don't accept bytes/unicode objects in sequence casters

src/common.cpp

@@ -577,6 +577,12 @@ PyObject **seq_get(PyObject *seq, size_t *size_out, PyObject **temp_out) noexcep
        goes wrong, it fails gracefully without reporting errors. Other
        overloads will then be tried. */
 
+    if (PyUnicode_CheckExact(seq) || PyBytes_CheckExact(seq)) {
+        *size_out = 0;
+        *temp_out = nullptr;
+        return nullptr;
+    }
+
 #if !defined(Py_LIMITED_API) && !defined(PYPY_VERSION)
     if (PyTuple_CheckExact(seq)) {
         size = (size_t) PyTuple_GET_SIZE(seq);

src/nb_type.cpp

@@ -1123,6 +1123,7 @@ void keep_alive(PyObject *nurse, PyObject *patient) {
     } else {
         PyObject *callback =
             PyCFunction_New(&keep_alive_callback_def, patient);
+
         PyObject *weakref = PyWeakref_NewRef(nurse, callback);
         if (!weakref) {
             Py_DECREF(callback);

tests/test_stl.cpp

@@ -439,4 +439,10 @@ NB_MODULE(test_stl_ext, m) {
         return x;
     });
 
+    m.def("vector_str", [](const std::vector<std::string>& x){
+        return x;
+    });
+    m.def("vector_str", [](std::string& x){
+        return x;
+    });
 }

tests/test_stl.py

@@ -820,3 +820,7 @@ def test69_complex_array():
         assert t.complex_array_float(np.array([val1_64, -1j, val2_64],dtype=np.complex64)) == [val1_32, (-0-1j), val2_32]
     except ImportError:
         pass
+
+def test70_vec_char():
+    assert isinstance(t.vector_str("123"), str)
+    assert isinstance(t.vector_str(["123", "345"]), list)