bpo-37645: add new function _PyObject_FunctionStr() (GH-14890)

Additional note: the `method_check_args` function in `Objects/descrobject.c` is written in such a way that it applies to all kinds of descriptors. In particular, a future re-implementation of `wrapper_descriptor` could use that code.

CC @vstinner @encukou 


https://bugs.python.org/issue37645



Automerge-Triggered-By: @encukou

1 files changed, 29 insertions, 28 deletions

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index dbab4cd4da..342b993e09 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -231,45 +231,38 @@ getset_set(PyGetSetDescrObject *descr, PyObject *obj, PyObject *value)
  *
  * First, common helpers
  */
-static const char *
-get_name(PyObject *func) {
-    assert(PyObject_TypeCheck(func, &PyMethodDescr_Type));
-    return ((PyMethodDescrObject *)func)->d_method->ml_name;
-}
-
-typedef void (*funcptr)(void);
-
 static inline int
 method_check_args(PyObject *func, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     assert(!PyErr_Occurred());
-    assert(PyObject_TypeCheck(func, &PyMethodDescr_Type));
     if (nargs < 1) {
-        PyErr_Format(PyExc_TypeError,
-                     "descriptor '%.200s' of '%.100s' "
-                     "object needs an argument",
-                     get_name(func), PyDescr_TYPE(func)->tp_name);
+        PyObject *funcstr = _PyObject_FunctionStr(func);
+        if (funcstr != NULL) {
+            PyErr_Format(PyExc_TypeError,
+                         "unbound method %U needs an argument", funcstr);
+            Py_DECREF(funcstr);
+        }
         return -1;
     }
     PyObject *self = args[0];
-    if (!_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
-                                  (PyObject *)PyDescr_TYPE(func)))
-    {
-        PyErr_Format(PyExc_TypeError,
-                     "descriptor '%.200s' for '%.100s' objects "
-                     "doesn't apply to a '%.100s' object",
-                     get_name(func), PyDescr_TYPE(func)->tp_name,
-                     Py_TYPE(self)->tp_name);
+    PyObject *dummy;
+    if (descr_check((PyDescrObject *)func, self, &dummy)) {
         return -1;
     }
     if (kwnames && PyTuple_GET_SIZE(kwnames)) {
-        PyErr_Format(PyExc_TypeError,
-                     "%.200s() takes no keyword arguments", get_name(func));
+        PyObject *funcstr = _PyObject_FunctionStr(func);
+        if (funcstr != NULL) {
+            PyErr_Format(PyExc_TypeError,
+                         "%U takes no keyword arguments", funcstr);
+            Py_DECREF(funcstr);
+        }
         return -1;
     }
     return 0;
 }
 
+typedef void (*funcptr)(void);
+
 static inline funcptr
 method_enter_call(PyThreadState *tstate, PyObject *func)
 {
@@ -387,8 +380,12 @@ method_vectorcall_NOARGS(
         return NULL;
     }
     if (nargs != 1) {
-        PyErr_Format(PyExc_TypeError,
-            "%.200s() takes no arguments (%zd given)", get_name(func), nargs-1);
+        PyObject *funcstr = _PyObject_FunctionStr(func);
+        if (funcstr != NULL) {
+            PyErr_Format(PyExc_TypeError,
+                "%U takes no arguments (%zd given)", funcstr, nargs-1);
+            Py_DECREF(funcstr);
+        }
         return NULL;
     }
     PyCFunction meth = (PyCFunction)method_enter_call(tstate, func);
@@ -410,9 +407,13 @@ method_vectorcall_O(
         return NULL;
     }
     if (nargs != 2) {
-        PyErr_Format(PyExc_TypeError,
-            "%.200s() takes exactly one argument (%zd given)",
-            get_name(func), nargs-1);
+        PyObject *funcstr = _PyObject_FunctionStr(func);
+        if (funcstr != NULL) {
+            PyErr_Format(PyExc_TypeError,
+                "%U takes exactly one argument (%zd given)",
+                funcstr, nargs-1);
+            Py_DECREF(funcstr);
+        }
         return NULL;
     }
     PyCFunction meth = (PyCFunction)method_enter_call(tstate, func);