Re: [efi:next 2/3] arch/x86/boot/compressed/eboot.c:26:16: sparse: incorrect type in return expression (different modifiers)

[Christopher Li <sparse-55XgFHCVCFZAfugRpC6u6w@public.gmane.org>]

On Tue, Nov 18, 2014 at 12:24 AM, Ard Biesheuvel
<ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
>
> No, the test case looks correct now. You may want to add a conflicting
> definition, for completeness, as that is an important case for sparse
> to verify.
> So you could just add
>
> static void *pure1(void); // conflicting declaration

Just to confirm. If function declare as non pure then second time
declare as pure, that  is a conflict error. That is very different from other
C attributes. C allow function declare attribute incrementally.

If what you said is true, then pure attribute is actually acting like a modifier
which don't fix not other non pure attribute.

> at the bottom, and ensure it is flagged by sparse as an error after
> you make your changes.

I am curios how does GCC behave on this incremental declare of pure
attribute. I just test it. GCC does not warn on the conflicting declare.

GCC seems warn on some thing shouldn't warn on the test case:

function "f2_ok" and "f5" shouldn't been warned. Strange.

validation/pure-function.c:14:1: warning: '__pure__' attribute ignored
[-Wattributes]
 static __attribute__((__pure__)) void*(*f2_ok)(void) = pure1;
 ^
validation/pure-function.c:15:1: warning: '__pure__' attribute ignored
[-Wattributes]
 static __attribute__((__pure__)) void*(*f3_error)(void) = non_pure1;
 ^
validation/pure-function.c:29:1: warning: '__pure__' attribute ignored
[-Wattributes]
 static __attribute__((__pure__)) int(*f5)(void) = pure2;
 ^
validation/pure-function.c:30:1: warning: '__pure__' attribute ignored
[-Wattributes]
 static __attribute__((__pure__)) int(*f6_error)(void) = non_pure2;


Chris