Why does using conditional operator ? : causes returning local temporary object?

I run into a problem where using the conditional operator returns garbage string_view in MSVC, because the string_view was backed by a temp object?.

#include <string>
#include <iostream>

std::string hello("Hello");
char world[6] = { "World" };

std::string_view ChooseString( bool first )
{
    // warning: returning address of local temporary object
    return first ? hello : world; // returned string_view is garbage
    
    // all other ways of returning string_view works fine
    /*if ( first )
        return hello;
    else
        return world;*/
    //return first ? std::string_view( hello ) : std::string_view( world );
    //return hello;
    //return world;
}

int main()
{
    std::cout << ChooseString(true) << std::endl;
    std::cout << ChooseString(false) << std::endl;
}

Then I tried clang and gcc on goldbot, they had the same behavior, where clang gave warning: returning address of local temporary object. Also just returning hello or world were fine too. Can someone explain why the first way returns temporary object?

Is it because a string object is constructed after conditional operator is evaluated?

>Solution :

Yes, the return type of condition operator is the common type of the operands. Given first ? hello : world;, i.e. the types of operands are std::string and const char[], the common type will be std::string. A temporary std::string needs to be constructed for world then the temporary is used to construct the std::string_view which is returned later.

On the other hand for first ? std::string_view( hello ) : std::string_view( world ) the return type is std::string_view, and all std::string_views are constructed from hello and world directly, then no trouble as above.