Re: [PATCH for-4.14] x86/cpu: fix build with clang 3.5

[Wei Liu <wl@xxxxxxx>]

On Tue, Jun 02, 2020 at 11:05:36AM +0200, Roger Pau Monne wrote:
> Clang 3.5 complains with:
> 
> common.c:794:24: error: statement expression not allowed at file scope
>                       i < ARRAY_SIZE(this_cpu(tss_page).ist_ssp); ++i )
>                                      ^
> /build/xen/include/asm/percpu.h:14:7: note: expanded from macro 'this_cpu'
>     (*RELOC_HIDE(&per_cpu__##var, get_cpu_info()->per_cpu_offset))
>       ^
> /build/xen/include/xen/compiler.h:104:3: note: expanded from macro 
> 'RELOC_HIDE'
>   ({ unsigned long __ptr;                       \
>   ^
> /build/xen/include/xen/lib.h:68:69: note: expanded from macro 'ARRAY_SIZE'
> #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]) + __must_be_array(x))
>                                                                     ^
> /build/xen/include/xen/compiler.h:85:57: note: expanded from macro 
> '__must_be_array'
>   BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0])))
>                                                         ^
> /build/xen/include/xen/lib.h:39:57: note: expanded from macro 
> 'BUILD_BUG_ON_ZERO'
> #define BUILD_BUG_ON_ZERO(cond) sizeof(struct { int:-!!(cond); })
>                                                         ^
> 
> Workaround this by defining the tss_page as a local variable. Adjust
> other users of the per-cpu tss_page to also use the newly introduced
> local variable.
> 
> No functional change expected.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Reviewed-by: Wei Liu <wl@xxxxxxx>