gh-99103: Normalize specialized traceback anchors against the current line (GH-99145)

Automerge-Triggered-By: GH:isidentical

1 files changed, 9 insertions, 4 deletions

diff --git a/Lib/traceback.py b/Lib/traceback.py
index 8d518728fa1..c43c4720ae5 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -586,12 +586,15 @@ def _extract_caret_anchors_from_line_segment(segment):
     if len(tree.body) != 1:
         return None
 
+    normalize = lambda offset: _byte_offset_to_character_offset(segment, offset)
     statement = tree.body[0]
     match statement:
         case ast.Expr(expr):
             match expr:
                 case ast.BinOp():
-                    operator_str = segment[expr.left.end_col_offset:expr.right.col_offset]
+                    operator_start = normalize(expr.left.end_col_offset)
+                    operator_end = normalize(expr.right.col_offset)
+                    operator_str = segment[operator_start:operator_end]
                     operator_offset = len(operator_str) - len(operator_str.lstrip())
 
                     left_anchor = expr.left.end_col_offset + operator_offset
@@ -601,9 +604,11 @@ def _extract_caret_anchors_from_line_segment(segment):
                         and not operator_str[operator_offset + 1].isspace()
                     ):
                         right_anchor += 1
-                    return _Anchors(left_anchor, right_anchor)
+                    return _Anchors(normalize(left_anchor), normalize(right_anchor))
                 case ast.Subscript():
-                    return _Anchors(expr.value.end_col_offset, expr.slice.end_col_offset + 1)
+                    subscript_start = normalize(expr.value.end_col_offset)
+                    subscript_end = normalize(expr.slice.end_col_offset + 1)
+                    return _Anchors(subscript_start, subscript_end)
 
     return None
 
@@ -1044,7 +1049,7 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
             self = frame.f_locals['self']
             if hasattr(self, wrong_name):
                 return f"self.{wrong_name}"
-    
+
     # Compute closest match
 
     if len(d) > _MAX_CANDIDATE_ITEMS: