bpo-40618: Disallow invalid targets in augassign and except clauses (GH-20083)

This commit fixes the new parser to disallow invalid targets in the
following scenarios:
- Augmented assignments must only accept a single target (Name,
  Attribute or Subscript), but no tuples or lists.
- `except` clauses should only accept a single `Name` as a target.

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>

1 files changed, 33 insertions, 36 deletions

diff --git a/Parser/pegen/parse.c b/Parser/pegen/parse.c
index b1b248187ea..851d17226d1 100644
--- a/Parser/pegen/parse.c
+++ b/Parser/pegen/parse.c
@@ -199,8 +199,8 @@ static KeywordToken *reserved_keywords[] = {
 #define star_targets_seq_type 1128
 #define star_target_type 1129
 #define star_atom_type 1130
-#define inside_paren_ann_assign_target_type 1131
-#define ann_assign_subscript_attribute_target_type 1132
+#define single_target_type 1131
+#define single_subscript_attribute_target_type 1132
 #define del_targets_type 1133
 #define del_target_type 1134
 #define del_t_atom_type 1135
@@ -501,8 +501,8 @@ static expr_ty star_targets_rule(Parser *p);
 static asdl_seq* star_targets_seq_rule(Parser *p);
 static expr_ty star_target_rule(Parser *p);
 static expr_ty star_atom_rule(Parser *p);
-static expr_ty inside_paren_ann_assign_target_rule(Parser *p);
-static expr_ty ann_assign_subscript_attribute_target_rule(Parser *p);
+static expr_ty single_target_rule(Parser *p);
+static expr_ty single_subscript_attribute_target_rule(Parser *p);
 static asdl_seq* del_targets_rule(Parser *p);
 static expr_ty del_target_rule(Parser *p);
 static expr_ty del_t_atom_rule(Parser *p);
@@ -1590,9 +1590,9 @@ compound_stmt_rule(Parser *p)
 
 // assignment:
 //     | NAME ':' expression ['=' annotated_rhs]
-//     | ('(' inside_paren_ann_assign_target ')' | ann_assign_subscript_attribute_target) ':' expression ['=' annotated_rhs]
+//     | ('(' single_target ')' | single_subscript_attribute_target) ':' expression ['=' annotated_rhs]
 //     | ((star_targets '='))+ (yield_expr | star_expressions) TYPE_COMMENT?
-//     | target augassign (yield_expr | star_expressions)
+//     | single_target augassign (yield_expr | star_expressions)
 //     | invalid_assignment
 static stmt_ty
 assignment_rule(Parser *p)
@@ -1642,13 +1642,13 @@ assignment_rule(Parser *p)
         }
         p->mark = _mark;
     }
-    { // ('(' inside_paren_ann_assign_target ')' | ann_assign_subscript_attribute_target) ':' expression ['=' annotated_rhs]
+    { // ('(' single_target ')' | single_subscript_attribute_target) ':' expression ['=' annotated_rhs]
         Token * _literal;
         void *a;
         expr_ty b;
         void *c;
         if (
-            (a = _tmp_20_rule(p))  // '(' inside_paren_ann_assign_target ')' | ann_assign_subscript_attribute_target
+            (a = _tmp_20_rule(p))  // '(' single_target ')' | single_subscript_attribute_target
             &&
             (_literal = _PyPegen_expect_token(p, 11))  // token=':'
             &&
@@ -1703,12 +1703,12 @@ assignment_rule(Parser *p)
         }
         p->mark = _mark;
     }
-    { // target augassign (yield_expr | star_expressions)
+    { // single_target augassign (yield_expr | star_expressions)
         expr_ty a;
         AugOperator* b;
         void *c;
         if (
-            (a = target_rule(p))  // target
+            (a = single_target_rule(p))  // single_target
             &&
             (b = augassign_rule(p))  // augassign
             &&
@@ -3350,7 +3350,7 @@ try_stmt_rule(Parser *p)
     return _res;
 }
 
-// except_block: 'except' expression ['as' target] ':' block | 'except' ':' block
+// except_block: 'except' expression ['as' NAME] ':' block | 'except' ':' block
 static excepthandler_ty
 except_block_rule(Parser *p)
 {
@@ -3367,7 +3367,7 @@ except_block_rule(Parser *p)
     UNUSED(_start_lineno); // Only used by EXTRA macro
     int _start_col_offset = p->tokens[_mark]->col_offset;
     UNUSED(_start_col_offset); // Only used by EXTRA macro
-    { // 'except' expression ['as' target] ':' block
+    { // 'except' expression ['as' NAME] ':' block
         Token * _keyword;
         Token * _literal;
         asdl_seq* b;
@@ -3378,7 +3378,7 @@ except_block_rule(Parser *p)
             &&
             (e = expression_rule(p))  // expression
             &&
-            (t = _tmp_48_rule(p), 1)  // ['as' target]
+            (t = _tmp_48_rule(p), 1)  // ['as' NAME]
             &&
             (_literal = _PyPegen_expect_token(p, 11))  // token=':'
             &&
@@ -9605,25 +9605,22 @@ star_atom_rule(Parser *p)
     return _res;
 }
 
-// inside_paren_ann_assign_target:
-//     | ann_assign_subscript_attribute_target
-//     | NAME
-//     | '(' inside_paren_ann_assign_target ')'
+// single_target: single_subscript_attribute_target | NAME | '(' single_target ')'
 static expr_ty
-inside_paren_ann_assign_target_rule(Parser *p)
+single_target_rule(Parser *p)
 {
     if (p->error_indicator) {
         return NULL;
     }
     expr_ty _res = NULL;
     int _mark = p->mark;
-    { // ann_assign_subscript_attribute_target
-        expr_ty ann_assign_subscript_attribute_target_var;
+    { // single_subscript_attribute_target
+        expr_ty single_subscript_attribute_target_var;
         if (
-            (ann_assign_subscript_attribute_target_var = ann_assign_subscript_attribute_target_rule(p))  // ann_assign_subscript_attribute_target
+            (single_subscript_attribute_target_var = single_subscript_attribute_target_rule(p))  // single_subscript_attribute_target
         )
         {
-            _res = ann_assign_subscript_attribute_target_var;
+            _res = single_subscript_attribute_target_var;
             goto done;
         }
         p->mark = _mark;
@@ -9643,14 +9640,14 @@ inside_paren_ann_assign_target_rule(Parser *p)
         }
         p->mark = _mark;
     }
-    { // '(' inside_paren_ann_assign_target ')'
+    { // '(' single_target ')'
         Token * _literal;
         Token * _literal_1;
         expr_ty a;
         if (
             (_literal = _PyPegen_expect_token(p, 7))  // token='('
             &&
-            (a = inside_paren_ann_assign_target_rule(p))  // inside_paren_ann_assign_target
+            (a = single_target_rule(p))  // single_target
             &&
             (_literal_1 = _PyPegen_expect_token(p, 8))  // token=')'
         )
@@ -9669,11 +9666,11 @@ inside_paren_ann_assign_target_rule(Parser *p)
     return _res;
 }
 
-// ann_assign_subscript_attribute_target:
+// single_subscript_attribute_target:
 //     | t_primary '.' NAME !t_lookahead
 //     | t_primary '[' slices ']' !t_lookahead
 static expr_ty
-ann_assign_subscript_attribute_target_rule(Parser *p)
+single_subscript_attribute_target_rule(Parser *p)
 {
     if (p->error_indicator) {
         return NULL;
@@ -11907,7 +11904,7 @@ _tmp_19_rule(Parser *p)
     return _res;
 }
 
-// _tmp_20: '(' inside_paren_ann_assign_target ')' | ann_assign_subscript_attribute_target
+// _tmp_20: '(' single_target ')' | single_subscript_attribute_target
 static void *
 _tmp_20_rule(Parser *p)
 {
@@ -11916,14 +11913,14 @@ _tmp_20_rule(Parser *p)
     }
     void * _res = NULL;
     int _mark = p->mark;
-    { // '(' inside_paren_ann_assign_target ')'
+    { // '(' single_target ')'
         Token * _literal;
         Token * _literal_1;
         expr_ty b;
         if (
             (_literal = _PyPegen_expect_token(p, 7))  // token='('
             &&
-            (b = inside_paren_ann_assign_target_rule(p))  // inside_paren_ann_assign_target
+            (b = single_target_rule(p))  // single_target
             &&
             (_literal_1 = _PyPegen_expect_token(p, 8))  // token=')'
         )
@@ -11937,13 +11934,13 @@ _tmp_20_rule(Parser *p)
         }
         p->mark = _mark;
     }
-    { // ann_assign_subscript_attribute_target
-        expr_ty ann_assign_subscript_attribute_target_var;
+    { // single_subscript_attribute_target
+        expr_ty single_subscript_attribute_target_var;
         if (
-            (ann_assign_subscript_attribute_target_var = ann_assign_subscript_attribute_target_rule(p))  // ann_assign_subscript_attribute_target
+            (single_subscript_attribute_target_var = single_subscript_attribute_target_rule(p))  // single_subscript_attribute_target
         )
         {
-            _res = ann_assign_subscript_attribute_target_var;
+            _res = single_subscript_attribute_target_var;
             goto done;
         }
         p->mark = _mark;
@@ -13073,7 +13070,7 @@ _loop1_47_rule(Parser *p)
     return _seq;
 }
 
-// _tmp_48: 'as' target
+// _tmp_48: 'as' NAME
 static void *
 _tmp_48_rule(Parser *p)
 {
@@ -13082,13 +13079,13 @@ _tmp_48_rule(Parser *p)
     }
     void * _res = NULL;
     int _mark = p->mark;
-    { // 'as' target
+    { // 'as' NAME
         Token * _keyword;
         expr_ty z;
         if (
             (_keyword = _PyPegen_expect_token(p, 531))  // token='as'
             &&
-            (z = target_rule(p))  // target
+            (z = _PyPegen_name_token(p))  // NAME
         )
         {
             _res = z;