Re: [Qemu-devel] [PATCH v2] linux-user: Suppress address-of-packed-member warnings in __get/put_user_e

[Richard Henderson <richard.henderson@linaro.org>]

On 10/9/18 9:18 AM, Peter Maydell wrote:
> Our __get_user_e() and __put_user_e() macros cause newer versions
> of clang to generate false-positive -Waddress-of-packed-member
> warnings if they are passed the address of a member of a packed
> struct (see https://bugs.llvm.org/show_bug.cgi?id=39113).
> Suppress these using the _Pragma() operator. Unfortunately
> _Pragma() support in gcc is broken in some gcc versions and
> in some usage contexts, so we limit the pragma usage here to clang.
> 
> To put in the pragmas we need to convert the macros from
> expressions to statements, but all the callsites effectively
> treat them as statements already so this is OK.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Changes v1->v2: _Pragma() in gcc appears to be a disaster area;
> limit the use of it to clang only, since it's just clang that
> emits the bogus warning in this case. Tested on clang-3.8.0,
> clang-7, gcc 5.4.0 and gcc 8.0.1.
> 
>  linux-user/qemu.h | 70 ++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 51 insertions(+), 19 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~