.7.0

Config Flags

No response

[pieh]

I did initial investigation - I think there are 2 discrete bugs:

1. relates to not tracking lazily loaded components when checking wether to rebuild pages from template which is main issue presented here
2. we are setting some internal flags only when gatsby-config exist, and when it doesn't gatsby does pre-v5 behaviour when it comes to figuring out which templates to regenerate (in this case change to any frontend file triggers regenerating all html files not just the ones that should be affected - so while this could help with workaround the issue if you don't need config, it's also not the most efficent)

[pieh]

#37712 adds a test case and a fix. I won't be able to get review on this until at least Monday, but at least letting you know that potential fix was prepared

[rebeljoi]

@pieh I see that the two referenced PRs has been merged. Will this be fixed in 5.8.0 or in a patch version of 5.7.x?

[pieh]

@rebeljoi Ah sorry. This is available now in gatsby@next so you could use that temporarily. This change has slight potential on introducing regresion elsewhere due to not using guaranteed stable sorted list of dynamic imports so we didn't want to backport it to stable / latest and monitor behaviour with this change. If we won't notice regressions this will be included in 5.8.0 that will be released in ~10 days

[rebeljoi]

@pieh Any status update?

[rebeljoi]

I can confirm this was fixed by #37749 which was released in https://www.gatsbyjs.com/docs/reference/release-notes/v5.8/.
Please close this issue.