(Supersedes #9152, authored by @LaBatata101)
## Summary
This PR replaces the current parser generated from LALRPOP to a
hand-written recursive descent parser.
It also updates the grammar for [PEP
646](https://peps.python.org/pep-0646/) so that the parser outputs the
correct AST. For example, in `data[*x]`, the index expression is now a
tuple with a single starred expression instead of just a starred
expression.
Beyond the performance improvements, the parser is also error resilient
and can provide better error messages. The behavior as seen by any
downstream tools isn't changed. That is, the linter and formatter can
still assume that the parser will _stop_ at the first syntax error. This
will be updated in the following months.
For more details about the change here, refer to the PR corresponding to
the individual commits and the release blog post.
## Test Plan
Write _lots_ and _lots_ of tests for both valid and invalid syntax and
verify the output.
## Acknowledgements
- @MichaReiser for reviewing 100+ parser PRs and continuously providing
guidance throughout the project
- @LaBatata101 for initiating the transition to a hand-written parser in
#9152
- @addisoncrump for implementing the fuzzer which helped
[catch](https://github.com/astral-sh/ruff/pull/10903)
[a](https://github.com/astral-sh/ruff/pull/10910)
[lot](https://github.com/astral-sh/ruff/pull/10966)
[of](https://github.com/astral-sh/ruff/pull/10896)
[bugs](https://github.com/astral-sh/ruff/pull/10877)
---------
Co-authored-by: Victor Hugo Gomes <labatata101@linuxmail.org>
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
This PR refactors the with item formatting to use more explicit layouts
to make it easier to understand the different formatting cases.
The benefit of the explicit layout is that it makes it easier to reasons
about layout transition between format runs. For example, today it's
possible that `SingleWithTarget` or `ParenthesizeIfExpands` add
parentheses around the with items for `with aaaaaaaaaa + bbbbbbbbbbbb:
pass`, resulting in `with (aaaaaaaaaa + bbbbbbbbbbbb): pass`. The
problem with this is that the next formatting pass uses the
`SingleParenthesizedContextExpression` layout that uses
`maybe_parenthesize_expression` which is different from
`parenthesize_if_expands(&expr)` or `optional_parentheses(&expr)`.
## Test Plan
`cargo test`
I ran the ecosystem checks locally and there are no changes.
## Summary
The motivating code here was:
```python
with test as (
# test
foo):
pass
```
Which we were formatting as:
```python
with test as
# test
(foo):
pass
```
`with` statements are oddly difficult. This PR makes a bunch of subtle
modifications and adds a more extensive test suite. For example, we now
only preserve parentheses if there's more than one `WithItem` _or_ a
trailing comma; before, we always preserved.
Our formatting is_not_ the same as Black, but here's a diff of our
formatted code vs. Black's for the `with.py` test suite. The primary
difference is that we tend to break parentheses when they contain
comments rather than move them to the end of the life (this is a
consistent difference that we make across the codebase):
```diff
diff --git a/crates/ruff_python_formatter/foo.py b/crates/ruff_python_formatter/foo.py
index 85e761080..31625c876 100644
--- a/crates/ruff_python_formatter/foo.py
+++ b/crates/ruff_python_formatter/foo.py
@@ -1,6 +1,4 @@
-with (
- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-), aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
+with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
...
# trailing
@@ -16,28 +14,33 @@ with (
# trailing
-with a, b: # a # comma # c # colon
+with (
+ a, # a # comma
+ b, # c
+): # colon
...
with (
- a as # a # as
- # own line
- b, # b # comma
+ a as ( # a # as
+ # own line
+ b
+ ), # b # comma
c, # c
): # colon
... # body
# body trailing own
-with (
- a as # a # as
+with a as ( # a # as
# own line
- bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb # b
-):
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+): # b
pass
-with (a,): # magic trailing comma
+with (
+ a,
+): # magic trailing comma
...
@@ -47,6 +50,7 @@ with a: # should remove brackets
with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as c:
...
+
with (
# leading comment
a
@@ -74,8 +78,7 @@ with (
with (
a # trailing same line comment
# trailing own line comment
- as b
-):
+) as b:
...
with (
@@ -87,7 +90,9 @@ with (
with (
a
# trailing own line comment
-) as b: # trailing as same line comment # trailing b same line comment
+) as ( # trailing as same line comment
+ b
+): # trailing b same line comment
...
with (
@@ -124,18 +129,24 @@ with ( # comment
...
with ( # outer comment
- CtxManager1() as example1, # inner comment
+ ( # inner comment
+ CtxManager1()
+ ) as example1,
CtxManager2() as example2,
CtxManager3() as example3,
):
...
-with CtxManager() as example: # outer comment
+with ( # outer comment
+ CtxManager()
+) as example:
...
with ( # outer comment
CtxManager()
-) as example, CtxManager2() as example2: # inner comment
+) as example, ( # inner comment
+ CtxManager2()
+) as example2:
...
with ( # outer comment
@@ -145,7 +156,9 @@ with ( # outer comment
...
with ( # outer comment
- (CtxManager1()), # inner comment
+ ( # inner comment
+ CtxManager1()
+ ),
CtxManager2(),
) as example:
...
@@ -179,7 +192,9 @@ with (
):
pass
-with a as (b): # foo
+with a as ( # foo
+ b
+):
pass
with f(
@@ -209,17 +224,13 @@ with f(
) as b, c as d:
pass
-with (
- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
-) as b:
+with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b:
pass
with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b:
pass
-with (
- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
-) as b, c as d:
+with aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b, c as d:
pass
with (
@@ -230,6 +241,8 @@ with (
pass
with (
- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
-) as b, c as d:
+ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb as b,
+ c as d,
+):
pass
```
Closes https://github.com/astral-sh/ruff/issues/6600.
## Test Plan
Before:
| project | similarity index |
|--------------|------------------|
| cpython | 0.75473 |
| django | 0.99804 |
| transformers | 0.99618 |
| twine | 0.99876 |
| typeshed | 0.74292 |
| warehouse | 0.99601 |
| zulip | 0.99727 |
After:
| project | similarity index |
|--------------|------------------|
| cpython | 0.75473 |
| django | 0.99804 |
| transformers | 0.99618 |
| twine | 0.99876 |
| typeshed | 0.74292 |
| warehouse | 0.99601 |
| zulip | 0.99727 |
`cargo test`
Micha Reiser
Dhruv Manilawala
Charlie Marsh