[Bug c++/68816] gcc fails to detect pointer overflow leading to undefined behaviour

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68816

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
   Last reconfirmed|2015-12-09 00:00:00         |
                 CC|                            |msebor at gcc dot gnu.org
         Resolution|---                         |INVALID

--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> ---
GCC warns for this case with -O2 -Wstrict-overflow=3 so I think this bug can be
closed as invalid.

$ cat x.c && /build/gcc-trunk-svn/gcc/xgcc -B /build/gcc-trunk-svn/gcc -O2 -S
-Wstrict-overflow=3 -xc++ x.c
extern void g( const char *);

void
f( const char * start, unsigned long ul)
{
    if (start + ul < start)
        g( start);
}
x.c: In function ‘void f(const char*, long unsigned int)’:
x.c:8:1: warning: assuming pointer wraparound does not occur when comparing P
+- C1 with P +- C2 [-Wstrict-overflow]
 }
 ^