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From: Cyril Hrubis <chrubis@suse.cz>
To: linux-api@vger.kernel.org
Cc: ltp@lists.linux.it, libc-alpha@sourceware.org
Subject: asm-generic/int-ll64.h wrongly used on x86_64?
Date: Fri, 19 Nov 2021 13:38:06 +0100	[thread overview]
Message-ID: <YZearmiVEw9/eor9@yuki> (raw)

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'}

Digging into the issue I've found that include/asm-generic/types.h looks like:

#ifndef _ASM_GENERIC_TYPES_H
#define _ASM_GENERIC_TYPES_H
/*
 * int-ll64 is used everywhere now.
 */
#include <asm-generic/int-ll64.h>

#endif /* _ASM_GENERIC_TYPES_H */

Which is the cause why you cannot print __u64 with PRIu64 and would
force every userspace code to explicitly cast any __u64 in order to get
rid warnings. I would say that it would be better to fix the headers so
that __u64 has the same type as uint64_t so that PRIu64 could be then
used to print __u64 as well.

-- 
Cyril Hrubis
chrubis@suse.cz

             reply	other threads:[~2021-11-19 12:37 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-19 12:38 Cyril Hrubis [this message]
2021-11-19 13:11 ` Florian Weimer
2021-11-19 13:53   ` Cyril Hrubis

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