On Tue, Feb 20, 2018 at 08:09:39AM -0800, Matthew Wilcox wrote:
>
> I have a feature request relating to bitwise and enums. The following
> does not work the way I would like it to:
>
> typedef __attribute__((bitwise)) enum {
> FOO,
> BAR,
> } my_t;
>
> static my_t f(int a)
> {
> if (a)
> return FOO;
> return BAR;
> };
>
> sparse complains:
>
> test.c:10:16: warning: incorrect type in return expression (different base types)
> test.c:10:16: expected restricted my_t
> test.c:10:16: got int
>
> (line 10 is, of course 'return BAR'; since FOO has value 0, it does not warn
> on line 9).
>
> I think it would be appropriate for the __attribute__((bitwise)) to
> apply not just to 'my_t' but also to 'FOO' and 'BAR'.
Yes, it's reasonable and intuitive.
It would be nice to have Al Viro's option on this, though.
> sparse doesn't whinge about this:
>
> typedef __attribute__((bitwise)) unsigned int my_t;
>
> typedef enum {
> FOO = (__attribute__((force)) my_t)0,
> BAR = (__attribute__((force)) my_t)1,
> } my_t;
>
> although GCC does complain about redefining a typedef. Maybe sparse
> should also warn about that?
That's clearly a bug.
> Oh, and I'd also like sparse to permit this:
>
> typedef __attribute__((bitwise)) enum {
> FOO = 1,
> BAR = 2,
> BAZ = 4,
> QUUX = 8,
> WIBBLE = 0x10,
> } my_t;
>
> (if you're defining enums for a bitwise type, you're almost certainly
> defining individual bits, so you want to do explicit assignment of values)
Sure. For me, it's implied by your first request.
Thanks for the feedback. I'll see what I can do in the coming days.
-- Luc
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