Boost C++ Libraries: Ticket #2508: Serialization emits lots of warnings for MSVC7.1 (non-polymorphic / shared_ptr)

component changed; owner set

Marshall Clow — Tue, 18 Nov 2008 00:54:43 GMT

owner set to Robert Ramey
component None → serialization

status changed

Robert Ramey — Sun, 04 Jan 2009 17:28:05 GMT

status new → assigned

Chard — Thu, 30 Jul 2009 13:38:50 GMT

In class: extended_type_info_typeid

Function:

    const extended_type_info *
    get_derived_extended_type_info(const T & t) const {
        // note: this implementation - based on usage of typeid (rtti)
        // only does something if the class has at least one virtual function.
        BOOST_STATIC_WARNING(boost::is_polymorphic<T>::value);
        return
            detail::extended_type_info_typeid_0::get_extended_type_info(
                typeid(t)
            );
    }

The 'warning' that the class should be polymorphic is incorrect, as illustrated by this issue.

The reason this issue has not shown itself to gcc users is that the gcc static warning macro does not appear to work.

We've investigated the division-by-zero method (for gcc 3.3), and it appears that gcc doesn't bother stamping out the "struct STATIC_WARNINGxxxx". By declaring an actual instance of the STATIC_WARNINGxxxx struct and then calling the f() method on it, the warnings then start trailing out…

In this case, MSVC71 is doing the 'right thing'.

Robert Ramey — Mon, 03 Aug 2009 22:39:20 GMT

what does test_static_warning show with your gcc system? same for you vc 7.1 system.

Robert Ramey

Chard — Wed, 05 Aug 2009 21:54:59 GMT

Replying to ramey:

what does test_static_warning show with your gcc system? same for you vc 7.1 system.

A colleague ran this test through his g++ 4.3.3 system, and it only reported eight warnings - not the required ten.

I believe it was the "f<A>()" variants that did not warn - which seem to align with the check (above) in the serialization code.

However, this is ultimately a side-issue (even though it may have disguised behaviour) and the main issue is that it looks like the serialization code for shared_ptr needs to check for polymorphism, and route accordingly. I see there are other places in the serialization code that do this with a bit of mpl::eval_if.

Regards...

PhilR — Fri, 07 Aug 2009 07:33:09 GMT

Replying to Chard:

Replying to ramey:

what does test_static_warning show with your gcc system? same for you vc 7.1 system.

A colleague ran this test through his g++ 4.3.3 system, and it only reported eight warnings - not the required ten. I believe it was the "f<A>()" variants that did not warn - which seem to align with the check (above) in the serialization code.

(I'm the "colleague".) I ran the test on g++ 4.3.3 and 3.3.x - both of these do not report static warnings on the f<A>() code. VC 7.1 does.

Phil

Robert Ramey — Sun, 23 Aug 2009 17:12:24 GMT

Hmmm - I ran test_static_warning on GCC 4.3.2 under cygwin and I get 10 warning messages. This looks OK to me. I'm not sure what to do now.

I will be tweaking shared_ptr_helper to eliminate the spurious warning.

Robert Ramey

attachment set

PhilR — Wed, 26 Aug 2009 18:24:29 GMT

attachment → test_static_warning.cpp-4.1.3-20080623pre-ubuntu.txt

Output of g++-4.1 on ubuntu 9.04

attachment set

PhilR — Wed, 26 Aug 2009 18:25:05 GMT

attachment → test_static_warning.cpp-4.2.4-ubuntu.txt

Output of g++-4.2 on ubuntu 9.04

attachment set

PhilR — Wed, 26 Aug 2009 18:25:31 GMT

attachment → test_static_warning.cpp-4.3.3-ubuntu.txt

Output of g++-4.3 on ubuntu 9.04

PhilR — Wed, 26 Aug 2009 18:30:08 GMT

I've attached the output of the 3 versions of g++ installed on Ubuntu 9.04. Each one was generated by the command line:

g++-4.x -v -Wall -W -Wextra -H -I../../../ test_static_warning.cpp -c (for x = 1, 2, 3) inside the directory boost/libs/serialization/test.

Let me know if there is anything else I can do that might pin this down for you,

Is it worth raising this as a separate ticket? (Does trac allow you to clone a ticket - that might be easier?)

Phil

Robert Ramey — Wed, 26 Aug 2009 20:59:11 GMT

I've fixed the original issue in the trunk.

I re-ran test_warning.cpp - dammit if I don't see only 8 warnings. I suspect I was wrong before.

As it is now - I don't know how to fix this. Any suggestions welcome.

Robert Ramey

status changed; resolution set

Robert Ramey — Fri, 11 Sep 2009 18:09:16 GMT

status assigned → closed
resolution → fixed

Reimplemented BOOST_STATIC_WARNING to depend upon boost::mpl::print. I've tested it on MSVC 7.1 and gcc 4.3.2 and it seems to work fine - though the output is "cleaner" with gcc. I've checked it into the trunk to see how it works.