[vlc-devel] [PATCH 2/2] thread: fix compilation with clang 7 or older

[Rémi Denis-Courmont]

Le vendredi 28 février 2020, 14:28:15 EET Alexandre Janniaux a écrit :
> On Fri, Feb 28, 2020 at 12:33:54PM +0200, Rémi Denis-Courmont wrote:
> > You can argue whether failing to implement errata is a bug or not. In this
> > case, it's a compiler bug anyway because it fails even in so-called C17
> > mode.
> Yes, I agree in C17 mode, that's exactly what I wrote
> in previous mails. Given that it has been fixed in
> 2018 and the clang version you tested are anteriors,
> it seems pretty obvious that it won't have this fixed
> for C17 mode.

From Clang point of view, the problem with that line of reasoning is that it 
fails to explain Clang 8+ accepting the code even in C11 mode.

From VLC point of view, the problem is that the patch fixes compilation but 
enables reading a const atomic, which is UB in pre-TC C11.

> But we never required it afaik with the
> current documentation on this.

I don't think the current documentation is worth anything here. The wiki can 
be edited by anybody and the NEWS changes were never discussed appropriately, 
as far as I can tell (you're welcome to prove me wrong and provide a link to 
asso meeting minutes or vlc-devel archives), and don't represent community 
consensus.

-- 
Rémi Denis-Courmont