fix named escapes in FSTRING_MIDDLE

pyupgrade/_string_helpers.py

@@ -1,11 +1,11 @@
 from __future__ import annotations
 
 import codecs
-import re
 import string
 from typing import Optional
 
-NAMED_UNICODE_RE = re.compile(r'(?<!\\)(?:\\\\)*(\\N\{[^}]+\})')
+from tokenize_rt import curly_escape
+from tokenize_rt import NAMED_UNICODE_RE
 
 DotFormatPart = tuple[str, Optional[str], Optional[str], Optional[str]]
 
@@ -53,16 +53,6 @@ def _convert_tup(tup: DotFormatPart) -> str:
     return ''.join(_convert_tup(tup) for tup in parsed)
 
 
-def curly_escape(s: str) -> str:
-    parts = NAMED_UNICODE_RE.split(s)
-    return ''.join(
-        part.replace('{', '{{').replace('}', '}}')
-        if not NAMED_UNICODE_RE.fullmatch(part)
-        else part
-        for part in parts
-    )
-
-
 def is_codec(encoding: str, name: str) -> bool:
     try:
         return codecs.lookup(encoding).name == name

setup.cfg

@@ -19,7 +19,7 @@ classifiers =
 [options]
 packages = find:
 install_requires =
-    tokenize-rt>=5.2.0
+    tokenize-rt>=6.1.0
 python_requires = >=3.9
 
 [options.packages.find]

tests/main_test.py

@@ -25,6 +25,8 @@ def test_main_noop(tmpdir, capsys):
 x=version_info
 def f():
     global x, y
+
+f'hello snowman: \\N{SNOWMAN}'
 '''
     f = tmpdir.join('f.py')
     f.write(s)