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

[Laurent Vivier]

On 05/10/2018 11:10, Peter Maydell wrote:
> On 5 October 2018 at 01:28, Laurent Vivier <address@hidden> wrote:
>> I have the following error when building on Fedora 28 and gcc (GCC)
>> 8.1.1 20180712 (Red Hat 8.1.1-5)
>>
>>   CC      aarch64_be-linux-user/target/arm/arm-semi.o
>> .../target/arm/arm-semi.c: In function ‘do_arm_semihosting’:
>> .../target/arm/arm-semi.c:270:1: error: unknown option after ‘#pragma
>> GCC diagnostic’ kind [-Werror=pragmas]
>>
>> Perhaps you should use a "#if defined(__clang__)" to apply your fix only
>> to clang?
> 
> I did test on gcc, but not that version. The point of the
>    _Pragma("GCC diagnostic ignored \"-Wpragmas\"");
> line is to suppress that error (which it does on my gcc 5)
> so I don't know why your gcc is complaining :-(

You should add Fedora 28 to you collection of virtual machines :)

> 
> If you add an extra diagnostic push, so:
> 
> +        _Pragma("GCC diagnostic push");                                     \
> +        _Pragma("GCC diagnostic ignored \"-Wpragmas\"");                    \
> +        _Pragma("GCC diagnostic push");                                     \
> +        _Pragma("GCC diagnostic ignored \"-Waddress-of-packed-member\"");   \
> 
> and then a balancing extra
> 
> +        _Pragma("GCC diagnostic pop");                                      \
> 
> at the end, I don't suppose that helps?

No, it doesn't help

> (I generally prefer to avoid marking things as clang- or gcc-
> specific where I can.)

I understand.
But it's a clang bug, it seems reasonable to have specific code to
workaround it.

Thanks,
Laurent