Re: netbsd-11 gcc bug

--pgp-sign-Multipart_Thu_May_28_14:40:34_2026-1
Content-Type: text/plain; charset=US-ASCII

This probably/obviously isn't the best place for this discussion, but...

At Mon, 25 May 2026 00:02:17 +0000, David Holland <[email protected]> wrote:
Subject: Re: netbsd-11 gcc bug
>
> The places where
> certain bits of undefined and unspecified behavior line up exactly
> with things that mattered in a compiler written forty years ago are no
> longer obvious, and so what's left is a vague general belief that the
> UB in the C standard is meant to be room for optimizers.

The reason for the "belief" that UB is (often) related to optimizers is
squarely resting on the fact that when the optimizer is turned off then
the UB goes away.  So it's not really a belief -- it's a demonstrable
fact!

That and the fact some of the compiler maintainers influencing the
standard have basically said that they explicitly rely on some UB
conditions to allow their optimization tricks to work.

So it's very difficult to separate many of the current cases of UB from
some aspect of optimization.

> You can try pushing back, but you aren't going to get anywhere.

As I said, efforts to eliminate UB from C are actually happening at the
standards committee level, so....

--
					Greg A. Woods <[email protected]>

Kelowna, BC     +1 250 762-7675           RoboHack <[email protected]>
Planix, Inc. <[email protected]>     Avoncote Farms <[email protected]>

--pgp-sign-Multipart_Thu_May_28_14:40:34_2026-1
Content-Type: application/pgp-signature
Content-Transfer-Encoding: 7bit
Content-Description: OpenPGP Digital Signature

-----BEGIN PGP SIGNATURE-----

iF0EABECAB0WIQRuK6dmwVAucmRxuh9mfXG3eL/0fwUCahi2WAAKCRBmfXG3eL/0
fxBXAJ9RKmJ/42G2QEC1zEMmbJfquoa5bQCguLEdzmeF3QBpXcdYiXcuLB82ygc=
=FTj+
-----END PGP SIGNATURE-----

--pgp-sign-Multipart_Thu_May_28_14:40:34_2026-1--