[v3.0] Always try to load config files via Node if possible

[lukastaegert]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

• resolves Error TRANSPILED_ESM_CONFIG provides insufficient information #4616
• resolves Rollup throws TRANSPILED_ESM_CONFIG error when importing ESM module #4617
• resolves Rollup cant parse plugin that dependend on ES package #4619

Description

As it turns out, bundling a config to CommonJS will not allow users to directly import ESM-only plugins. The solution here is to

• Load the config via Node's native mechanism if there is no --configPlugin
• Provide a helpful error message if this fails
• Add a timestamp parameter when loading in watch mode to allow reloading the config
• If a --configPlugin is used, we bundle to ESM instead of CJS to fix a similar issue with TypeScript configs. To allow loading the bundled config, we temporarily write it to disk with a timestamp in the name and extension .mjs and delete it again after loading.
• Add a new option --bundleConfigAsCjs to force bundling the config to CommonJS instead, even if no --configPlugin is used. We use the .cjs extension instead in this case. This also serves as a compatibility mode to e.g. run ESM configs that depend on things like __dirname.

[github-actions]

Thank you for your contribution! ❤️

You can try out this pull request locally by installing Rollup via

npm install rollup/rollup#esm-load-config

or load it into the REPL:
https://rollupjs.org/repl/?pr=4621

[codecov]

Codecov Report

Merging #4621 (51096cc) into release-3.0.0 (eac06ac) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@                Coverage Diff                @@
##           release-3.0.0    #4621      +/-   ##
=================================================
+ Coverage          98.97%   98.99%   +0.01%     
=================================================
  Files                211      211              
  Lines               7428     7439      +11     
  Branches            2101     2105       +4     
=================================================
+ Hits                7352     7364      +12     
  Misses                23       23              
+ Partials              53       52       -1     

Impacted Files	Coverage Δ
src/utils/options/mergeOptions.ts	100.00% <ø> (ø)
cli/run/loadConfigFile.ts	96.61% <100.00%> (+2.61%)	⬆️
src/utils/error.ts	99.46% <100.00%> (+<0.01%)	⬆️

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[rollup-bot]

This PR has been released as part of rollup@3.0.0-5. Note that this is a pre-release, so to test it, you need to install Rollup via npm install rollup@3.0.0-5 or npm install rollup@beta. It will likely become part of a regular release later.

[rollup-bot]

This PR has been released as part of rollup@3.0.0-6. Note that this is a pre-release, so to test it, you need to install Rollup via npm install rollup@3.0.0-6 or npm install rollup@beta. It will likely become part of a regular release later.

[rollup-bot]

This PR has been released as part of rollup@3.0.0-7. Note that this is a pre-release, so to test it, you need to install Rollup via npm install rollup@3.0.0-7 or npm install rollup@beta. It will likely become part of a regular release later.

[rollup-bot]

This PR has been released as part of rollup@3.0.0-8. Note that this is a pre-release, so to test it, you need to install Rollup via npm install rollup@3.0.0-8 or npm install rollup@beta. It will likely become part of a regular release later.

[rollup-bot]

This PR has been released as part of rollup@3.0.0. You can test it via npm install rollup.