## Summary
This PR adds a newtype wrapper around `Vec<FStringElement>` that derefs
to a `&Vec<FStringElement>`.
Both f-string and format specifier are made up of `Vec<FStringElement>`.
By creating a newtype wrapper around it, we can share the methods for
both parent types.
This PR modifies our AST so that nodes for string literals, bytes literals and f-strings all retain the following information:
- The quoting style used (double or single quotes)
- Whether the string is triple-quoted or not
- Whether the string is raw or not
This PR is a followup to #10256. Like with that PR, this PR does not, in itself, fix any bugs. However, it means that we will have the necessary information to preserve quoting style and rawness of strings in the `ExprGenerator` in a followup PR, which will allow us to provide a fix for https://github.com/astral-sh/ruff/issues/7799.
The information is recorded on the AST nodes using a bitflag field on each node, similarly to how we recorded the information on `Tok::String`, `Tok::FStringStart` and `Tok::FStringMiddle` tokens in #10298. Rather than reusing the bitflag I used for the tokens, however, I decided to create a custom bitflag for each AST node.
Using different bitflags for each node allows us to make invalid states unrepresentable: it is valid to set a `u` prefix on a string literal, but not on a bytes literal or an f-string. It also allows us to have better debug representations for each AST node modified in this PR.
The expression types in our AST are called `ExprYield`, `ExprAwait`,
`ExprStringLiteral` etc, except `ExprNamedExpr`, `ExprIfExpr` and
`ExprGenratorExpr`. This seems to align with [Python AST's
naming](https://docs.python.org/3/library/ast.html) but feels
inconsistent and excessive.
This PR removes the `Expr` postfix from `ExprNamedExpr`, `ExprIfExpr`,
and `ExprGeneratorExpr`.
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Fixes#6611
## Summary
This lint rule spots comments that are _intended_ to suppress or enable
the formatter, but will be ignored by the Ruff formatter.
We borrow some functions the formatter uses for determining comment
placement / putting them in context within an AST.
The analysis function uses an AST visitor to visit each comment and
attach it to the AST. It then uses that context to check:
1. Is this comment in an expression?
2. Does this comment have bad placement? (e.g. a `# fmt: skip` above a
function instead of at the end of a line)
3. Is this comment redundant?
4. Does this comment actually suppress any code?
5. Does this comment have ambiguous placement? (e.g. a `# fmt: off`
above an `else:` block)
If any of these are true, a violation is thrown. The reported reason
depends on the order of the above check-list: in other words, a `# fmt:
skip` comment on its own line within a list expression will be reported
as being in an expression, since that reason takes priority.
The lint suggests removing the comment as an unsafe fix, regardless of
the reason.
## Test Plan
A snapshot test has been created.
## Summary
This PR reduces the size of `Expr` from 80 to 64 bytes, by reducing the
sizes of...
- `ExprCall` from 72 to 56 bytes, by using boxed slices for `Arguments`.
- `ExprCompare` from 64 to 48 bytes, by using boxed slices for its
various vectors.
In testing, the parser gets a bit faster, and the linter benchmarks
improve quite a bit.
## Summary
This PR adds the `AnyNode` and `AnyNodeRef` implementation for
`FStringFormatSpec` node which will be required in the f-string
formatting.
The main usage for this is so that we can pass in the node directly to
`suppressed_node` in case debug expression is used to format is as
verbatim text.
This PR adds a `as_slice` method to all the string nodes which returns
all the parts of the nodes as a slice. This will be useful in the next
PR to split the string formatting to use this method to extract the
_single node_ or _implicitly concanated nodes_.
Rebase of #6365 authored by @davidszotten.
## Summary
This PR updates the AST structure for an f-string elements.
The main **motivation** behind this change is to have a dedicated node
for the string part of an f-string. Previously, the existing
`ExprStringLiteral` node was used for this purpose which isn't exactly
correct. The `ExprStringLiteral` node should include the quotes as well
in the range but the f-string literal element doesn't include the quote
as it's a specific part within an f-string. For example,
```python
f"foo {x}"
# ^^^^
# This is the literal part of an f-string
```
The introduction of `FStringElement` enum is helpful which represent
either the literal part or the expression part of an f-string.
### Rule Updates
This means that there'll be two nodes representing a string depending on
the context. One for a normal string literal while the other is a string
literal within an f-string. The AST checker is updated to accommodate
this change. The rules which work on string literal are updated to check
on the literal part of f-string as well.
#### Notes
1. The `Expr::is_literal_expr` method would check for
`ExprStringLiteral` and return true if so. But now that we don't
represent the literal part of an f-string using that node, this improves
the method's behavior and confines to the actual expression. We do have
the `FStringElement::is_literal` method.
2. We avoid checking if we're in a f-string context before adding to
`string_type_definitions` because the f-string literal is now a
dedicated node and not part of `Expr`.
3. Annotations cannot use f-string so we avoid changing any rules which
work on annotation and checks for `ExprStringLiteral`.
## Test Plan
- All references of `Expr::StringLiteral` were checked to see if any of
the rules require updating to account for the f-string literal element
node.
- New test cases are added for rules which check against the literal
part of an f-string.
- Check the ecosystem results and ensure it remains unchanged.
## Performance
There's a performance penalty in the parser. The reason for this remains
unknown as it seems that the generated assembly code is now different
for the `__reduce154` function. The reduce function body is just popping
the `ParenthesizedExpr` on top of the stack and pushing it with the new
location.
- The size of `FStringElement` enum is the same as `Expr` which is what
it replaces in `FString::format_spec`
- The size of `FStringExpressionElement` is the same as
`ExprFormattedValue` which is what it replaces
I tried reducing the `Expr` enum from 80 bytes to 72 bytes but it hardly
resulted in any performance gain. The difference can be seen here:
- Original profile: https://share.firefox.dev/3Taa7ES
- Profile after boxing some node fields:
https://share.firefox.dev/3GsNXpD
### Backtracking
I tried backtracking the changes to see if any of the isolated change
produced this regression. The problem here is that the overall change is
so small that there's only a single checkpoint where I can backtrack and
that checkpoint results in the same regression. This checkpoint is to
revert using `Expr` to the `FString::format_spec` field. After this
point, the change would revert back to the original implementation.
## Review process
The review process is similar to #7927. The first set of commits update
the node structure, parser, and related AST files. Then, further commits
update the linter and formatter part to account for the AST change.
---------
Co-authored-by: David Szotten <davidszotten@gmail.com>
## Summary
This PR updates the string nodes (`ExprStringLiteral`,
`ExprBytesLiteral`, and `ExprFString`) to account for implicit string
concatenation.
### Motivation
In Python, implicit string concatenation are joined while parsing
because the interpreter doesn't require the information for each part.
While that's feasible for an interpreter, it falls short for a static
analysis tool where having such information is more useful. Currently,
various parts of the code uses the lexer to get the individual string
parts.
One of the main challenge this solves is that of string formatting.
Currently, the formatter relies on the lexer to get the individual
string parts, and formats them including the comments accordingly. But,
with PEP 701, f-string can also contain comments. Without this change,
it becomes very difficult to add support for f-string formatting.
### Implementation
The initial proposal was made in this discussion:
https://github.com/astral-sh/ruff/discussions/6183#discussioncomment-6591993.
There were various AST designs which were explored for this task which
are available in the linked internal document[^1].
The selected variant was the one where the nodes were kept as it is
except that the `implicit_concatenated` field was removed and instead a
new struct was added to the `Expr*` struct. This would be a private
struct would contain the actual implementation of how the AST is
designed for both single and implicitly concatenated strings.
This implementation is achieved through an enum with two variants:
`Single` and `Concatenated` to avoid allocating a vector even for single
strings. There are various public methods available on the value struct
to query certain information regarding the node.
The nodes are structured in the following way:
```
ExprStringLiteral - "foo" "bar"
|- StringLiteral - "foo"
|- StringLiteral - "bar"
ExprBytesLiteral - b"foo" b"bar"
|- BytesLiteral - b"foo"
|- BytesLiteral - b"bar"
ExprFString - "foo" f"bar {x}"
|- FStringPart::Literal - "foo"
|- FStringPart::FString - f"bar {x}"
|- StringLiteral - "bar "
|- FormattedValue - "x"
```
[^1]: Internal document:
https://www.notion.so/astral-sh/Implicit-String-Concatenation-e036345dc48943f89e416c087bf6f6d9?pvs=4
#### Visitor
The way the nodes are structured is that the entire string, including
all the parts that are implicitly concatenation, is a single node
containing individual nodes for the parts. The previous section has a
representation of that tree for all the string nodes. This means that
new visitor methods are added to visit the individual parts of string,
bytes, and f-strings for `Visitor`, `PreorderVisitor`, and
`Transformer`.
## Test Plan
- `cargo insta test --workspace --all-features --unreferenced reject`
- Verify that the ecosystem results are unchanged
## Summary
This PR splits the `Constant` enum as individual literal nodes. It
introduces the following new nodes for each variant:
* `ExprStringLiteral`
* `ExprBytesLiteral`
* `ExprNumberLiteral`
* `ExprBooleanLiteral`
* `ExprNoneLiteral`
* `ExprEllipsisLiteral`
The main motivation behind this refactor is to introduce the new AST
node for implicit string concatenation in the coming PR. The elements of
that node will be either a string literal, bytes literal or a f-string
which can be implemented using an enum. This means that a string or
bytes literal cannot be represented by `Constant::Str` /
`Constant::Bytes` which creates an inconsistency.
This PR avoids that inconsistency by splitting the constant nodes into
it's own literal nodes, literal being the more appropriate naming
convention from a static analysis tool perspective.
This also makes working with literals in the linter and formatter much
more ergonomic like, for example, if one would want to check if this is
a string literal, it can be done easily using
`Expr::is_string_literal_expr` or matching against `Expr::StringLiteral`
as oppose to matching against the `ExprConstant` and enum `Constant`. A
few AST helper methods can be simplified as well which will be done in a
follow-up PR.
This introduces a new `Expr::is_literal_expr` method which is the same
as `Expr::is_constant_expr`. There are also intermediary changes related
to implicit string concatenation which are quiet less. This is done so
as to avoid having a huge PR which this already is.
## Test Plan
1. Verify and update all of the existing snapshots (parser, visitor)
2. Verify that the ecosystem check output remains **unchanged** for both
the linter and formatter
### Formatter ecosystem check
#### `main`
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75803 | 1799 | 1647 |
| django | 0.99983 | 2772 | 34 |
| home-assistant | 0.99953 | 10596 | 186 |
| poetry | 0.99891 | 317 | 17 |
| transformers | 0.99966 | 2657 | 330 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99978 | 3669 | 20 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 22 |
#### `dhruv/constant-to-literal`
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75803 | 1799 | 1647 |
| django | 0.99983 | 2772 | 34 |
| home-assistant | 0.99953 | 10596 | 186 |
| poetry | 0.99891 | 317 | 17 |
| transformers | 0.99966 | 2657 | 330 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99978 | 3669 | 20 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 22 |
## Summary
This PR adds a new `Singleton` enum for the `PatternMatchSingleton`
node.
Earlier the node was using the `Constant` enum but the value for this
pattern can only be either `None`, `True` or `False`. With the coming PR
to remove the `Constant`, this node required a new type to fill in.
This also has the benefit of narrowing the type down to only the
possible values for the node as evident by the removal of `unreachable`.
## Test Plan
Update the AST snapshots and run `cargo test`.
**Summary** Insert a newline after nested function and class
definitions, unless there is a trailing own line comment.
We need to e.g. format
```python
if platform.system() == "Linux":
if sys.version > (3, 10):
def f():
print("old")
else:
def f():
print("new")
f()
```
as
```python
if platform.system() == "Linux":
if sys.version > (3, 10):
def f():
print("old")
else:
def f():
print("new")
f()
```
even though `f()` is directly preceded by an if statement, not a
function or class definition. See the comments and fixtures for trailing
own line comment handling.
**Test Plan** I checked that the new content of `newlines.py` matches
black's formatting.
---------
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
## Motivation
The `ast::Arguments` for call argument are split into positional
arguments (args) and keywords arguments (keywords). We currently assume
that call consists of first args and then keywords, which is generally
the case, but not always:
```python
f(*args, a=2, *args2, **kwargs)
class A(*args, a=2, *args2, **kwargs):
pass
```
The consequence is accidentally reordering arguments
(https://github.com/astral-sh/ruff/pull/7268).
## Summary
`Arguments::args_and_keywords` returns an iterator of an `ArgOrKeyword`
enum that yields args and keywords in the correct order. I've fixed the
obvious `args` and `keywords` usages, but there might be some cases with
wrong assumptions remaining.
## Test Plan
The generator got new test cases, otherwise the stacked PR
(https://github.com/astral-sh/ruff/pull/7268) which uncovered this.
## Summary
The motivation here is that this enables us to implement `Ranged` in
crates that don't depend on `ruff_python_ast`.
Largely a mechanical refactor with a lot of regex, Clippy help, and
manual fixups.
## Test Plan
`cargo test`
## Summary
This PR introduces two new AST nodes to improve the representation of
`PatternMatchClass`. As a reminder, `PatternMatchClass` looks like this:
```python
case Point2D(0, 0, x=1, y=2):
...
```
Historically, this was represented as a vector of patterns (for the `0,
0` portion) and parallel vectors of keyword names (for `x` and `y`) and
values (for `1` and `2`). This introduces a bunch of challenges for the
formatter, but importantly, it's also really different from how we
represent similar nodes, like arguments (`func(0, 0, x=1, y=2)`) or
parameters (`def func(x, y)`).
So, firstly, we now use a single node (`PatternArguments`) for the
entire parenthesized region, making it much more consistent with our
other nodes. So, above, `PatternArguments` would be `(0, 0, x=1, y=2)`.
Secondly, we now have a `PatternKeyword` node for `x=1` and `y=2`. This
is much more similar to the how `Keyword` is represented within
`Arguments` for call expressions.
Closes https://github.com/astral-sh/ruff/issues/6866.
Closes https://github.com/astral-sh/ruff/issues/6880.
## Summary
If a lambda doesn't contain any parameters, or any parameter _tokens_
(like `*`), we can use `None` for the parameters. This feels like a
better representation to me, since, e.g., what should the `TextRange` be
for a non-existent set of parameters? It also allows us to remove
several sites where we check if the `Parameters` is empty by seeing if
it contains any arguments, so semantically, we're already trying to
detect and model around this elsewhere.
Changing this also fixes a number of issues with dangling comments in
parameter-less lambdas, since those comments are now automatically
marked as dangling on the lambda. (As-is, we were also doing something
not-great whereby the lambda was responsible for formatting dangling
comments on the parameters, which has been removed.)
Closes https://github.com/astral-sh/ruff/issues/6646.
Closes https://github.com/astral-sh/ruff/issues/6647.
## Test Plan
`cargo test`
## Summary
Instead, we set an `is_star` flag on `Stmt::Try`. This is similar to the
pattern we've migrated towards for `Stmt::For` (removing
`Stmt::AsyncFor`) and friends. While these are significant differences
for an interpreter, we tend to handle these cases identically or nearly
identically.
## Test Plan
`cargo test`
## Summary
Per the discussion in
https://github.com/astral-sh/ruff/discussions/6183, this PR adds an
`implicit_concatenated` flag to the string and bytes constant variants.
It's not actually _used_ anywhere as of this PR, but it is covered by
the tests.
Specifically, we now use a struct for the string and bytes cases, along
with the `Expr::FString` node. That struct holds the value, plus the
flag:
```rust
#[derive(Clone, Debug, PartialEq, is_macro::Is)]
pub enum Constant {
Str(StringConstant),
Bytes(BytesConstant),
...
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct StringConstant {
/// The string value as resolved by the parser (i.e., without quotes, or escape sequences, or
/// implicit concatenations).
pub value: String,
/// Whether the string contains multiple string tokens that were implicitly concatenated.
pub implicit_concatenated: bool,
}
impl Deref for StringConstant {
type Target = str;
fn deref(&self) -> &Self::Target {
self.value.as_str()
}
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct BytesConstant {
/// The bytes value as resolved by the parser (i.e., without quotes, or escape sequences, or
/// implicit concatenations).
pub value: Vec<u8>,
/// Whether the string contains multiple string tokens that were implicitly concatenated.
pub implicit_concatenated: bool,
}
impl Deref for BytesConstant {
type Target = [u8];
fn deref(&self) -> &Self::Target {
self.value.as_slice()
}
}
```
## Test Plan
`cargo test`
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## Summary
This PR adds the `AnyNodeRef.visit_preorder` method. I'll need this method to mark all comments of a suppressed node's children as formatted (in debug builds).
I'm not super happy with this because it now requires a double-dispatch where the `walk_*` methods call into `node.visit_preorder` and the `visit_preorder` then calls back into the visitor. Meaning,
the new implementation now probably results in way more function calls. The other downside is that `AnyNodeRef` now contains code that is difficult to auto-generate. This could be mitigated by extracting the `visit_preorder` method into its own `VisitPreorder` trait.
Anyway, this approach solves the need and avoids duplicating the visiting code once more.
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
`cargo test`
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## Summary
This PR renames the `MagicCommand` token to `IpyEscapeCommand` token and
`MagicKind` to `IpyEscapeKind` type to better reflect the purpose of the
token and type. Similarly, it renames the AST nodes from `LineMagic` to
`IpyEscapeCommand` prefixed with `Stmt`/`Expr` wherever necessary.
It also makes renames from using `jupyter_magic` to
`ipython_escape_commands` in various function names.
The mode value is still `Mode::Jupyter` because the escape commands are
part of the IPython syntax but the lexing/parsing is done for a Jupyter
notebook.
### Motivation behind the rename:
* IPython codebase defines it as "EscapeCommand" / "Escape Sequences":
* Escape Sequences:
292e3a2345/IPython/core/inputtransformer2.py (L329-L333)
* Escape command:
292e3a2345/IPython/core/inputtransformer2.py (L410-L411)
* The word "magic" is used mainly for the actual magic commands i.e.,
the ones starting with `%`/`%%`
(https://ipython.readthedocs.io/en/stable/interactive/reference.html#magic-command-system).
So, this avoids any confusion between the Magic token (`%`, `%%`) and
the escape command itself.
## Test Plan
* `cargo test` to make sure all renames are done correctly.
* `grep` for `jupyter_escape`/`magic` to make sure all renames are done
correctly.
## Summary
Per the suggestion in
https://github.com/astral-sh/ruff/discussions/6183, this PR removes
`AsyncWith`, `AsyncFor`, and `AsyncFunctionDef`, replacing them with an
`is_async` field on the non-async variants of those structs. Unlike an
interpreter, we _generally_ have identical handling for these nodes, so
separating them into distinct variants adds complexity from which we
don't really benefit. This can be seen below, where we get to remove a
_ton_ of code related to adding generic `Any*` wrappers, and a ton of
duplicate branches for these cases.
## Test Plan
`cargo test` is unchanged, apart from parser snapshots.
Part of #5062
Closes https://github.com/astral-sh/ruff/issues/5931
Implements formatting of a sequence of type parameters in a dedicated
struct for reuse by classes, functions, and type aliases (preparing for
#5929). Adds formatting of type parameters in class and function
definitions — previously, they were just elided.
## Summary
This PR leverages the `Arguments` AST node introduced in #6259 in the
formatter, which ensures that we correctly handle trailing comments in
calls, like:
```python
f(
1,
# comment
)
pass
```
(Previously, this was treated as a leading comment on `pass`.)
This also allows us to unify the argument handling across calls and
class definitions.
## Test Plan
A bunch of new fixture tests, plus improved Black compatibility.
## Summary
Similar to #6259, this PR adds a `TypeParams` node to the AST, to
capture the list of type parameters with their surrounding brackets.
If a statement lacks type parameters, the `type_params` field will be
`None`.
## Summary
This PR adds a new `Arguments` AST node, which we can use for function
calls and class definitions.
The `Arguments` node spans from the left (open) to right (close)
parentheses inclusive.
In the case of classes, the `Arguments` is an option, to differentiate
between:
```python
# None
class C: ...
# Some, with empty vectors
class C(): ...
```
In this PR, we don't really leverage this change (except that a few
rules get much simpler, since we don't need to lex to find the start and
end ranges of the parentheses, e.g.,
`crates/ruff/src/rules/pyupgrade/rules/lru_cache_without_parameters.rs`,
`crates/ruff/src/rules/pyupgrade/rules/unnecessary_class_parentheses.rs`).
In future PRs, this will be especially helpful for the formatter, since
we can track comments enclosed on the node itself.
## Test Plan
`cargo test`
## Summary
This PR renames a few AST nodes for clarity:
- `Arguments` is now `Parameters`
- `Arg` is now `Parameter`
- `ArgWithDefault` is now `ParameterWithDefault`
For now, the attribute names that reference `Parameters` directly are
changed (e.g., on `StmtFunctionDef`), but the attributes on `Parameters`
itself are not (e.g., `vararg`). We may revisit that decision in the
future.
For context, the AST node formerly known as `Arguments` is used in
function definitions. Formally (outside of the Python context),
"arguments" typically refers to "the values passed to a function", while
"parameters" typically refers to "the variables used in a function
definition". E.g., if you Google "arguments vs parameters", you'll get
some explanation like:
> A parameter is a variable in a function definition. It is a
placeholder and hence does not have a concrete value. An argument is a
value passed during function invocation.
We're thus deviating from Python's nomenclature in favor of a scheme
that we find to be more precise.
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## Summary
This PR removes the `Interactive` and `FunctionType` parser modes that are unused by ruff
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
`cargo test`
<!-- How was it tested? -->
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## Summary
This PR removes the type ignore node from the AST because our parser doesn't support it, and just having it around is confusing.
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
`cargo build`
<!-- How was it tested? -->
## Summary
This is a rewrite of the main comment placement logic. `place_comment`
now has three parts:
- place own line comments
- between branches
- after a branch
- place end-of-line comments
- after colon
- after a branch
- place comments for specific nodes (that include module level comments)
The rewrite fixed three bugs: `class A: # trailing comment` comments now
stay end-of-line, `try: # comment` remains end-of-line and deeply
indented try-else-finally comments remain with the right nested
statement.
It will be much easier to give more alternative branches nodes since
this is abstracted away by `is_node_with_body` and the first/last child
helpers. Adding new node types can now be done by adding an entry to the
`place_comment` match. The code went from 1526 lines before #6033 to
1213 lines now.
It thinks it easier to just read the new `placement.rs` rather than
reviewing the diff.
## Test Plan
The existing fixtures staying the same or improving plus new ones for
the bug fixes.
## Summary
This PR adds the implementation for the new Jupyter AST nodes i.e.,
`ExprLineMagic` and `StmtLineMagic`.
## Test Plan
Add test cases for `unparse` containing magic commands
resolves: #6087
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Part of #5062
Requires https://github.com/astral-sh/RustPython-Parser/pull/32
Adds visitation of type alias statements and type parameters in class
and function definitions.
Duplicates tests for `PreorderVisitor` into `Visitor` with new
snapshots. Testing required node implementations for the `TypeParam`
enum, which is a chunk of the diff and the reason we need `Ranged`
implementations in
https://github.com/astral-sh/RustPython-Parser/pull/32.
## Test Plan
<!-- How was it tested? -->
Adds unit tests with snapshots.
## Summary
This PR is a refactoring of placement.rs. The code got more consistent,
some comments were updated and some dead code was removed or replaced
with debug assertions. It also contains a bugfix for the placement of
end-of-branch comments with nested bodies inside try statements that
occurred when refactoring the nested body loop.
## Test Plan
The existing test cases don't change. I added a couple of cases that i
think should be tested but weren't, and a regression test for the bugfix
## Summary
Previously, `StmtIf` was defined recursively as
```rust
pub struct StmtIf {
pub range: TextRange,
pub test: Box<Expr>,
pub body: Vec<Stmt>,
pub orelse: Vec<Stmt>,
}
```
Every `elif` was represented as an `orelse` with a single `StmtIf`. This
means that this representation couldn't differentiate between
```python
if cond1:
x = 1
else:
if cond2:
x = 2
```
and
```python
if cond1:
x = 1
elif cond2:
x = 2
```
It also makes many checks harder than they need to be because we have to
recurse just to iterate over an entire if-elif-else and because we're
lacking nodes and ranges on the `elif` and `else` branches.
We change the representation to a flat
```rust
pub struct StmtIf {
pub range: TextRange,
pub test: Box<Expr>,
pub body: Vec<Stmt>,
pub elif_else_clauses: Vec<ElifElseClause>,
}
pub struct ElifElseClause {
pub range: TextRange,
pub test: Option<Expr>,
pub body: Vec<Stmt>,
}
```
where `test: Some(_)` represents an `elif` and `test: None` an else.
This representation is different tradeoff, e.g. we need to allocate the
`Vec<ElifElseClause>`, the `elif`s are now different than the `if`s
(which matters in rules where want to check both `if`s and `elif`s) and
the type system doesn't guarantee that the `test: None` else is actually
last. We're also now a bit more inconsistent since all other `else`,
those from `for`, `while` and `try`, still don't have nodes. With the
new representation some things became easier, e.g. finding the `elif`
token (we can use the start of the `ElifElseClause`) and formatting
comments for if-elif-else (no more dangling comments splitting, we only
have to insert the dangling comment after the colon manually and set
`leading_alternate_branch_comments`, everything else is taken of by
having nodes for each branch and the usual placement.rs fixups).
## Merge Plan
This PR requires coordination between the parser repo and the main ruff
repo. I've split the ruff part, into two stacked PRs which have to be
merged together (only the second one fixes all tests), the first for the
formatter to be reviewed by @michareiser and the second for the linter
to be reviewed by @charliermarsh.
* MH: Review and merge
https://github.com/astral-sh/RustPython-Parser/pull/20
* MH: Review and merge or move later in stack
https://github.com/astral-sh/RustPython-Parser/pull/21
* MH: Review and approve
https://github.com/astral-sh/RustPython-Parser/pull/22
* MH: Review and approve formatter PR
https://github.com/astral-sh/ruff/pull/5459
* CM: Review and approve linter PR
https://github.com/astral-sh/ruff/pull/5460
* Merge linter PR in formatter PR, fix ecosystem checks (ecosystem
checks can't run on the formatter PR and won't run on the linter PR, so
we need to merge them first)
* Merge https://github.com/astral-sh/RustPython-Parser/pull/22
* Create tag in the parser, update linter+formatter PR
* Merge linter+formatter PR https://github.com/astral-sh/ruff/pull/5459
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
The following code was previously leading to unstable formatting:
```python
try:
try:
pass
finally:
print(1) # issue7208
except A:
pass
```
The comment would be formatted as a trailing comment of `try` which is
unstable as an end-of-line comment gets two extra whitespaces.
This was originally found in
99b00efd5e/Lib/getpass.py (L68-L91)
## Test Plan
I added a regression test
