Re: [PATCH] Introduce hardbool attribute for C

[Sebastian Huber <sebastian.huber@embedded-brains.de>]

On 08.07.22 08:58, Richard Biener via Gcc-patches wrote:
> On Thu, Jul 7, 2022 at 10:00 PM Alexandre Oliva via Gcc-patches
> <gcc-patches@gcc.gnu.org>  wrote:
>>
>> This patch introduces hardened booleans in C.  The hardbool attribute,
>> when attached to an integral type, turns it into an enumerate type
>> with boolean semantics, using the named or implied constants as
>> representations for false and true.
>>
>> Expressions of such types decay to _Bool, trapping if the value is
>> neither true nor false, and _Bool can convert implicitly back to them.
>> Other conversions go through _Bool first.
>>
>> Regstrapped on x86_64-linux-gnu.  Ok to install?
> Does this follow some other compilers / language?  Is such feature used
> in existing code?  Why is it useful to allow arbitrary values for true/false?
> Why is the default 0 and ~0 rather than 0 and 1 as for _Bool?

Maybe this helps to catch errors caused by radiation which resulted in a 
bit flip in a processor register or other memory. If you use a single 
bit for true/false you can't detect such an error without special hardware.

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