Eric Niebler writes:
Any chance one of the MPL gurus could have a look at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29653 and see if any possible changes to mpl/aux_/has_tag<> could make gcc happy?
This is basically another side of yet another GCC 4.1.x regression: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28088 (which is now referenced from your bug report). I'm pretty sure I could come up with a workaround if we really, really want to see this work, but: it's already an intricate area in the library, specifically under GCC and _because_ of its non-conforming behavior that got broken in 4.1, so the cost of finding and implementing a workaround that doesn't break things is going to be pretty high. So, until somebody convinces me otherwise, I'd say this is a good enough answer (from http://tinyurl.com/yccfau): [ Caleb Epstein ] This is a regression in the gcc 4.1 series that will be fixed in gcc 4.1.2. See bug #28088 for details.
Preprocessed source code is attached to the bug report. FWIW, this is against Boost HEAD.
It surfaces in one of the basic MPL tests in RC_1_34_0 as well (see the above link). -- Aleksey Gurtovoy MetaCommunications Engineering