## Summary
The `RET504` rule, which looks for unnecessary assignments before return
statements, is a frequent source of issues (#4173, #4236, #4242, #1606,
#2950). Over time, we've tried to refine the logic to handle more cases.
For example, we now avoid analyzing any functions that contain any
function calls or attribute assignments, since those operations can
contain side effects (and so we mark them as a "read" on all variables
in the function -- we could do a better job with code graph analysis to
handle this limitation, but that'd be a more involved change.) We also
avoid flagging any variables that are the target of multiple
assignments. Ultimately, though, I'm not happy with the implementation
-- we just can't do sufficiently reliable analysis of arbitrary code
flow given the limited logic herein, and the existing logic is very hard
to reason about and maintain.
This PR refocuses the rule to only catch cases of the form:
```py
def f():
x = 1
return x
```
That is, we now only flag returns that are immediately preceded by an
assignment to the returned variable. While this is more limiting, in
some ways, it lets us flag more cases vis-a-vis the previous
implementation, since we no longer "fully eject" when functions contain
function calls and other effect-ful operations.
Closes#4173.
Closes#4236.
Closes#4242.
## Summary
We use `.trim()` and friends in a bunch of places, to strip whitespace
from source code. However, not all Unicode whitespace characters are
considered "whitespace" in Python, which only supports the standard
space, tab, and form-feed characters.
This PR audits our usages of `.trim()`, `.trim_start()`, `.trim_end()`,
and `char::is_whitespace`, and replaces them as appropriate with a new
`.trim_whitespace()` analogues, powered by a `PythonWhitespace` trait.
In general, the only place that should continue to use `.trim()` is
content within docstrings, which don't need to adhere to Python's
semantic definitions of whitespace.
Closes#4991.
## Summary
`ruff_newlines` becomes `ruff_python_whitespace`, and includes the
existing "universal newline" handlers alongside the Python
whitespace-specific utilities.
* Replace the unmaintained actions-rs/cargo that github actions
complains about using an old node version with plain cargo (this was the
original motivation for this PR)
* Use taiki-e/install-action to install critcmp directly
* Use a rust 1.70 nightly toolchain for udeps
* Cache python package build (this should cut a good chunk of ci time)
* yaml formatting courtesy of pycharm
Test Plan: CI itself
* Implement StmtPass
This implements StmtPass as `pass`.
The snapshot diff is small because pass mainly occurs in bodies and function (#4951) and if/for bodies.
* Implement StmtReturn
This implements StmtReturn as `return` or `return {value}`.
The snapshot diff is small because return occurs in functions (#4951)
* A basic StmtAssign formatter and better dummies for expressions
The goal of this PR was formatting StmtAssign since many nodes in the black tests (and in python in general) are after an assignment. This caused unstable formatting: The spacing of power op spacing depends on the type of the two involved expressions, but each expression was formatted as dummy string and re-parsed as a ExprName, so in the second round the different rules of ExprName were applied, causing unstable formatting.
This PR does not necessarily bring us closer to black's style, but it unlocks a good porting of black's test suite and is a basis for implementing the Expr nodes.
* fmt
* Review
* Use phf for confusables to reduce llvm lines
## Summary
This replaces FxHashMap for the confusables with a perfect hash map from the [phf crate](https://github.com/rust-phf/rust-phf) to reduce the generated llvm instructions.
A perfect hash function is one that doesn't have any collisions. We can build one because we know all keys at compile time. This improves hashmap efficiency, even though this is likely not noticeable in our case (except someone has a large non-english crate to test on).
The original hashmap contained a lot of duplicates, which i had to remove when phf_map complained, i did so by sorting the keys.
The important part that it reduces the llvm instructions generated (#3808, `RUSTFLAGS="-Csymbol-mangling-version=v0" cargo llvm-lines -p ruff --lib | head -20`):
```
Lines Copies Function name
----- ------ -------------
1740502 38973 (TOTAL)
27423 (1.6%, 1.6%) 1 (0.0%, 0.0%) ruff[cef4c65d96248843]::rules::ruff::rules::confusables::CONFUSABLES::{closure#0}
10193 (0.6%, 2.2%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::codes::RuleCodePrefix>::iter
8107 (0.5%, 2.6%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::codes::Rule>::noqa_code
7345 (0.4%, 3.0%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::checkers::ast::Checker as ruff_python_ast[3778b140caf21545]::visitor::Visitor>::visit_stmt
6412 (0.4%, 3.4%) 1 (0.0%, 0.0%) <<ruff[cef4c65d96248843]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_map::<toml_edit[7e3a6c5e67260672]:🇩🇪:spanned::SpannedDeserializer<toml_edit[7e3a6c5e67260672]:🇩🇪:value::ValueDeserializer>>
6412 (0.4%, 3.8%) 1 (0.0%, 0.0%) <<ruff[cef4c65d96248843]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_map::<toml_edit[7e3a6c5e67260672]:🇩🇪:table::TableMapAccess>
6409 (0.4%, 4.2%) 1 (0.0%, 0.0%) <<ruff[cef4c65d96248843]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_map::<toml_edit[7e3a6c5e67260672]:🇩🇪:datetime::DatetimeDeserializer>
5696 (0.3%, 4.5%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::checkers::ast::Checker as ruff_python_ast[3778b140caf21545]::visitor::Visitor>::visit_expr
4448 (0.3%, 4.7%) 1 (0.0%, 0.0%) ruff[cef4c65d96248843]::flake8_to_ruff::converter::convert
3702 (0.2%, 4.9%) 1 (0.0%, 0.0%) <&ruff[cef4c65d96248843]::registry::Linter as core[da82827a87f140f9]::iter::traits::collect::IntoIterator>::into_iter
3349 (0.2%, 5.1%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::registry::Linter>::code_for_rule
3132 (0.2%, 5.3%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::codes::Rule as core[da82827a87f140f9]::fmt::Debug>::fmt
3130 (0.2%, 5.5%) 1 (0.0%, 0.0%) <&str as core[da82827a87f140f9]::convert::From<&ruff[cef4c65d96248843]::codes::Rule>>::from
3130 (0.2%, 5.7%) 1 (0.0%, 0.0%) <&str as core[da82827a87f140f9]::convert::From<ruff[cef4c65d96248843]::codes::Rule>>::from
3130 (0.2%, 5.9%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::codes::Rule as core[da82827a87f140f9]::convert::AsRef<str>>::as_ref
3128 (0.2%, 6.0%) 1 (0.0%, 0.0%) <ruff[cef4c65d96248843]::codes::RuleIter>::get
2669 (0.2%, 6.2%) 1 (0.0%, 0.0%) <<ruff[cef4c65d96248843]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_seq::<toml_edit[7e3a6c5e67260672]:🇩🇪:array::ArraySeqAccess>
```
After:
```
Lines Copies Function name
----- ------ -------------
1710487 38900 (TOTAL)
10193 (0.6%, 0.6%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::codes::RuleCodePrefix>::iter
8107 (0.5%, 1.1%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::codes::Rule>::noqa_code
7345 (0.4%, 1.5%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::checkers::ast::Checker as ruff_python_ast[5588cd60041c8605]::visitor::Visitor>::visit_stmt
6412 (0.4%, 1.9%) 1 (0.0%, 0.0%) <<ruff[52408f46d2058296]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_map::<toml_edit[7e3a6c5e67260672]:🇩🇪:spanned::SpannedDeserializer<toml_edit[7e3a6c5e67260672]:🇩🇪:value::ValueDeserializer>>
6412 (0.4%, 2.2%) 1 (0.0%, 0.0%) <<ruff[52408f46d2058296]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_map::<toml_edit[7e3a6c5e67260672]:🇩🇪:table::TableMapAccess>
6409 (0.4%, 2.6%) 1 (0.0%, 0.0%) <<ruff[52408f46d2058296]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_map::<toml_edit[7e3a6c5e67260672]:🇩🇪:datetime::DatetimeDeserializer>
5696 (0.3%, 3.0%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::checkers::ast::Checker as ruff_python_ast[5588cd60041c8605]::visitor::Visitor>::visit_expr
4448 (0.3%, 3.2%) 1 (0.0%, 0.0%) ruff[52408f46d2058296]::flake8_to_ruff::converter::convert
3702 (0.2%, 3.4%) 1 (0.0%, 0.0%) <&ruff[52408f46d2058296]::registry::Linter as core[da82827a87f140f9]::iter::traits::collect::IntoIterator>::into_iter
3349 (0.2%, 3.6%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::registry::Linter>::code_for_rule
3132 (0.2%, 3.8%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::codes::Rule as core[da82827a87f140f9]::fmt::Debug>::fmt
3130 (0.2%, 4.0%) 1 (0.0%, 0.0%) <&str as core[da82827a87f140f9]::convert::From<&ruff[52408f46d2058296]::codes::Rule>>::from
3130 (0.2%, 4.2%) 1 (0.0%, 0.0%) <&str as core[da82827a87f140f9]::convert::From<ruff[52408f46d2058296]::codes::Rule>>::from
3130 (0.2%, 4.4%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::codes::Rule as core[da82827a87f140f9]::convert::AsRef<str>>::as_ref
3128 (0.2%, 4.5%) 1 (0.0%, 0.0%) <ruff[52408f46d2058296]::codes::RuleIter>::get
2669 (0.2%, 4.7%) 1 (0.0%, 0.0%) <<ruff[52408f46d2058296]::settings::options::Options as serde[d89b1b632568f5a3]:🇩🇪:Deserialize>::deserialize::__Visitor as serde[d89b1b632568f5a3]:🇩🇪:Visitor>::visit_seq::<toml_edit[7e3a6c5e67260672]:🇩🇪:array::ArraySeqAccess>
2659 (0.2%, 4.9%) 1 (0.0%, 0.0%) <&ruff[52408f46d2058296]::codes::Pylint as core[da82827a87f140f9]::iter::traits::collect::IntoIterator>::into_iter
```
I'd assume this has a positive effect both on compile time and on runtime, but i don't know the actual effect on compile times and can't really measure.
## Test plan
Check CI for any performance regressions.
This should fix#3808 if we merge it.
* clippy
* Update update_ambiguous_characters.py
