Re: Mangled function prototypes (phantom arguments)

[Alejandro Colomar <alx@kernel.org>]

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On 2026-05-29T00:10:23+0200, Alejandro Colomar wrote:
> Hi Mark,
> 
> On 2026-05-28T14:43:21-0700, Mark Harris wrote:
> > > > My view was always that they were the simplest expression of the
> > > > interface that the widest possible audience could understand, and
> > > > that seems to align with Michael's view.
> > >
> > > That doesn't provide much value, IMHO.  My opinion of the SYNOPSIS is
> > > that it's a quick reminder of how a function should be used.
> > 
> > I suggest a compromise.  Keep the array sizes, which are the part that
> > you claim adds value, and drop the forward declarations, which are the
> > part that confuses people.  So for example:
> > 
> > ssize_t read(int fd, void buf[count], size_t count);
> > 
> > Yes, count is used before its definition, but the goal is not to write
> > a valid function declaration; the existing one being invalid is
> > evidence of that.  It is difficult to imagine that anyone would have
> > trouble finding the definition of count without a forward declaration,
> > unless they are a compiler in which case they would also be tripped up
> > by the array-of-void.
> 
> I considered doing that some time ago.  I am worried about something: it
> might "work" if you're unlucky.
> 
> Let's say a relatively new programmer sees this and thinks it's valid C.
> And let's say it tries it in their own code, which may have a variable
> in scope (most likely, a global one) named 'count'.
> 
> 	extern int count;
> 
> 	ssize_t read(int fd, void buf[count], size_t count);
> 
> That's going to compile, but it's not what you'd expect.

Oh well, this one won't compile, because of void.  But it would work for
other arrays, such as arrays of char.

> 
> That's why I originally used [.count] notation.  That one if free from
> this problem.  However, GCC maintainers convinced me of using some
> syntax that is valid C (at least in the GNU dialect of it, which is the
> majoritary one anyway).
> 
> 
> Have a lovely night!
> Alex
> 
> -- 
> <https://www.alejandro-colomar.es>



-- 
<https://www.alejandro-colomar.es>

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