gh-143962: Improve name suggestions for not normalized names

Suggest the normalized name or the closest name to the normalized name.
If the suggested name is not ASCII, include also its ASCII representation.

Author: serhiy-storchaka

Lib/test/test_traceback.py

@@ -4250,6 +4250,21 @@ def __dir__(self):
         actual = self.get_suggestion(A(), 'blech')
         self.assertNotIn("Did you mean", actual)
 
+    def test_suggestions_not_normalized(self):
+        class A:
+            analization = None
+            fiⁿₐˡᵢᶻₐᵗᵢᵒₙ = None
+
+        self.assertIn("'finalization'", self.get_suggestion(A(), 'fiⁿₐˡᵢᶻₐᵗᵢᵒₙ'))
+
+        class B:
+            attr_a = None
+            attr_µ = None
+
+        suggestion = self.get_suggestion(B(), 'attr_\xb5')
+        self.assertIn("'attr_\u03bc'", suggestion)
+        self.assertIn(r"'attr_\u03bc'", suggestion)
+
 
 class GetattrSuggestionTests(BaseSuggestionTests):
     def test_suggestions_no_args(self):
@@ -4872,6 +4887,18 @@ def foo(self):
         actual = self.get_suggestion(instance.foo)
         self.assertIn("self.blech", actual)
 
+    def test_name_error_with_instance_not_normalized(self):
+        class A:
+            def __init__(self):
+                self.fiⁿₐˡᵢᶻₐᵗᵢᵒₙ = None
+            def foo(self):
+                analization = 1
+                x = fiⁿₐˡᵢᶻₐᵗᵢᵒₙ
+
+        instance = A()
+        actual = self.get_suggestion(instance.foo)
+        self.assertIn("self.finalization", actual)
+
     def test_unbound_local_error_with_instance(self):
         class A:
             def __init__(self):

Lib/traceback.py

@@ -1111,7 +1111,10 @@ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
             wrong_name = getattr(exc_value, "name_from", None)
             suggestion = _compute_suggestion_error(exc_value, exc_traceback, wrong_name)
             if suggestion:
-                self._str += f". Did you mean: '{suggestion}'?"
+                if suggestion.isascii():
+                    self._str += f". Did you mean: '{suggestion}'?"
+                else:
+                    self._str += f". Did you mean: '{suggestion}' ({suggestion!a})?"
         elif exc_type and issubclass(exc_type, ModuleNotFoundError):
             module_name = getattr(exc_value, "name", None)
             if module_name in sys.stdlib_module_names:
@@ -1129,7 +1132,10 @@ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
             wrong_name = getattr(exc_value, "name", None)
             suggestion = _compute_suggestion_error(exc_value, exc_traceback, wrong_name)
             if suggestion:
-                self._str += f". Did you mean: '{suggestion}'?"
+                if suggestion.isascii():
+                    self._str += f". Did you mean: '{suggestion}'?"
+                else:
+                    self._str += f". Did you mean: '{suggestion}' ({suggestion!a})?"
             if issubclass(exc_type, NameError):
                 wrong_name = getattr(exc_value, "name", None)
                 if wrong_name is not None and wrong_name in sys.stdlib_module_names:
@@ -1654,6 +1660,13 @@ def _check_for_nested_attribute(obj, wrong_name, attrs):
 def _compute_suggestion_error(exc_value, tb, wrong_name):
     if wrong_name is None or not isinstance(wrong_name, str):
         return None
+    not_normalized = False
+    if not wrong_name.isascii():
+        from unicodedata import normalize
+        normalized_name = normalize('NFKC', wrong_name)
+        if normalized_name != wrong_name:
+            not_normalized = True
+            wrong_name = normalized_name
     if isinstance(exc_value, AttributeError):
         obj = exc_value.obj
         try:
@@ -1699,6 +1712,8 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
             + list(frame.f_builtins)
         )
         d = [x for x in d if isinstance(x, str)]
+        if not_normalized and wrong_name in d:
+            return wrong_name
 
         # Check first if we are in a method and the instance
         # has the wrong name as attribute
@@ -1711,6 +1726,8 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
             if has_wrong_name:
                 return f"self.{wrong_name}"
 
+    if not_normalized and wrong_name in d:
+        return wrong_name
     try:
         import _suggestions
     except ImportError:

Misc/NEWS.d/next/Core_and_Builtins/2026-01-22-17-04-30.gh-issue-143962.dQR1a9.rst

@@ -0,0 +1,3 @@
+Name suggestion for not normalized name suggests now the normalized name or
+the closest name to the normalized name. If the suggested name is not ASCII,
+include also its ASCII representation.