Summary
--
This PR aims to resolve (or help to resolve) #18442 and #19357 by
encoding the CPython semantics around the `__class__` cell in our
semantic model. Namely,
> `__class__` is an implicit closure reference created by the compiler
if any methods in a class body refer to either `__class__` or super.
from the Python
[docs](https://docs.python.org/3/reference/datamodel.html#creating-the-class-object).
As noted in the variant docs by @AlexWaygood, we don't fully model this
behavior, opting always to create the `__class__` cell binding in a new
`ScopeKind::DunderClassCell` around each method definition, without
checking if any method in the class body actually refers to `__class__`
or `super`.
As such, this PR fixes#18442 but not #19357.
Test Plan
--
Existing tests, plus the tests from #19783, which now pass without any
rule-specific code.
Note that we opted not to alter the behavior of F841 here because
flagging `__class__` in these cases still seems helpful. See the
discussion in
https://github.com/astral-sh/ruff/pull/20048#discussion_r2296252395 and
in the test comments for more information.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Mikko Leppänen <mleppan23@gmail.com>
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## Summary
This PR also supresses the fix if the assignment expression target
shadows one of the lambda's parameters.
Fixes#18675
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
Add regression tests.
<!-- How was it tested? -->
Summary
--
Closes#18849 by adding a `## Known issues` section describing the
potential performance issues when fixing nested iterables. I also
deleted the comment check since the fix is already unsafe and added a
note to the `## Fix safety` docs.
Test Plan
--
Existing tests, updated to allow a fix when comments are present since
the fix is already unsafe.
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## Summary
This PR fixes `PLC2801` autofix creating a syntax error due to lack of
padding if it is directly after a keyword.
Fixes https://github.com/astral-sh/ruff/issues/18813
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
Add regression test
<!-- How was it tested? -->
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## Summary
I've also found another bug while fixing this, where the diagnostic
would not trigger if the `len` call argument variable was shadowed. This
fixed a few false negatives in the test cases.
Example:
```python
fruits = []
fruits = []
if len(fruits): # comment
...
```
Fixes#18811Fixes#18812
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
Add regression test
<!-- How was it tested? -->
---------
Co-authored-by: Charlie Marsh <crmarsh416@gmail.com>
## Summary
Ignore `__init__.py` files in `useless-import-alias` (PLC0414).
See discussion in #18365 and #6294: we want to allow redundant aliases
in `__init__.py` files, as they're almost always intentional explicit
re-exports.
Closes#18365Closes#6294
---------
Co-authored-by: Dylan <dylwil3@gmail.com>
## Summary
Fixes false positives (and incorrect autofixes) in `nested-min-max`
(`PLW3301`) when the outer `min`/`max` call only has a single argument.
Previously the rule would flatten:
```python
min(min([2, 3], [4, 1]))
```
into `min([2, 3], [4, 1])`, changing the semantics. The rule now skips
any nested call when the outer call has only one positional argument.
The pylint fixture and snapshot were updated accordingly.
## Test Plan
Ran Ruff against the updated `nested_min_max.py` fixture:
```shell
cargo run -p ruff -- check crates/ruff_linter/resources/test/fixtures/pylint/nested_min_max.py --no-cache --select=PLW3301 --preview
```
to verify that `min(min([2, 3], [4, 1]))` and `max(max([2, 4], [3, 1]))`
are no longer flagged. Updated the fixture and snapshot; all other
existing warnings remain unchanged. The code compiles and the unit tests
pass.
---
This PR was generated by an AI system in collaboration with maintainers:
@carljm, @ntBre
Fixes#16163
---------
Signed-off-by: Gene Parmesan Thomas <201852096+gopoto@users.noreply.github.com>
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>
## Summary
Implements `use-maxsplit-arg` (`PLC0207`)
https://pylint.readthedocs.io/en/latest/user_guide/messages/convention/use-maxsplit-arg.html
> Emitted when accessing only the first or last element of str.split().
The first and last element can be accessed by using str.split(sep,
maxsplit=1)[0] or str.rsplit(sep, maxsplit=1)[-1] instead.
This is part of https://github.com/astral-sh/ruff/issues/970
## Test Plan
`cargo test`
Additionally compared Ruff output to Pylint:
```
pylint --disable=all --enable=use-maxsplit-arg crates/ruff_linter/resources/test/fixtures/pylint/missing_maxsplit_arg.py
cargo run -p ruff -- check crates/ruff_linter/resources/test/fixtures/pylint/missing_maxsplit_arg.py --no-cache --select PLC0207
```
---------
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>
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## Summary
Fixes#18107
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
Snapshot tests
<!-- How was it tested? -->
Summary
--
While going through the syntax errors in [this comment], I was surprised
to see the error `name 'x' is assigned to before global declaration`,
which corresponds to [load-before-global-declaration (PLE0118)] and has
also been reimplemented as a syntax error (#17135). However, it looks
like neither of the implementations consider `global` declarations in
the top-level module scope, which is a syntax error in CPython:
```python
# try.py
x = None
global x
```
```shell
> python -m compileall -f try.py
Compiling 'try.py'...
*** File "try.py", line 2
global x
^^^^^^^^
SyntaxError: name 'x' is assigned to before global declaration
```
I'm not sure this is the best or most elegant solution, but it was a
quick fix that passed all of our tests.
Test Plan
--
New PLE0118 test case.
[this comment]:
https://github.com/astral-sh/ruff/issues/7633#issuecomment-1740424031
[load-before-global-declaration (PLE0118)]:
https://docs.astral.sh/ruff/rules/load-before-global-declaration/#load-before-global-declaration-ple0118
Summary
--
This PR implements detecting the use of `await` expressions outside of
async functions. This is a reimplementation of
[await-outside-async
(PLE1142)](https://docs.astral.sh/ruff/rules/await-outside-async/) as a
semantic syntax error.
Despite the rule name, PLE1142 also applies to `async for` and `async
with`, so these are covered here too.
Test Plan
--
Existing PLE1142 tests.
I also deleted more code from the `SemanticSyntaxCheckerVisitor` to
avoid changes in other parser tests.
We add support for `return` and `raise` statements in the control flow
graph: we simply add an edge to the terminal block, push the statements
to the current block, and proceed.
This implementation will have to be modified somewhat once we add
support for `try` statements - then we will need to check whether to
_defer_ the jump. But for now this will do!
Also in this PR: We fix the `unreachable` diagnostic range so that it
lumps together consecutive unreachable blocks.
This PR contains the scaffolding for a new control flow graph
implementation, along with its application to the `unreachable` rule. At
the moment, the implementation is a maximal over-approximation: no
control flow is modeled and all statements are counted as reachable.
With each additional statement type we support, this approximation will
improve.
So this PR just contains:
- A `ControlFlowGraph` struct and builder
- Support for printing the flow graph as a Mermaid graph
- Snapshot tests for the actual graphs
- (a very bad!) reimplementation of `unreachable` using the new structs
- Snapshot tests for `unreachable`
# Instructions for Viewing Mermaid snapshots
Unfortunately I don't know how to convince GitHub to render the Mermaid
graphs in the snapshots. However, you can view these locally in VSCode
if you install an extension that supports Mermaid graphs in Markdown,
and then add this to your `settings.json`:
```json
"files.associations": {
"*.md.snap": "markdown",
}
```
The PR addresses issue #16396 .
Specifically:
- If the exit statement contains a code keyword argument, it is
converted into a positional argument.
- If retrieving the code from the exit statement is not possible, a
violation is raised without suggesting a fix.
---------
Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>
## Summary
Resolves#16374.
`PLW0177` now also reports the pattern of a case branch if it is an
attribute access whose qualified name is that of either `np.nan` or
`math.nan`.
As the rule is in preview, the changes are not preview-gated.
## Test Plan
`cargo nextest run` and `cargo insta test`.
## Summary
Resolves 3/4 requests in #16217:
- ✅ Remove not special methods: `__cmp__`, `__div__`, `__nonzero__`, and
`__unicode__`.
- ✅ Add special methods: `__next__`, `__buffer__`, `__class_getitem__`,
`__mro_entries__`, `__release_buffer__`, and `__subclasshook__`.
- ✅ Support positional-only arguments.
- ❌ Add support for module functions `__dir__` and `__getattr__`. As
mentioned in the issue the check is scoped for methods rather than
module functions. I am hesitant to expand the scope of this check
without a discussion.
## Test Plan
- Manually confirmed each example file from the issue functioned as
expected.
- Ran cargo nextest to ensure `unexpected_special_method_signature` test
still passed.
Fixes#16217.
## Summary
Resolves#13294, follow-up to #13882.
At #13882, it was concluded that a fix should not be offered for raw
strings. This change implements that. The five rules in question are now
no longer always fixable.
## Test Plan
`cargo nextest run` and `cargo insta test`.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
The PR addresses the issue #16040 .
---
The logic used into the rule is the following:
Suppose to have an expression of the form
```python
if a cmp b:
c = d
```
where `a`,` b`, `c` and `d` are Python obj and `cmp` one of `<`, `>`,
`<=`, `>=`.
Then:
- `if a=c and b=d`
- if `<=` fix with `a = max(b, a)`
- if `>=` fix with `a = min(b, a)`
- if `>` fix with `a = min(a, b)`
- if `<` fix with `a = max(a, b)`
- `if a=d and b=c`
- if `<=` fix with `b = min(a, b)`
- if `>=` fix with `b = max(a, b)`
- if `>` fix with `b = max(b, a)`
- if `<` fix with `b = min(b, a)`
- do nothing, i.e., we cannot fix this case.
---
In total we have 8 different and possible cases.
```
| Case | Expression | Fix |
|-------|------------------|---------------|
| 1 | if a >= b: a = b | a = min(b, a) |
| 2 | if a <= b: a = b | a = max(b, a) |
| 3 | if a <= b: b = a | b = min(a, b) |
| 4 | if a >= b: b = a | b = max(a, b) |
| 5 | if a > b: a = b | a = min(a, b) |
| 6 | if a < b: a = b | a = max(a, b) |
| 7 | if a < b: b = a | b = min(b, a) |
| 8 | if a > b: b = a | b = max(b, a) |
```
I added them in the tests.
Please double-check that I didn't make any mistakes. It's quite easy to
mix up > and <.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
Follow-up to #15984.
Previously, `PLE1310` would only report when the object is a literal:
```python
'a'.strip('//') # error
foo = ''
foo.strip('//') # no error
```
After this change, objects whose type can be inferred to be either `str`
or `bytes` will also be reported in preview.
## Test Plan
`cargo nextest run` and `cargo insta test`.
## Summary
Resolves#15968.
Previously, these would be considered violations:
```python
b''.strip('//')
''.lstrip('//', foo = "bar")
```
...while these are not:
```python
b''.strip(b'//')
''.strip('\\b\\x08')
```
Ruff will now not report when the types of the object and that of the
argument mismatch, or when there are extra arguments.
## Test Plan
`cargo nextest run` and `cargo insta test`.
## Summary
This PR re-introduces the control-flow graph implementation which was
first introduced in #5384, and then removed in #9463 due to not being
feature complete. Mainly, it lacked the ability to process
`try`-`except` blocks, along with some more minor bugs.
Closes#8958 and #8959 and #14881.
## Overview of Changes
I will now highlight the major changes implemented in this PR, in order
of implementation.
1. Introduced a post-processing step in loop handling to find any
`continue` or `break` statements within the loop body and redirect them
appropriately.
2. Introduced a loop-continue block which is always placed at the end of
loop blocks, and ensures proper looping regardless of the internal logic
of the block. This resolves#8958.
3. Implemented `try` processing with the following logic (resolves
#8959):
1. In the example below the cfg first encounters a conditional
`ExceptionRaised` forking if an exception was (or will be) raised in the
try block. This is not possible to know (except for trivial cases) so we
assume both paths can be taken unconditionally.
2. Going down the `try` path the cfg goes `try`->`else`->`finally`
unconditionally.
3. Going down the `except` path the cfg will meet several conditional
`ExceptionCaught` which fork depending on the nature of the exception
caught. Again there's no way to know which exceptions may be raised so
both paths are assumed to be taken unconditionally.
4. If none of the exception blocks catch the exception then the cfg
terminates by raising a new exception.
5. A post-processing step is also implemented to redirect any `raises`
or `returns` within the blocks appropriately.
```python
def func():
try:
print("try")
except Exception:
print("Exception")
except OtherException as e:
print("OtherException")
else:
print("else")
finally:
print("finally")
```
```mermaid
flowchart TD
start(("Start"))
return(("End"))
block0[["`*(empty)*`"]]
block1["print(#quot;finally#quot;)\n"]
block2["print(#quot;else#quot;)\n"]
block3["print(#quot;try#quot;)\n"]
block4[["Exception raised"]]
block5["print(#quot;OtherException#quot;)\n"]
block6["try:
print(#quot;try#quot;)
except Exception:
print(#quot;Exception#quot;)
except OtherException as e:
print(#quot;OtherException#quot;)
else:
print(#quot;else#quot;)
finally:
print(#quot;finally#quot;)\n"]
block7["print(#quot;Exception#quot;)\n"]
block8["try:
print(#quot;try#quot;)
except Exception:
print(#quot;Exception#quot;)
except OtherException as e:
print(#quot;OtherException#quot;)
else:
print(#quot;else#quot;)
finally:
print(#quot;finally#quot;)\n"]
block9["try:
print(#quot;try#quot;)
except Exception:
print(#quot;Exception#quot;)
except OtherException as e:
print(#quot;OtherException#quot;)
else:
print(#quot;else#quot;)
finally:
print(#quot;finally#quot;)\n"]
start --> block9
block9 -- "Exception raised" --> block8
block9 -- "else" --> block3
block8 -- "Exception" --> block7
block8 -- "else" --> block6
block7 --> block1
block6 -- "OtherException" --> block5
block6 -- "else" --> block4
block5 --> block1
block4 --> return
block3 --> block2
block2 --> block1
block1 --> block0
block0 --> return
```
6. Implemented `with` processing with the following logic:
1. `with` statements have no conditional execution (apart from the
hidden logic handling the enter and exit), so the block is assumed to
execute unconditionally.
2. The one exception is that exceptions raised within the block may
result in control flow resuming at the end of the block. Since it is not
possible know if an exception will be raised, or if it will be handled
by the context manager, we assume that execution always continues after
`with` blocks even if the blocks contain `raise` or `return` statements.
This is handled in a post-processing step.
## Test Plan
Additional test fixtures and control-flow fixtures were added.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: dylwil3 <dylwil3@gmail.com>
This PR introduces three changes to the diagnostic and fix behavior
(still under preview) for [boolean-chained-comparison
(PLR1716)](https://docs.astral.sh/ruff/rules/boolean-chained-comparison/#boolean-chained-comparison-plr1716).
1. We now offer a _fix_ in the case of parenthesized expressions like
`(a < b) and b < c`. The fix will merge the chains of comparisons and
then balance parentheses by _adding_ parentheses to one side of the
expression.
2. We now trigger a diagnostic (and fix) in the case where some
comparisons have multiple comparators like `a < b < c and c < d`.
3. When adjacent comparators are parenthesized, we prefer the left
parenthesization and apply the replacement to the whole parenthesized
range. So, for example, `a < (b) and ((b)) < c` becomes `a < (b) < c`.
While these seem like somewhat disconnected changes, they are actually
related. If we only offered (1), then we would see the following fix
behavior:
```diff
- (a < b) and b < c and ((c < d))
+ (a < b < c) and ((c < d))
```
This is because the fix which add parentheses to the first pair of
comparisons overlaps with the fix that removes the `and` between the
second two comparisons. So the latter fix is deferred. However, the
latter fix does not get a second chance because, upon the next lint
iteration, there is no violation of `PLR1716`.
Upon adopting (2), however, both fixes occur by the time ruff completes
several iterations and we get:
```diff
- (a < b) and b < c and ((c < d))
+ ((a < b < c < d))
```
Finally, (3) fixes a previously unobserved bug wherein the autofix for
`a < (b) and b < c` used to result in `a<(b<c` which gives a syntax
error. It could in theory have been fixed in a separate PR, but seems to
be on theme here.
----------
- Closes#13524
- (1), (2), and (3) are implemented in separate commits for ease of
review and modification.
- Technically a user can trigger an error in ruff (by reaching max
iterations) if they have a humongous boolean chained comparison with
differing parentheses levels.
Kot
Brent Westbrook
Dan Parizher
frank
Dylan
Victor Hugo Gomes
Gideon
Gene Parmesan Thomas
Robsdedude
Nikolas Hearp
vjurczenia
Vasco Schiavo
InSync
Darius Carrier
cake-monotone
Mike Perlov
Jelle Zijlstra
Akira Noda
Auguste Lalande
Dylan
Thibaut Decombe
Matt Ord
Simon Brugman
Lokejoke
Harutaka Kawamura
Steve C
Charlie Marsh