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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>
This commit is contained in:
Lysandros Nikolaou 2020-05-14 23:13:50 +03:00 committed by GitHub
parent bcc3036095
commit ce21cfca7b
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 82 additions and 46 deletions
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17
Grammar/python.gram
View File

@ -89,12 +89,12 @@ assignment[stmt_ty]:
"Variable annotation syntax is",
_Py_AnnAssign(CHECK(_PyPegen_set_expr_context(p, a, Store)), b, c, 1, EXTRA)
) }
| a=('(' b=inside_paren_ann_assign_target ')' { b }
| ann_assign_subscript_attribute_target) ':' b=expression c=['=' d=annotated_rhs { d }] {
| a=('(' b=single_target ')' { b }
| single_subscript_attribute_target) ':' b=expression c=['=' d=annotated_rhs { d }] {
CHECK_VERSION(6, "Variable annotations syntax is", _Py_AnnAssign(a, b, c, 0, EXTRA)) }
| a=(z=star_targets '=' { z })+ b=(yield_expr | star_expressions) tc=[TYPE_COMMENT] {
_Py_Assign(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
| a=target b=augassign c=(yield_expr | star_expressions) {
| a=single_target b=augassign c=(yield_expr | star_expressions) {
_Py_AugAssign(a, b->kind, c, EXTRA) }
| invalid_assignment
@ -185,7 +185,7 @@ try_stmt[stmt_ty]:
| 'try' ':' b=block f=finally_block { _Py_Try(b, NULL, NULL, f, EXTRA) }
| 'try' ':' b=block ex=except_block+ el=[else_block] f=[finally_block] { _Py_Try(b, ex, el, f, EXTRA) }
except_block[excepthandler_ty]:
| 'except' e=expression t=['as' z=target { z }] ':' b=block {
| 'except' e=expression t=['as' z=NAME { z }] ':' b=block {
_Py_ExceptHandler(e, (t) ? ((expr_ty) t)->v.Name.id : NULL, b, EXTRA) }
| 'except' ':' b=block { _Py_ExceptHandler(NULL, NULL, b, EXTRA) }
finally_block[asdl_seq*]: 'finally' ':' a=block { a }
@ -573,12 +573,11 @@ star_atom[expr_ty]:
| '(' a=[star_targets_seq] ')' { _Py_Tuple(a, Store, EXTRA) }
| '[' a=[star_targets_seq] ']' { _Py_List(a, Store, EXTRA) }
inside_paren_ann_assign_target[expr_ty]:
| ann_assign_subscript_attribute_target
single_target[expr_ty]:
| single_subscript_attribute_target
| a=NAME { _PyPegen_set_expr_context(p, a, Store) }
| '(' a=inside_paren_ann_assign_target ')' { a }
ann_assign_subscript_attribute_target[expr_ty]:
| '(' a=single_target ')' { a }
single_subscript_attribute_target[expr_ty]:
| a=t_primary '.' b=NAME !t_lookahead { _Py_Attribute(a, b->v.Name.id, Store, EXTRA) }
| a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Store, EXTRA) }

5
Lib/test/test_grammar.py
View File

@ -1279,7 +1279,7 @@ class GrammarTests(unittest.TestCase):
def test_try(self):
### try_stmt: 'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
### | 'try' ':' suite 'finally' ':' suite
### except_clause: 'except' [expr ['as' expr]]
### except_clause: 'except' [expr ['as' NAME]]
try:
1/0
except ZeroDivisionError:
@ -1297,6 +1297,9 @@ class GrammarTests(unittest.TestCase):
except (EOFError, TypeError, ZeroDivisionError) as msg: pass
try: pass
finally: pass
with self.assertRaises(SyntaxError):
compile("try:\n pass\nexcept Exception as a.b:\n pass", "?", "exec")
compile("try:\n pass\nexcept Exception as a[b]:\n pass", "?", "exec")
def test_suite(self):
# simple_stmt | NEWLINE INDENT NEWLINE* (stmt NEWLINE*)+ DEDENT

25
Lib/test/test_peg_parser.py
View File

@ -35,6 +35,9 @@ TEST_CASES = [
('attribute_simple', 'a.b'),
('attributes_subscript', 'a.b[0]'),
('augmented_assignment', 'x += 42'),
('augmented_assignment_attribute', 'a.b.c += 42'),
('augmented_assignment_paren', '(x) += 42'),
('augmented_assignment_paren_subscript', '(x[0]) -= 42'),
('binop_add', '1 + 1'),
('binop_add_multiple', '1 + 1 + 1 + 1'),
('binop_all', '1 + 2 * 5 + 3 ** 2 - -3'),
@ -547,6 +550,11 @@ TEST_CASES = [
with a as (x, y):
pass
'''),
('with_list_target',
'''
with a as [x, y]:
pass
'''),
('yield', 'yield'),
('yield_expr', 'yield a'),
('yield_from', 'yield from a'),
@ -560,6 +568,9 @@ FAIL_TEST_CASES = [
("annotation_tuple", "(a,): int"),
("annotation_tuple_without_paren", "a,: int"),
("assignment_keyword", "a = if"),
("augmented_assignment_list", "[a, b] += 1"),
("augmented_assignment_tuple", "a, b += 1"),
("augmented_assignment_tuple_paren", "(a, b) += (1, 2)"),
("comprehension_lambda", "(a for a in lambda: b)"),
("comprehension_else", "(a for a in b if c else d"),
("del_call", "del a()"),
@ -589,6 +600,20 @@ FAIL_TEST_CASES = [
a
"""),
("not_terminated_string", "a = 'example"),
("try_except_attribute_target",
"""
try:
pass
except Exception as a.b:
pass
"""),
("try_except_subscript_target",
"""
try:
pass
except Exception as a[0]:
pass
"""),
]
FAIL_SPECIALIZED_MESSAGE_CASES = [

12
Lib/test/test_syntax.py
View File

@ -129,6 +129,18 @@ SyntaxError: cannot assign to __debug__
Traceback (most recent call last):
SyntaxError: cannot assign to conditional expression
>>> a, b += 1, 2
Traceback (most recent call last):
SyntaxError: invalid syntax
>>> (a, b) += 1, 2
Traceback (most recent call last):
SyntaxError: cannot assign to tuple
>>> [a, b] += 1, 2
Traceback (most recent call last):
SyntaxError: cannot assign to list
From compiler_complex_args():
>>> def f(None=1):

69
Parser/pegen/parse.c
View File

@ -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;