https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102357
Bug ID: 102357
Summary: The type specified by explicitly defaulted special
member function that is different with it should have
had is well-formed
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: xmh970252187 at gmail dot com
Target Milestone: ---
struct C{
C() = default;
C(C const volatile&) = default;
};
int main() {
}
GCC reports an error as a diagnosis while Clang merely reports a warning.
According to [dcl.fct.def#default-2]
> The type T1 of an explicitly defaulted special member function F is allowed
> to differ from the type T2 it would have had if it were implicitly declared,
> as follows:
>> [...]
> if T1 differs from T2
>> if F is an assignment operator, and the return type of T2 differs from the
>> return type of T2 or T1's parameter type is not a reference, the program is
>> ill-formed;
>> **otherwise, if F is explicitly defaulted on its first declaration, it is
>> defined as deleted;**
>>otherwise, the program is ill-formed.
As per the following
> otherwise, if F is explicitly defaulted on its first declaration, it is
> defined as deleted;
There are no requirements to let implementations report an diagnosis, let alone
make the program ill-formed. A warning is sufficient here.
