[PATCH] build_bug.h: Also define static_assert() when __CHECKER__ is defined

[Rasmus Villemoes]

On 26/01/2023 19.17, Christophe Leroy wrote:
> When doing a build with C=2, the following failure is encountered on
> several files:
> 
> 	  CHECK   arch/powerpc/cpu/mpc8xxx/fsl_lbc.c
> 	arch/powerpc/cpu/mpc8xxx/fsl_lbc.c: note: in included file (through arch/powerpc/include/asm/global_data.h, include/init.h):
> 	include/asm-generic/global_data.h:494:21: error: Expected ) in function declarator
> 	include/asm-generic/global_data.h:494:21: error: got (
> 
> And because of the error, the interesting part which are the
> warnings don't appear. This is because static_assert() is defined
> only when __CHECKER__ is not defined.
> 
> Add a stub when __CHECKER__ is defined. With that fix, the expected
> warnings are now seen:
> 

So sparse has supported _Static_assert since basically forever, and in
the linux version of build_bug.h, the static_assert definition is not
inside #ifndef __CHECKER__. So I think a better fix is to synchronize
build_bug.h with linux again, so that we actually also do those
static_asserts with sparse (if nothing else then as a sanity check of
sparse itself, it really should grok ICEs and barf at
'static_assert(sizeof(int) == 3)').

The __CHECKER__ guard around most of the file vanished from upstream in
527edbc18a70, just before the static_assert define was added in
6bab69c65013, and I didn't notice that discrepancy when porting that to
U-Boot in ef0f4e834c66.

Rasmus