https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101572
Bug ID: 101572
Summary: Temporary object lifetime is not prolonged as required
by the standard
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
In this example program
```
#include <iostream>
struct S
{
virtual ~S() { std::cout << "~S() "; }
};
struct U : S {};
int main()
{
[[maybe_unused]] auto && u = dynamic_cast<const U&>( static_cast<const S&>(
U{} ) );
std::cout << ". ";
}
```
https://gcc.godbolt.org/z/c9nE7Gsn6
the lifetime of temporary object is not prolonged as required by the standard:
https://en.cppreference.com/w/cpp/language/reference_initialization#Lifetime_of_a_temporary
Clang correctly prolongs it.
The problem seems in dynamic_cast.
