[Bug tree-optimization/114385] -Wrestrict false positive creating std::string from iterators

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114385

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Another workaround is to add:

        if (end-begin < 0) __builtin_unreachable();


I notice that this is not the same as:
[[assume(end-begin >= 0)]];

but that seems related to another bug report dealing with how we don't do
IPA_SRA over assume statements yet.