SCons: Properly handle overriding default values to bool options

The `dev=yes` and `production=yes` options work as aliases to set a number of
options, while still aiming to allow overriding specific options if the user
wishes so. (E.g. `production=yes use_lto=no` should work to enable production
defaults *but* disable LTO.)

That wasn't working as `ARGUMENTS.get()` returns a string and not a boolean as
expected by `BoolVariable`, and this wasn't flagged as a bug... So added a
helper method using SCons' `BoolVariable._text2bool` to do the conversion
manually.

SConstruct

@@ -55,7 +55,7 @@ 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)):
+if os.name == "nt" and (platform_arg == "android" or methods.get_cmdline_bool("use_mingw", False)):
     custom_tools = ["mingw"]
 elif platform_arg == "javascript":
     # Use generic POSIX build toolchain for Emscripten.
@@ -95,7 +95,7 @@ env_base.SConsignFile(".sconsign{0}.dblite".format(pickle.HIGHEST_PROTOCOL))
 
 customs = ["custom.py"]
 
-profile = ARGUMENTS.get("profile", False)
+profile = methods.get_cmdline_bool("profile", False)
 if profile:
     if os.path.isfile(profile):
         customs.append(profile)
@@ -325,17 +325,17 @@ if selected_platform in platform_list:
         env.Alias("compiledb", env.CompilationDatabase())
 
     # 'dev' and 'production' are aliases to set default options if they haven't been set
-    # manually by the user. We use `ARGUMENTS.get()` to check if they were manually set.
+    # manually by the user.
     if env["dev"]:
-        env["verbose"] = ARGUMENTS.get("verbose", True)
+        env["verbose"] = methods.get_cmdline_bool("verbose", True)
         env["warnings"] = ARGUMENTS.get("warnings", "extra")
-        env["werror"] = ARGUMENTS.get("werror", True)
+        env["werror"] = methods.get_cmdline_bool("werror", True)
         if env["tools"]:
-            env["tests"] = ARGUMENTS.get("tests", True)
+            env["tests"] = methods.get_cmdline_bool("tests", True)
     if env["production"]:
-        env["use_static_cpp"] = ARGUMENTS.get("use_static_cpp", True)
-        env["use_lto"] = ARGUMENTS.get("use_lto", True)
-        env["debug_symbols"] = ARGUMENTS.get("debug_symbols", False)
+        env["use_static_cpp"] = methods.get_cmdline_bool("use_static_cpp", True)
+        env["use_lto"] = methods.get_cmdline_bool("use_lto", True)
+        env["debug_symbols"] = methods.get_cmdline_bool("debug_symbols", False)
         if not env["tools"] and env["target"] == "debug":
             print(
                 "WARNING: Requested `production` build with `tools=no target=debug`, "

methods.py

@@ -6,9 +6,11 @@
 
 # We need to define our own `Action` method to control the verbosity of output
 # and whenever we need to run those commands in a subprocess on some platforms.
-from SCons.Script import Action
 from SCons import Node
+from SCons.Script import Action
+from SCons.Script import ARGUMENTS
 from SCons.Script import Glob
+from SCons.Variables.BoolVariable import _text2bool
 from platform_methods import run_in_subprocess
 
 
@@ -145,6 +147,17 @@ def parse_cg_file(fname, uniforms, sizes, conditionals):
     fs.close()
 
 
+def get_cmdline_bool(option, default):
+    """We use `ARGUMENTS.get()` to check if options were manually overridden on the command line,
+    and SCons' _text2bool helper to convert them to booleans, otherwise they're handled as strings.
+    """
+    cmdline_val = ARGUMENTS.get(option)
+    if cmdline_val is not None:
+        return _text2bool(cmdline_val)
+    else:
+        return default
+
+
 def detect_modules(search_path, recursive=False):
     """Detects and collects a list of C++ modules at specified path