https://svn.boost.org/trac10/ticket/4061 <p> arity_helper isn't fully qualified which triggers ADL and may instantiate templates we don't want. Please see the following (invalid) gcc bugreport that contains a test case. </p> <p> <a class="ext-link" href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43608"><span class="icon">​</span>http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43608</a> </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/4061 Trac 1.4.3 sefi@… Sun, 04 Apr 2010 09:28:38 GMT https://svn.boost.org/trac10/ticket/4061 https://svn.boost.org/trac10/ticket/4061 <ul> <li><strong>attachment</strong> → <span class="trac-field-new">gcc-4.5-mpl-1.42.0.patch</span> </li> </ul> <p> Proposed fix </p> Ticket Eric Niebler Tue, 20 Apr 2010 22:47:47 GMT https://svn.boost.org/trac10/ticket/4061#comment:2 https://svn.boost.org/trac10/ticket/4061#comment:2 <ul> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">fixed</span> </li> </ul> <p> (In <a class="changeset" href="https://svn.boost.org/trac10/changeset/61467" title="MPL: fixed #4061: gcc-4.5 compilation problems related to ...">[61467]</a>) MPL: fixed <a class="closed ticket" href="https://svn.boost.org/trac10/ticket/4061" title="#4061: Bugs: [MPL] gcc-4.5 compilation problems related to arity_helper (closed: fixed)">#4061</a>: gcc-4.5 compilation problems related to arity_helper, applied attached patch to the main aux_/template_arity.hpp and regenerated the corresponding file preprocessed/gcc/template_arity.hpp. No other preprocessed files are affected. </p> <p> This patch seemed to be fine as all it does is to qualify an internal name in order to avoid it being looked up through ADL. This appears to be reasonably safe as this name is internal and not supposed to be found using ADL in the first place. </p> Ticket