https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104282
Bug ID: 104282
Summary: Copy elision when initializing a base-class subobject
with aggregate initialization
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
The program
```
#include <iostream>
struct A {
A() { std::cout << "A "; }
A(const A&) { std::cout << "Acopy "; }
A(A&&) { std::cout << "Amove "; }
~A() { std::cout << "~A "; }
};
struct B : A { };
int main() {
B b{ A{} };
}
```
if compiled by GCC, prints `A ~A `, showing that there is no copy/move of the
temporary `A{}`.
Clang prints on the other hand `A Amove ~A ~A `, which looks correct, because
of "no elision when initializing a base-class subobject", see
https://en.cppreference.com/w/cpp/language/copy_elision
Demo: https://gcc.godbolt.org/z/rafEsTdd9
