If I'm not mistaken, the treatment of forward declarations proposed in the article actually breaks the C standard, which would be a rather pressing concern. As far as I am aware, that is the reason why things are the way they are right now in C land.
(In the past, there were more legitimate concerns on the ease of implementation. Nowadays, as the article points out, they are pretty moot, other than having to keep backwards-compatibility.)
I'm also rather bothered that on the bit on const execution in the article, there was no discussion on how to deal with functions that may not terminate or take rather long to execute. Especially considering the unit tests motivation, this seems like a rather blaring omission.
(In the past, there were more legitimate concerns on the ease of implementation. Nowadays, as the article points out, they are pretty moot, other than having to keep backwards-compatibility.)
I'm also rather bothered that on the bit on const execution in the article, there was no discussion on how to deal with functions that may not terminate or take rather long to execute. Especially considering the unit tests motivation, this seems like a rather blaring omission.