[boost] [rational, spirit] 1.68.0 beta 2 bug report

Subject: [boost] [rational, spirit] 1.68.0 beta 2 bug report
From: James E. King III (jking_at_[hidden])
Date: 2018-07-12 01:07:45

A bug reported by someone using a version of 1.68.0 (not specified):

https://github.com/qtumproject/cpp-eth-qtum/issues/31#issuecomment-404257256

Seems to have something to do with the new pow template that was added to
rational.
This came from an old pull request that was simplified, however it seems
pow is now a template defined in the namespace boost, and seems to have
caused some issues.  I'd guess this is only an issue inside boost namespace
(so all boost headers) and not external namespaces.  Not sure at the moment
if the fix should be in rational or spirit.  We could instead back out the
change to rational for 1.68.0 where pow() was added into namespace boost.

https://github.com/boostorg/rational/pull/21

- Jim