执行scons platform=windows generate_bindings=yes时触发路径不存在错误

问题描述 #

我正在学习GDNative C++教程，在gdtest/godot-cpp目录下执行命令：

scons platform=windows generate_bindings=yes

触发如下错误：

C:\Users\Antonio>cd gdtest

C:\Users\Antonio\gdtest>cd godot-cpp

C:\Users\Antonio\gdtest\godot-cpp>scons platform=windows generate_bindings=yes
scons: Reading SConscript files ...

scons: *** Path for option target_path does not exist: demo/bin/
File "C:\Users\Antonio\gdtest\godot-cpp\SConstruct.py", line 26, in <module>

现有文件夹路径：

C:\Users\Antonio\gdtest\demo\bin
C:\Users\Antonio\gdtest\godot-cpp
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin
C:\Users\Antonio\gdtest
C:\msys64\mingw64\bin

SConstruct文件内容：

import os

opts = Variables([], ARGUMENTS)

# Gets the standard flags CC, CCX, etc.
env = DefaultEnvironment()

# Define our options
opts.Add(EnumVariable('target', "Compilation target", 'debug', ['d', 'debug', 'r', 'release']))
opts.Add(EnumVariable('platform', "Compilation platform", '', ['', 'windows', 'linuxbsd', 'linux', 'osx']))
opts.Add(EnumVariable('p', "Compilation target, alias for 'platform'", '', ['', 'windows', 'linuxbsd', '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.', 'demo/bin/'))
opts.Add(PathVariable('target_name', 'The library name.', 'libgdexample', 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()

# For the reference:
# - CCFLAGS are compilation flags shared between C and C++
# - CFLAGS are for C-specific compilation flags
# - CXXFLAGS are for C++-specific compilation flags
# - CPPFLAGS are for pre-processor flags
# - CPPDEFINES are for pre-processor defines
# - LINKFLAGS are for linking flags

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

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

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(CPPDEFINES=['WIN32', '_WIN32', '_WINDOWS', '_CRT_SECURE_NO_WARNINGS'])
    env.Append(CCFLAGS=['-W3', '-GR'])
    env.Append(CXXFLAGS='/std:c++17')
    if env['target'] in ('debug', 'd'):
        env.Append(CPPDEFINES=['_DEBUG'])
        env.Append(CCFLAGS=['-EHsc', '-MDd', '-ZI'])
        env.Append(LINKFLAGS=['-DEBUG'])
    else:
        env.Append(CPPDEFINES=['NDEBUG'])
        env.Append(CCFLAGS=['-O2', '-EHsc', '-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))

已安装VS 2022，求解决该路径错误问题。

解决方案 #

1. 修正相对路径指向 #

错误核心是SConstruct中target_path的默认值为demo/bin/，但当前执行目录是gdtest/godot-cpp，相对路径会指向gdtest/godot-cpp/demo/bin/，而实际存在的路径是gdtest/demo/bin/。

修改SConstruct中的对应行：

# 原代码
opts.Add(PathVariable('target_path', 'The path where the lib is installed.', 'demo/bin/'))
# 修改为
opts.Add(PathVariable('target_path', 'The path where the lib is installed.', '../demo/bin/'))

2. 自动创建目标子目录 #

编译Windows平台时，代码会自动在target_path后追加win64/，即最终路径为../demo/bin/win64/，需要确保该目录存在。可以手动创建，或者在SConstruct中添加自动创建逻辑：
在opts.Update(env)之后添加：

# 确保目标路径存在
import os
if not os.path.exists(env['target_path']):
    os.makedirs(env['target_path'])

3. 验证VS环境变量加载 #

确保执行scons时是在VS 2022开发者命令提示符中运行，这样才能正确加载编译器所需的环境变量，避免后续编译出现工具链缺失问题。

内容的提问来源于stack exchange，提问作者Antoner8