Commit graph

308 commits

Author SHA1 Message Date
Dhruv Manilawala
5f40371ffc
Use ExprFString for StringLike::FString variant (#10311)
## Summary

This PR updates the `StringLike::FString` variant to use `ExprFString`
instead of `FStringLiteralElement`.

For context, the reason it used `FStringLiteralElement` is that the node
is actually the string part of an f-string ("foo" in `f"foo{x}"`). But,
this is inconsistent with other variants where the captured value is the
_entire_ string.

This is also problematic w.r.t. implicitly concatenated strings. Any
rules which work with `StringLike::FString` doesn't account for the
string part in an implicitly concatenated f-strings. For example, we
don't flag confusable character in the first part of `"𝐁ad" f"𝐁ad
string"`, but only the second part
(https://play.ruff.rs/16071c4c-a1dd-4920-b56f-e2ce2f69c843).

### Update `PYI053`

_This is included in this PR because otherwise it requires a temporary
workaround to be compatible with the old logic._

This PR also updates the `PYI053` (`string-or-bytes-too-long`) rule for
f-string to consider _all_ the visible characters in a f-string,
including the ones which are implicitly concatenated. This is consistent
with implicitly concatenated strings and bytes.

For example,

```python
def foo(
	# We count all the characters here
    arg1: str = '51 character ' 'stringgggggggggggggggggggggggggggggggg',
	# But not here because of the `{x}` replacement field which _breaks_ them up into two chunks
    arg2: str = f'51 character {x} stringgggggggggggggggggggggggggggggggggggggggggggg',
) -> None: ...
```

This PR fixes it to consider all _visible_ characters inside an f-string
which includes expressions as well.

fixes: #10310 
fixes: #10307 

## Test Plan

Add new test cases and update the snapshots.

## Review

To facilitate the review process, the change have been split into two
commits: one which has the code change while the other has the test
cases and updated snapshots.
2024-03-14 13:30:22 +05:30
Alex Waygood
c2e15f38ee
Unify enums used for internal representation of quoting style (#10383) 2024-03-13 17:19:17 +00:00
Dhruv Manilawala
32d6f84e3d
Add methods to iter over f-string elements (#10309)
## Summary

This PR adds methods on `FString` to iterate over the two different kind
of elements it can have - literals and expressions. This is similar to
the methods we have on `ExprFString`.

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
2024-03-13 08:46:55 +00:00
Charlie Marsh
dbf82233b8
Gate f-string struct size test for Rustc < 1.76 (#10371)
Closes https://github.com/astral-sh/ruff/issues/10319.
2024-03-12 15:46:36 -04:00
Alex Waygood
1d97f27335
Start tracking quoting style in the AST (#10298)
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.
2024-03-08 19:11:47 +00:00
Micha Reiser
8ea5b08700
refactor: Use QualifiedName for Imported::call_path (#10214)
## Summary

When you try to remove an internal representation leaking into another
type and end up rewriting a simple version of `smallvec`.

The goal of this PR is to replace the `Box<[&'a str]>` with
`Box<QualifiedName>` to avoid that the internal `QualifiedName`
representation leaks (and it gives us a nicer API too). However, doing
this when `QualifiedName` uses `SmallVec` internally gives us all sort
of funny lifetime errors. I was lost but @BurntSushi came to rescue me.
He figured out that `smallvec` has a variance problem which is already
tracked in https://github.com/servo/rust-smallvec/issues/146

To fix the variants problem, I could use the smallvec-2-alpha-4 or
implement our own smallvec. I went with implementing our own small vec
for this specific problem. It obviously isn't as sophisticated as
smallvec (only uses safe code), e.g. it doesn't perform any size
optimizations, but it does its job.

Other changes:

* Removed `Imported::qualified_name` (the version that returns a
`String`). This can be replaced by calling `ToString` on the qualified
name.
* Renamed `Imported::call_path` to `qualified_name` and changed its
return type to `&QualifiedName`.
* Renamed `QualifiedName::imported` to `user_defined` which is the more
common term when talking about builtins vs the rest/user defined
functions.


## Test plan

`cargo test`
2024-03-06 09:55:59 +01:00
Micha Reiser
184241f99a
Remove Expr postfix from ExprNamed, ExprIf, and ExprGenerator (#10229)
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`.
2024-03-04 12:55:01 +01:00
Micha Reiser
a6d892b1f4
Split CallPath into QualifiedName and UnqualifiedName (#10210)
## Summary

Charlie can probably explain this better than I but it turns out,
`CallPath` is used for two different things:

* To represent unqualified names like `version` where `version` can be a
local variable or imported (e.g. `from sys import version` where the
full qualified name is `sys.version`)
* To represent resolved, full qualified names

This PR splits `CallPath` into two types to make this destinction clear.

> Note: I haven't renamed all `call_path` variables to `qualified_name`
or `unqualified_name`. I can do that if that's welcomed but I first want
to get feedback on the approach and naming overall.

## Test Plan

`cargo test`
2024-03-04 09:06:51 +00:00
Micha Reiser
db25a563f7
Remove unneeded lifetime bounds (#10213)
## Summary

This PR removes the unneeded lifetime `'b` from many of our `Visitor`
implementations.

The lifetime is unneeded because it is only constraint by `'a`, so we
can use `'a` directly.

## Test Plan

`cargo build`
2024-03-03 18:12:11 +00:00
Micha Reiser
e725b6fdaf
CallPath newtype wrapper (#10201)
## Summary

This PR changes the `CallPath` type alias to a newtype wrapper. 

A newtype wrapper allows us to limit the API and to experiment with
alternative ways to implement matching on `CallPath`s.



## Test Plan

`cargo test`
2024-03-03 16:54:24 +01:00
Jane Lewis
0293908b71
Implement RUF028 to detect useless formatter suppression comments (#9899)
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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.
2024-02-28 19:21:06 +00:00
Micha Reiser
77c5561646
Add parenthesized flag to ExprTuple and ExprGenerator (#9614) 2024-02-26 15:35:20 +00:00
Charlie Marsh
0304623878
[perflint] Catch a wider range of mutations in PERF101 (#9955)
## Summary

This PR ensures that if a list `x` is modified within a `for` loop, we
avoid flagging `list(x)` as unnecessary. Previously, we only detected
calls to exactly `.append`, and they couldn't be nested within other
statements.

Closes https://github.com/astral-sh/ruff/issues/9925.
2024-02-12 12:17:55 -05:00
Charlie Marsh
6f0e4ad332
Remove unnecessary string cloning from the parser (#9884)
Closes https://github.com/astral-sh/ruff/issues/9869.
2024-02-09 16:03:27 -05:00
Charlie Marsh
49fe1b85f2
Reduce size of Expr from 80 to 64 bytes (#9900)
## 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.
2024-02-09 02:53:13 +00:00
Micha Reiser
fe7d965334
Reduce Result<Tok, LexicalError> size by using Box<str> instead of String (#9885) 2024-02-08 20:36:22 +00:00
Micha Reiser
688177ff6a
Use Rust 1.76 (#9897) 2024-02-08 18:20:08 +00:00
Charlie Marsh
daae28efc7
Respect async with in timeout-without-await (#9859)
Closes https://github.com/astral-sh/ruff/issues/9855.
2024-02-06 12:04:24 -05:00
Dhruv Manilawala
36b752876e
Implement AnyNode/AnyNodeRef for FStringFormatSpec (#9836)
## 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.
2024-02-05 19:23:43 +00:00
Charlie Marsh
ea1c089652
Use AhoCorasick to speed up quote match (#9773)
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## Summary

When I was looking at the v0.2.0 release, this method showed up in a
CodSpeed regression (we were calling it more), so I decided to quickly
look at speeding it up. @BurntSushi suggested using Aho-Corasick, and it
looks like it's about 7 or 8x faster:

```text
Parser/AhoCorasick      time:   [8.5646 ns 8.5914 ns 8.6191 ns]
Parser/Iterator         time:   [64.992 ns 65.124 ns 65.271 ns]
```

## Test Plan

`cargo test`
2024-02-02 09:57:39 -05:00
Micha Reiser
ce14f4dea5
Range formatting API (#9635) 2024-01-31 11:13:37 +01:00
Micha Reiser
5fe0fdd0a8
Delete is_node_with_body method (#9643) 2024-01-25 14:41:13 +00:00
Alex Waygood
a1e65a92bd
Move is_tuple_parenthesized from the formatter to ruff_python_ast (#9533)
This allows it to be used in the linter as well as the formatter. It
will be useful in #9474
2024-01-15 16:10:40 +00:00
Chammika Mannakkara
0003c730e0
[flake8-simplify] Implement enumerate-for-loop (SIM113) (#7777)
Implements SIM113 from #998

Added tests
Limitations 
   - No fix yet
   - Only flag cases where index variable immediately precede `for` loop

@charliermarsh please review and let me know any improvements

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
2024-01-14 11:00:59 -05:00
Charlie Marsh
009430e034
[ruff] Avoid treating named expressions as static keys (RUF011) (#9494)
Closes https://github.com/astral-sh/ruff/issues/9487.
2024-01-12 14:33:45 -05:00
Charlie Marsh
a31a314b2b
Account for possibly-empty f-string values in truthiness logic (#9484)
Closes https://github.com/astral-sh/ruff/issues/9479.
2024-01-11 21:16:19 -05:00
Micha Reiser
f192c72596
Remove type parameter from parse_* methods (#9466) 2024-01-11 19:41:19 +01:00
Micha Reiser
94968fedd5
Use Rust 1.75 toolchain (#9437) 2024-01-08 18:03:16 +01:00
Charlie Marsh
701697c37e
Support variable keys in static dictionary key rule (#9411)
Closes https://github.com/astral-sh/ruff/issues/9410.
2024-01-06 20:44:40 +00:00
Charlie Marsh
0e202718fd
Misc. small tweaks from perusing modules (#9383) 2024-01-03 12:30:25 -05:00
Charlie Marsh
9073220887
Make all dependencies workspace dependencies (#9333)
## Summary

This PR modifies our `Cargo.toml` files to use workspace dependencies
for _all_ dependencies, rather than the status quo of sporadically
trying to use workspace dependencies for those dependencies that are
used across multiple crates. I find the current situation more confusing
and harder to manage, since we have a mix of workspace and crate-local
dependencies, whereas this setup consistently uses the same approach for
all dependencies.
2024-01-02 13:41:59 +00:00
Charlie Marsh
1c9268d2ff
Remove some unused dependencies (#9330) 2023-12-31 07:38:16 -05:00
Charlie Marsh
e80260a3c5
Remove source path from parser errors (#9322)
## Summary

I always found it odd that we had to pass this in, since it's really
higher-level context for the error. The awkwardness is further evidenced
by the fact that we pass in fake values everywhere (even outside of
tests). The source path isn't actually used to display the error; it's
only accessed elsewhere to _re-display_ the error in certain cases. This
PR modifies to instead pass the path directly in those cases.
2023-12-30 20:33:05 +00:00
Charlie Marsh
eb9a1bc5f1
Use consistent re-export from ruff_source_file (#9320)
Right now, we both re-export (via `pub use`) and mark the modules
themselves a `pub`, so they can be imported through two different paths.
2023-12-30 14:48:45 -05:00
Charlie Marsh
2895e7d126
Respect mixed return and raise cases in return-type analysis (#9310)
## Summary

Given:

```python
from somewhere import get_cfg

def lookup_cfg(cfg_description):
    cfg = get_cfg(cfg_description)
    if cfg is not None:
        return cfg
    raise AttributeError(f"No cfg found matching {cfg_description}")
```

We were analyzing the method from last-to-first statement. So we saw the
`raise`, then assumed the method _always_ raised. In reality, though, it
_might_ return. This PR improves the branch analysis to respect these
mixed cases.

Closes https://github.com/astral-sh/ruff/issues/9269.
Closes https://github.com/astral-sh/ruff/issues/9304.
2023-12-29 16:46:37 +00:00
Charlie Marsh
a9ceef5b5d
[ruff] Add never-union rule to detect redundant typing.NoReturn and typing.Never (#9217)
## Summary

Adds a rule to detect unions that include `typing.NoReturn` or
`typing.Never`. In such cases, the use of the bottom type is redundant.

Closes https://github.com/astral-sh/ruff/issues/9113.

## Test Plan

`cargo test`
2023-12-21 20:53:31 +00:00
Charlie Marsh
5ccc21aea2
Add support for NoReturn in auto-return-typing (#9206)
## Summary

Given a function like:

```python
def func(x: int):
    if not x:
        raise ValueError
    else:
        raise TypeError
```

We now correctly use `NoReturn` as the return type, rather than `None`.

Closes https://github.com/astral-sh/ruff/issues/9201.
2023-12-20 00:06:31 -05:00
Dhruv Manilawala
18452cf477
Add as_slice method for all string nodes (#9111)
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_.
2023-12-13 06:31:20 +00:00
Dhruv Manilawala
96ae9fe685
Introduce StringLike enum (#9016)
## Summary

This PR introduces a new `StringLike` enum which is a narrow type to
indicate string-like nodes. These includes the string literals, bytes
literals, and the literal parts of f-strings.

The main motivation behind this is to avoid repetition of rule calling
in the AST checker. We add a new `analyze::string_like` function which
takes in the enum and calls all the respective rule functions which
expects atleast 2 of the variants of this enum.

I'm open to discarding this if others think it's not that useful at this
stage as currently only 3 rules require these nodes.

As suggested
[here](https://github.com/astral-sh/ruff/pull/8835#discussion_r1414746934)
and
[here](https://github.com/astral-sh/ruff/pull/8835#discussion_r1414750204).

## Test Plan

`cargo test`
2023-12-07 16:39:13 +00:00
Dhruv Manilawala
cdac90ef68
New AST nodes for f-string elements (#8835)
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>
2023-12-07 10:28:05 -06:00
Dhruv Manilawala
ef7778d794
Fix preorder visitor tests (#9025)
Follow-up PR to #9009 to fix the `PreorderVisitor` test cases as
suggested here: https://github.com/astral-sh/ruff/pull/9009#discussion_r1416459688
2023-12-06 16:58:51 +00:00
Dhruv Manilawala
bd443ebe91
Add visitor tests for strings, bytes, f-strings (#9009)
This PR adds tests for visitor implementation for string literals, bytes
literals and f-strings.
2023-12-06 10:52:19 -06:00
Micha Reiser
7e390d3772
Move ParenthesizedExpr to ruff_python_parser (#8987) 2023-12-04 05:36:28 +00:00
Charlie Marsh
e5db72459e
Detect implicit returns in auto-return-types (#8952)
## Summary

Adds detection for branches without a `return` or `raise`, so that we
can properly `Optional` the return types. I'd like to remove this and
replace it with our code graph analysis from the `unreachable.rs` rule,
but it at least fixes the worst offenders.

Closes #8942.
2023-12-01 12:35:01 -05:00
Charlie Marsh
6435e4e4aa
Enable auto-return-type involving Optional and Union annotations (#8885)
## Summary

Previously, this was only supported for Python 3.10 and later, since we
always use the PEP 604-style unions.
2023-11-28 18:35:55 -08:00
Dhruv Manilawala
ec7456bac0
Rename as_str to to_str (#8886)
This PR renames the method on `StringLiteralValue` from `as_str` to
`to_str`. The main motivation is to follow the naming convention as
described in the [Rust API
Guidelines](https://rust-lang.github.io/api-guidelines/naming.html#ad-hoc-conversions-follow-as_-to_-into_-conventions-c-conv).
This method can perform a string allocation in case the string is
implicitly concatenated.
2023-11-28 18:50:42 -06:00
Dhruv Manilawala
b28556d739
Update E402 to work at cell level for notebooks (#8872)
## Summary

This PR updates the `E402` rule to work at cell level for Jupyter
notebooks. This is enabled only in preview to gather feedback.

The implementation basically resets the import boundary flag on the
semantic model when we encounter the first statement in a cell.

Another potential solution is to introduce `E403` rule that is
specifically for notebooks that works at cell level while `E402` will be
disabled for notebooks.

## Test Plan

Add a notebook with imports in multiple cells and verify that the rule
works as expected.

resolves: #8669
2023-11-29 00:32:35 +00:00
Dhruv Manilawala
501cca8b72
Remove #[allow(unused_variables)] from visitor methods (#8828)
Small follow-up to remove `#[allow(unused_variables)]` from visitor
methods and use underscore prefix for unused variables instead.
2023-11-25 00:09:46 +00:00
Dhruv Manilawala
626b0577cd
Explicit as_str (no deref), add no allocation methods (#8826)
## Summary

This PR is a follow-up to the AST refactor which does the following:
- Remove `Deref` implementation on `StringLiteralValue` and use explicit
`as_str` calls instead. The `Deref` implementation would implicitly
perform allocations in case of implicitly concatenated strings. This is
to make sure the allocation is explicit.
- Now, certain methods can be implemented to do zero allocations which
have been implemented in this PR. They are:
    - `is_empty`
    - `len`
    - `chars`
    - Custom `PartialEq` implementation to compare each character

## Test Plan

Run the linter test suite and make sure all tests pass.
2023-11-25 00:03:59 +00:00
Dhruv Manilawala
017e829115
Update string nodes for implicit concatenation (#7927)
## 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
2023-11-24 17:55:41 -06:00