https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102609
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
If we're right about that, then I agree that a warning would be useful for
classes that have no such implicit conversion from S to S*.
I think the warning would give a false positive in the case below, so a way to
disable it locally would be needed (e.g. via a diagnostic pragma).
struct S {
int f(this S*); // warning: explicit object parameter of pointer type can
only match if an implicit conversion to S* exists
};
struct T : S {
operator T*();
};
T t;
int i = t.f(); // derived class has the required conversion
