Re: [PATCH] warn for more impossible null pointer tests

[Koning, Paul via Gcc-patches]

> On Sep 1, 2021, at 1:35 PM, Jeff Law via Gcc-patches 
> <gcc-patches@gcc.gnu.org> wrote:
> 
> Generally OK.  There's some C++ front-end bits that Jason ought to take a 
> quick looksie at.   Second, how does this interact with targets that allow 
> objects at address 0?   We have a few targets like that and that makes me 
> wonder if we should be suppressing some, if not all, of these warnings for 
> targets that turn on -fno-delete-null-pointer-checks?

But in C, the pointer constant 0 represents the null (invalid) pointer, not the 
actual address zero necessarily.

If a target supports objects at address zero, how does it represent the pointer 
value 0 (which we usually refer to as NULL)?  Is the issue simply ignored?  It 
seems to me it is in pdp11, which I would guess is one of the targets for which 
objects at address 0 make sense.

        paul