Re: Help sought from C++ expert: is this `value' a type or something else (what)?

[Alan Mackenzie]

Hello, Óscar.

On Thu, Jan 19, 2023 at 17:22:41 +0100, Óscar Fuentes wrote:
> Alan Mackenzie <acm@muc.de> writes:

> > Hello, Emacs.
> >
> > In the following test file, templates-9.cc from the CC Mode test suite,
> > on the indicated line, what is the syntactic significance of `value'?
> > Traditionally, it has fontified with the default face, but recently after
> > some (not yet committed) changes in CC Mode, it has started getting
> > font-lock-type-face.
> >
> > I don't understand the file at all, hardly, and can't work out whether
> > the old (non-) fontification was correct, or whether the new
> > fontification of f-l-type-face is correct.  Help would be appreciated.
> >
> > Just as a matter of interest, in c++-ts-mode a treesit-query-error gets
> > thrown.  It isn't clear to me whether the file is still valid C++.

> It is not valid C++ because it misses quite a few declarations.

Yes.  Michael Duggan has identified the file as part of an early boost
source, and clearly there are bits missing.

> The parser has no way of knowing what `value' is unless it can see the
> relevant declarations. And even then, in the general case, it is not
> possible to really know unless your "parser" is, actually, a C++ front
> end. So both c++-mode and c++-ts-mode are out of their breadth here.

c++-ts-mode is a little disappointing, here.  It displays virtually
everything (including "value") in font-lock-type-face.

I've managed to track down the bug in my uncommitted CC Mode changes and
fix it.

> IMAO, a reasonable heuristic is to consider it a value unless it is
> preceded by `typename'.

Yes.  That is the general consensus from all who answered me, so a big
thank you to yourself and the other people!

-- 
Alan Mackenzie (Nuremberg, Germany).