[Bug middle-end/119693] GCC assumes wrong bounds for strlen() return value, causing bogus bounds check elimination

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119693

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So the max strlen should be `PTRDIFF_MAX - 1`. Because the max array size is
PTRDIFF_MAX which includes the null character so it should be -1.

So this is the confusing part I think. And where the `off by one` comes into
play.