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[3.12] gh-105938: Emit a SyntaxWarning for escaped braces in an f-string (GH-105939) (#105941)

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(cherry picked from commit 6586cee27f)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
This commit is contained in:
Miss Islington (bot) 2023-06-20 06:09:48 -07:00 • committed by GitHub
parent cc18a8b78a
commit fea0d2fbaa
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3 changed files with 18 additions and 6 deletions
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11
Lib/test/test_fstring.py
View file

@ -13,6 +13,7 @@ import re
import types import types
import decimal import decimal
import unittest import unittest
import warnings
from test import support from test import support
from test.support.os_helper import temp_cwd from test.support.os_helper import temp_cwd
from test.support.script_helper import assert_python_failure, assert_python_ok from test.support.script_helper import assert_python_failure, assert_python_ok
@ -904,7 +905,7 @@ x = (
self.assertEqual(f'2\x203', '2 3') self.assertEqual(f'2\x203', '2 3')
self.assertEqual(f'\x203', ' 3') self.assertEqual(f'\x203', ' 3')
with self.assertWarns(DeprecationWarning): # invalid escape sequence with self.assertWarns(SyntaxWarning): # invalid escape sequence
value = eval(r"f'\{6*7}'") value = eval(r"f'\{6*7}'")
self.assertEqual(value, '\\42') self.assertEqual(value, '\\42')
with self.assertWarns(SyntaxWarning): # invalid escape sequence with self.assertWarns(SyntaxWarning): # invalid escape sequence
@ -1037,7 +1038,7 @@ x = (
] ]
for case, expected_result in deprecated_cases: for case, expected_result in deprecated_cases:
with self.subTest(case=case, expected_result=expected_result): with self.subTest(case=case, expected_result=expected_result):
with self.assertWarns(DeprecationWarning): with self.assertWarns(SyntaxWarning):
result = eval(case) result = eval(case)
self.assertEqual(result, expected_result) self.assertEqual(result, expected_result)
self.assertEqual(fr'\{{\}}', '\\{\\}') self.assertEqual(fr'\{{\}}', '\\{\\}')
@ -1046,6 +1047,12 @@ x = (
self.assertEqual(fr'\}}{1+1}', '\\}2') self.assertEqual(fr'\}}{1+1}', '\\}2')
self.assertEqual(fr'{1+1}\}}', '2\\}') self.assertEqual(fr'{1+1}\}}', '2\\}')
def test_fstring_backslash_before_double_bracket_warns_once(self):
with warnings.catch_warnings(record=True) as w:
eval(r"f'\{{'")
self.assertEqual(len(w), 1)
self.assertEqual(w[0].category, SyntaxWarning)
def test_fstring_backslash_prefix_raw(self): def test_fstring_backslash_prefix_raw(self):
self.assertEqual(f'\\', '\\') self.assertEqual(f'\\', '\\')
self.assertEqual(f'\\\\', '\\\\') self.assertEqual(f'\\\\', '\\\\')

7
Parser/string_parser.c
View file

@ -12,6 +12,11 @@ static int
warn_invalid_escape_sequence(Parser *p, const char *first_invalid_escape, Token *t) warn_invalid_escape_sequence(Parser *p, const char *first_invalid_escape, Token *t)
{ {
unsigned char c = *first_invalid_escape; unsigned char c = *first_invalid_escape;
if ((t->type == FSTRING_MIDDLE || t->type == FSTRING_END) && (c == '{' || c == '}')) { // in this case the tokenizer has already emitted a warning,
// see tokenizer.c:warn_invalid_escape_sequence
return 0;
}
int octal = ('4' <= c && c <= '7'); int octal = ('4' <= c && c <= '7');
PyObject *msg = PyObject *msg =
octal octal
@ -31,7 +36,7 @@ warn_invalid_escape_sequence(Parser *p, const char *first_invalid_escape, Token
if (PyErr_WarnExplicitObject(category, msg, p->tok->filename, if (PyErr_WarnExplicitObject(category, msg, p->tok->filename,
t->lineno, NULL, NULL) < 0) { t->lineno, NULL, NULL) < 0) {
if (PyErr_ExceptionMatches(category)) { if (PyErr_ExceptionMatches(category)) {
/* Replace the DeprecationWarning exception with a SyntaxError /* Replace the Syntax/DeprecationWarning exception with a SyntaxError
to get a more accurate error report */ to get a more accurate error report */
PyErr_Clear(); PyErr_Clear();

6
Parser/tokenizer.c
View file

@ -1559,12 +1559,12 @@ warn_invalid_escape_sequence(struct tok_state *tok, int first_invalid_escape_cha
return -1; return -1;
} }
if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg, tok->filename, if (PyErr_WarnExplicitObject(PyExc_SyntaxWarning, msg, tok->filename,
tok->lineno, NULL, NULL) < 0) { tok->lineno, NULL, NULL) < 0) {
Py_DECREF(msg); Py_DECREF(msg);
if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) { if (PyErr_ExceptionMatches(PyExc_SyntaxWarning)) {
/* Replace the DeprecationWarning exception with a SyntaxError /* Replace the SyntaxWarning exception with a SyntaxError
to get a more accurate error report */ to get a more accurate error report */
PyErr_Clear(); PyErr_Clear();
return syntaxerror(tok, "invalid escape sequence '\\%c'", (char) first_invalid_escape_char); return syntaxerror(tok, "invalid escape sequence '\\%c'", (char) first_invalid_escape_char);