On Sun, Sep 07, 2014 at 02:36:53PM +0200, Ard Biesheuvel wrote:
> This code snippet:
>
> static void bar(void const *arg)
> {
> int (*foo)(void) = arg;
> }
>
> produces the following warning:
>
> test.c:4:28: warning: incorrect type in initializer (different modifiers)
> test.c:4:28: expected int ( *foo )( ... )
> test.c:4:28: got void const *arg
>
> which is caused by the fact that the function pointer 'foo' is not annotated
> as being a pointer to const data. However, dereferencing a function pointer
> does not produce an lvalue, so a function pointer points to const data by
> definition, and we should treat it accordingly.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
As a data point: gcc does not warn about this case either, whereas it
does warn about "int *foo = arg". So, this seems fine to me.
Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
> OK, so while my v1 did solve the example case, it turns out universally treating
> function pointers as pointers to const data produces so much fallout that it
> does more harm than good.
Can you elaborate on the fallout, and ideally provide that rationale in
the commit message?
- Josh Triplett
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