Support Python 3.14

[InSyncWithFoo]

This is the tracking issue for updates required to support Python 3.14.

The major changes are (so far) as follows:

• PEP 750 – Template Strings Implement template strings #17851
• PEP 758 – Allow except and except* expressions without parentheses
  • Make syntax error for unparenthesized except tuples version specific to before 3.14 #17660
• PEP 649 – Deferred Evaluation Of Annotations Using Descriptors (and PEP 749)
  • Implement deferred annotations for Python 3.14 #17658
• PEP 765 – Disallow return/break/continue that exit a finally block

Parser Updates

• Support for template strings
  • Let's delay opening an issue for this until the implementation is actually merged in to CPython
• PEP 758 – Allow except and except* expressions without parentheses
  • Might be a quick fix to these lines

Formatter Updates

• Support for template strings
  • Let's delay opening an issue for this until the implementation is actually merged in to CPython
• Decide how to handle formatting for unparenthesized except tuples

Syntax Errors

• PEP 765 – Disallow return/break/continue that exit a finally block
  • At the moment, similar errors are only detected by lint rules and may or may not be folded into the more general checks for compiler-emitted syntax errors (see the excellent [syntax-errors] Remaining syntax errors raised by the compiler #17412 for a discussion). It might make sense to implement this as a lint rule until and unless things like "break outside of loop" are detected as syntax errors.

Semantic Model

• Visit template strings in a similar manner to f-strings; in particular we will need to read the "interpolated values" as references
• 3.14 deferred evaluation of annotations #15100

Affected Rules

It is probably best to wait until the first round of changes to the semantic model have been made before tackling these.

• missing-f-string-syntax (RUF027)
• invalid-pathlib-with-suffix (PTH210) [flake8-use-pathlib] Skip single dots for invalid-pathlib-with-suffix (PTH210) on versions >= 3.14 #19331
• starmap-zip (RUF058) [ruff] Allow strict kwarg when checking for starmap-zip (RUF058) in Python 3.14+ #19333
• Many of the rules in `flake8-type-checking
• flake8-future-annotations-fa
• unnecessary-future-import (UP010)

More generally - we should grep for documentation or rules that suggest or mention from __future__ import annotations and see if these need to be updated to exclude Python 3.14+.

Below the fold is a list of rules that may need to be adjusted to handle t-strings correctly.

Rules possibly affected by t-strings

• unused-method-argument (ARG002)
• useless-expression (B018)
• f-string-docstring (B021)
• unnecessary-generator-set (C401)
• unnecessary-collection-call (C408)
• unnecessary-map (C417)
• call-datetime-strptime-without-zone (DTZ007)
• whitespace-before-close-bracket (E202)
• whitespace-before-punctuation (E203)
• missing-whitespace (E231)
• unexpected-spaces-around-keyword-parameter-equals (E251)
• raw-string-in-exception (EM101)
• f-string-in-exception (EM102)
• f-string-missing-placeholders (F541)
• f-string-number-format (FURB116)
• logging-f-string (G004)
• f-string-in-get-text-func-call (INT001)
• single-line-implicit-string-concatenation (ISC001)
• multi-line-implicit-string-concatenation (ISC002)
• explicit-string-concatenation (ISC003)
• single-string-slots (PLC0205)
• invalid-character-backspace (PLE2510)
• invalid-character-sub (PLE2512)
• invalid-character-esc (PLE2513)
• invalid-character-nul (PLE2514)
• invalid-character-zero-width-space (PLE2515)
• no-self-use (PLR6301)
• assert-on-string-literal (PLW0129)
• pytest-raises-too-broad (PT011)
• pytest-assert-always-false (PT015)
• pytest-fail-without-message (PT016)
• pytest-warns-too-broad (PT030)
• explicit-f-string-type-conversion (RUF010)
• invalid-index-type (RUF016)
• in-empty-collection (RUF060)
• unused-noqa (RUF100)
• hardcoded-bind-all-interfaces (S104)
• hardcoded-temp-file (S108)
• suspicious-mark-safe-usage (S308)
• suspicious-url-open-usage (S310)
• hardcoded-sql-expression (S608)
• unsafe-markup-use (S704)
• multiple-with-statements (SIM117)
• expr-or-true (SIM222)
• expr-and-false (SIM223)
• raise-vanilla-args (TRY003)
• unnecessary-encode-utf8 (UP012)
• native-literals (UP018)
• unicode-kind-prefix (UP025)
• printf-string-formatting (UP031)

Miscellaneous To-Dos

• Run generate_known_standard_library.py and make sure annotationlib is added

[AlexWaygood]

Thanks. The PEP outlining the release schedule says that the first beta is scheduled for May 6th. I think adding support before then would be premature, as interfaces will be constantly changing until then, but we can add support as soon as we enter the beta period. https://peps.python.org/pep-0745/

[dylwil3]

(@InSyncWithFoo I hope you don't mind me hijacking this issue as the official tracking issue 😄 )

[InSyncWithFoo]

@dylwil3 You can't exactly "hijack" it when it was created for this very purpose in the first place, can you?

[MichaReiser]

We may also need to go through all string related rules to determine if they should apply to the new template strings

[Rogdham]

Run generate_known_standard_library.py and make sure annotationlib is added

I have created the PR #18014 after upgrading upstream Python library stdlibs.

I can confirm that annotationlib and compression are both added.