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 Mon, Nov 17, 2014 at 1:58 AM, Ard Biesheuvel
<ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
> I can confirm that this patch removes the incorrect warning during the
> kernel build that triggered all of this.
> However, I think your testcase is not quite correct: in particular,
> this assignment
>
> static void*(*f1_err)(void) = pure1;

I see. Thanks for the review. So the above case should not raise
error. However, the following one should:

static __pure void *(*f3_err) = non_pure_func;

I got it the other way around. I will add that to the test case
and send out the second round review.

> Note the 2 calls to __efi_early(). The purpose of __pure here is to
> instruct GCC to emit only a single call to __efi_early(), because it
> will return the same value both times.

That is good to know.

> In other words, GCC is allowed emit fewer calls to a __pure function
> than there are calls in the source, and the same applies to calls
> through a pure function pointer. However, if the pure pointer points
> to a function that is not pure, i.e., back-to-back invocations may
> legally return different results, then calling it through a pure
> pointer is a bug, and needs to be flagged.

I am convinced :-)

Chris