fix: reject str in tp_init with hashlib-compatible error

Add PyUnicode_Check before PyArg_ParseTupleAndKeywords in all 4
tp_init functions, raising 'Strings must be encoded before hashing'
when str is passed. Needed for PyPy where tp_vectorcall is not
supported and tp_init is the fallback constructor path.

Author: ifduyue

src/_xxhash.c

@@ -555,6 +555,11 @@ static int PYXXH32_init(PYXXH32Object *self, PyObject *args, PyObject *kwargs)
 
     buf.buf = buf.obj = NULL;
 
+    if (PyTuple_GET_SIZE(args) >= 1 && PyUnicode_Check(PyTuple_GET_ITEM(args, 0))) {
+        PyErr_SetString(PyExc_TypeError,
+            "Strings must be encoded before hashing");
+        return -1;
+    }
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|y*I:__init__", keywords, &buf, &seed)) {
         return -1;
     }
@@ -910,6 +915,11 @@ static int PYXXH64_init(PYXXH64Object *self, PyObject *args, PyObject *kwargs)
 
     buf.buf = buf.obj = NULL;
 
+    if (PyTuple_GET_SIZE(args) >= 1 && PyUnicode_Check(PyTuple_GET_ITEM(args, 0))) {
+        PyErr_SetString(PyExc_TypeError,
+            "Strings must be encoded before hashing");
+        return -1;
+    }
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|y*K:__init__", keywords, &buf, &seed)) {
         return -1;
     }
@@ -1264,6 +1274,11 @@ static int PYXXH3_64_init(PYXXH3_64Object *self, PyObject *args, PyObject *kwarg
 
     buf.buf = buf.obj = NULL;
 
+    if (PyTuple_GET_SIZE(args) >= 1 && PyUnicode_Check(PyTuple_GET_ITEM(args, 0))) {
+        PyErr_SetString(PyExc_TypeError,
+            "Strings must be encoded before hashing");
+        return -1;
+    }
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|y*K:__init__", keywords, &buf, &seed)) {
         return -1;
     }
@@ -1627,6 +1642,11 @@ static int PYXXH3_128_init(PYXXH3_128Object *self, PyObject *args, PyObject *kwa
 
     buf.buf = buf.obj = NULL;
 
+    if (PyTuple_GET_SIZE(args) >= 1 && PyUnicode_Check(PyTuple_GET_ITEM(args, 0))) {
+        PyErr_SetString(PyExc_TypeError,
+            "Strings must be encoded before hashing");
+        return -1;
+    }
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|y*K:__init__", keywords, &buf, &seed)) {
         return -1;
     }