https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98206
Bug ID: 98206
Summary: UBSan: Casting from multiple inheritance base to
derived class triggers undefined behavior sanitizer
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: rbock at eudoxos dot de
Target Milestone: ---
The following code incorrectly triggers undefined behavior sanitizer:
// -------------------------------------
#include <iostream>
#include <string_view>
template<typename Derived>
struct Base1
{
char c1;
};
template<typename Derived>
struct Base2
{
char c2;
auto& get2() const
{
return static_cast<const Derived&>(*this);
}
};
struct X : public Base1<X>, public Base2<X>
{
X(std::string_view d) : data{d} {}
std::string_view data;
};
int main()
{
auto x = X{"cheesecake"};
std::cout << x.get2().data << std::endl;
}
// -------------------------------------
See also discussion here:
https://stackoverflow.com/a/65178320/2173029
