[Bug c/22485] pointer +- integer is never NULL

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2005-07-14 15:19 -------
Subject: Re:  pointer +- integer is never NULL

"falk at debian dot org" <gcc-bugzilla@gcc.gnu.org> writes:

| (In reply to comment #4)
| > Hmmmm.
| > I swear we just had this discussion for VRP purposes, and that a bug was
| > recently fixed so that we don't assume that pointer + - integer is NULL. 
| 
| Well, I checked C99 and C++, and they explain a few cases, never mentioning
| null pointers, and then say everything else is undefined. Maybe this was
| different in C89? Seems unlikely, though...

I'm failing to find anything in the C++ standard that suggests that the
following shall be undefined

   (reinterpret_cast<int*>(0) + 5) - 5

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22485