Example of the perils of binding rvalues to const ref

[Arjan via Digitalmars-d]

On Tuesday, 16 September 2014 at 15:30:49 UTC, Andrei 
Alexandrescu wrote:
> http://www.slideshare.net/yandex/rust-c
>
> C++ code:
>
> std::string get_url() {
>     return "http://yandex.ru";
> }
>
> string_view get_scheme_from_url(string_view url) {
>     unsigned colon = url.find(':');
>     return url.substr(0, colon);
> }
>
> int main() {
>     auto scheme = get_scheme_from_url(get_url());
>     std::cout << scheme << "\n";
>     return 0;
> }
>
> string_view has an implicit constructor from const string& (see 
> "basic_string_view(const basic_string<charT, traits, 
> Allocator>& str) noexcept;" in 
> https://isocpp.org/files/papers/N3762.html). The function 
> get_url() returns an rvalue, which in turn gets bound to a

Forgive me my ignorance but  get_url() returns a std::string (on 
the stack), so its address can be token.
And iirc the explainer Scott Meyers explained once "iff you can 
take its address its not a rvalue its a lvalue". So isn't the 
get_scheme_from_url() not simply holding a const ref to 
temporary? (which most compiler warn about)

...Or am I missing the point?

> reference to const and implicitly passed to string_view's 
> constructor. The obtained view refers to a dead string.
>
>
> Andrei