godot/SConstruct

#!/usr/bin/env python

EnsureSConsVersion(3, 0, 0)
EnsurePythonVersion(3, 5)

# System
import glob
import os
import pickle
import sys
from collections import OrderedDict

# Local
import methods
import glsl_builders

# Scan possible build platforms

platform_list = []  # list of platforms
platform_opts = {}  # options for each platform
platform_flags = {}  # flags for each platform

active_platforms = []
active_platform_ids = []
platform_exporters = []
platform_apis = []

for x in sorted(glob.glob("platform/*")):
    if not os.path.isdir(x) or not os.path.exists(x + "/detect.py"):
        continue
    tmppath = "./" + x

    sys.path.insert(0, tmppath)
    import detect

    if os.path.exists(x + "/export/export.cpp"):
        platform_exporters.append(x[9:])
    if os.path.exists(x + "/api/api.cpp"):
        platform_apis.append(x[9:])
    if detect.is_active():
        active_platforms.append(detect.get_name())
        active_platform_ids.append(x)
    if detect.can_build():
        x = x.replace("platform/", "")  # rest of world
        x = x.replace("platform\\", "")  # win32
        platform_list += [x]
        platform_opts[x] = detect.get_opts()
        platform_flags[x] = detect.get_flags()
    sys.path.remove(tmppath)
    sys.modules.pop("detect")

methods.save_active_platforms(active_platforms, active_platform_ids)

custom_tools = ["default"]

platform_arg = ARGUMENTS.get("platform", ARGUMENTS.get("p", False))

if os.name == "nt" and (platform_arg == "android" or ARGUMENTS.get("use_mingw", False)):
    custom_tools = ["mingw"]
elif platform_arg == "javascript":
    # Use generic POSIX build toolchain for Emscripten.
    custom_tools = ["cc", "c++", "ar", "link", "textfile", "zip"]

env_base = Environment(tools=custom_tools)
if "TERM" in os.environ:
    env_base["ENV"]["TERM"] = os.environ["TERM"]
env_base.AppendENVPath("PATH", os.getenv("PATH"))
env_base.AppendENVPath("PKG_CONFIG_PATH", os.getenv("PKG_CONFIG_PATH"))
env_base.disabled_modules = []
env_base.module_version_string = ""
env_base.msvc = False

env_base.__class__.disable_module = methods.disable_module

env_base.__class__.add_module_version_string = methods.add_module_version_string

env_base.__class__.add_source_files = methods.add_source_files
env_base.__class__.use_windows_spawn_fix = methods.use_windows_spawn_fix

env_base.__class__.add_shared_library = methods.add_shared_library
env_base.__class__.add_library = methods.add_library
env_base.__class__.add_program = methods.add_program
env_base.__class__.CommandNoCache = methods.CommandNoCache
env_base.__class__.Run = methods.Run
env_base.__class__.disable_warnings = methods.disable_warnings
env_base.__class__.module_check_dependencies = methods.module_check_dependencies

env_base["x86_libtheora_opt_gcc"] = False
env_base["x86_libtheora_opt_vc"] = False

# avoid issues when building with different versions of python out of the same directory
env_base.SConsignFile(".sconsign{0}.dblite".format(pickle.HIGHEST_PROTOCOL))

# Build options

customs = ["custom.py"]

profile = ARGUMENTS.get("profile", False)
if profile:
    if os.path.isfile(profile):
        customs.append(profile)
    elif os.path.isfile(profile + ".py"):
        customs.append(profile + ".py")

opts = Variables(customs, ARGUMENTS)

# Target build options
opts.Add("arch", "Platform-dependent architecture (arm/arm64/x86/x64/mips/...)", "")
opts.Add(EnumVariable("bits", "Target platform bits", "default", ("default", "32", "64")))
opts.Add("p", "Platform (alias for 'platform')", "")
opts.Add("platform", "Target platform (%s)" % ("|".join(platform_list),), "")
opts.Add(EnumVariable("target", "Compilation target", "debug", ("debug", "release_debug", "release")))
opts.Add(EnumVariable("optimize", "Optimization type", "speed", ("speed", "size")))

opts.Add(BoolVariable("tools", "Build the tools (a.k.a. the Godot editor)", True))
opts.Add(BoolVariable("tests", "Build the unit tests", False))
opts.Add(BoolVariable("use_lto", "Use link-time optimization", False))
opts.Add(BoolVariable("use_precise_math_checks", "Math checks use very precise epsilon (debug option)", False))

# Components
opts.Add(BoolVariable("deprecated", "Enable deprecated features", True))
opts.Add(BoolVariable("minizip", "Enable ZIP archive support using minizip", True))
opts.Add(BoolVariable("xaudio2", "Enable the XAudio2 audio driver", False))
opts.Add("custom_modules", "A list of comma-separated directory paths containing custom modules to build.", "")

# Advanced options
opts.Add(BoolVariable("verbose", "Enable verbose output for the compilation", False))
opts.Add(BoolVariable("progress", "Show a progress indicator during compilation", True))
opts.Add(EnumVariable("warnings", "Level of compilation warnings", "all", ("extra", "all", "moderate", "no")))
opts.Add(BoolVariable("werror", "Treat compiler warnings as errors", False))
opts.Add(BoolVariable("dev", "If yes, alias for verbose=yes warnings=extra werror=yes", False))
opts.Add("extra_suffix", "Custom extra suffix added to the base filename of all generated binary files", "")
opts.Add(BoolVariable("vsproj", "Generate a Visual Studio solution", False))
opts.Add(EnumVariable("macports_clang", "Build using Clang from MacPorts", "no", ("no", "5.0", "devel")))
opts.Add(BoolVariable("disable_3d", "Disable 3D nodes for a smaller executable", False))
opts.Add(BoolVariable("disable_advanced_gui", "Disable advanced GUI nodes and behaviors", False))
opts.Add(BoolVariable("no_editor_splash", "Don't use the custom splash screen for the editor", False))
opts.Add("system_certs_path", "Use this path as SSL certificates default for editor (for package maintainers)", "")

# Thirdparty libraries
# opts.Add(BoolVariable('builtin_assimp', "Use the built-in Assimp library", True))
opts.Add(BoolVariable("builtin_bullet", "Use the built-in Bullet library", True))
opts.Add(BoolVariable("builtin_certs", "Use the built-in SSL certificates bundles", True))
opts.Add(BoolVariable("builtin_enet", "Use the built-in ENet library", True))
opts.Add(BoolVariable("builtin_freetype", "Use the built-in FreeType library", True))
opts.Add(BoolVariable("builtin_glslang", "Use the built-in glslang library", True))
opts.Add(BoolVariable("builtin_libogg", "Use the built-in libogg library", True))
opts.Add(BoolVariable("builtin_libpng", "Use the built-in libpng library", True))
opts.Add(BoolVariable("builtin_libtheora", "Use the built-in libtheora library", True))
opts.Add(BoolVariable("builtin_libvorbis", "Use the built-in libvorbis library", True))
opts.Add(BoolVariable("builtin_libvpx", "Use the built-in libvpx library", True))
opts.Add(BoolVariable("builtin_libwebp", "Use the built-in libwebp library", True))
opts.Add(BoolVariable("builtin_wslay", "Use the built-in wslay library", True))
opts.Add(BoolVariable("builtin_mbedtls", "Use the built-in mbedTLS library", True))
opts.Add(BoolVariable("builtin_miniupnpc", "Use the built-in miniupnpc library", True))
opts.Add(BoolVariable("builtin_opus", "Use the built-in Opus library", True))
opts.Add(BoolVariable("builtin_pcre2", "Use the built-in PCRE2 library", True))
opts.Add(BoolVariable("builtin_pcre2_with_jit", "Use JIT compiler for the built-in PCRE2 library", True))
opts.Add(BoolVariable("builtin_recast", "Use the built-in Recast library", True))
opts.Add(BoolVariable("builtin_rvo2", "Use the built-in RVO2 library", True))
opts.Add(BoolVariable("builtin_squish", "Use the built-in squish library", True))
opts.Add(BoolVariable("builtin_vulkan", "Use the built-in Vulkan loader library and headers", True))
opts.Add(BoolVariable("builtin_xatlas", "Use the built-in xatlas library", True))
opts.Add(BoolVariable("builtin_zlib", "Use the built-in zlib library", True))
opts.Add(BoolVariable("builtin_zstd", "Use the built-in Zstd library", True))

# Compilation environment setup
opts.Add("CXX", "C++ compiler")
opts.Add("CC", "C compiler")
opts.Add("LINK", "Linker")
opts.Add("CCFLAGS", "Custom flags for both the C and C++ compilers")
opts.Add("CFLAGS", "Custom flags for the C compiler")
opts.Add("CXXFLAGS", "Custom flags for the C++ compiler")
opts.Add("LINKFLAGS", "Custom flags for the linker")

# add platform specific options

for k in platform_opts.keys():
    opt_list = platform_opts[k]
    for o in opt_list:
        opts.Add(o)

# Update the environment now as the "custom_modules" option may be
# defined in a file rather than specified via the command line.
opts.Update(env_base)

# Detect modules.
modules_detected = OrderedDict()
module_search_paths = ["modules"]  # Built-in path.

if env_base["custom_modules"]:
    paths = env_base["custom_modules"].split(",")
    for p in paths:
        try:
            module_search_paths.append(methods.convert_custom_modules_path(p))
        except ValueError as e:
            print(e)
            Exit(255)

for path in module_search_paths:
    # Note: custom modules can override built-in ones.
    modules_detected.update(methods.detect_modules(path))
    include_path = os.path.dirname(path)
    if include_path:
        env_base.Prepend(CPPPATH=[include_path])

# Add module options.
for name, path in modules_detected.items():
    enabled = True
    sys.path.insert(0, path)
    import config

    try:
        enabled = config.is_enabled()
    except AttributeError:
        pass
    sys.path.remove(path)
    sys.modules.pop("config")
    opts.Add(BoolVariable("module_" + name + "_enabled", "Enable module '%s'" % (name,), enabled))

methods.write_modules(modules_detected)

# Update the environment again after all the module options are added.
opts.Update(env_base)
Help(opts.GenerateHelpText(env_base))

# add default include paths

env_base.Prepend(CPPPATH=["#"])

# configure ENV for platform
env_base.platform_exporters = platform_exporters
env_base.platform_apis = platform_apis

if env_base["use_precise_math_checks"]:
    env_base.Append(CPPDEFINES=["PRECISE_MATH_CHECKS"])

if env_base["target"] == "debug":
    env_base.Append(CPPDEFINES=["DEBUG_MEMORY_ALLOC", "DISABLE_FORCED_INLINE"])

    # The two options below speed up incremental builds, but reduce the certainty that all files
    # will properly be rebuilt. As such, we only enable them for debug (dev) builds, not release.

    # To decide whether to rebuild a file, use the MD5 sum only if the timestamp has changed.
    # http://scons.org/doc/production/HTML/scons-user/ch06.html#idm139837621851792
    env_base.Decider("MD5-timestamp")
    # Use cached implicit dependencies by default. Can be overridden by specifying `--implicit-deps-changed` in the command line.
    # http://scons.org/doc/production/HTML/scons-user/ch06s04.html
    env_base.SetOption("implicit_cache", 1)

if not env_base["tools"]:
    # Export templates can't run unit test tool.
    env_base["tests"] = False

if env_base["no_editor_splash"]:
    env_base.Append(CPPDEFINES=["NO_EDITOR_SPLASH"])

if not env_base["deprecated"]:
    env_base.Append(CPPDEFINES=["DISABLE_DEPRECATED"])

env_base.platforms = {}

selected_platform = ""

if env_base["platform"] != "":
    selected_platform = env_base["platform"]
elif env_base["p"] != "":
    selected_platform = env_base["p"]
    env_base["platform"] = selected_platform
else:
    # Missing `platform` argument, try to detect platform automatically
    if sys.platform.startswith("linux"):
        selected_platform = "linuxbsd"
    elif sys.platform == "darwin":
        selected_platform = "osx"
    elif sys.platform == "win32":
        selected_platform = "windows"
    else:
        print("Could not detect platform automatically. Supported platforms:")
        for x in platform_list:
            print("\t" + x)
        print("\nPlease run SCons again and select a valid platform: platform=<string>")

    if selected_platform != "":
        print("Automatically detected platform: " + selected_platform)
        env_base["platform"] = selected_platform

if selected_platform in ["linux", "bsd", "x11"]:
    if selected_platform == "x11":
        # Deprecated alias kept for compatibility.
        print('Platform "x11" has been renamed to "linuxbsd" in Godot 4.0. Building for platform "linuxbsd".')
    # Alias for convenience.
    selected_platform = "linuxbsd"
    env_base["platform"] = selected_platform

if selected_platform in platform_list:
    tmppath = "./platform/" + selected_platform
    sys.path.insert(0, tmppath)
    import detect

    if "create" in dir(detect):
        env = detect.create(env_base)
    else:
        env = env_base.Clone()

    # Compilation DB requires SCons 3.1.1+.
    from SCons import __version__ as scons_raw_version

    scons_ver = env._get_major_minor_revision(scons_raw_version)

    if scons_ver >= (4, 0, 0):
        env.Tool("compilation_db")
        env.Alias("compiledb", env.CompilationDatabase())

    if env["dev"]:
        env["verbose"] = True
        env["warnings"] = "extra"
        env["werror"] = True
        if env["tools"]:
            env["tests"] = True

    env.extra_suffix = ""

    if env["extra_suffix"] != "":
        env.extra_suffix += "." + env["extra_suffix"]

    # Environment flags
    CCFLAGS = env.get("CCFLAGS", "")
    env["CCFLAGS"] = ""
    env.Append(CCFLAGS=str(CCFLAGS).split())

    CFLAGS = env.get("CFLAGS", "")
    env["CFLAGS"] = ""
    env.Append(CFLAGS=str(CFLAGS).split())

    CXXFLAGS = env.get("CXXFLAGS", "")
    env["CXXFLAGS"] = ""
    env.Append(CXXFLAGS=str(CXXFLAGS).split())

    LINKFLAGS = env.get("LINKFLAGS", "")
    env["LINKFLAGS"] = ""
    env.Append(LINKFLAGS=str(LINKFLAGS).split())

    # Platform specific flags
    flag_list = platform_flags[selected_platform]
    for f in flag_list:
        if not (f[0] in ARGUMENTS):  # allow command line to override platform flags
            env[f[0]] = f[1]

    # Must happen after the flags definition, so that they can be used by platform detect
    detect.configure(env)

    # Set our C and C++ standard requirements.
    # C++17 is required as we need guaranteed copy elision as per GH-36436.
    # Prepending to make it possible to override.
    # This needs to come after `configure`, otherwise we don't have env.msvc.
    if not env.msvc:
        # Specifying GNU extensions support explicitly, which are supported by
        # both GCC and Clang. Both currently default to gnu11 and gnu++14.
        env.Prepend(CFLAGS=["-std=gnu11"])
        env.Prepend(CXXFLAGS=["-std=gnu++17"])
    else:
        # MSVC doesn't have clear C standard support, /std only covers C++.
        # We apply it to CCFLAGS (both C and C++ code) in case it impacts C features.
        env.Prepend(CCFLAGS=["/std:c++17"])

    # Enforce our minimal compiler version requirements
    cc_version = methods.get_compiler_version(env) or [-1, -1]
    cc_version_major = cc_version[0]
    cc_version_minor = cc_version[1]

    if methods.using_gcc(env):
        # GCC 8 before 8.4 has a regression in the support of guaranteed copy elision
        # which causes a build failure: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86521
        if cc_version_major == 8 and cc_version_minor < 4:
            print(
                "Detected GCC 8 version < 8.4, which is not supported due to a "
                "regression in its C++17 guaranteed copy elision support. Use a "
                'newer GCC version, or Clang 6 or later by passing "use_llvm=yes" '
                "to the SCons command line."
            )
            Exit(255)
        elif cc_version_major < 7:
            print(
                "Detected GCC version older than 7, which does not fully support "
                "C++17. Supported versions are GCC 7, 9 and later. Use a newer GCC "
                'version, or Clang 6 or later by passing "use_llvm=yes" to the '
                "SCons command line."
            )
            Exit(255)
    elif methods.using_clang(env):
        # Apple LLVM versions differ from upstream LLVM version \o/, compare
        # in https://en.wikipedia.org/wiki/Xcode#Toolchain_versions
        if env["platform"] == "osx" or env["platform"] == "iphone":
            vanilla = methods.is_vanilla_clang(env)
            if vanilla and cc_version_major < 6:
                print(
                    "Detected Clang version older than 6, which does not fully support "
                    "C++17. Supported versions are Clang 6 and later."
                )
                Exit(255)
            elif not vanilla and cc_version_major < 10:
                print(
                    "Detected Apple Clang version older than 10, which does not fully "
                    "support C++17. Supported versions are Apple Clang 10 and later."
                )
                Exit(255)
        elif cc_version_major < 6:
            print(
                "Detected Clang version older than 6, which does not fully support "
                "C++17. Supported versions are Clang 6 and later."
            )
            Exit(255)

    # Configure compiler warnings
    if env.msvc:  # MSVC
        # Truncations, narrowing conversions, signed/unsigned comparisons...
        disable_nonessential_warnings = ["/wd4267", "/wd4244", "/wd4305", "/wd4018", "/wd4800"]
        if env["warnings"] == "extra":
            env.Append(CCFLAGS=["/Wall"])  # Implies /W4
        elif env["warnings"] == "all":
            env.Append(CCFLAGS=["/W3"] + disable_nonessential_warnings)
        elif env["warnings"] == "moderate":
            env.Append(CCFLAGS=["/W2"] + disable_nonessential_warnings)
        else:  # 'no'
            env.Append(CCFLAGS=["/w"])
        # Set exception handling model to avoid warnings caused by Windows system headers.
        env.Append(CCFLAGS=["/EHsc"])

        if env["werror"]:
            env.Append(CCFLAGS=["/WX"])
    else:  # GCC, Clang
        gcc_common_warnings = []

        if methods.using_gcc(env):
            gcc_common_warnings += ["-Wshadow-local", "-Wno-misleading-indentation"]

        if env["warnings"] == "extra":
            env.Append(CCFLAGS=["-Wall", "-Wextra", "-Wwrite-strings", "-Wno-unused-parameter"] + gcc_common_warnings)
            env.Append(CXXFLAGS=["-Wctor-dtor-privacy", "-Wnon-virtual-dtor"])
            if methods.using_gcc(env):
                env.Append(
                    CCFLAGS=[
                        "-Walloc-zero",
                        "-Wduplicated-branches",
                        "-Wduplicated-cond",
                        "-Wstringop-overflow=4",
                        "-Wlogical-op",
                    ]
                )
                # -Wnoexcept was removed temporarily due to GH-36325.
                env.Append(CXXFLAGS=["-Wplacement-new=1"])
                if cc_version_major >= 9:
                    env.Append(CCFLAGS=["-Wattribute-alias=2"])
            elif methods.using_clang(env):
                env.Append(CCFLAGS=["-Wimplicit-fallthrough"])
        elif env["warnings"] == "all":
            env.Append(CCFLAGS=["-Wall"] + gcc_common_warnings)
        elif env["warnings"] == "moderate":
            env.Append(CCFLAGS=["-Wall", "-Wno-unused"] + gcc_common_warnings)
        else:  # 'no'
            env.Append(CCFLAGS=["-w"])

        if env["werror"]:
            env.Append(CCFLAGS=["-Werror"])
            # FIXME: Temporary workaround after the Vulkan merge, remove once warnings are fixed.
            if methods.using_gcc(env):
                env.Append(CXXFLAGS=["-Wno-error=cpp"])
                if cc_version_major == 7:  # Bogus warning fixed in 8+.
                    env.Append(CCFLAGS=["-Wno-error=strict-overflow"])
            else:
                env.Append(CXXFLAGS=["-Wno-error=#warnings"])
        else:  # always enable those errors
            env.Append(CCFLAGS=["-Werror=return-type"])

    if hasattr(detect, "get_program_suffix"):
        suffix = "." + detect.get_program_suffix()
    else:
        suffix = "." + selected_platform

    if env["target"] == "release":
        if env["tools"]:
            print("Tools can only be built with targets 'debug' and 'release_debug'.")
            Exit(255)
        suffix += ".opt"
        env.Append(CPPDEFINES=["NDEBUG"])

    elif env["target"] == "release_debug":
        if env["tools"]:
            suffix += ".opt.tools"
        else:
            suffix += ".opt.debug"
    else:
        if env["tools"]:
            suffix += ".tools"
        else:
            suffix += ".debug"

    if env["arch"] != "":
        suffix += "." + env["arch"]
    elif env["bits"] == "32":
        suffix += ".32"
    elif env["bits"] == "64":
        suffix += ".64"

    suffix += env.extra_suffix

    sys.path.remove(tmppath)
    sys.modules.pop("detect")

    modules_enabled = OrderedDict()
    env.module_icons_paths = []
    env.doc_class_path = {}

    for name, path in modules_detected.items():
        if not env["module_" + name + "_enabled"]:
            continue
        sys.path.insert(0, path)
        env.current_module = name
        import config

        if config.can_build(env, selected_platform):
            config.configure(env)
            # Get doc classes paths (if present)
            try:
                doc_classes = config.get_doc_classes()
                doc_path = config.get_doc_path()
                for c in doc_classes:
                    env.doc_class_path[c] = path + "/" + doc_path
            except:
                pass
            # Get icon paths (if present)
            try:
                icons_path = config.get_icons_path()
                env.module_icons_paths.append(path + "/" + icons_path)
            except:
                # Default path for module icons
                env.module_icons_paths.append(path + "/" + "icons")
            modules_enabled[name] = path

        sys.path.remove(path)
        sys.modules.pop("config")

    env.module_list = modules_enabled

    methods.update_version(env.module_version_string)

    env["PROGSUFFIX"] = suffix + env.module_version_string + env["PROGSUFFIX"]
    env["OBJSUFFIX"] = suffix + env["OBJSUFFIX"]
    # (SH)LIBSUFFIX will be used for our own built libraries
    # LIBSUFFIXES contains LIBSUFFIX and SHLIBSUFFIX by default,
    # so we need to append the default suffixes to keep the ability
    # to link against thirdparty libraries (.a, .so, .lib, etc.).
    if os.name == "nt":
        # On Windows, only static libraries and import libraries can be
        # statically linked - both using .lib extension
        env["LIBSUFFIXES"] += [env["LIBSUFFIX"]]
    else:
        env["LIBSUFFIXES"] += [env["LIBSUFFIX"], env["SHLIBSUFFIX"]]
    env["LIBSUFFIX"] = suffix + env["LIBSUFFIX"]
    env["SHLIBSUFFIX"] = suffix + env["SHLIBSUFFIX"]

    if env["tools"]:
        env.Append(CPPDEFINES=["TOOLS_ENABLED"])
    if env["disable_3d"]:
        if env["tools"]:
            print(
                "Build option 'disable_3d=yes' cannot be used with 'tools=yes' (editor), "
                "only with 'tools=no' (export template)."
            )
            Exit(255)
        else:
            env.Append(CPPDEFINES=["_3D_DISABLED"])
    if env["disable_advanced_gui"]:
        if env["tools"]:
            print(
                "Build option 'disable_advanced_gui=yes' cannot be used with 'tools=yes' (editor), "
                "only with 'tools=no' (export template)."
            )
            Exit(255)
        else:
            env.Append(CPPDEFINES=["ADVANCED_GUI_DISABLED"])
    if env["minizip"]:
        env.Append(CPPDEFINES=["MINIZIP_ENABLED"])

    editor_module_list = ["regex"]
    if env["tools"] and not env.module_check_dependencies("tools", editor_module_list):
        print(
            "Build option 'module_"
            + x
            + "_enabled=no' cannot be used with 'tools=yes' (editor), only with 'tools=no' (export template)."
        )
        Exit(255)

    if not env["verbose"]:
        methods.no_verbose(sys, env)

    if not env["platform"] == "server":
        GLSL_BUILDERS = {
            "RD_GLSL": env.Builder(
                action=env.Run(glsl_builders.build_rd_headers, 'Building RD_GLSL header: "$TARGET"'),
                suffix="glsl.gen.h",
                src_suffix=".glsl",
            ),
            "GLSL_HEADER": env.Builder(
                action=env.Run(glsl_builders.build_raw_headers, 'Building GLSL header: "$TARGET"'),
                suffix="glsl.gen.h",
                src_suffix=".glsl",
            ),
        }
        env.Append(BUILDERS=GLSL_BUILDERS)

    scons_cache_path = os.environ.get("SCONS_CACHE")
    if scons_cache_path != None:
        CacheDir(scons_cache_path)
        print("Scons cache enabled... (path: '" + scons_cache_path + "')")

    if env["vsproj"]:
        env.vs_incs = []
        env.vs_srcs = []

    Export("env")

    # Build subdirs, the build order is dependent on link order.
    SConscript("core/SCsub")
    SConscript("servers/SCsub")
    SConscript("scene/SCsub")
    SConscript("editor/SCsub")
    SConscript("drivers/SCsub")

    SConscript("platform/SCsub")
    SConscript("modules/SCsub")
    if env["tests"]:
        SConscript("tests/SCsub")
    SConscript("main/SCsub")

    SConscript("platform/" + selected_platform + "/SCsub")  # Build selected platform.

    # Microsoft Visual Studio Project Generation
    if env["vsproj"]:
        env["CPPPATH"] = [Dir(path) for path in env["CPPPATH"]]
        methods.generate_vs_project(env, GetOption("num_jobs"))
        methods.generate_cpp_hint_file("cpp.hint")

    # Check for the existence of headers
    conf = Configure(env)
    if "check_c_headers" in env:
        for header in env["check_c_headers"]:
            if conf.CheckCHeader(header[0]):
                env.AppendUnique(CPPDEFINES=[header[1]])

elif selected_platform != "":
    if selected_platform == "list":
        print("The following platforms are available:\n")
    else:
        print('Invalid target platform "' + selected_platform + '".')
        print("The following platforms were detected:\n")

    for x in platform_list:
        print("\t" + x)

    print("\nPlease run SCons again and select a valid platform: platform=<string>")

    if selected_platform == "list":
        # Exit early to suppress the rest of the built-in SCons messages
        Exit()
    else:
        Exit(255)

# The following only makes sense when the 'env' is defined, and assumes it is.
if "env" in locals():
    methods.show_progress(env)
    # TODO: replace this with `env.Dump(format="json")`
    # once we start requiring SCons 4.0 as min version.
    methods.dump(env)