On Fri, May 18, 2018 at 10:51 AM, Jonathan Wakely <jwak...@redhat.com> wrote:
> On 18/05/18 10:29 -0400, Jason Merrill wrote:
>>
>> The second patch is some libstdc++ changes to avoid warnings from uses
>> of the standard library when this warning is on. More are almost
>> certainly needed. Jonathan, how would you like me to handle this WRT
>> the library? Check in both patches and let you follow up as needed?
>
>
> Yes, please go ahead and commit the library patch, we'll deal with the
> rest as needed (I'll give myself a TODO to test with -Wdeprecated-copy
> and fix what I find).
>
> I'm not sure we need the "Avoid implicit deprecation" comments. Adding
> defaulted definitions is good style anyway, so needs no justification.
> I'll make sure nobody removes them again in the name of cleaning up
> unnecessary noise (which they aren't).
OK.
> Did you change your mind about leaving the exception hierarchy without
> the defaulted ops, to get warnings for slicing?
Yes, because the warning also triggers in cases where we know the
dynamic type of the object, such as
exception e;
throw e;
I think a slicing warning should be separate.
Also because these functions are required by the standard, as below.
> I've just realised that our user-declared destructors on the exception
> classes (which exist so we can control where the key function is
> emitted) mean they have no implicit move ops. But the standard implies
> they should have implicitly-declared move ops (because it doesn't
> declare any special members for those classes). I'll open a bug.
Hmm, looks to me like it declares special members.
21.8.2 Class exception [exception]
namespace std {
class exception {
public:
exception() noexcept;
exception(const exception&) noexcept;
exception& operator=(const exception&) noexcept;
virtual ~exception();
virtual const char* what() const noexcept;
};
}
Jason
