Re: [Boost-bugs] [Boost C++ Libraries] #11897: Compile failure in type_traits_detail::mp_valid_impl with CUDA 7.0

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11897: Compile failure in type_traits_detail::mp_valid_impl with CUDA 7.0
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-01-11 14:57:23

#11897: Compile failure in type_traits_detail::mp_valid_impl with CUDA 7.0
-------------------------------+-------------------------
  Reporter:  a.grund@…         |      Owner:  johnmaddock
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  type_traits
   Version:  Boost 1.60.0      |   Severity:  Showstopper
Resolution:                    |   Keywords:
-------------------------------+-------------------------

Comment (by Alex Grund <a.grund@…>):

 Yes, but the implementation of `BOOST_WORKAROUND` is:

 {{{
 #  define BOOST_WORKAROUND(symbol, test)                \
          ((symbol ## _WORKAROUND_GUARD + 0 == 0) &&     \
          (symbol != 0) && (1 % (( (symbol test) ) + 1)))
 }}}

 There is a check if that symbol evaluates to `0` causing the failure I
 described above. This is why `BOOST_WORKAROUND` cannot be used for this!

 So:[[BR]]
 1) Currently not. But similar uses of variadic templates will probably
 fail. Currently nothing else uses `mp_defer` (1.60) but other code in
 future versions may use that as well and run into the same bug.[[BR]]
 2) No because `BOOST_WORKAROUND` always evaluates to false for this. Prior
 to 7.5 the symbol is undefined causing the `(symbol != 0)` check to fail,
 and in >=7.5 the 2nd part of the check will fail.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11897#comment:8>
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