[Bug c++/90647] Warn on returning a lambda with captured local variables

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90647

--- Comment #1 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Antony Polukhin from comment #0)
> Consider the example:
> 
> auto test(int s) {
>     return [&s] { return s; };
> }
> 
> 
> `s` is a local variable, so we return a lambda that has a dangling reference.
> 
> It would be nice to have a warning for such cases.

Under -Wreturn-local-addr, or a new flag?