boostorg/tuple — pull request #4 by MarcelRaad (2014-06-03 12:33:14+00:00)
Title: Make tuple constructor explicit

Otherwise everything implicitly convertible to the data type of the first element is implicitly convertible to a boost::tuple, which has led to long-unnoticed bugs in production code. This change is also consistent with the TR1 and C++11 tuple.