ENH: apply exclude pattern before import

This helps to filter out parts of a big package to be documented which
might fail during import.

Author: elcorto

src/sphinx_autodoc/main.py

@@ -364,20 +364,23 @@ def main():
 
     print(f"processing package: {package_name}")
     package = importlib.import_module(package_name)
+
+    if args.exclude is not None:
+        rex = re.compile(args.exclude)
+        mod_filter = lambda name: rex.search(name) is None
+    else:
+        mod_filter = lambda name: True
+
     mods = [
         Module(
             name,
             source=args.source,
             apipath=args.apipath,
             docpath=args.docpath,
         )
-        for name in walk_package(package)
+        for name in walk_package(package) if mod_filter(name)
     ]
 
-    if args.exclude is not None:
-        rex = re.compile(args.exclude)
-        mods = [mod for mod in mods if rex.search(mod.name) is None]
-
     modules_api = ""
     modules_doc = ""