Re: [boost] [log] Release Candidate 4 released

Subject: Re: [boost] [log] Release Candidate 4 released
From: Jamie Allsop (ja11sop_at_[hidden])
Date: 2010-01-29 16:24:58

Kim Barrett wrote:
> On Jan 28, 2010, at 8:50 PM, Jamie Allsop wrote:
>> I tried building this on Linux using gcc 4.2.4 with boost 1.41. I
>> could build boost fine but not this unfortunately. Some (hopefully
>> useful) log build output is pasted at the end of this post for your
>> convenience.
> 
> [... snipped lots of error spew ...]
> 
> ../boost/intrusive/detail/is_stateful_value_traits.hpp:39: error: ‘& boost::intrusive::derivation_value_traits<T, NodeTraits, LinkMode>::to_value_ptr [with T = boost::log_mt_posix::basic_attribute_set<char>::implementation::node, NodeTraits = boost::log_mt_posix::<unnamed>::ordered_list<boost::log_mt_posix::basic_attribute_set<char>::implementation::node, boost::log_mt_posix::basic_attribute_set<char>::node_base>::node_traits, boost::intrusive::link_mode_type LinkMode = safe_link]’ is not a valid template argument for type ‘const boost::log_mt_posix::basic_attribute_set<char>::implementation::node* (*)(const boost::log_mt_posix::basic_attribute_set<char>::node_base*)’ because function ‘static typename boost::pointer_to_other<typename NodeTraits::node_ptr, const T>::type boost::intrusive::derivation_value_traits<T, NodeTraits, LinkMode>::to_value_ptr(typename NodeTraits::const_node_ptr) [with T = boost::log_mt_posix::basic_attribute_set<char>::implementation::node, NodeTrait
s = boost::log_mt_posix::<unnamed>::ordered_list<boost::log_mt_posix::basic_attribute_set<char>::implementation::node, boost::log_mt_posix::basic_attribute_set<char>::node_base>::node_traits, boost::intrusive::link_mode_type LinkMode = safe_link]’ has not external linkage 
> 
> The combination of gcc version (gcc 4.2.x), the reported error reason
> (has not external linkage) and the type in the error location
> including names in an anonymous namespace (occurrences of <unnamed>)
> lead me to believe this is the same as a problem I've encountered a
> number of times, most recently yesterday.
> 
> The issue seems to be that gcc 4.2 contains (the beginnings of?) an
> optimization to exclude symbols from anonymous namespaces from the set
> of external linker symbols, as a space optimization, and possibly with
> other benefits. Unfortunately, in gcc 4.2 this seems to have been
> somewhat botched because these symbols still need to be treated as
> having external linkage as far as various C++ language features are
> concerned, and that doesn't appear to be done correctly. These
> problems seem to have been addressed in gcc 4.3.
> 
> The only workaround I've found for this is to change the relevant
> anonymous namespace to be a named namespace, typically some "detail"
> or "impl" type of namespace since these aren't supposed to be public
> names. I've only encountered this problem with gcc 4.2.x; 4.1 doesn't
> have the (attempt at) the relevant optimization, and this problem
> seems to have been fixed in gcc 4.3.

Thanks! Just confirming that 4.3 does indeed work as expected. You saved 
me a lot of leg work, very much appreciated.

Jamie