On Wed, 5 Mar 2025 11:51:59 +0300 Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > On Wed, Mar 05, 2025 at 09:40:43AM +0100, Markus Elfring wrote: > > >>> The address of a data structure member was determined before > > >>> a corresponding null pointer check in the implementation of > > >>> the functions “dpu_hw_pp_enable_te” and “dpu_hw_pp_get_vsync_info”. > > >>> > > >>> Thus avoid the risk for undefined behaviour by removing extra > > >>> initialisations for the variable “c” (also because it was already > > >>> reassigned with the same value behind this pointer check). > > > There is no undefined behavior here. > > > > Is there a need to improve the wording precision? > > > > There are words which denote a special meaning according to aspects of > > the programming language “C”. > > https://en.cppreference.com/w/c/language/behavior > > > > Dereferences of null pointers are treated in special ways. > > This not a dereference. It's just pointer math. And the 'fun' starts because NULL isn't required to use the all-zero bit pattern. Regardless of the bit-pattern, things like (void *)(1 - 1) are valid NULL pointers. Of course, while C allows this, I doubt NULL has ever been other than 0. (It was 0 on a system I used many years ago where the O/S invalid pointer was ~0.) I know Clang has started warning about arithmetic on NULL. I wonder when it is going to start warning about memset(p, 0, sz) for anything that contains a pointer - equally invalid. David
