On Fri, 5 Oct 2018, Tmplt wrote:
today some code of mine using std::string_view broke out of seemingly
nowhere; the following program is a minimal recreation of the odd
behavior I'm seeing:
$ cat string_view_test.cpp
#include <string_view>
#include <string>
#include <iostream>
int main()
{
std::string str = "Victory of Eagles";
std::string_view sv = true ? str : "";
What do you think is the type of true?str:"" ? It is going to be
std::string (prvalue), you would need both arms to be the same type to get
an lvalue. Your string_view thus refers to a temporary copy of str, which
gets destructed at the end of the line.
std::cout << sv << "\n";
}
The above program, when compiled with g++ v7.3.0 or v8.2.0 via
$ g++ -std=c++17 string_view_test.cpp
prints "of Eagles" when run where "Victory of Eagles" is expected.
Omitting the in-lined if-else, and instead just
std::string_view sv = str;
solves the issue, but I have no idea why. What's up with this behavior?
--
Marc Glisse
