https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101458
Bug ID: 101458
Summary: An invalid covaraint return type is accepted
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: xmh970252187 at gmail dot com
Target Milestone: ---
struct L{};
struct M:L{};
L l;
M m;
struct A{
virtual L&& fun(){
return std::move(l);
}
};
struct B:A{
M& fun(){
return m;
}
};
In terms of [class.virtual#7.1]
> The return type of an overriding function shall be either identical to the
> return type of the overridden function or covariant with the classes of the
> functions. If a function D::f overrides a function B::f, the return types
> of the functions are covariant if they satisfy the following criteria:
>> both are pointers to classes, both are lvalue references to classes, or both
>> are rvalue references to classes
It is obvious that the return type of `A::fun` is an rvalue reference while
that of `B::fun` is an lvalue reference. The overriding function defined in `B`
has an invalid covariant type, whereas GCC accept the code.
