bpo-40679: use a function's qualname in error messages

Lib/test/test_extcall.py

@@ -500,6 +500,45 @@
  ...
  TypeError: f() missing 5 required keyword-only arguments: 'a', 'b', 'c', 'd', and 'e'
 
+Test that functions are referred to by their __qualname__s:
+
+ >>> class A:
+ ... def method(self, x, y):
+ ... pass
+ ... @staticmethod
+ ... def static_method():
+ ... pass
+ ... @staticmethod
+ ... def positional_only(arg, /):
+ ... pass
+
+ >>> a_object = A()
+
+ >>> a_object.method("x")
+ Traceback (most recent call last):
+ ...
+ TypeError: A.method() missing 1 required positional argument: 'y'
+
+ >>> A.static_method("oops it's an argument")
+ Traceback (most recent call last):
+ ...
+ TypeError: A.static_method() takes 0 positional arguments but 1 was given
+
+ >>> A.positional_only(arg="x")
+ Traceback (most recent call last):
+ ...
+ TypeError: A.positional_only() got some positional-only arguments passed as keyword arguments: 'arg'
+
+ >>> a_object.method(bad='x')
+ Traceback (most recent call last):
+ ...
+ TypeError: A.method() got an unexpected keyword argument 'bad'
+
+ >>> a_object.method("x", "y", x="oops")
+ Traceback (most recent call last):
+ ...
+ TypeError: A.method() got multiple values for argument 'x'
+
 """
 
 import sys

Lib/test/test_keywordonlyarg.py

@@ -63,7 +63,8 @@ def f(a, b=None, *, c=None):
  pass
  with self.assertRaises(TypeError) as exc:
  f(1, 2, 3)
- expected = "f() takes from 1 to 2 positional arguments but 3 were given"
+ expected = (f"{f.__qualname__}() takes from 1 to 2 "
+ "positional arguments but 3 were given")
  self.assertEqual(str(exc.exception), expected)
 
  def testSyntaxErrorForFunctionCall(self):

Misc/NEWS.d/next/Core and Builtins/2020-05-19-19-39-49.bpo-40679.SVzz9p.rst

@@ -0,0 +1 @@
+Certain error messages about too few or too many arguments now refer to a function by its :term:`qualified name`.

Python/ceval.c

@@ -3875,7 +3875,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
 
 static void
 format_missing(PyThreadState *tstate, const char *kind,
- PyCodeObject *co, PyObject *names)
+ PyCodeObject *co, PyObject *names, PyObject *qualname)
 {
  int err;
  Py_ssize_t len = PyList_GET_SIZE(names);
@@ -3928,7 +3928,7 @@ format_missing(PyThreadState *tstate, const char *kind,
  return;
  _PyErr_Format(tstate, PyExc_TypeError,
  "%U() missing %i required %s argument%s: %U",
- co->co_name,
+ qualname,
  len,
  kind,
  len == 1 ? "" : "s",
@@ -3939,7 +3939,7 @@ format_missing(PyThreadState *tstate, const char *kind,
 static void
 missing_arguments(PyThreadState *tstate, PyCodeObject *co,
  Py_ssize_t missing, Py_ssize_t defcount,
- PyObject **fastlocals)
+ PyObject **fastlocals, PyObject *qualname)
 {
  Py_ssize_t i, j = 0;
  Py_ssize_t start, end;
@@ -3971,14 +3971,14 @@ missing_arguments(PyThreadState *tstate, PyCodeObject *co,
  }
  }
  assert(j == missing);
- format_missing(tstate, kind, co, missing_names);
+ format_missing(tstate, kind, co, missing_names, qualname);
  Py_DECREF(missing_names);
 }
 
 static void
 too_many_positional(PyThreadState *tstate, PyCodeObject *co,
  Py_ssize_t given, Py_ssize_t defcount,
- PyObject **fastlocals)
+ PyObject **fastlocals, PyObject *qualname)
 {
  int plural;
  Py_ssize_t kwonly_given = 0;
@@ -4022,7 +4022,7 @@ too_many_positional(PyThreadState *tstate, PyCodeObject *co,
  }
  _PyErr_Format(tstate, PyExc_TypeError,
  "%U() takes %U positional argument%s but %zd%U %s given",
- co->co_name,
+ qualname,
  sig,
  plural ? "s" : "",
  given,
@@ -4034,7 +4034,8 @@ too_many_positional(PyThreadState *tstate, PyCodeObject *co,
 
 static int
 positional_only_passed_as_keyword(PyThreadState *tstate, PyCodeObject *co,
- Py_ssize_t kwcount, PyObject* const* kwnames)
+ Py_ssize_t kwcount, PyObject* const* kwnames,
+ PyObject *qualname)
 {
  int posonly_conflicts = 0;
  PyObject* posonly_names = PyList_New(0);
@@ -4079,7 +4080,7 @@ positional_only_passed_as_keyword(PyThreadState *tstate, PyCodeObject *co,
  _PyErr_Format(tstate, PyExc_TypeError,
  "%U() got some positional-only arguments passed"
  " as keyword arguments: '%U'",
- co->co_name, error_names);
+ qualname, error_names);
  Py_DECREF(error_names);
  goto fail;
  }
@@ -4180,7 +4181,7 @@ _PyEval_EvalCode(PyThreadState *tstate,
  if (keyword == NULL || !PyUnicode_Check(keyword)) {
  _PyErr_Format(tstate, PyExc_TypeError,
  "%U() keywords must be strings",
- co->co_name);
+ qualname);
  goto fail;
  }
 
@@ -4211,14 +4212,14 @@ _PyEval_EvalCode(PyThreadState *tstate,
 
  if (co->co_posonlyargcount
  && positional_only_passed_as_keyword(tstate, co,
- kwcount, kwnames))
+ kwcount, kwnames, qualname))
  {
  goto fail;
  }
 
  _PyErr_Format(tstate, PyExc_TypeError,
  "%U() got an unexpected keyword argument '%S'",
- co->co_name, keyword);
+ qualname, keyword);
  goto fail;
  }
 
@@ -4231,7 +4232,7 @@ _PyEval_EvalCode(PyThreadState *tstate,
  if (GETLOCAL(j) != NULL) {
  _PyErr_Format(tstate, PyExc_TypeError,
  "%U() got multiple values for argument '%S'",
- co->co_name, keyword);
+ qualname, keyword);
  goto fail;
  }
  Py_INCREF(value);
@@ -4240,7 +4241,7 @@ _PyEval_EvalCode(PyThreadState *tstate,
 
  /* Check the number of positional arguments */
  if ((argcount > co->co_argcount) && !(co->co_flags & CO_VARARGS)) {
- too_many_positional(tstate, co, argcount, defcount, fastlocals);
+ too_many_positional(tstate, co, argcount, defcount, fastlocals, qualname);
  goto fail;
  }
 
@@ -4254,7 +4255,7 @@ _PyEval_EvalCode(PyThreadState *tstate,
  }
  }
  if (missing) {
- missing_arguments(tstate, co, missing, defcount, fastlocals);
+ missing_arguments(tstate, co, missing, defcount, fastlocals, qualname);
  goto fail;
  }
  if (n > m)
@@ -4292,7 +4293,7 @@ _PyEval_EvalCode(PyThreadState *tstate,
  missing++;
  }
  if (missing) {
- missing_arguments(tstate, co, missing, -1, fastlocals);
+ missing_arguments(tstate, co, missing, -1, fastlocals, qualname);
  goto fail;
  }
  }