Are clang++ and libc++ compatible?

Trying to build news/pan with clang++ dies with

gmake[3]: Entering directory `/usr/ports/news/pan/work/pan-0.139/pan/general'
  CXX    file-util.o
In file included from file-util.cc:38:
In file included from ./log.h:26:
/usr/include/c++/v1/deque:907:49: error: invalid application of 'sizeof' to an
      incomplete type 'value_type' (aka 'pan::Log::Entry')
    static const difference_type __block_size = sizeof(value_type) < 256 ? 4...

Anyone know how to fix either clang++ or libc++?

-- 
Steve