mute FSTRING_MIDDLE tokens

src/flake8/processor.py

@@ -5,6 +5,7 @@
 import ast
 import contextlib
 import logging
+import sys
 import tokenize
 from typing import Any
 from typing import Generator
@@ -178,7 +179,7 @@ def next_logical_line(self) -> None:
         self.blank_lines = 0
         self.tokens = []
 
-    def build_logical_line_tokens(self) -> _Logical:
+    def build_logical_line_tokens(self) -> _Logical:  # noqa: C901
         """Build the mapping, comments, and logical line lists."""
         logical = []
         comments = []
@@ -195,6 +196,11 @@ def build_logical_line_tokens(self) -> _Logical:
                 continue
             if token_type == tokenize.STRING:
                 text = mutate_string(text)
+            elif (
+                sys.version_info >= (3, 12)
+                and token_type == tokenize.FSTRING_MIDDLE
+            ):
+                text = "x" * len(text)
             if previous_row:
                 (start_row, start_column) = start
                 if previous_row != start_row:

tests/integration/test_plugins.py

@@ -197,3 +197,35 @@ def test_physical_line_plugin_multiline_string(tmpdir, capsys):
 '''
     out, err = capsys.readouterr()
     assert out == expected
+
+
+def yields_logical_line(logical_line):
+    yield 0, f"T001 {logical_line!r}"
+
+
+def test_logical_line_plugin(tmpdir, capsys):
+    cfg_s = f"""\
+[flake8]
+extend-ignore = F
+[flake8:local-plugins]
+extension =
+    T = {yields_logical_line.__module__}:{yields_logical_line.__name__}
+"""
+
+    cfg = tmpdir.join("tox.ini")
+    cfg.write(cfg_s)
+
+    src = """\
+f'hello world'
+"""
+    t_py = tmpdir.join("t.py")
+    t_py.write_binary(src.encode())
+
+    with tmpdir.as_cwd():
+        assert main(("t.py", "--config", str(cfg))) == 1
+
+    expected = """\
+t.py:1:1: T001 "f'xxxxxxxxxxx'"
+"""
+    out, err = capsys.readouterr()
+    assert out == expected