Boost C++ Libraries: Ticket #5668: epoll_reactor implicit type conversion warnings:

version changed

anonymous — Tue, 30 Aug 2011 14:47:50 GMT

version Boost 1.46.1 → Boost 1.47.0

I have checked, and this is still a problem in boost 1.47.0. Is there any plan to address this?

Fri, 09 Dec 2011 16:54:16 GMT

Anyone?

status changed; resolution set

chris_kohlhoff — Tue, 29 May 2012 01:35:24 GMT

status new → closed
resolution → wontfix

I am not going to make this change. Asio's use is the approach shown in epoll's man page. Furthermore, -Wconversion is not part of -Wall or -Wextra and it is not feasible (or desirable) to suppress all possible warnings.

If you want to propose that these constants be made unsigned then I suggest you raise a ticket against glibc.

anonymous — Wed, 04 Jul 2012 15:27:28 GMT

Replying to chris_kohlhoff:

I am not going to make this change. Asio's use is the approach shown in epoll's man page. Furthermore, -Wconversion is not part of -Wall or -Wextra and it is not feasible (or desirable) to suppress all possible warnings.

I don't think OP implied that -Wconversion was a part of -Wall or -Wextra, merely that specification of -Werror turns all warnings into errors, and thus this warning is an error. Although I agree with you that it is not possible to suppress all warnings, all reasonably expected warnings should be accounted for, but -Wconversion is a legitimate option. In this case the use of the #define-d value of EPOLLET produces a value that is a different sign than the rvalue of the statement. The fact that "events" member of struct epoll_event is defined as uint32_t suggests that a wrapper such as suggested would be appropriate in assigning the value.

If you want to propose that these constants be made unsigned then I suggest you raise a ticket against glibc.

Until and unless glibc starts defining these as variables with real types, this isn't going to happen. The responsibility thus lies with the library/application developer to use it appropriately.

In this case, it is true that the man page for epoll suggests the use as you have it, but man pages are not definitive sources of all usage, merely examples.

I find it unfortunate that you are unwilling to accept this as a bug.

chris_kohlhoff — Thu, 05 Jul 2012 01:31:14 GMT

I have no idea what you mean about "real types", since integer constants can be unsigned. The glibc maintainers evidently agree and a fix was applied late last year to make the constant unsigned:

http://sourceware.org/bugzilla/show_bug.cgi?id=13538

benoit@… — Thu, 05 Jul 2012 01:38:08 GMT

Thanks Chris! I'll see if the tools guys are more willing to get up to date on glibc than they are on removing -Wconversion.