Building wallet with MSYS2 MinGW under Windows

Get install file msys2-$ARCH-*.exe from https://msys2.github.io, where $ARCH is i686 or x86_64 (matching your system).
Open MSYS2 MinGW32 Shell (from Start menu).

All actions taken under 32-bit (mingw32) shell

Replace <treads> to number of threads (cores) used to build.

Preparing to build

$ pacman -Suy git make tar zip mingw-w64-i686-gcc mingw-w64-i686-boost mingw-w64-i686-libpng mingw-w64-i686-openssl mingw-w64-i686-zlib
$ mkdir /c/devel && cd /c/devel

Building Berkley DB

$ wget http://download.oracle.com/berkeley-db/db-4.8.30.tar.gz
$ tar xzf db-4.8.30.tar.gz
$ cd db-4.8.30/build_unix
$ ../dist/configure --enable-mingw --enable-cxx --disable-replication --prefix=/mingw32
$ make -j <threads> && make install

Cloning repository

$ cd ..
$ git clone https://github.com/GOSTSec/gostcoin.git
$ cd gostcoin

Building wallet daemon

$ cd src
$ make -f makefile.mingw -j <threads>

You will found gostcoind.exe in src folder.

Build wallet with QT GUI

Building Qt 5.9 Opensource staticly

[!] Requires Python 2.7

Download and install Python, for example, to C:\devel\Python27 and add it to PATH

$ export PATH="$PATH:/c/devel/Python27"

Building QT

cd /c/devel/
$ wget http://download.qt.io/official_releases/qt/5.9/5.9.2/single/qt-everywhere-opensource-src-5.9.2.zip
$ unzip qt-everywhere-opensource-src-5.9.2.zip
$ cd qt-everywhere-opensource-src-5.9.2
$ CXXFLAGS="--Wno-deprecated-declarations" ./configure -static -release -opensource -confirm-license -platform win32-g++ -prefix "C:\devel\qt5.9.2-static" -nomake examples -nomake tests -nomake tools -opengl desktop -no-angle -make libs -qt-zlib -qt-libpng -qt-libjpeg -qt-freetype -qt-pcre -sql-sqlite
$ make -j <threads> && make install

Building QREncode

$ cd ..
$ wget https://fukuchi.org/works/qrencode/qrencode-4.0.0.tar.gz
$ tar xzf qrencode-4.0.0.tar.gz
$ cd qrencode-4.0.0
$ ./configure --enable-static --prefix=/mingw32
$ make -j <threads> && make install

Build wallet with QT

$ cd ../gostcoin
$ export PATH="$PATH:/c/devel/qt5.9.2-static/bin"
$ qmake RELEASE=1 USE_QRCODE=1 USE_IPV6=1 USE_BUILD_INFO=1
$ make -j <threads>

You will found gostcoin-qt.exe in release folder.