SCons: Add emitter to declutter build objects

SConstruct

@@ -14,6 +14,7 @@ from importlib.util import module_from_spec, spec_from_file_location
 from types import ModuleType
 
 from SCons import __version__ as scons_raw_version
+from SCons.Builder import ListEmitter
 
 # Explicitly resolve the helper modules, this is done to avoid clash with
 # modules of the same name that might be randomly added (e.g. someone adding
@@ -251,6 +252,13 @@ opts.Add(BoolVariable("engine_update_check", "Enable engine update checks in the
 opts.Add(BoolVariable("steamapi", "Enable minimal SteamAPI integration for usage time tracking (editor only)", False))
 opts.Add("cache_path", "Path to a directory where SCons cache files will be stored. No value disables the cache.", "")
 opts.Add("cache_limit", "Max size (in GiB) for the SCons cache. 0 means no limit.", "0")
+opts.Add(
+    BoolVariable(
+        "redirect_build_objects",
+        "Enable redirecting built objects/libraries to `bin/obj/` to declutter the repository.",
+        True,
+    )
+)
 
 # Thirdparty libraries
 opts.Add(BoolVariable("builtin_brotli", "Use the built-in Brotli library", True))
@@ -1057,6 +1065,14 @@ if env["ninja"]:
 if env["threads"]:
     env.Append(CPPDEFINES=["THREADS_ENABLED"])
 
+# Ensure build objects are put in their own folder.
+env.Prepend(LIBEMITTER=methods.redirect_emitter)
+env.Prepend(SHLIBEMITTER=methods.redirect_emitter)
+for key in (emitters := env.StaticObject.builder.emitter):
+    emitters[key] = ListEmitter([methods.redirect_emitter] + env.Flatten(emitters[key]))
+for key in (emitters := env.SharedObject.builder.emitter):
+    emitters[key] = ListEmitter([methods.redirect_emitter] + env.Flatten(emitters[key]))
+
 # Build subdirs, the build order is dependent on link order.
 Export("env")
 

methods.py

@@ -14,8 +14,7 @@
 from misc.utility.color import print_error, print_info, print_warning
 
 # Get the "Godot" folder name ahead of time
-base_folder_path = str(os.path.abspath(Path(__file__).parent)) + "/"
-base_folder_only = os.path.basename(os.path.normpath(base_folder_path))
+base_folder = Path(__file__).parent.resolve()
 
 # Listing all the folders we have converted
 # for SCU in scu_builders.py
@@ -79,6 +78,34 @@ def add_source_files(self, sources, files, allow_gen=False):
     return True
 
 
+def redirect_emitter(target, source, env):
+    """
+    Emitter to automatically redirect object/library build files to the `bin/obj` directory,
+    retaining subfolder structure. External build files will attempt to retain subfolder
+    structure relative to their environment's parent directory, sorted under `bin/obj/external`.
+    If `redirect_build_objects` is `False`, or an external build file isn't relative to the
+    passed environment, this emitter does nothing.
+    """
+    if not env["redirect_build_objects"]:
+        return target, source
+    redirected_targets = []
+    for item in env.Flatten(target):
+        if isinstance(item, str):
+            item = env.File(item)
+        path = Path(item.get_abspath()).resolve()
+        try:
+            item = env.File(f"#bin/obj/{path.relative_to(base_folder)}")
+        except ValueError:
+            # External file; most likely a custom module. Assume relevant environment was passed.
+            alt_base = Path(env.Dir(".").get_abspath()).parent.resolve()
+            try:
+                item = env.File(f"#bin/obj/external/{path.relative_to(alt_base)}")
+            except ValueError:
+                pass
+        redirected_targets.append(item)
+    return redirected_targets, source
+
+
 def disable_warnings(self):
     # 'self' is the environment
     if self.msvc and not using_clang(self):
@@ -754,7 +781,7 @@ def show_progress(env):
     if env["ninja"]:
         return
 
-    NODE_COUNT_FILENAME = f"{base_folder_path}.scons_node_count"
+    NODE_COUNT_FILENAME = base_folder / ".scons_node_count"
 
     class ShowProgress:
         def __init__(self):

platform/android/SCsub

@@ -43,7 +43,7 @@ env_thirdparty.disable_warnings()
 thirdparty_obj = env_thirdparty.SharedObject("#thirdparty/misc/ifaddrs-android.cc")
 android_objects.append(thirdparty_obj)
 
-lib = env_android.add_shared_library("#bin/libgodot", [android_objects], SHLIBSUFFIX=env["SHLIBSUFFIX"])
+lib = env_android.add_shared_library("#bin/libgodot", android_objects, redirect_build_objects=False)
 
 # Needed to force rebuilding the platform files when the thirdparty code is updated.
 env.Depends(lib, thirdparty_obj)
@@ -77,9 +77,7 @@ if lib_arch_dir != "":
         lib_tools_dir = ""
 
     out_dir = "#platform/android/java/lib/libs/" + lib_tools_dir + lib_type_dir + "/" + lib_arch_dir
-    env_android.Command(
-        out_dir + "/libgodot_android.so", "#bin/libgodot" + env["SHLIBSUFFIX"], Move("$TARGET", "$SOURCE")
-    )
+    env_android.Command(out_dir + "/libgodot_android.so", lib, Move("$TARGET", "$SOURCE"))
 
     stl_lib_path = (
         str(env["ANDROID_NDK_ROOT"]) + "/sources/cxx-stl/llvm-libc++/libs/" + lib_arch_dir + "/libc++_shared.so"

platform/windows/SCsub

@@ -8,6 +8,8 @@ from pathlib import Path
 
 import platform_windows_builders
 
+from methods import redirect_emitter
+
 sources = []
 
 common_win = [
@@ -49,6 +51,7 @@ def arrange_program_clean(prog):
         Clean(prog, extra_files_to_clean)
 
 
+env["BUILDERS"]["RES"].emitter = redirect_emitter
 res_file = "godot_res.rc"
 res_target = "godot_res" + env["OBJSUFFIX"]
 res_obj = env.RES(res_target, res_file)

platform/windows/detect.py

@@ -368,7 +368,7 @@ def configure_msvc(env: "SConsEnvironment", vcvars_msvc_config):
         from tempfile import mkstemp
 
         # Ensure we have a location to write captured output to, in case of false positives.
-        capture_path = methods.base_folder_path + "platform/windows/msvc_capture.log"
+        capture_path = methods.base_folder / "platform" / "windows" / "msvc_capture.log"
         with open(capture_path, "wt", encoding="utf-8"):
             pass