Re: [avr-libc-dev] [bug #34695] fixed width int types without __attribute__(mode)

[Georg-Johann Lay]

David Brown a écrit:

> While I agree with your principle here, I think there is good reason for 
> changing the typedefs in this case - and nothing to lose.  People use 
> different tools with their code, such as static error checkers, 
> documentation generators, and "smart" editors like Eclipse.  They also 
> sometimes read the files.
>
> The use of __attribute__((__mode__)) as the sole way to define sizes 
> seems to me to be gratuitously non-standard.  I am all in favour of 
> using non-standard constructs or extensions when they are a help - 
> making source code clearer, shorter or more readable, letting the 
> compiler generate smaller or faster object code, or simply implementing 
> features that can't be expressed in standard C.  But this is not such a 
> case.

-mint8 is non-standard C

> I also wonder if there are differences in the way gcc treats "mode" 
> attribute definitions from standard definitions.  In particular, in C a 
> "unsigned char" is /not/ identical to an "8-bit unsigned int".  The 
> "unsigned char" has different aliasing properties than an "unsigned int" 
> of any size.  Will code that relies on the these aliasing properties 
> work correctly with "uint8_t" as defined in avr-libc?  And will it 
> /always/ work correctly, with future versions of avr-gcc?

Aliasing is a good point.

But as the moment discussing -mint8 features is void because that 
feature is broken some time now (PR46261).

Johann