bpo-41979: Accept star-unpacking on with-item targets (GH-22611)
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
diff --git a/Grammar/python.gram b/Grammar/python.gram
index e4533b1..2f52bd7 100644
--- a/Grammar/python.gram
+++ b/Grammar/python.gram
@@ -182,7 +182,7 @@
| ASYNC 'with' a[asdl_withitem_seq*]=','.with_item+ ':' tc=[TYPE_COMMENT] b=block {
CHECK_VERSION(5, "Async with statements are", _Py_AsyncWith(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
with_item[withitem_ty]:
- | e=expression 'as' t=target &(',' | ')' | ':') { _Py_withitem(e, t, p->arena) }
+ | e=expression 'as' t=star_target &(',' | ')' | ':') { _Py_withitem(e, t, p->arena) }
| invalid_with_item
| e=expression { _Py_withitem(e, NULL, p->arena) }
diff --git a/Lib/test/test_with.py b/Lib/test/test_with.py
index b1d7a15..f21bf65 100644
--- a/Lib/test/test_with.py
+++ b/Lib/test/test_with.py
@@ -7,7 +7,7 @@
import sys
import unittest
from collections import deque
-from contextlib import _GeneratorContextManager, contextmanager
+from contextlib import _GeneratorContextManager, contextmanager, nullcontext
class MockContextManager(_GeneratorContextManager):
@@ -641,6 +641,12 @@
self.assertEqual(blah.two, 2)
self.assertEqual(blah.three, 3)
+ def testWithExtendedTargets(self):
+ with nullcontext(range(1, 5)) as (a, *b, c):
+ self.assertEqual(a, 1)
+ self.assertEqual(b, [2, 3])
+ self.assertEqual(c, 4)
+
class ExitSwallowsExceptionTestCase(unittest.TestCase):
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-10-09-10-55-50.bpo-41979.ImXIk2.rst b/Misc/NEWS.d/next/Core and Builtins/2020-10-09-10-55-50.bpo-41979.ImXIk2.rst
new file mode 100644
index 0000000..3250309
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-10-09-10-55-50.bpo-41979.ImXIk2.rst
@@ -0,0 +1 @@
+Star-unpacking is now allowed for with item's targets in the PEG parser.
diff --git a/Parser/parser.c b/Parser/parser.c
index 1bd74a3..0d92256 100644
--- a/Parser/parser.c
+++ b/Parser/parser.c
@@ -4290,7 +4290,10 @@
return _res;
}
-// with_item: expression 'as' target &(',' | ')' | ':') | invalid_with_item | expression
+// with_item:
+// | expression 'as' star_target &(',' | ')' | ':')
+// | invalid_with_item
+// | expression
static withitem_ty
with_item_rule(Parser *p)
{
@@ -4301,12 +4304,12 @@
}
withitem_ty _res = NULL;
int _mark = p->mark;
- { // expression 'as' target &(',' | ')' | ':')
+ { // expression 'as' star_target &(',' | ')' | ':')
if (p->error_indicator) {
D(p->level--);
return NULL;
}
- D(fprintf(stderr, "%*c> with_item[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "expression 'as' target &(',' | ')' | ':')"));
+ D(fprintf(stderr, "%*c> with_item[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "expression 'as' star_target &(',' | ')' | ':')"));
Token * _keyword;
expr_ty e;
expr_ty t;
@@ -4315,12 +4318,12 @@
&&
(_keyword = _PyPegen_expect_token(p, 520)) // token='as'
&&
- (t = target_rule(p)) // target
+ (t = star_target_rule(p)) // star_target
&&
_PyPegen_lookahead(1, _tmp_47_rule, p)
)
{
- D(fprintf(stderr, "%*c+ with_item[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "expression 'as' target &(',' | ')' | ':')"));
+ D(fprintf(stderr, "%*c+ with_item[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "expression 'as' star_target &(',' | ')' | ':')"));
_res = _Py_withitem ( e , t , p -> arena );
if (_res == NULL && PyErr_Occurred()) {
p->error_indicator = 1;
@@ -4331,7 +4334,7 @@
}
p->mark = _mark;
D(fprintf(stderr, "%*c%s with_item[%d-%d]: %s failed!\n", p->level, ' ',
- p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "expression 'as' target &(',' | ')' | ':')"));
+ p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "expression 'as' star_target &(',' | ')' | ':')"));
}
{ // invalid_with_item
if (p->error_indicator) {