Unable to create c++ dll using Scons

Question

I am trying to compile a c++ program in Scons. For c++ its giving the following error:

o Untitled_game_godot\bin\win64\libgd.dll -shared -Lgodot-cpp\bin -llibgodot-cpp.windows.debug.64
o not recognized as an internal command

I've tried to change env.Replace(CXX = "C:/cygwin/bin/") or env.Replace(CXX = "C:/cygwin/bin/g++.exe") but it doesn't helps.

Please can anybody help me with this, who knows about this?

I attached my Scons file, working directory, and environment variables below

Sconstruct

#!python
import os, subprocess

opts = Variables([], ARGUMENTS)

# Gets the standard flags CC, CCX, etc.
env = DefaultEnvironment(tools = ['g++', 'link'])
#env.Replace(CXX = "compiler/g++.exe")

# Define our options
opts.Add(EnumVariable('target', "Compilation target", 'debug', ['d', 'debug', 'r', 'release']))
opts.Add(EnumVariable('platform', "Compilation platform", '', ['', 'windows', 'x11', 'linux', 'osx']))
opts.Add(EnumVariable('p', "Compilation target, alias for 'platform'", '', ['', 'windows', 'x11', 'linux', 'osx']))
opts.Add(BoolVariable('use_llvm', "Use the LLVM / Clang compiler", 'no'))
opts.Add(PathVariable('target_path', 'The path where the lib is installed.', 'Untitled_game_godot/bin/'))
opts.Add(PathVariable('target_name', 'The library name.', 'libgd', PathVariable.PathAccept))

# Local dependency paths, adapt them to your setup
godot_headers_path = "godot-cpp/godot-headers/"
cpp_bindings_path = "godot-cpp/"
cpp_library = "libgodot-cpp"

# only support 64 at this time..
bits = 64

# Updates the environment with the option variables.
opts.Update(env)

# Process some arguments
if env['use_llvm']:
    env['CC'] = 'clang'
    env['CXX'] = 'clang++'

if env['p'] != '':
    env['platform'] = env['p']

if env['platform'] == '':
    print("No valid target platform selected.")
    quit();

# Check our platform specifics
if env['platform'] == "osx":
    env['target_path'] += 'osx/'
    cpp_library += '.osx'
    if env['target'] in ('debug', 'd'):
        env.Append(CCFLAGS = ['-g','-O2', '-arch', 'x86_64', '-std=c++17'])
        env.Append(LINKFLAGS = ['-arch', 'x86_64'])
    else:
        env.Append(CCFLAGS = ['-g','-O3', '-arch', 'x86_64', '-std=c++17'])
        env.Append(LINKFLAGS = ['-arch', 'x86_64'])

elif env['platform'] in ('x11', 'linux'):
    env['target_path'] += 'x11/'
    cpp_library += '.linux'
    if env['target'] in ('debug', 'd'):
        env.Append(CCFLAGS = ['-fPIC', '-g3','-Og', '-std=c++17'])
    else:
        env.Append(CCFLAGS = ['-fPIC', '-g','-O3', '-std=c++17'])

elif env['platform'] == "windows":
    env['target_path'] += 'win64/'
    cpp_library += '.windows'
    # This makes sure to keep the session environment variables on windows,
    # that way you can run scons in a vs 2017 prompt and it will find all the required tools
    env.Append(ENV = os.environ)

    env.Append(CCFLAGS = ['-DWIN32', '-D_WIN32', '-D_WINDOWS', '-W3', '-GR', '-D_CRT_SECURE_NO_WARNINGS'])
    if env['target'] in ('debug', 'd'):
        env.Append(CCFLAGS = ['-EHsc', '-D_DEBUG', '-MDd'])
    else:
        env.Append(CCFLAGS = ['-O2', '-EHsc', '-DNDEBUG', '-MD'])

if env['target'] in ('debug', 'd'):
    cpp_library += '.debug'
else:
    cpp_library += '.release'

cpp_library += '.' + str(bits)

# make sure our binding library is properly includes
env.Append(CPPPATH=['.', godot_headers_path, cpp_bindings_path + 'include/', cpp_bindings_path + 'include/core/', cpp_bindings_path + 'include/gen/'])
env.Append(LIBPATH=[cpp_bindings_path + 'bin/'])
env.Append(LIBS=[cpp_library])

# tweak this if you want to use different folders, or more folders, to store your source code in.
env.Append(CPPPATH=['src/'])
sources = Glob('src/*.cpp')

library = env.SharedLibrary(target=env['target_path'] + env['target_name'] , source=sources)

Default(library)

# Generates help for the -h scons option.
Help(opts.GenerateHelpText(env))

Working tree

.
├── Untitled_game_godot
│   ├── UI
│   │   └── main_menu
│   └── bin
│       └── win64
└── godot-cpp
    ├── __pycache__
    ├── bin
    ├── godot-headers
    │   ├── android
    │   ├── arvr
    │   ├── gdnative
    │   ├── images
    │   │   └── faq
    │   ├── nativescript
    │   ├── net
    │   ├── pluginscript
    │   └── videodecoder
    ├── include
    │   ├── core
    │   └── gen
    ├── misc
    │   ├── ci
    │   ├── hooks
    │   └── scripts
    ├── src
    │   ├── core
    │   └── gen
    └── test
        └── src

All environment variables:

ALLUSERSPROFILE=C:\ProgramData
APPDATA=C:\Users\mihac\AppData\Roaming
CL=C:\cygwin64\bin\cl.exe
CommandPromptType=Native
CommonProgramFiles=C:\Program Files\Common Files
CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
CommonProgramW6432=C:\Program Files\Common Files
COMPUTERNAME=DESKTOP-257N8M8
ComSpec=C:\Windows\system32\cmd.exe
DevEnvDir=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\
DriverData=C:\Windows\System32\Drivers\DriverData
ExtensionSdkDir=C:\Program Files (x86)\Microsoft SDKs\Windows Kits\10\ExtensionSDKs
Framework40Version=v4.0
FrameworkDir=C:\Windows\Microsoft.NET\Framework64\
FrameworkDir64=C:\Windows\Microsoft.NET\Framework64\
FrameworkVersion=v4.0.30319
FrameworkVersion64=v4.0.30319
HOMEDRIVE=C:
HOMEPATH=\Users\mihac
HTMLHelpDir=C:\Program Files (x86)\HTML Help Workshop
INCLUDE=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\ATLMFC\include;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\include;C:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um;C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt;C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared;C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um;C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt;C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\cppwinrt
LIB=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\ATLMFC\lib\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\lib\x64;C:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\lib\um\x64;C:\Program Files (x86)\Windows Kits\10\lib\10.0.18362.0\ucrt\x64;C:\Program Files (x86)\Windows Kits\10\lib\10.0.18362.0\um\x64
LIBPATH=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\ATLMFC\lib\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\lib\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\lib\x86\store\references;C:\Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.18362.0;C:\Program Files (x86)\Windows Kits\10\References\10.0.18362.0;C:\Windows\Microsoft.NET\Framework64\v4.0.30319
LOCALAPPDATA=C:\Users\mihac\AppData\Local
LOGONSERVER=\\DESKTOP-257N8M8
NETFXSDKDir=C:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\
NUMBER_OF_PROCESSORS=12
OneDrive=C:\Users\mihac\OneDrive
OneDriveConsumer=C:\Users\mihac\OneDrive
OS=Windows_NT
Path=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\\Extensions\Microsoft\IntelliCode\CLI;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\bin\HostX64\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\VC\VCPackages;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\TestWindow;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\bin\Roslyn;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Team Tools\Performance Tools\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Team Tools\Performance Tools;C:\Program Files (x86)\Microsoft Visual Studio\Shared\Common\VSPerfCollectionTools\vs2019\\x64;C:\Program Files (x86)\Microsoft Visual Studio\Shared\Common\VSPerfCollectionTools\vs2019\;C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools\x64\;C:\Program Files (x86)\HTML Help Workshop;C:\Program Files (x86)\Windows Kits\10\bin\10.0.18362.0\x64;C:\Program Files (x86)\Windows Kits\10\bin\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\\MSBuild\Current\Bin;C:\Windows\Microsoft.NET\Framework64\v4.0.30319;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\Tools\;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\ProgramData\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\Program Files\NVIDIA Corporation\NVIDIA NvDLISR;C:\Program Files\Git\cmd;D:\Apps\bin;C:\Program Files (x86)\dotnet\;C:\Users\mihac\AppData\Local\Programs\Python\Python310;C:\Users\mihac\AppData\Local\Programs\Python\Python310\Scripts;C:\Users\mihac\AppData\Local\Programs\Python\Python310\Scripts\;C:\Users\mihac\AppData\Local\Programs\Python\Python310\;C:\Users\mihac\AppData\Local\Microsoft\WindowsApps;C:\Users\mihac\AppData\Local\Programs\Microsoft VS Code\bin;D:\Apps\php5;D:\Apps\php5\ext;C:\cygwin64\bin;;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\Ninja
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
Platform=x64
PROCESSOR_ARCHITECTURE=AMD64
PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 158 Stepping 10, GenuineIntel
PROCESSOR_LEVEL=6
PROCESSOR_REVISION=9e0a
ProgramData=C:\ProgramData
ProgramFiles=C:\Program Files
ProgramFiles(x86)=C:\Program Files (x86)
ProgramW6432=C:\Program Files
PROMPT=$P$G
PSModulePath=C:\Program Files\WindowsPowerShell\Modules;C:\Windows\system32\WindowsPowerShell\v1.0\Modules
PUBLIC=C:\Users\Public
PYTHONPATH=C:\Users\mihac\AppData\Local\Programs\Python\Python310
SESSIONNAME=Console
SystemDrive=C:
SystemRoot=C:\Windows
TEMP=C:\Users\mihac\AppData\Local\Temp
TMP=C:\Users\mihac\AppData\Local\Temp
UCRTVersion=10.0.18362.0
UniversalCRTSdkDir=C:\Program Files (x86)\Windows Kits\10\
USERDOMAIN=DESKTOP-257N8M8
USERDOMAIN_ROAMINGPROFILE=DESKTOP-257N8M8
USERNAME=mihac
USERPROFILE=C:\Users\mihac
VCIDEInstallDir=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\VC\
VCINSTALLDIR=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\
VCToolsInstallDir=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.28.29333\
VCToolsRedistDir=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Redist\MSVC\14.28.29325\
VCToolsVersion=14.28.29333
VisualStudioVersion=16.0
VS160COMNTOOLS=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\Tools\
VSCMD_ARG_app_plat=Desktop
VSCMD_ARG_HOST_ARCH=x64
VSCMD_ARG_TGT_ARCH=x64
VSCMD_VER=16.8.3
VSINSTALLDIR=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\
windir=C:\Windows
WindowsLibPath=C:\Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.18362.0;C:\Program Files (x86)\Windows Kits\10\References\10.0.18362.0
WindowsSdkBinPath=C:\Program Files (x86)\Windows Kits\10\bin\
WindowsSdkDir=C:\Program Files (x86)\Windows Kits\10\
WindowsSDKLibVersion=10.0.18362.0\
WindowsSdkVerBinPath=C:\Program Files (x86)\Windows Kits\10\bin\10.0.18362.0\
WindowsSDKVersion=10.0.18362.0\
WindowsSDK_ExecutablePath_x64=C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools\x64\
WindowsSDK_ExecutablePath_x86=C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools\
__DOTNET_ADD_64BIT=1
__DOTNET_PREFERRED_BITNESS=64
__VSCMD_PREINIT_PATH=C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\ProgramData\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\Program Files\NVIDIA Corporation\NVIDIA NvDLISR;C:\Program Files\Git\cmd;D:\Apps\bin;C:\Program Files (x86)\dotnet\;C:\Users\mihac\AppData\Local\Programs\Python\Python310;C:\Users\mihac\AppData\Local\Programs\Python\Python310\Scripts;C:\Users\mihac\AppData\Local\Programs\Python\Python310\Scripts\;C:\Users\mihac\AppData\Local\Programs\Python\Python310\;C:\Users\mihac\AppData\Local\Microsoft\WindowsApps;C:\Users\mihac\AppData\Local\Programs\Microsoft VS Code\bin;D:\Apps\php5;D:\Apps\php5\ext;C:\cygwin64\bin;
__VSCMD_script_err_count=0

Answer 1

If you want to build on windows using Cygwin's compilers, you need to run SCons via Cygwin's python, from Cygwin's shell.

Otherwise it defaults to using windows compilers, file path separator, etc.

Also a side note, it's preferred to call

env = Environment(tools = ['g++', 'link'])

And not

env = DefaultEnvironment(tools = ['g++', 'link'])

Also lots of other items you'll need to change if you want to build on cygwin.

You'd likely be better served to use mingw or msvc if you're building on a windows platform.