[Bug ipa/108871] attribute nonnull does not spot nullptr O2 and above when function inlined

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108871

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #5)
> (In reply to Andrew Pinski from comment #3)
> > *** Bug 108893 has been marked as a duplicate of this bug. ***
> 
> N.B. this one is about __attribute__((access(read_only, 1))) not nonnull.
> The docs already seem to imply that it requires a non-null pointer:
> 
>   The read_only access mode specifies that the pointer to which it applies
> is used to
>   read the referenced object but not write to it. Unless the argument
> specifying the
>   size of the access denoted by size-index is zero, the referenced object
> must be
>   initialized.
> 
> If a non-zero size implies an initialized object, then it also implies a
> non-null pointer (since a null pointer doesn't point to an initialized
> object).
> 
> I don't know if we want this PR to be specific to the nonnull attribute, or
> if it makes sense to use it for access(read_only) too.

On the other side, looking at glibc sources, access attributes there are used
on many functions together with nonnull attributes for the same arguments and
in many cases in places where there are not nonnull attributes.  So, making
access attribute imply non-null might not be desirable in real-world unless it
is already implied.
So it might be just that it is badly documented.