Comment 4 for bug 1597594

OK, I do have "boost/optional.hpp", it is in /usr/include, but FindOptional is not finding it.
I tried a local change as follows...

diff -r c8d6c0d1a6fe CMakeModules/FindOptional.cmake
--- a/CMakeModules/FindOptional.cmake Sun Jul 03 18:11:07 2016 +0200
+++ b/CMakeModules/FindOptional.cmake Wed Jul 06 15:05:42 2016 +1000
@@ -4,8 +4,8 @@
 ENDIF()

 FIND_PATH(OPTIONAL_INCLUDE_DIR optional.hpp
- /usr/local/include
- /usr/include
+ /usr/local/include/boost
+ /usr/include/boost
   ${SOURCE_BASE_DIR}/Optional-master
 )

and cmake now finds optional in Fedora 24, for what it's worth.
Doesn't help fix the original issue, which appears to be a result of changes introduced in boost-1.60.0.

Cheers,
Terry