"All rights reserved" no longer means anything anymore. In the past, you had to state that you want to reserve copyright, but now this has become the default even if you say nothing.

Either way, this does not conflict with GPLv3; if the author decides to reserve all rights, and then use their reserved right to license the work under a certain license like GPLv3, that is totally fine. Notably, the phrase "All rights reserved" does not recapture any rights that you don't have. It is the same logic under which you're allowed to license your own GPLv3 code under a proprietary, non-FOSS license, but that doesn't revoke the GPLv3 license itself.

> Kind of sad it's not self hosted yet :-D

Self hosting a language is only really a useful exercise if the language is designed for writing compilers. Easylang doesn't seem to be intended for that, so there are always better things to spend one's time on, as there's an infinite amount of work that goes into making a language, and writing a compiler is not a trivial task. There are better ways to stress test a language.

I'm more worried on the advertising clause, which would afaik make it gpl-incompatible for anyone else. (and probably also unfit for osi defined open source)