How can Autoconf help with the transition to stricter compilation defaults?

[Aaron Ballman via cfe-commits]

On Thu, Nov 10, 2022 at 1:12 PM Jonathan Wakely via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
>
> On Thu, 10 Nov 2022 at 17:58, Jonathan Wakely wrote:
> >
> > On Thu, 10 Nov 2022 at 17:52, Nick Bowler wrote:
> > > It saddens me to see so much breakage happening in "modern C", a
> > > language that has (until now) a long history of new language features
> > > being carefully introduced to avoid these sort of problems.
> >
> > The features were introduced in 1999.
>
> Well, some of them were. Some more are coming now in C2x but the
> problem has existed since C99 it's just that compilers "protected"
> most users from having to fix their code at the time. But it's been
> more than two decades and it's time to accept that missing prototypes,
> implicit conversions between pointers and ints etc are a hazard and
> should be diagnosed not ignored for the benefit of people who never
> want to fix their questionable code.

Functions without prototypes were deprecated in ANSI C and came into
ISO C as deprecated. They were obsoleted with the release of the 2nd
edition of K&R C (circa 1978) when prototypes were introduced, IIRC.
They've literally never been a recommended practice in standard C.
Implicit function declarations and implicit int were outright removed
from C99 without a deprecation period due to the security concerns
they caused.

~Aaron