Re: [PATCH] KEYS: trusted: fix -Wvarags warning

On Fri, Oct 12, 2018 at 10:05 AM Nick Desaulniers
[off-list ref] wrote:

On Fri, Oct 12, 2018 at 8:14 AM Denis Kenzior [off-list ref] wrote:

quoted

Hi James,

quoted

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So can't we simply use 'bool' or uint32 as the type for h3 instead
of re-ordering everything

The problem is the standard is ambiguious.  The only thing that's
guaranteed to work for all time is a char *.  If you want to keep the
order, what I'd suggest is inserting a dummy pointer argument which is
always expected to be NULL between the h3 and the varargs.

So maybe I'm misunderstanding something, but the issue seems to be that
unsigned char is promoted to 'unsigned char *' by Clang and probably
unsigned int or int by gcc.

No. This is extremely well defined behavior in C.  In C, integral
types are NEVER promoted to pointer to integer types, only to larger
integral types through rules more complicated than the correct flags
to pass to `tar`.
https://xkcd.com/1168/

And may have their signedness converted.
https://wiki.sei.cmu.edu/confluence/display/c/INT02-C.+Understand+integer+conversion+rules
is the reference I use, though I always feel like there's quite a bit
of mental gymnastics involved interpreting it.

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So instead of having unsigned char h3, can't we simply have bool h3 or
unsigned int h3?

int is the default argument promotion. Proposed:
https://github.com/ClangBuiltLinux/linux/issues/41#issuecomment-428365339

quoted

Regards,
-Denis

--
Thanks,
~Nick Desaulniers

-- 
Thanks,
~Nick Desaulniers