On Fri, Jun 19, 2020 at 12:26AM +0200, Luc Van Oostenryck wrote:
> If the file is being checked with sparse, use the version of
> __unqual_scalar_typeof() using _Generic(), leaving the unoptimized
> version only for the oldest versions of GCC.
>
> This reverts commit
> b398ace5d2ea ("compiler_types.h: Use unoptimized __unqual_scalar_typeof for
> sparse")
>
> Note: a recent version of sparse will be needed (minimum v0.6.2-rc2
> or later than 2020-05-28).
>
> Cc: Marco Elver <el...@google.com>
> Cc: Borislav Petkov <b...@suse.de>
> Cc: Will Deacon <w...@kernel.org>
> Link: https://marc.info/?l=linux-sparse&m=159233481816454
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenr...@gmail.com>
Definitely support this change, so in principle:
Acked-by: Marco Elver <el...@google.com>
But, I think sparse still isn't entirely happy with all legal uses of
_Generic. Running latest sparse on:
void test_Generic_conversion(void)
{
#define TEST_WITH_QUALIFIER(type, selection_type)
\
do {
\
type var = 0;
\
_Generic(var, selection_type: (void (*)(type))0)(var);
\
} while (0)
/* Expect no errors. */
TEST_WITH_QUALIFIER(const int, int);
TEST_WITH_QUALIFIER(volatile int, int);
TEST_WITH_QUALIFIER(_Atomic int, int);
TEST_WITH_QUALIFIER(register int, int);
}
results in
generic-test.c:9:9: error: no generic selection for 'int const var'
generic-test.c:10:9: error: no generic selection for 'int volatile var'
generic-test.c:11:9: error: no generic selection for 'int [atomic] var'
Whereas GCC or Clang accept this as expected. I can't find the
standardese right now, but in [1] we have:
"[...] The conversion is performed in type domain only: it
discards the top-level cvr-qualifiers and atomicity and applies
array-to-pointer/function-to-pointer transformations to the type
of the controlling expression [...]"
[1] https://en.cppreference.com/w/c/language/generic
Thanks,
-- Marco
