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SubjectRE: [Intel-wired-lan] [PATCH] iavf: Use printf instead of gnu_printf for iavf_debug_d
Date
> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On
> Behalf Of Nathan Chancellor
> Sent: Wednesday, January 9, 2019 8:22 PM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com>
> Cc: netdev@vger.kernel.org; Nick Desaulniers <ndesaulniers@google.com>;
> linux-kernel@vger.kernel.org; Miguel Ojeda
> <miguel.ojeda.sandonis@gmail.com>; intel-wired-lan@lists.osuosl.org;
> Nathan Chancellor <natechancellor@gmail.com>; David S. Miller
> <davem@davemloft.net>
> Subject: [Intel-wired-lan] [PATCH] iavf: Use printf instead of gnu_printf for
> iavf_debug_d
>
> Clang warns:
>
> In file included from drivers/net/ethernet/intel/iavf/iavf_main.c:4:
> In file included from drivers/net/ethernet/intel/iavf/iavf.h:37:
> In file included from drivers/net/ethernet/intel/iavf/iavf_type.h:8:
> drivers/net/ethernet/intel/iavf/iavf_osdep.h:49:18: warning: 'format'
> attribute argument not supported: gnu_printf [-Wignored-attributes]
> __attribute__ ((format(gnu_printf, 3, 4)));
> ^
> 1 warning generated.
>
> We can convert from gnu_printf to printf without any side effects for two
> reasons:
>
> 1. All iavf_debug instances use standard printf formats, as pointed out
> by Miguel Ojeda at the below link, meaning gnu_printf is not strictly
> required.
>
> 2. However, GCC has aliased printf to gnu_printf on Linux since at least
> 2010 based on git history.
>
> From gcc/c-family/c-format.c:
>
> /* Attributes such as "printf" are equivalent to those such as
> "gnu_printf" unless this is overridden by a target. */
> static const target_ovr_attr gnu_target_overrides_format_attributes[] =
> {
> { "gnu_printf", "printf" },
> { "gnu_scanf", "scanf" },
> { "gnu_strftime", "strftime" },
> { "gnu_strfmon", "strfmon" },
> { NULL, NULL }
> };
>
> The mentioned override only happens on Windows (mingw32). Changing
> from gnu_printf to printf is a no-op for GCC and stops Clang from warning.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/111
> Suggested-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> drivers/net/ethernet/intel/iavf/iavf_osdep.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Tested-by: Andrew Bowers <andrewx.bowers@intel.com>


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