[Bug libstdc++/65470] regex_search corrupts matches when haystack is destroyed

["aral at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65470

--- Comment #3 from aral at gmx dot de ---
I don't argue that it might be a misunderstanding of the user, hence my
suggestion 1) - however, I disagree with your wording "clearly documented" as
far as

(a) http://en.cppreference.com/w/cpp/regex/regex_search and
(b) http://www.cplusplus.com/reference/regex/regex_search/

are concerned. I could not find any clear statement on "c++ official language
reference" with a google search. Is (a) official?

Either way, (a) states 
"7) The overload 3 is prohibited from accepting temporary strings, otherwise
this function populates match_results m with string iterators that become
invalid immediately."

I do not find this very clear, especially since 7) is denoted "since C++14",
and the temporary strings are already a problem in C++11.

How about a statement like this for 2), 3), 5) and 6)? And maybe a clearer
wording? I find the abscence of such a warning, along with the "const"
statement in the parameter declaration (indicating one could submit a string
literal for const charT* s) misleading to say the least.