Implement noconvert for std::filesystem::path

include/pybind11/stl/filesystem.h

@@ -58,7 +58,13 @@ struct path_caster {
         return nullptr;
     }
 
-    bool load(handle handle, bool) {
+    bool load(handle handle, bool convert) {
+        if (!convert
+            && PyObject_IsInstance(handle.ptr(), module_::import("pathlib").attr("Path").ptr())
+                   != 1) {
+            return false;
+        }
+
         // PyUnicode_FSConverter and PyUnicode_FSDecoder normally take care of
         // calling PyOS_FSPath themselves, but that's broken on PyPy (PyPy
         // issue #3168) so we do it ourselves instead.

tests/test_stl.cpp

@@ -456,6 +456,10 @@ TEST_SUBMODULE(stl, m) {
     // test_fs_path
     m.attr("has_filesystem") = true;
     m.def("parent_path", [](const std::filesystem::path &path) { return path.parent_path(); });
+    m.def(
+        "parent_path_noconvert",
+        [](const std::filesystem::path &path) { return path.parent_path(); },
+        py::arg("arg0").noconvert());
     m.def("parent_paths", [](const std::vector<std::filesystem::path> &paths) {
         std::vector<std::filesystem::path> result;
         result.reserve(paths.size());

tests/test_stl.py

@@ -279,6 +279,16 @@ def __fspath__(self):
     assert m.parent_path(b"foo/bar") == Path("foo")
     assert m.parent_path(PseudoStrPath()) == Path("foo")
     assert m.parent_path(PseudoBytesPath()) == Path("foo")
+    # Single argument noconvert
+    assert m.parent_path_noconvert(Path("foo/bar")) == Path("foo")
+    with pytest.raises(TypeError):
+        m.parent_path_noconvert("foo/bar")
+    with pytest.raises(TypeError):
+        m.parent_path_noconvert(b"foo/bar")
+    with pytest.raises(TypeError):
+        m.parent_path_noconvert(PseudoStrPath())
+    with pytest.raises(TypeError):
+        m.parent_path_noconvert(PseudoBytesPath())
     # std::vector
     assert m.parent_paths(["foo/bar", "foo/baz"]) == [Path("foo"), Path("foo")]
     # py::typing::List
@@ -311,6 +321,11 @@ def test_path_typing(doc):
         doc(m.parent_path)
         == "parent_path(arg0: os.PathLike | str | bytes) -> pathlib.Path"
     )
+    # Single argument noconvert
+    assert (
+        doc(m.parent_path_noconvert)
+        == "parent_path_noconvert(arg0: pathlib.Path) -> pathlib.Path"
+    )
     # std::vector
     assert (
         doc(m.parent_paths)