Brent Westbrook 0115fd3757 Avoid reusing nested, interpolated quotes before Python 3.12 (#20930) ... ## Summary Fixes #20774 by tracking whether an `InterpolatedStringState` element is nested inside of another interpolated element. This feels like kind of a naive fix, so I'm welcome to other ideas. But it resolves the problem in the issue and clears up the syntax error in the black compatibility test, without affecting many other cases. The other affected case is actually interesting too because the [input](96b156303b/crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/fstring.py (L707)) is invalid, but the previous quote selection fixed the invalid syntax: ```pycon Python 3.11.13 (main, Sep 2 2025, 14:20:25) [Clang 20.1.4 ] on linux Type "help", "copyright", "credits" or "license" for more information. >>> f'{1: abcd "{'aa'}" }' # input File "<stdin>", line 1 f'{1: abcd "{'aa'}" }' ^^ SyntaxError: f-string: expecting '}' >>> f'{1: abcd "{"aa"}" }' # old output Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: Invalid format specifier ' abcd "aa" ' for object of type 'int' >>> f'{1: abcd "{'aa'}" }' # new output File "<stdin>", line 1 f'{1: abcd "{'aa'}" }' ^^ SyntaxError: f-string: expecting '}' ``` We now preserve the invalid syntax in the input. Unfortunately, this also seems to be another edge case I didn't consider in https://github.com/astral-sh/ruff/pull/20867 because we don't flag this as a syntax error after 0.14.1: <details><summary>Shell output</summary> <p> ``` > uvx ruff@0.14.0 check --ignore ALL --target-version py311 - <<EOF f'{1: abcd "{'aa'}" }' EOF invalid-syntax: Cannot reuse outer quote character in f-strings on Python 3.11 (syntax was added in Python 3.12) --> -:1:14 | 1 | f'{1: abcd "{'aa'}" }' | ^ | Found 1 error. > uvx ruff@0.14.1 check --ignore ALL --target-version py311 - <<EOF f'{1: abcd "{'aa'}" }' EOF All checks passed! > uvx python@3.11 -m ast <<EOF f'{1: abcd "{'aa'}" }' EOF Traceback (most recent call last): File "<frozen runpy>", line 198, in _run_module_as_main File "<frozen runpy>", line 88, in _run_code File "/home/brent/.local/share/uv/python/cpython-3.11.13-linux-x86_64-gnu/lib/python3.11/ast.py", line 1752, in <module> main() File "/home/brent/.local/share/uv/python/cpython-3.11.13-linux-x86_64-gnu/lib/python3.11/ast.py", line 1748, in main tree = parse(source, args.infile.name, args.mode, type_comments=args.no_type_comments) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/brent/.local/share/uv/python/cpython-3.11.13-linux-x86_64-gnu/lib/python3.11/ast.py", line 50, in parse return compile(source, filename, mode, flags, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "<stdin>", line 1 f'{1: abcd "{'aa'}" }' ^^ SyntaxError: f-string: expecting '}' ``` </p> </details> I assumed that was the same `ParseError` as the one caused by `f"{1:""}"`, but this is a nested interpolation inside of the format spec. ## Test Plan New test copied from the black compatibility test. I guess this is a duplicate now, I started working on this branch before the new black tests were imported, so I could delete the separate test in our fixtures if that's preferable.		2025-10-17 08:49:16 -04:00
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test/fixtures	Avoid reusing nested, interpolated quotes before Python 3.12 (#20930)	2025-10-17 08:49:16 -04:00