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Re: [Qemu-devel] [PATCH v2] use _Static_assert in QEMU_BUILD_BUG_ON
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2] use _Static_assert in QEMU_BUILD_BUG_ON |
Date: |
Tue, 14 Mar 2017 12:43:56 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 |
On 03/14/2017 11:59 AM, Andreas Grapentin wrote:
> QEMU_BUILD_BUG_ON should use C11's _Static_assert, if the compiler supports
> it,
> to provide more readable messages on failure.
>
> with _Static_assert:
>
>> In file included from /qemu/include/qemu/osdep.h:36:0,
>> from /qemu/qga/commands.c:13:
>> /qemu/qga/commands.c: In function ‘qmp_guest_exec_status’:
>> /qemu/include/qemu/compiler.h:94:30: error: static assertion failed: "not
>> expecting: sizeof(*&gei->finished) > sizeof(void *)"
>> #define QEMU_BUILD_BUG_ON(x) _Static_assert((x), #x)
Manual copy-and-paste? Because this is missing the ! present in the
actual definition...
>> ^
>> /qemu/include/qemu/atomic.h:146:5: note: in expansion of macro
>> ‘QEMU_BUILD_BUG_ON’
>> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
>> ^~~~~~~~~~~~~~~~~
>> /qemu/include/qemu/atomic.h:417:5: note: in expansion of macro
>> ‘atomic_load_acquire’
>> atomic_load_acquire(ptr)
>> ^~~~~~~~~~~~~~~~~~~
>> /qemu/qga/commands.c:160:21: note: in expansion of macro ‘atomic_mb_read’
>> bool finished = atomic_mb_read(&gei->finished);
>> ^~~~~~~~~~~~~~
>
> Signed-off-by: Andreas Grapentin <address@hidden>
> ---
> +++ b/include/qemu/compiler.h
> @@ -90,7 +90,9 @@
> int:(x) ? -1 : 1; \
> }
>
> -#ifdef __COUNTER__
> +#if defined(CONFIG_STATIC_ASSERT)
> +#define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
...here.
But that's trivial, if the maintainer would like to correct the commit
message.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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