gh-99211: Point to except/except* on syntax errors when mixing them (GH-99215)

Automerge-Triggered-By: GH:lysnikolaou

Author: lysnikolaou

Grammar/python.gram

@@ -1254,7 +1254,9 @@ invalid_try_stmt:
     | a='try' ':' NEWLINE !INDENT {
         RAISE_INDENTATION_ERROR("expected an indented block after 'try' statement on line %d", a->lineno) }
     | 'try' ':' block !('except' | 'finally') { RAISE_SYNTAX_ERROR("expected 'except' or 'finally' block") }
-    | a='try' ':' block* ((except_block+ except_star_block) | (except_star_block+ except_block)) block* {
+    | 'try' ':' block* except_block+ a='except' b='*' expression ['as' NAME] ':' {
+        RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "cannot have both 'except' and 'except*' on the same 'try'") }
+    | 'try' ':' block* except_star_block+ a='except' [expression ['as' NAME]] ':' {
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "cannot have both 'except' and 'except*' on the same 'try'") }
 invalid_except_stmt:
     | 'except' '*'? a=expression ',' expressions ['as' NAME ] ':' {

Lib/test/test_syntax.py

@@ -2017,12 +2017,12 @@ def test_generator_in_function_call(self):
     def test_except_then_except_star(self):
         self._check_error("try: pass\nexcept ValueError: pass\nexcept* TypeError: pass",
                           r"cannot have both 'except' and 'except\*' on the same 'try'",
-                          lineno=1, end_lineno=1, offset=1, end_offset=4)
+                          lineno=3, end_lineno=3, offset=1, end_offset=8)
 
     def test_except_star_then_except(self):
         self._check_error("try: pass\nexcept* ValueError: pass\nexcept TypeError: pass",
                           r"cannot have both 'except' and 'except\*' on the same 'try'",
-                          lineno=1, end_lineno=1, offset=1, end_offset=4)
+                          lineno=3, end_lineno=3, offset=1, end_offset=7)
 
     def test_empty_line_after_linecont(self):
         # See issue-40847