Re: asm-generic/int-ll64.h wrongly used on x86_64?

[Florian Weimer <fweimer@redhat.com>]

* Cyril Hrubis:

> Hi!
> I was writing simple userspace code that prints the values from the
> struct statx the line in question looks like:
>
> 	printf("%" PRIu64 "\n", st.stx_size);
>
> This unexpectedly gives me warning on x86_64:
>
> warning: format '%lu' expects argument of type 'long unsigned int', but argument 5 has type '__u64' {aka 'long long unsigned int'}

The correct format depends on whether you use struct statx from the
glibc headers or the Linux UAPI headers.  glibc uses uint64_t, Linux
uses __u64.  uint64_t in glibc prefers unsigned long if the type is
64-bit, Linux uses unsigned long long unconditionally.

One solution is to use %ju and cast to (uintmax_t).  Other cast-based
approaches are possible as well.

I'm not happy with the situation because those casts reduce type safety
and may suppress relevant compiler warnings.

Thanks,
Florian