Window compilation issue. LNK1181 error

[spyroot]

Describe the bug
A clear and concise description of what the bug is.

I think there is some issue when compiling under the window

I'm using the MSVC console.

LINK : warning LNK4044: unrecognized option '/fopenmp'; ignored
LINK : fatal error LNK1181: cannot open input file 'mujoco210.lib'
error: command 'D:\dev\VC\Tools\MSVC\14.29.30133\bin\HostX86\x86\link.exe' failed with exit code 1181

To Reproduce
Steps to reproduce the behavior.

Expected behavior
A clear and concise description of what you expected to happen.

Open VC Console.
conda activate env_name

set MUJOCO_PY_MUJOCO_PATH=C:\Users\X.mujoco\mujoco210
set PATH=C:\Users\X.mujoco\mujoco210;%PATH%

clone repo
python setup.py build

LINK : warning LNK4044: unrecognized option '/fopenmp'; ignored
LINK : fatal error LNK1181: cannot open input file 'mujoco210.lib'
error: command 'D:\dev\VC\Tools\MSVC\14.29.30133\bin\HostX86\x86\link.exe' failed with exit code 1181

Error Messages
Including more/longer error messages gives us more information to work with.

(X) c:\mujoco-py>python setup.py build
running build
Removing old mujoco_py cext c:\mujoco-py\mujoco_py\generated\cymj_2.1.2.14_38_windowsextensionbuilder_38.so
running build_ext
building 'mujoco_py.cymj' extension
cl : Command line warning D9025 : overriding '/W3' with '/w'
cl : Command line warning D9002 : ignoring unknown option '-fopenmp'
dummyshim.c
cl : Command line warning D9025 : overriding '/W3' with '/w'
cl : Command line warning D9002 : ignoring unknown option '-fopenmp'
cymj.c
C:\Users\X\anaconda3\envs\X\lib\site-packages\numpy\core\include\numpy\npy_1_7_deprecated_api.h(14) : Warning Msg: Using deprecated NumPy API, disable it with #define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
LINK : warning LNK4044: unrecognized option '/fopenmp'; ignored
LINK : fatal error LNK1181: cannot open input file 'mujoco210.lib'
error: command 'D:\dev\VC\Tools\MSVC\14.29.30133\bin\HostX86\x86\link.exe' failed with exit code 1181

Desktop (please complete the following information):

• OS: [e.g. Win32]
• Python Version [e.g. 3.8]
• Mujoco Version [e.g. 2.1.1]
• mujoco-py version [e.g. upstream git clone]

Environment

• output of: echo $LD_LIBRARY_PATH
• output of: echo $HOME
• output of: echo $USER

VC related

VCIDEInstallDir=D:\dev\Common7\IDE\VC
VCINSTALLDIR=D:\dev\VC
VCToolsInstallDir=D:\dev\VC\Tools\MSVC\14.29.30133
VCToolsRedistDir=D:\dev\VC\Redist\MSVC\14.29.30133
VCToolsVersion=14.29.30133
VisualStudioVersion=16.0
VS160COMNTOOLS=D:\dev\Common7\Tools
VSCMD_ARG_app_plat=Desktop
VSCMD_ARG_HOST_ARCH=x86
VSCMD_ARG_TGT_ARCH=x86
VSCMD_VER=16.11.10
VSINSTALLDIR=D:\dev\

Path=C:\Users\X.mujoco\mujoco210;
MUJOCO_PY_MUJOCO_PATH=C:\Users\X.mujoco\mujoco210

Conda and the rest

CommandPromptType=Native
CommonProgramFiles=C:\Program Files\Common Files
CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
CommonProgramW6432=C:\Program Files\Common Files
COMPUTERNAME=X
ComSpec=C:\WINDOWS\system32\cmd.exe
CONDA_DEFAULT_ENV=X
CONDA_EXE=C:\Users\X\anaconda3\Scripts\conda.exe
CONDA_PREFIX=C:\Users\X\anaconda3\envs\X
CONDA_PROMPT_MODIFIER=(X)
CONDA_PYTHON_EXE=C:\Users\X\anaconda3\python.exe
CONDA_SHLVL=1

Additional context
Add any other context about the problem here.

I think somewhere the path to the lib file doesn't resolve correctly or maybe something different.

LINK : warning LNK4044: unrecognized option '/fopenmp'; ignored
LINK : fatal error LNK1181: cannot open input file 'mujoco210.lib'
error: command 'D:\dev\VC\Tools\MSVC\14.29.30133\bin\HostX86\x86\link.exe' failed with exit code 1181

First I think for VC it must /openmp
https://docs.microsoft.com/en-us/cpp/build/reference/openmp-enable-openmp-2-0-support?view=msvc-170
But it was ignored anyway.

So the root cause
LINK: fatal error LNK1181: cannot open input file 'mujoco210.lib'

[spyroot]

Note if I add Lib and indicate direct path (mujoco) like

set LIB=C:\Users\X.mujoco\mujoco210\Lib;%LIB%

I get a million unresolved

LINK : warning LNK4044: unrecognized option '/fopenmp'; ignored
Creating library c:\mujoco-py\mujoco_py\generated_pyxbld_2.1.2.14_38_windowsextensionbuilder\temp.win32-3.8\Release\mujoco-py\mujoco_py/gl\cymj.cp38-win_amd64.lib and object c:\mujoco-py\mujoco_py\generated_pyxbld_2.1.2.14_38_windowsextensionbuilder\temp.win32-3.8\Release\mujoco-py\mujoco_py/gl\cymj.cp38-win_amd64.exp
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_referenceConstraint
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_integratePos
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_deleteVFS
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_jac
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_rnePostConstraint
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_setConst
cymj.obj : error LNK2001: unresolved external symbol __imp__mju_insertionSortInt
cymj.obj : error LNK2001: unresolved external symbol __imp__PyUnicode_AsEncodedString
cymj.obj : error LNK2001: unresolved external symbol __imp__mjv_initPerturb
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_version
cymj.obj : error LNK2001: unresolved external symbol __imp__PyFrozenSet_Type
cymj.obj : error LNK2001: unresolved external symbol __imp__mj_activate

[spyroot]

folks I complied by hand by can you tell me how I can overwrite -fopenmp

In Extension Builder

        extra_compile_args=[
            '-fopenmp',  # needed for OpenMP # in case of window /openmp
            '-w',  # suppress numpy compilation warnings / no need that
        ],

class MujocoExtensionBuilder():

CYMJ_DIR_PATH = abspath(dirname(__file__))

def __init__(self, mujoco_path):
    self.mujoco_path = mujoco_path
    python_version = str(sys.version_info.major) + str(sys.version_info.minor)
    self.version = '%s_%s_%s' % (get_version(), python_version, self.build_base())
    self.extension = Extension(
        'mujoco_py.cymj',
        sources=[join(self.CYMJ_DIR_PATH, "cymj.pyx")],
        include_dirs=[
            self.CYMJ_DIR_PATH,
            join(mujoco_path, 'include'),
            np.get_include(),
        ],
        libraries=['mujoco210'],
        library_dirs=[join(mujoco_path, 'bin')],
        extra_compile_args=[
            '-fopenmp',  # needed for OpenMP
            '-w',  # suppress numpy compilation warnings
        ],
        extra_link_args=['-fopenmp'],
        language='c')

[spyroot]

I added a pull request it fixes window compilation issues with the visual studio
#686