gh-130425: Add "Did you mean [...]" suggestions for del obj.attr

Lib/test/test_traceback.py

@@ -4020,8 +4020,7 @@ def test_dont_swallow_subexceptions_of_falsey_exceptiongroup(self):
 
 global_for_suggestions = None
 
-
-class SuggestionFormattingTestBase:
+class SuggestionFormattingTestBaseParent:
     def get_suggestion(self, obj, attr_name=None):
         if attr_name is not None:
             def callable():
@@ -4033,8 +4032,12 @@ def callable():
             callable, slice_start=-1, slice_end=None
         )
         return result_lines[0]
-
-    def test_getattr_suggestions(self):
+
+class BaseSuggestionTests(SuggestionFormattingTestBaseParent):
+    """
+    Subclasses need to implement the get_suggestion method.
+    """
+    def test_suggestions(self):
         class Substitution:
             noise = more_noise = a = bc = None
             blech = None
@@ -4074,63 +4077,88 @@ class CaseChangeOverSubstitution:
             (EliminationOverAddition, "'bluc'?"),
             (CaseChangeOverSubstitution, "'BLuch'?"),
         ]:
-            actual = self.get_suggestion(cls(), 'bluch')
+            obj = cls()
+            actual = self.get_suggestion(obj, 'bluch')
             self.assertIn(suggestion, actual)
 
-    def test_getattr_suggestions_underscored(self):
+    def test_suggestions_underscored(self):
         class A:
             bluch = None
 
-        self.assertIn("'bluch'", self.get_suggestion(A(), 'blach'))
-        self.assertIn("'bluch'", self.get_suggestion(A(), '_luch'))
-        self.assertIn("'bluch'", self.get_suggestion(A(), '_bluch'))
+        obj = A()
+        self.assertIn("'bluch'", self.get_suggestion(obj, 'blach'))
+        self.assertIn("'bluch'", self.get_suggestion(obj, '_luch'))
+        self.assertIn("'bluch'", self.get_suggestion(obj, '_bluch'))
 
         class B:
             _bluch = None
             def method(self, name):
                 getattr(self, name)
 
-        self.assertIn("'_bluch'", self.get_suggestion(B(), '_blach'))
-        self.assertIn("'_bluch'", self.get_suggestion(B(), '_luch'))
-        self.assertNotIn("'_bluch'", self.get_suggestion(B(), 'bluch'))
+        obj = B()
+        self.assertIn("'_bluch'", self.get_suggestion(obj, '_blach'))
+        self.assertIn("'_bluch'", self.get_suggestion(obj, '_luch'))
+        self.assertNotIn("'_bluch'", self.get_suggestion(obj, 'bluch'))
 
-        self.assertIn("'_bluch'", self.get_suggestion(partial(B().method, '_blach')))
-        self.assertIn("'_bluch'", self.get_suggestion(partial(B().method, '_luch')))
-        self.assertIn("'_bluch'", self.get_suggestion(partial(B().method, 'bluch')))
+        if hasattr(self, 'test_with_method_call'):
+            self.assertIn("'_bluch'", self.get_suggestion(partial(obj.method, '_blach')))
+            self.assertIn("'_bluch'", self.get_suggestion(partial(obj.method, '_luch')))
+            self.assertIn("'_bluch'", self.get_suggestion(partial(obj.method, 'bluch')))
 
-    def test_getattr_suggestions_do_not_trigger_for_long_attributes(self):
+    def test_do_not_trigger_for_long_attributes(self):
         class A:
             blech = None
 
-        actual = self.get_suggestion(A(), 'somethingverywrong')
+        obj = A()
+        actual = self.get_suggestion(obj, 'somethingverywrong')
         self.assertNotIn("blech", actual)
 
-    def test_getattr_error_bad_suggestions_do_not_trigger_for_small_names(self):
+    def test_do_not_trigger_for_small_names(self):
         class MyClass:
             vvv = mom = w = id = pytho = None
 
+        obj = MyClass()
         for name in ("b", "v", "m", "py"):
             with self.subTest(name=name):
-                actual = self.get_suggestion(MyClass, name)
+                actual = self.get_suggestion(obj, name)
                 self.assertNotIn("Did you mean", actual)
                 self.assertNotIn("'vvv", actual)
                 self.assertNotIn("'mom'", actual)
                 self.assertNotIn("'id'", actual)
                 self.assertNotIn("'w'", actual)
                 self.assertNotIn("'pytho'", actual)
 
-    def test_getattr_suggestions_do_not_trigger_for_big_dicts(self):
+    def test_do_not_trigger_for_big_dicts(self):
         class A:
             blech = None
         # A class with a very big __dict__ will not be considered
         # for suggestions.
         for index in range(2000):
             setattr(A, f"index_{index}", None)
 
-        actual = self.get_suggestion(A(), 'bluch')
-        self.assertNotIn("blech", actual)
+        obj = A()
+        actual = self.get_suggestion(obj, 'bluch')
+        self.assertNotIn("blech", actual)  
 
-    def test_getattr_suggestions_no_args(self):
+class GetattrSuggestionTests(BaseSuggestionTests):
+    def get_suggestion(self, obj, attr_name=None):
+        if attr_name is not None:
+            def callable():
+                getattr(obj, attr_name)
+        else:
+            callable = obj
+
+        result_lines = self.get_exception(
+            callable, slice_start=-1, slice_end=None
+        )
+        return result_lines[0]
+
+    def test_with_method_call(self):
+        # This is a placeholder method to make
+        # hasattr(self, 'test_with_method_call') return True
+        pass
+
+    def test_suggestions_no_args(self):
         class A:
             blech = None
             def __getattr__(self, attr):
@@ -4147,7 +4175,7 @@ def __getattr__(self, attr):
         actual = self.get_suggestion(A(), 'bluch')
         self.assertIn("blech", actual)
 
-    def test_getattr_suggestions_invalid_args(self):
+    def test_suggestions_invalid_args(self):
         class NonStringifyClass:
             __str__ = None
             __repr__ = None
@@ -4171,13 +4199,24 @@ def __getattr__(self, attr):
             actual = self.get_suggestion(cls(), 'bluch')
             self.assertIn("blech", actual)
 
-    def test_getattr_suggestions_for_same_name(self):
+    def test_suggestions_for_same_name(self):
         class A:
             def __dir__(self):
                 return ['blech']
         actual = self.get_suggestion(A(), 'blech')
         self.assertNotIn("Did you mean", actual)
 
+class DelattrSuggestionTests(BaseSuggestionTests):
+    def get_suggestion(self, obj, attr_name):
+        def callable():
+            delattr(obj, attr_name)
+
+        result_lines = self.get_exception(
+            callable, slice_start=-1, slice_end=None
+        )
+        return result_lines[0]
+
+class SuggestionFormattingTestBase(SuggestionFormattingTestBaseParent):
     def test_attribute_error_with_failing_dict(self):
         class T:
             bluch = 1
@@ -4655,6 +4694,49 @@ class CPythonSuggestionFormattingTests(
     """
 
 
+class PurePythonGetattrSuggestionFormattingTests(
+    PurePythonExceptionFormattingMixin,
+    GetattrSuggestionTests,
+    unittest.TestCase,
+):
+    """
+    Same set of tests (for attribute access) as above using the pure Python implementation of
+    traceback printing in traceback.py.
+    """
+
+
+class PurePythonDelattrSuggestionFormattingTests(
+    PurePythonExceptionFormattingMixin,
+    DelattrSuggestionTests,
+    unittest.TestCase,
+):
+    """
+    Same set of tests (for attribute deletion) as above using the pure Python implementation of
+    traceback printing in traceback.py.
+    """
+
+
+@cpython_only
+class CPythonGetattrSuggestionFormattingTests(
+    CAPIExceptionFormattingMixin,
+    GetattrSuggestionTests,
+    unittest.TestCase,
+):
+    """
+    Same set of tests (for attribute access) as above but with Python's internal traceback printing.
+    """
+
+
+@cpython_only
+class CPythonDelattrSuggestionFormattingTests(
+    CAPIExceptionFormattingMixin,
+    DelattrSuggestionTests,
+    unittest.TestCase,
+):
+    """
+    Same set of tests (for attribute deletion) as above but with Python's internal traceback printing.
+    """
+
 class MiscTest(unittest.TestCase):
 
     def test_all(self):

Misc/NEWS.d/next/Core_and_Builtins/2025-02-22-01-23-23.gh-issue-130425.x5SNQ8.rst

@@ -0,0 +1,2 @@
+Add ``"Did you mean: 'attr'?"`` suggestion when using ``del obj.attr`` if ``attr``
+does not exist.

Objects/dictobject.c

@@ -6939,6 +6939,7 @@ store_instance_attr_lock_held(PyObject *obj, PyDictValues *values,
         PyErr_Format(PyExc_AttributeError,
                         "'%.100s' object has no attribute '%U'",
                         Py_TYPE(obj)->tp_name, name);
+        _PyObject_SetAttributeErrorContext(obj, name);
         return -1;
     }