TYPO3 Core

Lars Peter Søndergaard wrote:

This seems to have been a very recent change, and it causes the validator at validator.w3.org now to warn about a lot of self-closing tags, that should no longer be self-closing.

(How do I edit)
This was bad wording on my part. Should be: "warn about a lot of self-closing tags with trailing />, that no longer should have that trailing /"

+1 on this issue.
I can have a fully valid code but the self closing tags sends info notice on the validator and this can be easily improved.

Here's the explanations :
https://github.com/validator/validator/wiki/Markup-%C2%BB-Void-elements#trailing-slashes-in-void-element-start-tags-do-not-mark-the-start-tags-as-self-closing
https://github.com/validator/validator/wiki/Markup-%C2%BB-Void-elements#trailing-slashes-directly-preceded-by-unquoted-attribute-values

The rendering of tags should depends on if the document is a xml document and on the html doctype.

Some enhancements have been done recently: see https://github.com/TYPO3/typo3/blob/569724111c8d04b9fca2119f1c454e0ac17021d4/typo3/sysext/core/Classes/Type/DocType.php#L114 and its usage.

But the TagBuilder still needs to adapt: https://github.com/TYPO3/Fluid/blob/c4c625884f6486afd8fb0ae7fc190b14051dc40c/src/Core/ViewHelper/TagBuilder.php#L255

The Fluid view helper format.nl2br should be updated too. It uses the PHP function nl2br() which renders <br /> by default.