------------------

* Fixes a regression in 3.8.0 affecting nested task cancellation inside
sync_to_async.

------------------

* Adds support for Python 3.12.

* Drops support for (end-of-life) Python 3.7.

* Fixes task cancellation propagation to subtasks when using synchronous Django
middleware.

* Allows nesting ``sync_to_async`` via ``asyncio.wait_for``.

* Corrects WSGI adapter handling of root path.

* Handles case where `"client"` is ``None`` in WsgiToAsgi adapter.

------------------

* The type annotations for SyncToAsync and AsyncToSync have been changed to
more accurately reflect the kind of callables they return.

------------------

* On Python 3.10 and below, the version of the "typing_extensions" package
is now constrained to be at least version 4 (as we depend on functionality
in that version and above)

------------------

* Contextvars are now required for the implementation of `sync` as Python 3.6
is now no longer a supported version.

* sync_to_async and async_to_sync now pass-through

* Debug and Lifespan State extensions have resulted in a typing change for some
request and response types. This change should be backwards-compatible.

* ``asgiref`` frames will now be hidden in Django tracebacks by default.

* Raw performance and garbage collection improvements in Local, SyncToAsync,
and AsyncToSync.

Stable style

- Fix crash when ` fmt: off` is used before a closing parenthesis or bracket. (4363)

Packaging

- Packaging metadata updated: docs are explictly linked, the issue tracker is now also
linked. This improves the PyPI listing for Black. (4345)

Parser

- Fix regression where Black failed to parse a multiline f-string containing another
multiline string (4339)
- Fix regression where Black failed to parse an escaped single quote inside an f-string
(4401)
- Fix bug with Black incorrectly parsing empty lines with a backslash (4343)
- Fix bugs with Black's tokenizer not handling `\{` inside f-strings very well (4422)
- Fix incorrect line numbers in the tokenizer for certain tokens within f-strings
(4423)

Performance

- Improve performance when a large directory is listed in `.gitignore` (4415)

_Blackd_

- Fix blackd (and all extras installs) for docker container (4357)

This is a bugfix release to fix two regressions in the new f-string parser introduced in
24.4.1.

Parser

- Fix regression where certain complex f-strings failed to parse (4332)

Performance

- Fix bad performance on certain complex string literals (4331)

Highlights

- Add support for the new Python 3.12 f-string syntax introduced by PEP 701 (3822)

Stable style

- Fix crash involving indented dummy functions containing newlines (4318)

Parser

- Add support for type parameter defaults, a new syntactic feature added to Python 3.13
by PEP 696 (4327)

Integrations

- Github Action now works even when `git archive` is skipped (4313)

Stable style

- Fix unwanted crashes caused by AST equivalency check (4290)

Preview style

- `if` guards in `case` blocks are now wrapped in parentheses when the line is too long.
(4269)
- Stop moving multiline strings to a new line unless inside brackets (4289)

Integrations

- Add a new option `use_pyproject` to the GitHub Action `psf/black`. This will read the
Black version from `pyproject.toml`. (4294)

Highlights

This release is a milestone: it fixes Black's first CVE security vulnerability. If you
run Black on untrusted input, or if you habitually put thousands of leading tab
characters in your docstrings, you are strongly encouraged to upgrade immediately to fix
[CVE-2024-21503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-21503).

This release also fixes a bug in Black's AST safety check that allowed Black to make
incorrect changes to certain f-strings that are valid in Python 3.12 and higher.

Stable style

- Don't move comments along with delimiters, which could cause crashes (4248)
- Strengthen AST safety check to catch more unsafe changes to strings. Previous versions
of Black would incorrectly format the contents of certain unusual f-strings containing
nested strings with the same quote type. Now, Black will crash on such strings until
support for the new f-string syntax is implemented. (4270)
- Fix a bug where line-ranges exceeding the last code line would not work as expected
(4273)

Performance

- Fix catastrophic performance on docstrings that contain large numbers of leading tab
characters. This fixes
[CVE-2024-21503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-21503).
(4278)

Documentation

- Note what happens when `--check` is used with `--quiet` (4236)

Stable style

- Fixed a bug where comments where mistakenly removed along with redundant parentheses
(4218)

Preview style

- Move the `hug_parens_with_braces_and_square_brackets` feature to the unstable style
due to an outstanding crash and proposed formatting tweaks (4198)
- Fixed a bug where base expressions caused inconsistent formatting of \*\* in tenary
expression (4154)
- Checking for newline before adding one on docstring that is almost at the line limit
(4185)
- Remove redundant parentheses in `case` statement `if` guards (4214).

Configuration

- Fix issue where _Black_ would ignore input files in the presence of symlinks (4222)
- _Black_ now ignores `pyproject.toml` that is missing a `tool.black` section when
discovering project root and configuration. Since _Black_ continues to use version
control as an indicator of project root, this is expected to primarily change behavior
for users in a monorepo setup (desirably). If you wish to preserve previous behavior,
simply add an empty `[tool.black]` to the previously discovered `pyproject.toml`
(4204)

Output

- Black will swallow any `SyntaxWarning`s or `DeprecationWarning`s produced by the `ast`
module when performing equivalence checks (4189)

Integrations

- Add a JSONSchema and provide a validate-pyproject entry-point (4181)

Bugfix release to fix a bug that made Black unusable on certain file systems with strict
limits on path length.

Preview style

- Consistently add trailing comma on typed parameters (4164)

Configuration

- Shorten the length of the name of the cache file to fix crashes on file systems that
do not support long paths (4176)

Highlights

This release introduces the new 2024 stable style (4106), stabilizing the following
changes:

- Add parentheses around `if`-`else` expressions (2278)
- Dummy class and function implementations consisting only of `...` are formatted more
compactly (3796)
- If an assignment statement is too long, we now prefer splitting on the right-hand side
(3368)
- Hex codes in Unicode escape sequences are now standardized to lowercase (2916)
- Allow empty first lines at the beginning of most blocks (3967, 4061)
- Add parentheses around long type annotations (3899)
- Enforce newline after module docstrings (3932, 4028)
- Fix incorrect magic trailing comma handling in return types (3916)
- Remove blank lines before class docstrings (3692)
- Wrap multiple context managers in parentheses if combined in a single `with` statement
(3489)
- Fix bug in line length calculations for power operations (3942)
- Add trailing commas to collection literals even if there's a comment after the last
entry (3393)
- When using `--skip-magic-trailing-comma` or `-C`, trailing commas are stripped from
subscript expressions with more than 1 element (3209)
- Add extra blank lines in stubs in a few cases (3564, 3862)
- Accept raw strings as docstrings (3947)
- Split long lines in case blocks (4024)
- Stop removing spaces from walrus operators within subscripts (3823)
- Fix incorrect formatting of certain async statements (3609)
- Allow combining ` fmt: skip` with other comments (3959)

There are already a few improvements in the `--preview` style, which are slated for the
2025 stable style. Try them out and
[share your feedback](https://github.com/psf/black/issues). In the past, the preview
style has included some features that we were not able to stabilize. This year, we're
adding a separate `--unstable` style for features with known problems. Now, the
`--preview` style only includes features that we actually expect to make it into next
year's stable style.

Stable style

Several bug fixes were made in features that are moved to the stable style in this
release:

- Fix comment handling when parenthesising conditional expressions (4134)
- Fix bug where spaces were not added around parenthesized walruses in subscripts,
unlike other binary operators (4109)
- Remove empty lines before docstrings in async functions (4132)
- Address a missing case in the change to allow empty lines at the beginning of all
blocks, except immediately before a docstring (4130)
- For stubs, fix logic to enforce empty line after nested classes with bodies (4141)

Preview style

- Add `--unstable` style, covering preview features that have known problems that would
block them from going into the stable style. Also add the `--enable-unstable-feature`
flag; for example, use
`--enable-unstable-feature hug_parens_with_braces_and_square_brackets` to apply this
preview feature throughout 2024, even if a later Black release downgrades the feature
to unstable (4096)
- Format module docstrings the same as class and function docstrings (4095)
- Fix crash when using a walrus in a dictionary (4155)
- Fix unnecessary parentheses when wrapping long dicts (4135)
- Stop normalizing spaces before ` fmt: skip` comments (4146)

Configuration

- Print warning when configuration in `pyproject.toml` contains an invalid key (4165)
- Fix symlink handling, properly ignoring symlinks that point outside of root (4161)
- Fix cache mtime logic that resulted in false positive cache hits (4128)
- Remove the long-deprecated `--experimental-string-processing` flag. This feature can
currently be enabled with `--preview --enable-unstable-feature string_processing`.
(4096)

Integrations

- Revert the change to run Black's pre-commit integration only on specific git hooks
(3940) for better compatibility with older versions of pre-commit (4137)

Packaging

- Fixed a bug that included dependencies from the `d` extra by default (4108)

Highlights

It's almost 2024, which means it's time for a new edition of _Black_'s stable style!
Together with this release, we'll put out an alpha release 24.1a1 showcasing the draft
2024 stable style, which we'll finalize in the January release. Please try it out and
[share your feedback](https://github.com/psf/black/issues/4042).

This release (23.12.0) will still produce the 2023 style. Most but not all of the
changes in `--preview` mode will be in the 2024 stable style.

Stable style

- Fix bug where ` fmt: off` automatically dedents when used with the `--line-ranges`
option, even when it is not within the specified line range. (4084)
- Fix feature detection for parenthesized context managers (4104)

Preview style

- Prefer more equal signs before a break when splitting chained assignments (4010)
- Standalone form feed characters at the module level are no longer removed (4021)
- Additional cases of immediately nested tuples, lists, and dictionaries are now
indented less (4012)
- Allow empty lines at the beginning of all blocks, except immediately before a
docstring (4060)
- Fix crash in preview mode when using a short `--line-length` (4086)
- Keep suites consisting of only an ellipsis on their own lines if they are not
functions or class definitions (4066) (4103)

Configuration

- `--line-ranges` now skips _Black_'s internal stability check in `--safe` mode. This
avoids a crash on rare inputs that have many unformatted same-content lines. (4034)

Packaging

- Upgrade to mypy 1.7.1 (4049) (4069)
- Faster compiled wheels are now available for CPython 3.12 (4070)

Integrations

- Enable 3.12 CI (4035)
- Build docker images in parallel (4054)
- Build docker images with 3.12 (4055)

Highlights

- Support formatting ranges of lines with the new `--line-ranges` command-line option
(4020)

Stable style

- Fix crash on formatting bytes strings that look like docstrings (4003)
- Fix crash when whitespace followed a backslash before newline in a docstring (4008)
- Fix standalone comments inside complex blocks crashing Black (4016)
- Fix crash on formatting code like `await (a ** b)` (3994)
- No longer treat leading f-strings as docstrings. This matches Python's behaviour and
fixes a crash (4019)

Preview style

- Multiline dicts and lists that are the sole argument to a function are now indented
less (3964)
- Multiline unpacked dicts and lists as the sole argument to a function are now also
indented less (3992)
- In f-string debug expressions, quote types that are visible in the final string are
now preserved (4005)
- Fix a bug where long `case` blocks were not split into multiple lines. Also enable
general trailing comma rules on `case` blocks (4024)
- Keep requiring two empty lines between module-level docstring and first function or
class definition (4028)
- Add support for single-line format skip with other comments on the same line (3959)

Configuration

- Consistently apply force exclusion logic before resolving symlinks (4015)
- Fix a bug in the matching of absolute path names in `--include` (3976)

Performance

- Fix mypyc builds on arm64 on macOS (4017)

Integrations

- Black's pre-commit integration will now run only on git hooks appropriate for a code
formatter (3940)

Highlights

- Maintenance release to get a fix out for GitHub Action edge case (3957)

Preview style

- Fix merging implicit multiline strings that have inline comments (3956)
- Allow empty first line after block open before a comment or compound statement (3967)

Packaging

- Change Dockerfile to hatch + compile black (3965)

Integrations

- The summary output for GitHub workflows is now suppressible using the `summary`
parameter. (3958)
- Fix the action failing when Black check doesn't pass (3957)

Documentation

- It is known Windows documentation CI is broken
https://github.com/psf/black/issues/3968

Stable style

- Fix comments getting removed from inside parenthesized strings (3909)

Preview style

- Fix long lines with power operators getting split before the line length (3942)
- Long type hints are now wrapped in parentheses and properly indented when split across
multiple lines (3899)
- Magic trailing commas are now respected in return types. (3916)
- Require one empty line after module-level docstrings. (3932)
- Treat raw triple-quoted strings as docstrings (3947)

Configuration

- Fix cache versioning logic when `BLACK_CACHE_DIR` is set (3937)

Parser

- Fix bug where attributes named `type` were not accepted inside `match` statements
(3950)
- Add support for PEP 695 type aliases containing lambdas and other unusual expressions
(3949)

Output

- Black no longer attempts to provide special errors for attempting to format Python 2
code (3933)
- Black will more consistently print stacktraces on internal errors in verbose mode
(3938)

Integrations

- The action output displayed in the job summary is now wrapped in Markdown (3914)

Due to various issues, the previous release (23.9.0) did not include compiled mypyc
wheels, which make Black significantly faster. These issues have now been fixed, and
this release should come with compiled wheels once again.

There will be no wheels for Python 3.12 due to a bug in mypyc. We will provide 3.12
wheels in a future release as soon as the mypyc bug is fixed.

Packaging

- Upgrade to mypy 1.5.1 (3864)

Performance

- Store raw tuples instead of NamedTuples in Black's cache, improving performance and
decreasing the size of the cache (3877)

Preview style

- More concise formatting for dummy implementations (3796)
- In stub files, add a blank line between a statement with a body (e.g an
`if sys.version_info > (3, x):`) and a function definition on the same level (3862)
- Fix a bug whereby spaces were removed from walrus operators within subscript(3823)

Configuration

- Black now applies exclusion and ignore logic before resolving symlinks (3846)

Performance

- Avoid importing `IPython` if notebook cells do not contain magics (3782)
- Improve caching by comparing file hashes as fallback for mtime and size (3821)

_Blackd_

- Fix an issue in `blackd` with single character input (3558)

Integrations

- Black now has an
[official pre-commit mirror](https://github.com/psf/black-pre-commit-mirror). Swapping
`https://github.com/psf/black` to `https://github.com/psf/black-pre-commit-mirror` in
your `.pre-commit-config.yaml` will make Black about 2x faster (3828)
- The `.black.env` folder specified by `ENV_PATH` will now be removed on the completion
of the GitHub Action (3759)

Highlights

- Runtime support for Python 3.7 has been removed. Formatting 3.7 code will still be
supported until further notice (3765)

Stable style

- Fix a bug where an illegal trailing comma was added to return type annotations using
PEP 604 unions (3735)
- Fix several bugs and crashes where comments in stub files were removed or mishandled
under some circumstances (3745)
- Fix a crash with multi-line magic comments like `type: ignore` within parentheses
(3740)
- Fix error in AST validation when _Black_ removes trailing whitespace in a type comment
(3773)

Preview style

- Implicitly concatenated strings used as function args are no longer wrapped inside
parentheses (3640)
- Remove blank lines between a class definition and its docstring (3692)

Configuration

- The `--workers` argument to _Black_ can now be specified via the `BLACK_NUM_WORKERS`
environment variable (3743)
- `.pytest_cache`, `.ruff_cache` and `.vscode` are now excluded by default (3691)
- Fix _Black_ not honouring `pyproject.toml` settings when running `--stdin-filename`
and the `pyproject.toml` found isn't in the current working directory (3719)
- _Black_ will now error if `exclude` and `extend-exclude` have invalid data types in
`pyproject.toml`, instead of silently doing the wrong thing (3764)

Packaging

- Upgrade mypyc from 0.991 to 1.3 (3697)
- Remove patching of Click that mitigated errors on Python 3.6 with `LANG=C` (3768)

Parser

- Add support for the new PEP 695 syntax in Python 3.12 (3703)

Performance

- Speed up _Black_ significantly when the cache is full (3751)
- Avoid importing `IPython` in a case where we wouldn't need it (3748)

Output

- Use aware UTC datetimes internally, avoids deprecation warning on Python 3.12 (3728)
- Change verbose logging to exactly mirror _Black_'s logic for source discovery (3749)

_Blackd_

- The `blackd` argument parser now shows the default values for options in their help
text (3712)

Integrations

- Black is now tested with
[`PYTHONWARNDEFAULTENCODING = 1`](https://docs.python.org/3/library/io.html#io-encoding-warning)
(3763)
- Update GitHub Action to display black output in the job summary (3688)

Documentation

- Add a CITATION.cff file to the root of the repository, containing metadata on how to
cite this software (3723)
- Update the _classes_ and _exceptions_ documentation in Developer reference to match
the latest code base (3755)

Highlights

This release fixes a longstanding confusing behavior in Black's GitHub action, where the
version of the action did not determine the version of Black being run (issue 3382). In
addition, there is a small bug fix around imports and a number of improvements to the
preview style.

Please try out the
[preview style](https://black.readthedocs.io/en/stable/the_black_code_style/future_style.html#preview-style)
with `black --preview` and tell us your feedback. All changes in the preview style are
expected to become part of Black's stable style in January 2024.

Stable style

- Import lines with ` fmt: skip` and ` fmt: off` no longer have an extra blank line
added when they are right after another import line (3610)

Preview style

- Add trailing commas to collection literals even if there's a comment after the last
entry (3393)
- `async def`, `async for`, and `async with` statements are now formatted consistently
compared to their non-async version. (3609)
- `with` statements that contain two context managers will be consistently wrapped in
parentheses (3589)
- Let string splitters respect [East Asian Width](https://www.unicode.org/reports/tr11/)
(3445)
- Now long string literals can be split after East Asian commas and periods (`、` U+3001
IDEOGRAPHIC COMMA, `。` U+3002 IDEOGRAPHIC FULL STOP, & `，` U+FF0C FULLWIDTH COMMA)
besides before spaces (3445)
- For stubs, enforce one blank line after a nested class with a body other than just
`...` (3564)
- Improve handling of multiline strings by changing line split behavior (1879)

Parser

- Added support for formatting files with invalid type comments (3594)

Integrations

- Update GitHub Action to use the version of Black equivalent to action's version if
version input is not specified (3543)
- Fix missing Python binary path in autoload script for vim (3508)

Documentation

- Document that only the most recent release is supported for security issues;
vulnerabilities should be reported through Tidelift (3612)

Highlights

This is the first release of 2023, and following our
[stability policy](https://black.readthedocs.io/en/stable/the_black_code_style/index.html#stability-policy),
it comes with a number of improvements to our stable style, including improvements to
empty line handling, removal of redundant parentheses in several contexts, and output
that highlights implicitly concatenated strings better.

There are also many changes to the preview style; try out `black --preview` and give us
feedback to help us set the stable style for next year.

In addition to style changes, Black now automatically infers the supported Python
versions from your `pyproject.toml` file, removing the need to set Black's target
versions separately.

Stable style

- Introduce the 2023 stable style, which incorporates most aspects of last year's
preview style (3418). Specific changes:
- Enforce empty lines before classes and functions with sticky leading comments
 (3302) (22.12.0)
- Reformat empty and whitespace-only files as either an empty file (if no newline is
 present) or as a single newline character (if a newline is present) (3348)
 (22.12.0)
- Implicitly concatenated strings used as function args are now wrapped inside
 parentheses (3307) (22.12.0)
- Correctly handle trailing commas that are inside a line's leading non-nested parens
 (3370) (22.12.0)
- `--skip-string-normalization` / `-S` now prevents docstring prefixes from being
 normalized as expected (3168) (since 22.8.0)
- When using `--skip-magic-trailing-comma` or `-C`, trailing commas are stripped from
 subscript expressions with more than 1 element (3209) (22.8.0)
- Implicitly concatenated strings inside a list, set, or tuple are now wrapped inside
 parentheses (3162) (22.8.0)
- Fix a string merging/split issue when a comment is present in the middle of
 implicitly concatenated strings on its own line (3227) (22.8.0)
- Docstring quotes are no longer moved if it would violate the line length limit
 (3044, 3430) (22.6.0)
- Parentheses around return annotations are now managed (2990) (22.6.0)
- Remove unnecessary parentheses around awaited objects (2991) (22.6.0)
- Remove unnecessary parentheses in `with` statements (2926) (22.6.0)
- Remove trailing newlines after code block open (3035) (22.6.0)
- Code cell separators `%%` are now standardised to ` %%` (2919) (22.3.0)
- Remove unnecessary parentheses from `except` statements (2939) (22.3.0)
- Remove unnecessary parentheses from tuple unpacking in `for` loops (2945) (22.3.0)
- Avoid magic-trailing-comma in single-element subscripts (2942) (22.3.0)
- Fix a crash when a colon line is marked between ` fmt: off` and ` fmt: on` (3439)

Preview style

- Format hex codes in unicode escape sequences in string literals (2916)
- Add parentheses around `if`-`else` expressions (2278)
- Improve performance on large expressions that contain many strings (3467)
- Fix a crash in preview style with assert + parenthesized string (3415)
- Fix crashes in preview style with walrus operators used in function return annotations
and except clauses (3423)
- Fix a crash in preview advanced string processing where mixed implicitly concatenated
regular and f-strings start with an empty span (3463)
- Fix a crash in preview advanced string processing where a standalone comment is placed
before a dict's value (3469)
- Fix an issue where extra empty lines are added when a decorator has ` fmt: skip`
applied or there is a standalone comment between decorators (3470)
- Do not put the closing quotes in a docstring on a separate line, even if the line is
too long (3430)
- Long values in dict literals are now wrapped in parentheses; correspondingly
unnecessary parentheses around short values in dict literals are now removed; long
string lambda values are now wrapped in parentheses (3440)
- Fix two crashes in preview style involving edge cases with docstrings (3451)
- Exclude string type annotations from improved string processing; fix crash when the
return type annotation is stringified and spans across multiple lines (3462)
- Wrap multiple context managers in parentheses when targeting Python 3.9+ (3489)
- Fix several crashes in preview style with walrus operators used in `with` statements
or tuples (3473)
- Fix an invalid quote escaping bug in f-string expressions where it produced invalid
code. Implicitly concatenated f-strings with different quotes can now be merged or
quote-normalized by changing the quotes used in expressions. (3509)
- Fix crash on `await (yield)` when Black is compiled with mypyc (3533)

Configuration

- Black now tries to infer its `--target-version` from the project metadata specified in
`pyproject.toml` (3219)

Packaging

- Upgrade mypyc from `0.971` to `0.991` so mypycified _Black_ can be built on armv7
(3380)
- This also fixes some crashes while using compiled Black with a debug build of
 CPython
- Drop specific support for the `tomli` requirement on 3.11 alpha releases, working
around a bug that would cause the requirement not to be installed on any non-final
Python releases (3448)
- Black now depends on `packaging` version `22.0` or later. This is required for new
functionality that needs to parse part of the project metadata (3219)

Output

- Calling `black --help` multiple times will return the same help contents each time
(3516)
- Verbose logging now shows the values of `pyproject.toml` configuration variables
(3392)
- Fix false symlink detection messages in verbose output due to using an incorrect
relative path to the project root (3385)

Integrations

- Move 3.11 CI to normal flow now that all dependencies support 3.11 (3446)
- Docker: Add new `latest_prerelease` tag automation to follow latest black alpha
release on docker images (3465)

Documentation

- Expand `vim-plug` installation instructions to offer more explicit options (3468)

-------------

Released 2023-08-17

-   Fix issue with regex flags in shell completion. :issue:`2581`
-   Bash version detection issues a warning instead of an error. :issue:`2574`
-   Fix issue with completion script for Fish shell. :issue:`2567`

-------------

Released 2023-07-18

-   Fix an issue with type hints for ``click.group()``. :issue:`2558`

-------------

Released 2023-07-13

-   Fix an issue with type hints for ``click.command()``, ``click.option()``, and
 other decorators. Introduce typing tests. :issue:`2558`

-------------

Released 2023-07-06

-   Replace all ``typing.Dict`` occurrences to ``typing.MutableMapping`` for
 parameter hints. :issue:`2255`
-   Improve type hinting for decorators and give all generic types parameters.
 :issue:`2398`
-   Fix return value and type signature of `shell_completion.add_completion_class`
 function. :pr:`2421`
-   Bash version detection doesn't fail on Windows. :issue:`2461`
-   Completion works if there is a dot (``.``) in the program name. :issue:`2166`
-   Improve type annotations for pyright type checker. :issue:`2268`
-   Improve responsiveness of ``click.clear()``. :issue:`2284`
-   Improve command name detection when using Shiv or PEX. :issue:`2332`
-   Avoid showing empty lines if command help text is empty. :issue:`2368`
-   ZSH completion script works when loaded from ``fpath``. :issue:`2344`.
-   ``EOFError`` and ``KeyboardInterrupt`` tracebacks are not suppressed when
 ``standalone_mode`` is disabled. :issue:`2380`
-   ``group.command`` does not fail if the group was created with a custom
 ``command_class``. :issue:`2416`
-   ``multiple=True`` is allowed for flag options again and does not require
 setting ``default=()``. :issue:`2246, 2292, 2295`
-   Make the decorators returned by ``argument()`` and ``option()`` reusable when the
 ``cls`` parameter is used. :issue:`2294`
-   Don't fail when writing filenames to streams with strict errors. Replace invalid
 bytes with the replacement character (``�``). :issue:`2395`
-   Remove unnecessary attempt to detect MSYS2 environment. :issue:`2355`
-   Remove outdated and unnecessary detection of App Engine environment. :pr:`2554`
-   ``echo()`` does not fail when no streams are attached, such as with ``pythonw`` on
 Windows. :issue:`2415`
-   Argument with ``expose_value=False`` do not cause completion to fail. :issue:`2336`

"""""""""""""

* fixing/test for a regression introduced in 5.0.7 that prevented ``import validate`` from working

"""""""""""""

* update testing to validate against python version 2.7 and 3.5-3.11
* update broken links / non-existent services and references

Older Releases
""""""""""""""

--------------------------

- Fix: coverage used to fail when measuring code using :func:`runpy.run_path
<python:runpy.run_path>` with a :class:`Path <python:pathlib.Path>` argument.
This is now fixed, thanks to `Ask Hjorth Larsen <pull 1819_>`_.

- Fix: backslashes preceding a multi-line backslashed string could confuse the
HTML report.  This is now fixed, thanks to `LiuYinCarl <pull 1828_>`_.

- Now we publish wheels for Python 3.13, both regular and free-threaded.

.. _pull 1819: https://github.com/nedbat/coveragepy/pull/1819
.. _pull 1828: https://github.com/nedbat/coveragepy/pull/1828


.. _changes_7-6-0:

--------------------------

- Exclusion patterns can now be multi-line, thanks to `Daniel Diniz <pull
1807_>`_.  This enables many interesting exclusion use-cases, including those
requested in issues `118 <issue 118_>`_ (entire files), `996
<issue 996_>`_ (multiple lines only when appearing together), `1741
<issue 1741_>`_ (remainder of a function), and `1803 <issue 1803_>`_
(arbitrary sequence of marked lines).  See the :ref:`multi_line_exclude`
section of the docs for more details and examples.

- The JSON report now includes per-function and per-class coverage information.
Thanks to `Daniel Diniz <pull 1809_>`_ for getting the work started. This
closes `issue 1793`_ and `issue 1532`_.

- Fixed an incorrect calculation of "(no class)" lines in the HTML classes
report.

- Python 3.13.0b3 is supported.

.. _issue 118: https://github.com/nedbat/coveragepy/issues/118
.. _issue 996: https://github.com/nedbat/coveragepy/issues/996
.. _issue 1532: https://github.com/nedbat/coveragepy/issues/1532
.. _issue 1741: https://github.com/nedbat/coveragepy/issues/1741
.. _issue 1793: https://github.com/nedbat/coveragepy/issues/1793
.. _issue 1803: https://github.com/nedbat/coveragepy/issues/1803
.. _pull 1807: https://github.com/nedbat/coveragepy/pull/1807
.. _pull 1809: https://github.com/nedbat/coveragepy/pull/1809

.. _changes_7-5-4:

--------------------------

- If you attempt to combine statement coverage data with branch coverage data,
coverage.py used to fail with the message "Can't combine arc data with line
data" or its reverse, "Can't combine line data with arc data."  These
messages used internal terminology, making it hard for people to understand
the problem.  They are now changed to mention "branch coverage data" and
"statement coverage data."

- Fixed a minor branch coverage problem with wildcard match/case cases using
names or guard clauses.

- Started testing on 3.13 free-threading (nogil) builds of Python.  I'm not
claiming full support yet.  Closes `issue 1799`_.

.. _issue 1799: https://github.com/nedbat/coveragepy/issues/1799


.. _changes_7-5-3:

--------------------------

- Performance improvements for combining data files, especially when measuring
line coverage. A few different quadratic behaviors were eliminated. In one
extreme case of combining 700+ data files, the time dropped from more than
three hours to seven minutes.  Thanks for Kraken Tech for funding the fix.

- Performance improvements for generating HTML reports, with a side benefit of
reducing memory use, closing `issue 1791`_.  Thanks to Daniel Diniz for
helping to diagnose the problem.

.. _issue 1791: https://github.com/nedbat/coveragepy/issues/1791


.. _changes_7-5-2:

--------------------------

- Fix: nested matches of exclude patterns could exclude too much code, as
reported in `issue 1779`_.  This is now fixed.

- Changed: previously, coverage.py would consider a module docstring to be an
executable statement if it appeared after line 1 in the file, but not
executable if it was the first line.  Now module docstrings are never counted
as executable statements.  This can change coverage.py's count of the number
of statements in a file, which can slightly change the coverage percentage
reported.

- In the HTML report, the filter term and "hide covered" checkbox settings are
remembered between viewings, thanks to `Daniel Diniz <pull 1776_>`_.

- Python 3.13.0b1 is supported.

- Fix: parsing error handling is improved to ensure bizarre source files are
handled gracefully, and to unblock oss-fuzz fuzzing, thanks to `Liam DeVoe
<pull 1788_>`_. Closes `issue 1787`_.

.. _pull 1776: https://github.com/nedbat/coveragepy/pull/1776
.. _issue 1779: https://github.com/nedbat/coveragepy/issues/1779
.. _issue 1787: https://github.com/nedbat/coveragepy/issues/1787
.. _pull 1788: https://github.com/nedbat/coveragepy/pull/1788


.. _changes_7-5-1:

--------------------------

- Fix: a pragma comment on the continuation lines of a multi-line statement
now excludes the statement and its body, the same as if the pragma is
on the first line. This closes `issue 754`_. The fix was contributed by
`Daniel Diniz <pull 1773_>`_.

- Fix: very complex source files like `this one <resolvent_lookup_>`_ could
cause a maximum recursion error when creating an HTML report.  This is now
fixed, closing `issue 1774`_.

- HTML report improvements:

- Support files (JavaScript and CSS) referenced by the HTML report now have
 hashes added to their names to ensure updated files are used instead of
 stale cached copies.

- Missing branch coverage explanations that said "the condition was never
 false" now read "the condition was always true" because it's easier to
 understand.

- Column sort order is remembered better as you move between the index pages,
 fixing `issue 1766`_.  Thanks, `Daniel Diniz <pull 1768_>`_.


.. _resolvent_lookup: https://github.com/sympy/sympy/blob/130950f3e6b3f97fcc17f4599ac08f70fdd2e9d4/sympy/polys/numberfields/resolvent_lookup.py
.. _issue 754: https://github.com/nedbat/coveragepy/issues/754
.. _issue 1766: https://github.com/nedbat/coveragepy/issues/1766
.. _pull 1768: https://github.com/nedbat/coveragepy/pull/1768
.. _pull 1773: https://github.com/nedbat/coveragepy/pull/1773
.. _issue 1774: https://github.com/nedbat/coveragepy/issues/1774


.. _changes_7-5-0:

--------------------------

- Added initial support for function and class reporting in the HTML report.
There are now three index pages which link to each other: files, functions,
and classes.  Other reports don't yet have this information, but it will be
added in the future where it makes sense.  Feedback gladly accepted!
Finishes `issue 780`_.

- Other HTML report improvements:

- There is now a "hide covered" checkbox to filter out 100% files, finishing
 `issue 1384`_.

- The index page is always sorted by one of its columns, with clearer
 indications of the sorting.

- The "previous file" shortcut key didn't work on the index page, but now it
 does, fixing `issue 1765`_.

- The debug output showing which configuration files were tried now shows
absolute paths to help diagnose problems where settings aren't taking effect,
and is renamed from "attempted_config_files" to the more logical
"config_files_attempted."

- Python 3.13.0a6 is supported.

.. _issue 780: https://github.com/nedbat/coveragepy/issues/780
.. _issue 1384: https://github.com/nedbat/coveragepy/issues/1384
.. _issue 1765: https://github.com/nedbat/coveragepy/issues/1765


.. _changes_7-4-4:

--------------------------

- Fix: in some cases, even with ``[run] relative_files=True``, a data file
could be created with absolute path names.  When combined with other relative
data files, it was random whether the absolute file names would be made
relative or not. If they weren't, then a file would be listed twice in
reports, as detailed in `issue 1752`_.  This is now fixed: absolute file
names are always made relative when combining.  Thanks to Bruno Rodrigues dos
Santos for support.

- Fix: the last case of a match/case statement had an incorrect message if the
branch was missed.  It said the pattern never matched, when actually the
branch is missed if the last case always matched.

- Fix: clicking a line number in the HTML report now positions more accurately.

- Fix: the ``report:format`` setting was defined as a boolean, but should be a
string.  Thanks, `Tanaydin Sirin <pull 1754_>`_.  It is also now documented
on the :ref:`configuration page <config_report_format>`.

.. _issue 1752: https://github.com/nedbat/coveragepy/issues/1752
.. _pull 1754: https://github.com/nedbat/coveragepy/pull/1754


.. _changes_7-4-3:

--------------------------

- Fix: in some cases, coverage could fail with a RuntimeError: "Set changed
size during iteration." This is now fixed, closing `issue 1733`_.

.. _issue 1733: https://github.com/nedbat/coveragepy/issues/1733


.. _changes_7-4-2:

--------------------------

- Fix: setting ``COVERAGE_CORE=sysmon`` no longer errors on 3.11 and lower,
thanks `Hugo van Kemenade <pull 1747_>`_.  It now issues a warning that
sys.monitoring is not available and falls back to the default core instead.

.. _pull 1747: https://github.com/nedbat/coveragepy/pull/1747


.. _changes_7-4-1:

--------------------------

- Python 3.13.0a3 is supported.

- Fix: the JSON report now includes an explicit format version number, closing
`issue 1732`_.

.. _issue 1732: https://github.com/nedbat/coveragepy/issues/1732


.. _changes_7-4-0:

--------------------------

- In Python 3.12 and above, you can try an experimental core based on the new
:mod:`sys.monitoring <python:sys.monitoring>` module by defining a
``COVERAGE_CORE=sysmon`` environment variable.  This should be faster for
line coverage, but not for branch coverage, and plugins and dynamic contexts
are not yet supported with it.  I am very interested to hear how it works (or
doesn't!) for you.


.. _changes_7-3-4:

--------------------------

- Fix: the change for multi-line signature exclusions in 7.3.3 broke other
forms of nested clauses being excluded properly.  This is now fixed, closing
`issue 1713`_.

- Fix: in the HTML report, selecting code for copying won't select the line
numbers also. Thanks, `Robert Harris <pull 1717_>`_.

.. _issue 1713: https://github.com/nedbat/coveragepy/issues/1713
.. _pull 1717: https://github.com/nedbat/coveragepy/pull/1717


.. _changes_7-3-3:

--------------------------

- Fix: function definitions with multi-line signatures can now be excluded by
matching any of the lines, closing `issue 684`_.  Thanks, `Jan Rusak,
Maciej Kowalczyk and Joanna Ejzel <pull 1705_>`_.

- Fix: XML reports could fail with a TypeError if files had numeric components
that were duplicates except for leading zeroes, like ``file1.py`` and
``file001.py``.  Fixes `issue 1709`_.

- The ``coverage annotate`` command used to announce that it would be removed
in a future version. Enough people got in touch to say that they use it, so
it will stay.  Don't expect it to keep up with other new features though.

- Added new :ref:`debug options <cmd_run_debug>`:

- ``pytest`` writes the pytest test name into the debug output.

- ``dataop2`` writes the full data being added to CoverageData objects.

.. _issue 684: https://github.com/nedbat/coveragepy/issues/684
.. _pull 1705: https://github.com/nedbat/coveragepy/pull/1705
.. _issue 1709: https://github.com/nedbat/coveragepy/issues/1709


.. _changes_7-3-2:

--------------------------

- The ``coverage lcov`` command ignored the ``[report] exclude_lines`` and
``[report] exclude_also`` settings (`issue 1684`_).  This is now fixed,
thanks `Jacqueline Lee <pull 1685_>`_.

- Sometimes SQLite will create journal files alongside the coverage.py database
files.  These are ephemeral, but could be mistakenly included when combining
data files.  Now they are always ignored, fixing `issue 1605`_. Thanks to
Brad Smith for suggesting fixes and providing detailed debugging.

- On Python 3.12+, we now disable SQLite writing journal files, which should be
a little faster.

- The new 3.12 soft keyword ``type`` is properly bolded in HTML reports.

- Removed the "fullcoverage" feature used by CPython to measure the coverage of
early-imported standard library modules.  CPython `stopped using it
<88054_>`_ in 2021, and it stopped working completely in Python 3.13.

.. _issue 1605: https://github.com/nedbat/coveragepy/issues/1605
.. _issue 1684: https://github.com/nedbat/coveragepy/issues/1684
.. _pull 1685: https://github.com/nedbat/coveragepy/pull/1685
.. _88054: https://github.com/python/cpython/issues/88054


.. _changes_7-3-1:

--------------------------

- The semantics of stars in file patterns has been clarified in the docs.  A
leading or trailing star matches any number of path components, like a double
star would.  This is different than the behavior of a star in the middle of a
pattern.  This discrepancy was `identified by Sviatoslav Sydorenko
<starbad_>`_, who `provided patient detailed diagnosis <pull 1650_>`_ and
graciously agreed to a pragmatic resolution.

- The API docs were missing from the last version. They are now `restored
<apidocs_>`_.

.. _apidocs: https://coverage.readthedocs.io/en/latest/api_coverage.html
.. _starbad: https://github.com/nedbat/coveragepy/issues/1407#issuecomment-1631085209
.. _pull 1650: https://github.com/nedbat/coveragepy/pull/1650

.. _changes_7-3-0:

--------------------------

- Added a :meth:`.Coverage.collect` context manager to start and stop coverage
data collection.

- Dropped support for Python 3.7.

- Fix: in unusual circumstances, SQLite cannot be set to asynchronous mode.
Coverage.py would fail with the error ``Safety level may not be changed
inside a transaction.`` This is now avoided, closing `issue 1646`_.  Thanks
to Michael Bell for the detailed bug report.

- Docs: examples of configuration files now include separate examples for the
different syntaxes: .coveragerc, pyproject.toml, setup.cfg, and tox.ini.

- Fix: added ``nosemgrep`` comments to our JavaScript code so that
semgrep-based SAST security checks won't raise false alarms about security
problems that aren't problems.

- Added a CITATION.cff file, thanks to `Ken Schackart <pull 1641_>`_.

.. _pull 1641: https://github.com/nedbat/coveragepy/pull/1641
.. _issue 1646: https://github.com/nedbat/coveragepy/issues/1646


.. _changes_7-2-7:

--------------------------

- Fix: reverted a `change from 6.4.3 <pull 1347b_>`_ that helped Cython, but
also increased the size of data files when using dynamic contexts, as
described in the now-fixed `issue 1586`_. The problem is now avoided due to a
recent change (`issue 1538 <issue 1538b_>`_).  Thanks to `Anders Kaseorg
<pull 1629_>`_ and David Szotten for persisting with problem reports and
detailed diagnoses.

- Wheels are now provided for CPython 3.12.

.. _pull 1347b: https://github.com/nedbat/coveragepy/pull/1347
.. _issue 1538b: https://github.com/nedbat/coveragepy/issues/1538
.. _issue 1586: https://github.com/nedbat/coveragepy/issues/1586
.. _pull 1629: https://github.com/nedbat/coveragepy/pull/1629


.. _changes_7-2-6:

--------------------------

- Fix: the ``lcov`` command could raise an IndexError exception if a file is
translated to Python but then executed under its own name.  Jinja2 does this
when rendering templates.  Fixes `issue 1553`_.

- Python 3.12 beta 1 now inlines comprehensions.  Previously they were compiled
as invisible functions and coverage.py would warn you if they weren't
completely executed.  This no longer happens under Python 3.12.

- Fix: the ``coverage debug sys`` command includes some environment variables
in its output.  This could have included sensitive data.  Those values are
now hidden with asterisks, closing `issue 1628`_.

.. _issue 1553: https://github.com/nedbat/coveragepy/issues/1553
.. _issue 1628: https://github.com/nedbat/coveragepy/issues/1628


.. _changes_7-2-5:

--------------------------

- Fix: ``html_report()`` could fail with an AttributeError on ``isatty`` if run
in an unusual environment where sys.stdout had been replaced.  This is now
fixed.


.. _changes_7-2-4:

--------------------------

PyCon 2023 sprint fixes!

- Fix: with ``relative_files = true``, specifying a specific file to include or
omit wouldn't work correctly (`issue 1604`_).  This is now fixed, with
testing help by `Marc Gibbons <pull 1608_>`_.

- Fix: the XML report would have an incorrect ``<source>`` element when using
relative files and the source option ended with a slash (`issue 1541`_).
This is now fixed, thanks to `Kevin Brown-Silva <pull 1608_>`_.

- When the HTML report location is printed to the terminal, it's now a
terminal-compatible URL, so that you can click the location to open the HTML
file in your browser.  Finishes `issue 1523`_ thanks to `Ricardo Newbery
<pull 1613_>`_.

- Docs: a new :ref:`Migrating page <migrating>` with details about how to
migrate between major versions of coverage.py.  It currently covers the
wildcard changes in 7.x.  Thanks, `Brian Grohe <pull 1610_>`_.

.. _issue 1523: https://github.com/nedbat/coveragepy/issues/1523
.. _issue 1541: https://github.com/nedbat/coveragepy/issues/1541
.. _issue 1604: https://github.com/nedbat/coveragepy/issues/1604
.. _pull 1608: https://github.com/nedbat/coveragepy/pull/1608
.. _pull 1609: https://github.com/nedbat/coveragepy/pull/1609
.. _pull 1610: https://github.com/nedbat/coveragepy/pull/1610
.. _pull 1613: https://github.com/nedbat/coveragepy/pull/1613


.. _changes_7-2-3:

--------------------------

- Fix: the :ref:`config_run_sigterm` setting was meant to capture data if a
process was terminated with a SIGTERM signal, but it didn't always.  This was
fixed thanks to `Lewis Gaul <pull 1600_>`_, closing `issue 1599`_.

- Performance: HTML reports with context information are now much more compact.
File sizes are typically as small as one-third the previous size, but can be
dramatically smaller. This closes `issue 1584`_ thanks to `Oleh Krehel
<pull 1587_>`_.

- Development dependencies no longer use hashed pins, closing `issue 1592`_.

.. _issue 1584: https://github.com/nedbat/coveragepy/issues/1584
.. _pull 1587: https://github.com/nedbat/coveragepy/pull/1587
.. _issue 1592: https://github.com/nedbat/coveragepy/issues/1592
.. _issue 1599: https://github.com/nedbat/coveragepy/issues/1599
.. _pull 1600: https://github.com/nedbat/coveragepy/pull/1600


.. _changes_7-2-2:

--------------------------

- Fix: if a virtualenv was created inside a source directory, and a sourced
package was installed inside the virtualenv, then all of the third-party
packages inside the virtualenv would be measured.  This was incorrect, but
has now been fixed: only the specified packages will be measured, thanks to
`Manuel Jacob <pull 1560_>`_.

- Fix: the ``coverage lcov`` command could create a .lcov file with incorrect
LF (lines found) and LH (lines hit) totals.  This is now fixed, thanks to
`Ian Moore <pull 1583_>`_.

- Fix: the ``coverage xml`` command on Windows could create a .xml file with
duplicate ``<package>`` elements. This is now fixed, thanks to `Benjamin
Parzella <pull 1574_>`_, closing `issue 1573`_.

.. _pull 1560: https://github.com/nedbat/coveragepy/pull/1560
.. _issue 1573: https://github.com/nedbat/coveragepy/issues/1573
.. _pull 1574: https://github.com/nedbat/coveragepy/pull/1574
.. _pull 1583: https://github.com/nedbat/coveragepy/pull/1583


.. _changes_7-2-1:

--------------------------

- Fix: the PyPI page had broken links to documentation pages, but no longer
does, closing `issue 1566`_.

- Fix: public members of the coverage module are now properly indicated so that
mypy will find them, fixing `issue 1564`_.

.. _issue 1564: https://github.com/nedbat/coveragepy/issues/1564
.. _issue 1566: https://github.com/nedbat/coveragepy/issues/1566


.. _changes_7-2-0:

--------------------------

- Added a new setting ``[report] exclude_also`` to let you add more exclusions
without overwriting the defaults.  Thanks, `Alpha Chen <pull 1557_>`_,
closing `issue 1391`_.

- Added a :meth:`.CoverageData.purge_files` method to remove recorded data for
a particular file.  Contributed by `Stephan Deibel <pull 1547_>`_.

- Fix: when reporting commands fail, they will no longer congratulate
themselves with messages like "Wrote XML report to file.xml" before spewing a
traceback about their failure.

- Fix: arguments in the public API that name file paths now accept pathlib.Path
objects.  This includes the ``data_file`` and ``config_file`` arguments to
the Coverage constructor and the ``basename`` argument to CoverageData.
Closes `issue 1552`_.

- Fix: In some embedded environments, an IndexError could occur on stop() when
the originating thread exits before completion.  This is now fixed, thanks to
`Russell Keith-Magee <pull 1543_>`_, closing `issue 1542`_.

- Added a ``py.typed`` file to announce our type-hintedness.  Thanks,
`KotlinIsland <pull 1550_>`_.

.. _issue 1391: https://github.com/nedbat/coveragepy/issues/1391
.. _issue 1542: https://github.com/nedbat/coveragepy/issues/1542
.. _pull 1543: https://github.com/nedbat/coveragepy/pull/1543
.. _pull 1547: https://github.com/nedbat/coveragepy/pull/1547
.. _pull 1550: https://github.com/nedbat/coveragepy/pull/1550
.. _issue 1552: https://github.com/nedbat/coveragepy/issues/1552
.. _pull 1557: https://github.com/nedbat/coveragepy/pull/1557


.. _changes_7-1-0:

--------------------------

- Added: the debug output file can now be specified with ``[run] debug_file``
in the configuration file.  Closes `issue 1319`_.

- Performance: fixed a slowdown with dynamic contexts that's been around since
6.4.3.  The fix closes `issue 1538`_.  Thankfully this doesn't break the
`Cython change`_ that fixed `issue 972`_.  Thanks to Mathieu Kniewallner for
the deep investigative work and comprehensive issue report.

- Typing: all product and test code has type annotations.

.. _Cython change: https://github.com/nedbat/coveragepy/pull/1347
.. _issue 972: https://github.com/nedbat/coveragepy/issues/972
.. _issue 1319: https://github.com/nedbat/coveragepy/issues/1319
.. _issue 1538: https://github.com/nedbat/coveragepy/issues/1538


.. _changes_7-0-5:

--------------------------

- Fix: On Python 3.7, a file with type annotations but no ``from __future__
import annotations`` would be missing statements in the coverage report. This
is now fixed, closing `issue 1524`_.

.. _issue 1524: https://github.com/nedbat/coveragepy/issues/1524


.. _changes_7-0-4:

--------------------------

- Performance: an internal cache of file names was accidentally disabled,
resulting in sometimes drastic reductions in performance.  This is now fixed,
closing `issue 1527`_.   Thanks to Ivan Ciuvalschii for the reproducible test
case.

.. _issue 1527: https://github.com/nedbat/coveragepy/issues/1527


.. _changes_7-0-3:

--------------------------

- Fix: when using pytest-cov or pytest-xdist, or perhaps both, the combining
step could fail with ``assert row is not None`` using 7.0.2.  This was due to
a race condition that has always been possible and is still possible. In
7.0.1 and before, the error was silently swallowed by the combining code.
Now it will produce a message "Couldn't combine data file" and ignore the
data file as it used to do before 7.0.2.  Closes `issue 1522`_.

.. _issue 1522: https://github.com/nedbat/coveragepy/issues/1522


.. _changes_7-0-2:

--------------------------

- Fix: when using the ``[run] relative_files = True`` setting, a relative
``[paths]`` pattern was still being made absolute.  This is now fixed,
closing `issue 1519`_.

- Fix: if Python doesn't provide tomllib, then TOML configuration files can
only be read if coverage.py is installed with the ``[toml]`` extra.
Coverage.py will raise an error if TOML support is not installed when it sees
your settings are in a .toml file. But it didn't understand that
``[tools.coverage]`` was a valid section header, so the error wasn't reported
if you used that header, and settings were silently ignored.  This is now
fixed, closing `issue 1516`_.

- Fix: adjusted how decorators are traced on PyPy 7.3.10, fixing `issue 1515`_.

- Fix: the ``coverage lcov`` report did not properly implement the
``--fail-under=MIN`` option.  This has been fixed.

- Refactor: added many type annotations, including a number of refactorings.
This should not affect outward behavior, but they were a bit invasive in some
places, so keep your eyes peeled for oddities.

- Refactor: removed the vestigial and long untested support for Jython and
IronPython.

.. _issue 1515: https://github.com/nedbat/coveragepy/issues/1515
.. _issue 1516: https://github.com/nedbat/coveragepy/issues/1516
.. _issue 1519: https://github.com/nedbat/coveragepy/issues/1519


.. _changes_7-0-1:

========================

*August 7, 2024*

Welcome to Django 5.1!

These release notes cover the :ref:`new features <whats-new-5.1>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-5.1>` you
should be aware of when upgrading from Django 5.0 or earlier. We've
:ref:`begun the deprecation process for some features
<deprecated-features-5.1>`.

See the :doc:`/howto/upgrade-version` guide if you're updating an existing
project.

Python compatibility
====================

Django 5.1 supports Python 3.10, 3.11, and 3.12. We **highly recommend** and
only officially support the latest release of each series.

.. _whats-new-5.1:

What's new in Django 5.1
========================

``{% querystring %}`` template tag
-----------------------------------

Django 5.1 introduces the :ttag:`{% querystring %} <querystring>` template
tag, simplifying the modification of query parameters in URLs, making it easier
to generate links that maintain existing query parameters while adding or
changing specific ones.

For instance, navigating pagination and query strings in templates can be
cumbersome. Consider this template fragment that dynamically generates a URL
for navigating to the next page within a paginated view:

.. code-block:: html+django

 { Linebreaks added for readability, this should be one, long line. }
 <a href="?{% for key, values in request.GET.iterlists %}
   {% if key != "page" %}
     {% for value in values %}
       {{ key }}={{ value }}&
     {% endfor %}
   {% endif %}
 {% endfor %}page={{ page.next_page_number }}">Next page</a>

When switching to using this new template tag, the above magically becomes:

.. code-block:: html+django

 <a href="{% querystring page=page.next_page_number %}">Next page</a>

PostgreSQL Connection Pools
---------------------------

Django 5.1 also introduces :ref:`connection pool <postgresql-pool>` support for
PostgreSQL. As the time to establish a new connection can be relatively long,
keeping connections open can reduce latency.

To use a connection pool with `psycopg`_, you can set the ``"pool"`` option
inside :setting:`OPTIONS` to be a dict to be passed to
:class:`~psycopg:psycopg_pool.ConnectionPool`, or to ``True`` to use the
``ConnectionPool`` defaults::

 DATABASES = {
     "default": {
         "ENGINE": "django.db.backends.postgresql",
          ...
         "OPTIONS": {
             "pool": {
                 "min_size": 2,
                 "max_size": 4,
                 "timeout": 10,
             }
         },
     },
 }

.. _psycopg: https://www.psycopg.org/

Middleware to require authentication by default
-----------------------------------------------

The new :class:`~django.contrib.auth.middleware.LoginRequiredMiddleware`
redirects all unauthenticated requests to a login page. Views can allow
unauthenticated requests by using the new
:func:`~django.contrib.auth.decorators.login_not_required` decorator.

The :class:`~django.contrib.auth.middleware.LoginRequiredMiddleware` respects
the ``login_url`` and ``redirect_field_name`` values set via the
:func:`~.django.contrib.auth.decorators.login_required` decorator, but does not
support setting ``login_url`` or ``redirect_field_name`` via the
:class:`~django.contrib.auth.mixins.LoginRequiredMixin`.

Minor features
--------------

:mod:`django.contrib.admin`
~~~~~~~~~~~~~~~~~~~~~~~~~~~

* :attr:`.ModelAdmin.list_display` now supports using ``__`` lookups to list
fields from related models.

:mod:`django.contrib.auth`
~~~~~~~~~~~~~~~~~~~~~~~~~~

* The default iteration count for the PBKDF2 password hasher is increased from
720,000 to 870,000.

* The default ``parallelism`` of the ``ScryptPasswordHasher`` is 
increased from 1 to 5, to follow OWASP recommendations.

* :class:`~django.contrib.auth.forms.BaseUserCreationForm` and
:class:`~django.contrib.auth.forms.AdminPasswordChangeForm` now support
disabling password-based authentication by setting an unusable password on
form save. This is now available in the admin when visiting the user creation
and password change pages.

* :func:`~.django.contrib.auth.decorators.login_required`,
:func:`~.django.contrib.auth.decorators.permission_required`, and
:func:`~.django.contrib.auth.decorators.user_passes_test` decorators now
support wrapping asynchronous view functions.

* ``ReadOnlyPasswordHashWidget`` now includes a button to reset the user's
password, which replaces the link previously embedded in the
``ReadOnlyPasswordHashField``'s help text, improving the overall
accessibility of the
:class:`~django.contrib.auth.forms.UserChangeForm`.

:mod:`django.contrib.