The lifetime-extension of a temporary object can be performed only once, when the temporary object gets bound to the first reference. After that, the knowledge that the reference refers to a temporary object is gone, so further lifetime extensions are not possible. The case that is puzzling you A const& refnop = A(a).nothing(); is similar … Read more
The standard does not mandate any memory area (heap/stack) for them, but they are just like local variables “automatic storage”, that is at the end of the expression (or longer when bound to a ref-to-const) they are destructed. Most implementations will store them on the stack just like local variables. edit: As James Kanze pointed … Read more
All your questions boil down to a rule in C++ which says that a temporary object (one that has no name) cannot be bound to a non-const reference. (Because Stroustrup felt it could provoke logical errors…) The one catch, is that you can invoke a method on a temporary: so X(1).modify() is fine but f7(X(1)) … Read more
This is old extension to Visual Studio, the only reference I could find on the Microsoft site was this bug report: Temporary Objects Can be Bound to Non-Const References, which has the following example code: struct A {}; A f1(); void f2(A&); int main() { f2(f1()); // This line SHALL trigger an error, but it … Read more
The original case for not allowing references to temporaries was for function parameters. Suppose this was allowed: void inc(double& x) { x += 0.1; } int i = 0; inc(i); Why isn’t i changed?