Date: Sat, 17 Jan 2026 10:25:53 -0800
On Saturday, 17 January 2026 08:37:45 Pacific Standard Time Sebastian Wittmeier
via Std-Proposals wrote:
> You say the clearing version of bit_cast could change the value on a
> round-trip cast, if there is a type with padding bits as intermediate type?
Yes, that would be a side-effect.
> Conceptually that should not work, as the type with padding has not enough
> bits for representation, but the one solution gives a compile error and the
> other just quietly clears bits and modifies the value.
Indeed.
One is potentially surprising behaviour, the other is an annoyance that might
need to be worked around. Neither is ideal.
via Std-Proposals wrote:
> You say the clearing version of bit_cast could change the value on a
> round-trip cast, if there is a type with padding bits as intermediate type?
Yes, that would be a side-effect.
> Conceptually that should not work, as the type with padding has not enough
> bits for representation, but the one solution gives a compile error and the
> other just quietly clears bits and modifies the value.
Indeed.
One is potentially surprising behaviour, the other is an annoyance that might
need to be worked around. Neither is ideal.
-- Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Principal Engineer - Intel Data Center - Platform & Sys. Eng.
Received on 2026-01-17 18:26:03