Temp fix decade-long Sphinx bug breaking our CSS during partial rebuilds (#2496)

* Add temp fix for Sphinx failing to copy static files

* Gate the temp fix feature behind a dev-machine specific file

* Move the temp fix into a contained script file + update .gitignore comment

* Remove extraneous commits + add annotations and docstrings

* Fix broken URL link in docstring

* Extra safety for when we notice we shouldn't run

* Fix some pathing stuff + test with ./make.py serve

* Fix paths

* Update top-of-file docstring

* Fix dirs

Author: pushfoo

.gitignore

@@ -58,3 +58,7 @@ temp/
 .python-version
 
 .flake8
+
+# pending: Sphinx 8.1.4 + deps are verified as working with Arcade
+# see util/sphinx_static_file_temp_fix.py
+.ENABLE_DEVMACHINE_SPHINX_STATIC_FIX

doc/conf.py

@@ -28,6 +28,7 @@
 
 HERE = Path(__file__).resolve()
 REPO_LOCAL_ROOT = HERE.parent.parent
+
 ARCADE_MODULE = REPO_LOCAL_ROOT / "arcade"
 UTIL_DIR = REPO_LOCAL_ROOT / "util"
 
@@ -88,14 +89,17 @@ def run_util(filename, run_name="__main__", init_globals=None):
 
     runpy.run_path(full_str, **kwargs)
 
+# Temp fix for Sphinx not copying static files  # pending: post-3.0 refactor
+# Enable by creating a .ENABLE_DEVMACHINE_SPHINX_STATIC_FIX
+run_util("sphinx_static_file_temp_fix.py")
+
 # Make thumbnails for the example code screenshots
 run_util("generate_example_thumbnails.py")
 # Create a tabular representation of the resources with embeds
 run_util("create_resources_listing.py", init_globals=RESOURCE_GLOBALS)
 # Run the generate quick API index script
 run_util('../util/update_quick_index.py')
 
-
 autodoc_inherit_docstrings = False
 autodoc_default_options = {
     'members': True,

util/sphinx_static_file_temp_fix.py

@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+"""
+Gets 3.0 out the door by temp fixing Sphinx rebuild not copying CSS.
+
+IMPORTANT: ONLY LOCAL DEVELOPER MACHINES NEED THIS!
+
+## Who should use this?
+
+If `./make.py clean` seems like the only way to get `./make.py html` or
+`./make.py serve` to serve your modified CSS, then yes, it's for you.
+
+## How do I use this?
+
+1. `cd` to the repo root
+2. `touch .ENABLE_DEVMACHINE_SPHINX_STATIC_FIX`
+3. `./make.py html` with working CSS change updates copying
+
+## When should I be careful?
+
+Keep the following in mind:
+
+1. It is a temp fix which *seems* to work with both:
+
+   * `./make.py html`
+   * `./make.py serve`
+
+3. No real config options other on/off via file presence
+
+## What's Broken in Sphinx?
+
+1. Sphinx has a long-standing bug which fails to copy static files
+   https://github.com/sphinx-doc/sphinx/issues/1810
+
+2. The fix is slated for 8.2.0 and the fix PR merged on Jan 13, 2025:
+   https://github.com/sphinx-doc/sphinx/pull/13236
+
+3. No, Arcade 3.0 **will not wait** for the following:
+
+   1. Sphinx 3.2.0 to ship the fix for the problem
+   2. Themes to become compatible
+   3. Plugins to become compatible
+   4. Our customizations to be tested with all of the above
+
+"""
+
+import sys
+import logging
+from pathlib import Path
+from sphinx import __version__ as sphinx_version
+
+UTIL_DIR = Path(__file__).parent.resolve()
+REPO_ROOT = UTIL_DIR.parent.resolve()
+
+# Ensure we get utility & Arcade imports first
+sys.path.insert(0, str(REPO_ROOT))
+
+log = logging.getLogger(__name__)
+
+DOC_DIR = REPO_ROOT / "doc"
+STATIC_SOURCE_DIR = DOC_DIR / "_static"
+
+ENABLE_DEVMACHINE_SPHINX_STATIC_FIX = REPO_ROOT / ".ENABLE_DEVMACHINE_SPHINX_STATIC_FIX"
+
+BUILD_DIR = REPO_ROOT / "build"
+BUILD_HTML_DIR = BUILD_DIR / "html"
+BUILD_STATIC_DIR = BUILD_HTML_DIR / "_static"
+BUILD_CSS_DIR = BUILD_STATIC_DIR / "css"
+
+STATIC_CSS_DIR = STATIC_SOURCE_DIR / "css"
+force_copy_on_change = {  # pending: sphinx >= 8.1.4
+    source_file: BUILD_CSS_DIR / source_file.name
+    for source_file in STATIC_CSS_DIR.glob("*.css")
+}
+
+
+def force_sync(src: Path, dest: Path, dry: bool = False) -> None:
+    """Sync a single file from ``src`` to ``dest``.
+
+    Caveats:
+
+    1. Assumes both are `pathlib.Path` instances
+    2. Assumes both are small
+    3. Fails hard when a file isn't found
+
+    """
+    if sphinx_version >= '8.1.4':
+        log.warning(
+            'Sphinx >= 8.1.4 may patch broken _static copy\n'
+            '  (see https://github.com/sphinx-doc/sphinx/issues/1810)')
+    try:
+        if src.read_text() != dest.read_text():
+            if dry:
+                log.info(f" DRY : {src} was out of date, but dry run left it as-is!")
+            # shutil.copyfile(src, dest)
+            else:
+                log.info(f" SYNC: {src} was out of date!")
+
+        else:
+            log.info(f" SKIP: {src} is current!")
+    except Exception as e:
+        log.error(f" FAIL: {src} failed: {e}")
+        raise e
+
+
+def main():
+    if not ENABLE_DEVMACHINE_SPHINX_STATIC_FIX.exists():
+        log.info(f"SKIP: Force-sync found no {ENABLE_DEVMACHINE_SPHINX_STATIC_FIX} file!")
+        return
+    elif not BUILD_HTML_DIR.exists():
+        log.info(f"SKIP: {BUILD_HTML_DIR} does not exist yet.")
+        return
+
+    log.info(f"SYNC: Force-sync enable file found")
+    for src, dest in force_copy_on_change.items():
+        force_sync(src, dest)
+
+
+if __name__ == "__main__":
+    main()