TYPO3 Core

I previously reported at https://github.com/TYPO3/CmsComposerInstallers/issues/142 but got told the corresponding code belongs to the core instead.

Another option would be to document, that an extension is only complete with at lease a composer.json AND a Resources/Public/Icons/Extension.[png|svg] file

Other than what you have written, any further idea when exactly should happen what?

Sorry, but I've no good idea.

Would it help to document what TYPO3 does in this process? Or maybe even more verbosely output that on command line when running composer commands?

Yeah, that would help. I guess documenting it somewhere would probably not help, but an more verbose output would help.

How could this be fixed? Any conceptual ideas?

I guess TYPO3 will index.php will be called if an asset is requested that doesn't exist. TYPO3 could check the URL and compare the asset and hash and output an Exception with instructions to check that the folder exists within the extension, and that one needs to trigger dumpautoload.

Another option would be to document, that an extension is only complete with at lease a composer.json AND a Resources/Public/Icons/Extension.[png|svg] file

That sounds like the easiest and best approach. How would that look like? Would composer prevent installing / enabling the extension and output an error instead? Maybe a warning at the moment in order to stay compatible and not breaking?

I created a PR for the docs about how to proceed when adding the Resources/Public folder after installation:
https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-CoreApi/pull/2838

I don't like the idea that an Extension.[svg|png] file must exist as it has only "decorative" character in the extension manager. For a Composer-based installation the extension manager is not really necessary, so why insist to have an extension icon file?

In fact, I am thinking to remove it in my project-specific extensions as it adds no value to the extension and project and is just overhead.

Some suggestions, since you asked for feedback :)

Another option would be to document, that an extension is only complete with at lease a composer.json AND a Resources/Public/Icons/Extension.[png|svg] file

Veto. Extension don't need public resources. This would force developers to add files they dont need. And it would create a bunch of `_assets` symlinks for extension which don't need them at all.

How could this be fixed? Any conceptual ideas?

This only happens when a public directory is expected to exist, but it does not. Typical use case for an exception.

→ Check if the requested ressource was expected to have a symlink in _assets → throw a custom exception → add a documentation for the exception number with possible reasons and solutions.

more verbosely output [the asset symlink creation process] on command line when running composer commands?

Agree. It would help to notify cli users what happens here - something like „TYPO3 created a symlink in /_assets/ for all existing /Resources/Public/ subdirectories in all packages“.

Workarounds for build systems which generate the public folder after the composer command?

Several possible solutions:

1. Switch the build order - build assets first and therefore create the /Resource/Public/ directory, then run your composer build afterwards
2. Trigger the asset build script - Run `composer dumpautoload` oder `composer install` yet again as final buildstep. This wont change the app, already fetched packages are not fetched again, this will basically only trigger all related scripts like the _assets-symlink-builder.
3. Add an empty /Resources/Public/ directory to your VCS - for example with a `.gitkeep` file