Re: Differences between clang and gcc handling of int[static n] function arguments

[Jonathan Wakely <jwakely.gcc@gmail.com>]

On Wed, 24 May 2023 at 10:06, Florian Weimer wrote:
>
> * Jonathan Wakely via Gcc:
>
> >> It seems it might even be trivial enough for me to investigate and
> >> tackle myself, in some spare time.
> >>
> >> I see very little code using either of these features, so it's
> >> definitely not a high priority task regardless.
> >>
> >
> > Glibc uses the nonnull attribute in many places. Libstdc++ uses it in a few
> > places.
>
> Note that the glibc uses are frequently incompatible with libstdc++

Do you mean incompatible with libstdc++ specifically, or incompatible
with "common C++ idioms"?

> (std::vector in particular).  Unfortunately, there is no consensus to
> fix this.  For example, one issue is that
>
>   memset(vec.data(), 0, sizeof(decltype(vec)::value_type) * vec.size())
>
> isn't necessarily defined even for vectors of POD type.

It's not really idiomatic C++ code anyway. Why would you write that, instead of:

vec.assign(vec.size(), {});
or:
std::fill_n(vec.begin(), vec.size(), range_value_t<decltype(vec)>:{});
?

(The latter optimizes to the ideal code, but I think I know how to
make the former optimize to the same thing.)