Hello, I have a problem when compiling with the current trunk version (rev. 77432) of Boost.Accumulator: In file included from projects/boost-trunk/boost/accumulators/framework/accumulator_set.hpp:28:0, from projects/boost-trunk/boost/accumulators/accumulators.hpp:12, ... projects/boost-trunk/boost/accumulators/framework/accumulators/droppable_accumulator.hpp: In copy constructor 'boost::accumulators::droppable_accumulator<Accumulator>::droppable_accumulator(const boost::accumulators::droppable_accumulator<Accumulator>&)': projects/boost-trunk/boost/accumulators/framework/accumulators/droppable_accumulator.hpp:173:54: error: expected type-specifier projects/boost-trunk/boost/accumulators/framework/accumulators/droppable_accumulator.hpp:173:54: error: expected '>' projects/boost-trunk/boost/accumulators/framework/accumulators/droppable_accumulator.hpp:173:54: error: expected '(' projects/boost-trunk/boost/accumulators/framework/accumulators/droppable_accumulator.hpp:173:82: error: expected ')' before 'const' My system is: OS: Fedora 14 x86_64 Compiler: GCC 4.6.1 Compiler's Flags: --ansi -pedantic -Wall -Wextra I think you need to change line 173: : droppable_accumulator::base(*static_cast<droppable_accumulator::base const *>(&that)) with the following (note the addition of "typename") : droppable_accumulator::base(*static_cast<typename droppable_accumulator::base const *>(&that)) After this addition all seems to work. Could you fix it, please? Thank you very much. Best, -- Marco