Skip to content

gh-160268: Fix tokenize on a mismatched closing bracket in an f-string #160272

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
lysnikolaou merged 2 commits into from
Oct 22, 2026
+21 −14
Merged

gh-160268: Fix tokenize on a mismatched closing bracket in an f-string #160272

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
335b375
gh-160268: Fix tokenize on a mismatched closing bracket in an f-string
lysnikolaou Oct 22, 2026
bff1466
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 22, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 11 additions & 9 deletions Lib/test/test_tokenize.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2675,15 +2675,17 @@ def test_tolerant_incompatible_prefix_position_after_non_ascii(self):
)

def test_tolerant_fstring_closer_at_expression_entry_depth(self):
source = "f'1:{]]{}}r}''"
for extra_tokens, position in ((False, (1, 6)), (True, (1, 7))):
with self.subTest(extra_tokens=extra_tokens):
with self.assertRaises(tokenize.TokenError) as caught:
self._get_tokens(source, extra_tokens=extra_tokens)
self.assertEqual(
caught.exception.args,
("f-string: unmatched ']'", position),
)
cases = [
("f'1:{]]{}}r}''", ("f-string: unmatched ']'", (1, 6))),
("f'{]a'", ("f-string: unmatched ']'", (1, 4))),
("t'{\nx)'", ("t-string: unmatched ')'", (2, 2))),
]
for source, error in cases:
for extra_tokens in (False, True):
with self.subTest(source=source, extra_tokens=extra_tokens):
with self.assertRaises(tokenize.TokenError) as caught:
self._get_tokens(source, extra_tokens=extra_tokens)
self.assertEqual(caught.exception.args, error)

def test_int(self):

Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-10-22-17-37-27.gh-issue-160268.gJ2iDx.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix a crash in :mod:`tokenize` when a mismatched closing bracket follows the opening brace of an f-string or t-string replacement field, as in ``f'{]a'``. It now raises the same "unmatched" error as the parser.
14 changes: 9 additions & 5 deletions Parser/lexer/lexer.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -447,11 +447,12 @@ _PyLexer_get_normal(struct tok_state *tok, ftstring_state *current, struct token
if (tok->level > 0) {
tok->level--;
int opening = tok->parenstack[tok->level];
if (!tok->tok_extra_tokens && !((opening == '(' && c == ')') ||
(opening == '[' && c == ']') ||
(opening == '{' && c == '}'))) {
if (!((opening == '(' && c == ')') ||
(opening == '[' && c == ']') ||
(opening == '{' && c == '}'))) {
/* Do not match a closer against the brace that opened the
* current replacement field. */
* current replacement field. The f-string state relies on
* that brace, so this is checked even with extra tokens. */
if (current != NULL && opening == '{') {
int bracket_depth =
_PyLexer_FTStringBracketDepth(tok, current);
Expand All @@ -461,7 +462,10 @@ _PyLexer_get_normal(struct tok_state *tok, ftstring_state *current, struct token
_PyLexer_StringPrefix(current->kind), c));
}
}
if (tok->parenlinenostack[tok->level] != tok->lineno) {
if (tok->tok_extra_tokens) {
/* Allow other mismatched brackets. */
}
else if (tok->parenlinenostack[tok->level] != tok->lineno) {
return MAKE_TOKEN(_PyTokenizer_syntaxerror(tok,
"closing parenthesis '%c' does not match "
"opening parenthesis '%c' on line %d",
Expand Down
Loading