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bpo-40631: Disallow single parenthesized star target (GH-24027)

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Lysandros Nikolaou 2021-01-03 01:14:21 +02:00 committed by GitHub
parent 8f8de7380c
commit 2ea320dddd
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4 changed files with 979 additions and 700 deletions
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13
Grammar/python.gram
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@ -580,18 +580,23 @@ star_targets[expr_ty]:
| a=star_target !',' { a }
| a=star_target b=(',' c=star_target { c })* [','] {
_Py_Tuple(CHECK(asdl_expr_seq*, _PyPegen_seq_insert_in_front(p, a, b)), Store, EXTRA) }
star_targets_seq[asdl_expr_seq*]: a[asdl_expr_seq*]=','.star_target+ [','] { a }
star_targets_list_seq[asdl_expr_seq*]: a[asdl_expr_seq*]=','.star_target+ [','] { a }
star_targets_tuple_seq[asdl_expr_seq*]:
| a=star_target b=(',' c=star_target { c })+ [','] { (asdl_expr_seq*) _PyPegen_seq_insert_in_front(p, a, b) }
| a=star_target ',' { (asdl_expr_seq*) _PyPegen_singleton_seq(p, a) }
star_target[expr_ty] (memo):
| '*' a=(!'*' star_target) {
_Py_Starred(CHECK(expr_ty, _PyPegen_set_expr_context(p, a, Store)), Store, EXTRA) }
| target_with_star_atom
target_with_star_atom[expr_ty] (memo):
| 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) }
| star_atom
star_atom[expr_ty]:
| a=NAME { _PyPegen_set_expr_context(p, a, Store) }
| '(' a=star_target ')' { _PyPegen_set_expr_context(p, a, Store) }
| '(' a=[star_targets_seq] ')' { _Py_Tuple(a, Store, EXTRA) }
| '[' a=[star_targets_seq] ']' { _Py_List(a, Store, EXTRA) }
| '(' a=target_with_star_atom ')' { _PyPegen_set_expr_context(p, a, Store) }
| '(' a=[star_targets_tuple_seq] ')' { _Py_Tuple(a, Store, EXTRA) }
| '[' a=[star_targets_list_seq] ']' { _Py_List(a, Store, EXTRA) }
single_target[expr_ty]:
| single_subscript_attribute_target

25
Lib/test/test_unpack_ex.py
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@ -346,6 +346,31 @@ Now some general starred expressions (all fail).
...
SyntaxError: can't use starred expression here
>>> (*x),y = 1, 2 # doctest:+ELLIPSIS
Traceback (most recent call last):
...
SyntaxError: can't use starred expression here
>>> (((*x))),y = 1, 2 # doctest:+ELLIPSIS
Traceback (most recent call last):
...
SyntaxError: can't use starred expression here
>>> z,(*x),y = 1, 2, 4 # doctest:+ELLIPSIS
Traceback (most recent call last):
...
SyntaxError: can't use starred expression here
>>> z,(*x) = 1, 2 # doctest:+ELLIPSIS
Traceback (most recent call last):
...
SyntaxError: can't use starred expression here
>>> ((*x),y) = 1, 2 # doctest:+ELLIPSIS
Traceback (most recent call last):
...
SyntaxError: can't use starred expression here
Some size constraints (all fail.)
>>> s = ", ".join("a%d" % i for i in range(1<<8)) + ", *rest = range(1<<8 + 1)"

2
Misc/NEWS.d/next/Core and Builtins/2020-12-31-20-58-22.bpo-40631.deRMCx.rst Normal file
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@ -0,0 +1,2 @@
Fix regression where a single parenthesized starred expression was a valid
assignment target.

1639
Parser/parser.c
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