fix: handle Python 3.15 removal of the legacy sre_parse module

pcre/_stdlib_re.py

@@ -11,9 +11,18 @@ def _load_parser():
     if parser is not None:
         return parser
 
-    with warnings.catch_warnings():
-        warnings.simplefilter("ignore", DeprecationWarning)
-        import sre_parse as parser
+    # Python <= 3.10 hides the parser behind the deprecated top-level
+    # ``sre_parse`` module; Python 3.15 removes that alias entirely.
+    try:
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            import sre_parse as parser
+    except ModuleNotFoundError as exc:  # pragma: no cover - Python >= 3.15
+        raise ImportError(
+            "stdlib re internals unavailable: expected re._parser "
+            "(Python 3.11+) or sre_parse (Python <= 3.10); this interpreter "
+            "provides neither"
+        ) from exc
 
     return parser
 

tests/test_python_coverage_audit.py

@@ -28,10 +28,15 @@
 
 def test_stdlib_parser_fallback(monkeypatch: pytest.MonkeyPatch) -> None:
     # Python 3.10 does not expose ``re._parser`` at module scope, while newer
-    # releases do.  Either state should exercise our fallback loader.
+    # releases do.  Python 3.15 removes the legacy ``sre_parse`` module, so on
+    # that interpreter the fallback must degrade with a clear ImportError.
     monkeypatch.delattr(re, "_parser", raising=False)
-    parser = stdlib_re._load_parser()
-    assert callable(parser.parse)
+    if importlib.util.find_spec("sre_parse") is not None:
+        parser = stdlib_re._load_parser()
+        assert callable(parser.parse)
+    else:
+        with pytest.raises(ImportError):
+            stdlib_re._load_parser()
 
 
 def test_stdlib_parser_exported_path(monkeypatch: pytest.MonkeyPatch) -> None: