I should perhaps add that for the 32-bit version, I' getting g++ (i686-win32-sjlj-rev0, Built by MinGW-W64 project) 7.1.0 with g++ --version, i.e. 7.1.0 as well.
Hi Mark, I DO agree that the MinGW-64 package versioning is extremely confusing... so would you share what you get with g++ --version ? FYI I'm getting g++ (x86_64-win32-sjlj-rev0, Built by MinGW-W64 project) 7.1.0 Copyright (C) 2017 Free Software Foundation, Inc. - i.e. 7.1.0, which would make your "1.5.0" so ancient as to be unbelievable. With the 7.1.0 I do have some problems, but none as basic as not even finding the libs you mention, be it in 64 or 32 bits.
Hi Lin, For the latter question, try strings libmylib.a > mytxt to get an idea what the lib exports (not trivial, though). Hope that may help, Emanuel