[PATCH] Improvements to valid range checks in debug mode

[François Dumont]

I just come back to this email and it sounds like the right moment to 
commit it.

On 27/02/20 2:06 pm, Jonathan Wakely wrote:
> These should wait for stage 1 but I'm posting them now for comment.
>
> With the change to __gnu_debug::__valid_range we now get a debug
> assertion for:
>
>   std::string s;
>   std::min_element(std::string::iterator{}, s.end());
>
> where previously it would just crash with undefined behaviour.
>