gh-133357: Fix SyntaxError carret location on invalid starred exprs

Grammar/python.gram

@@ -1500,7 +1500,10 @@ invalid_kvpair:
 invalid_starred_expression_unpacking:
     | a='*' expression '=' b=expression { RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "cannot assign to iterable argument unpacking") }
 invalid_starred_expression:
-    | '*' { RAISE_SYNTAX_ERROR("Invalid star expression") }
+    | a='*' { 
+        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
+            a, 
+            "invalid star expression") } 
 
 invalid_fstring_replacement_field:
     | '{' a='=' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "f-string: valid expression required before '='") }

Lib/test/test_syntax.py

@@ -2320,22 +2320,22 @@
     >>> A[*(1:2)]
     Traceback (most recent call last):
         ...
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
     >>> A[*(1:2)] = 1
     Traceback (most recent call last):
         ...
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
     >>> del A[*(1:2)]
     Traceback (most recent call last):
         ...
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 
 A[*:] and A[:*]
 
     >>> A[*:]
     Traceback (most recent call last):
         ...
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
     >>> A[:*]
     Traceback (most recent call last):
         ...
@@ -2346,7 +2346,7 @@
     >>> A[*]
     Traceback (most recent call last):
         ...
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 
 A[**]
 
@@ -2623,23 +2623,23 @@ def f(x: *b)
 
     >>> f(**x, *)
     Traceback (most recent call last):
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 
     >>> f(x, *:)
     Traceback (most recent call last):
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 
     >>> f(x, *)
     Traceback (most recent call last):
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 
     >>> f(x = 5, *)
     Traceback (most recent call last):
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 
     >>> f(x = 5, *:)
     Traceback (most recent call last):
-    SyntaxError: Invalid star expression
+    SyntaxError: invalid star expression
 """
 
 import re

Misc/NEWS.d/next/Core_and_Builtins/2025-05-05-19-42-11.gh-issue-133357.moEEdA.rst

@@ -0,0 +1,2 @@
+Fix the location of the :exc:`SyntaxError` carret on invalid starred
+expressions.