compiling issue

[zewangnew]

I met the following two errors when I tried to build and install the package by typing "make"
Error 1: src/sim.cpp:192:76: error: no match for ‘operator<<’ (operand types are ‘std::basic_ostream’ and ‘std::stringstream’ {aka ‘std::__cxx11::basic_stringstream’})
192 | str << "Sim: process = " << process() << " iteration = " << iteration() <<
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^~
Error 2: /usr/include/c++/9/ostream:691:5: error: no type named ‘type’ in ‘struct std::enable_if<false, std::basic_ostream&>’
make: *** [Makefile:83: obj/sim.o] Error 1
Any help?
Thanks

[zewangnew]

I temporarily passed compiling by blocking the content of sim::info. This error is an operator overloading issue but did not sort it out.