Install zlib from it's source, solve my similar error. Download last version from this then:

configure
make -j4
make install

Solution 1: ignore bitmap.go

Your code doesn't use bitmap so you don't need to compile this file, and then you will not encounter this error.

put //go:build ignore to bitmap.go

//go:build ignore     // 👈

// ...
//#include "screen/goScreen.h"
#include "bitmap/goBitmap.h"
*/
import "C"

import (
    "unsafe"

    "github.com/vcaesar/tt"
)
// ...

Solution2: install MinGW-W64.{gcc, g++}

go to sourceforge to download MinGW-W64 GCC

Select what you want

• version:{..., 8.1.0, 7.3.0, 6.4.0, 5.4.0, ...}
• arch. : x86_64, i686^{similarly x86}
• threads: posix, win32
• exception: sjlj, dwarf, seh

I select x86_64-win32-seh^8.1.0

and then

1. unzip the file.

2. copy the path: for example C:\downloads\x86_64-8.1.0-release-win32-seh-rt_v6-rev0\mingw64\bin (which contains: gcc.exe, g++.exe)

3. set go env: CC, CXX

   • go env -w CC=C:\downloads\x86_64-8.1.0-release-win32-seh-rt_v6-rev0\mingw64\bin\gcc
   • go env -w CXX=C:\downloads\x86_64-8.1.0-release-win32-seh-rt_v6-rev0\mingw64\bin\g++

Finally, try to go build again. It should work.

• See more issues of build errors: robotgo/issues/100

It is probably easiest to use CMake to configure your project which uses dlib. It avoids setting all those paths manually. During CMake configure step you can disable usage of libraries like zlib which you don't have/want/need. Here is an example CMakeLists.txt which works for me:

cmake_minimum_required(VERSION 2.6)
PROJECT(DatasetClassifier CXX C)
set(dlib_DIR "" CACHE PATH "Path to dlib") # http://dlib.net/
include(${dlib_DIR}/dlib/cmake)
ADD_EXECUTABLE(DatasetClassifier DatasetClassifier.cpp)
TARGET_LINK_LIBRARIES(DatasetClassifier ${dlib_LIBRARIES})