## Summary
Rename `infer_symbol_type` to `infer_symbol_public_type`, and allow it
to work on symbols with more than one definition. For now, use the most
cautious/sound inference, which is the union of all definitions. We can
prune this union more in future by eliminating definitions if we can
show that they can't be visible (this requires both that the symbol is
definitely later reassigned, and that there is no intervening
call/import that might be able to see the over-written definition).
## Test Plan
Added a test showing inference of union from multiple definitions.
## Summary
This PR updates the entire parser stack in multiple ways:
### Make the lexer lazy
* https://github.com/astral-sh/ruff/pull/11244
* https://github.com/astral-sh/ruff/pull/11473
Previously, Ruff's lexer would act as an iterator. The parser would
collect all the tokens in a vector first and then process the tokens to
create the syntax tree.
The first task in this project is to update the entire parsing flow to
make the lexer lazy. This includes the `Lexer`, `TokenSource`, and
`Parser`. For context, the `TokenSource` is a wrapper around the `Lexer`
to filter out the trivia tokens[^1]. Now, the parser will ask the token
source to get the next token and only then the lexer will continue and
emit the token. This means that the lexer needs to be aware of the
"current" token. When the `next_token` is called, the current token will
be updated with the newly lexed token.
The main motivation to make the lexer lazy is to allow re-lexing a token
in a different context. This is going to be really useful to make the
parser error resilience. For example, currently the emitted tokens
remains the same even if the parser can recover from an unclosed
parenthesis. This is important because the lexer emits a
`NonLogicalNewline` in parenthesized context while a normal `Newline` in
non-parenthesized context. This different kinds of newline is also used
to emit the indentation tokens which is important for the parser as it's
used to determine the start and end of a block.
Additionally, this allows us to implement the following functionalities:
1. Checkpoint - rewind infrastructure: The idea here is to create a
checkpoint and continue lexing. At a later point, this checkpoint can be
used to rewind the lexer back to the provided checkpoint.
2. Remove the `SoftKeywordTransformer` and instead use lookahead or
speculative parsing to determine whether a soft keyword is a keyword or
an identifier
3. Remove the `Tok` enum. The `Tok` enum represents the tokens emitted
by the lexer but it contains owned data which makes it expensive to
clone. The new `TokenKind` enum just represents the type of token which
is very cheap.
This brings up a question as to how will the parser get the owned value
which was stored on `Tok`. This will be solved by introducing a new
`TokenValue` enum which only contains a subset of token kinds which has
the owned value. This is stored on the lexer and is requested by the
parser when it wants to process the data. For example:
8196720f80/crates/ruff_python_parser/src/parser/expression.rs (L1260-L1262)
[^1]: Trivia tokens are `NonLogicalNewline` and `Comment`
### Remove `SoftKeywordTransformer`
* https://github.com/astral-sh/ruff/pull/11441
* https://github.com/astral-sh/ruff/pull/11459
* https://github.com/astral-sh/ruff/pull/11442
* https://github.com/astral-sh/ruff/pull/11443
* https://github.com/astral-sh/ruff/pull/11474
For context,
https://github.com/RustPython/RustPython/pull/4519/files#diff-5de40045e78e794aa5ab0b8aacf531aa477daf826d31ca129467703855408220
added support for soft keywords in the parser which uses infinite
lookahead to classify a soft keyword as a keyword or an identifier. This
is a brilliant idea as it basically wraps the existing Lexer and works
on top of it which means that the logic for lexing and re-lexing a soft
keyword remains separate. The change here is to remove
`SoftKeywordTransformer` and let the parser determine this based on
context, lookahead and speculative parsing.
* **Context:** The transformer needs to know the position of the lexer
between it being at a statement position or a simple statement position.
This is because a `match` token starts a compound statement while a
`type` token starts a simple statement. **The parser already knows
this.**
* **Lookahead:** Now that the parser knows the context it can perform
lookahead of up to two tokens to classify the soft keyword. The logic
for this is mentioned in the PR implementing it for `type` and `match
soft keyword.
* **Speculative parsing:** This is where the checkpoint - rewind
infrastructure helps. For `match` soft keyword, there are certain cases
for which we can't classify based on lookahead. The idea here is to
create a checkpoint and keep parsing. Based on whether the parsing was
successful and what tokens are ahead we can classify the remaining
cases. Refer to #11443 for more details.
If the soft keyword is being parsed in an identifier context, it'll be
converted to an identifier and the emitted token will be updated as
well. Refer
8196720f80/crates/ruff_python_parser/src/parser/expression.rs (L487-L491).
The `case` soft keyword doesn't require any special handling because
it'll be a keyword only in the context of a match statement.
### Update the parser API
* https://github.com/astral-sh/ruff/pull/11494
* https://github.com/astral-sh/ruff/pull/11505
Now that the lexer is in sync with the parser, and the parser helps to
determine whether a soft keyword is a keyword or an identifier, the
lexer cannot be used on its own. The reason being that it's not
sensitive to the context (which is correct). This means that the parser
API needs to be updated to not allow any access to the lexer.
Previously, there were multiple ways to parse the source code:
1. Passing the source code itself
2. Or, passing the tokens
Now that the lexer and parser are working together, the API
corresponding to (2) cannot exists. The final API is mentioned in this
PR description: https://github.com/astral-sh/ruff/pull/11494.
### Refactor the downstream tools (linter and formatter)
* https://github.com/astral-sh/ruff/pull/11511
* https://github.com/astral-sh/ruff/pull/11515
* https://github.com/astral-sh/ruff/pull/11529
* https://github.com/astral-sh/ruff/pull/11562
* https://github.com/astral-sh/ruff/pull/11592
And, the final set of changes involves updating all references of the
lexer and `Tok` enum. This was done in two-parts:
1. Update all the references in a way that doesn't require any changes
from this PR i.e., it can be done independently
* https://github.com/astral-sh/ruff/pull/11402
* https://github.com/astral-sh/ruff/pull/11406
* https://github.com/astral-sh/ruff/pull/11418
* https://github.com/astral-sh/ruff/pull/11419
* https://github.com/astral-sh/ruff/pull/11420
* https://github.com/astral-sh/ruff/pull/11424
2. Update all the remaining references to use the changes made in this
PR
For (2), there were various strategies used:
1. Introduce a new `Tokens` struct which wraps the token vector and add
methods to query a certain subset of tokens. These includes:
1. `up_to_first_unknown` which replaces the `tokenize` function
2. `in_range` and `after` which replaces the `lex_starts_at` function
where the former returns the tokens within the given range while the
latter returns all the tokens after the given offset
2. Introduce a new `TokenFlags` which is a set of flags to query certain
information from a token. Currently, this information is only limited to
any string type token but can be expanded to include other information
in the future as needed. https://github.com/astral-sh/ruff/pull/11578
3. Move the `CommentRanges` to the parsed output because this
information is common to both the linter and the formatter. This removes
the need for `tokens_and_ranges` function.
## Test Plan
- [x] Update and verify the test snapshots
- [x] Make sure the entire test suite is passing
- [x] Make sure there are no changes in the ecosystem checks
- [x] Run the fuzzer on the parser
- [x] Run this change on dozens of open-source projects
### Running this change on dozens of open-source projects
Refer to the PR description to get the list of open source projects used
for testing.
Now, the following tests were done between `main` and this branch:
1. Compare the output of `--select=E999` (syntax errors)
2. Compare the output of default rule selection
3. Compare the output of `--select=ALL`
**Conclusion: all output were same**
## What's next?
The next step is to introduce re-lexing logic and update the parser to
feed the recovery information to the lexer so that it can emit the
correct token. This moves us one step closer to having error resilience
in the parser and provides Ruff the possibility to lint even if the
source code contains syntax errors.
<!--
Thank you for contributing to Ruff! To help us out with reviewing,
please consider the following:
- Does this pull request include a summary of the change? (See below.)
- Does this pull request include a descriptive title?
- Does this pull request include references to any relevant issues?
-->
## Summary
Introduces the skeleton of the flow graph. So far it doesn't actually
handle any non-linear control flow :) But it does show how we can go
from an expression that references a symbol, backward through the flow
graph, to find reachable definitions of that symbol.
Adding non-linear control flow will mean adding flow nodes with multiple
predecessors, which will introduce more complexity into
`ReachableDefinitionsIterator.next()`. But one step at a time.
## Test Plan
Added a (very basic) test.
## Summary
Give red-knot the ability to infer int literal types. This is quick and
easy, mostly because these types are a convenient way to observe
control-flow handling with simple assignments.
## Test Plan
Added test.
* Add a module type, `ModuleTypeId`
* Add an attribute lookup method `get_member` for `Type`
* Only implemented for `ModuleTypeId` and `ClassTypeId`
* [x] Should this be a trait?
*Answer: no*
* [x] Uses `unwrap`, but we should remove that. Maybe add a new variant
to `QueryError`?
*Answer: Return `Option<Type>` as is done elsewhere*
* Add `infer_definition_type` case for `Import`
* Add `infer_expr_type` case for `Attribute`
* Add a test to exercise these
* [x] remove all NOTE/FIXME/TODO after discussing with reviewers
## Summary
Lots of TODOs and things to clean up here, but it demonstrates the
working lint rule.
## Test Plan
```
➜ cat main.py
from typing import override
from base import B
class C(B):
@override
def method(self): pass
➜ cat base.py
class B: pass
➜ cat typing.py
def override(func):
return func
```
(We provide our own `typing.py` since we don't have typeshed vendored or
type stub support yet.)
```
➜ ./target/debug/red_knot main.py
...
1 0.012086s TRACE red_knot Main Loop: Tick
[crates/red_knot/src/main.rs:157:21] diagnostics = [
"Method C.method is decorated with `typing.override` but does not override any base class method",
]
```
If we add `def method(self): pass` to class `B` in `base.py` and run
red_knot again, there is no lint error.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
This PR vendors typeshed!
- The first commit vendors the stdlib directory from typeshed into a new crates/red_knot/vendored_typeshed directory.
- The second commit adjusts various linting config files to make sure that the vendored code is excluded from typo checks, formatting checks, etc.
- The LICENSE and README.md files are also vendored, but all other directories and files (stubs, scripts, tests, test_cases, etc.) are excluded. We should have no need for them (except possibly stubs/, discussed in more depth below).
- Similar to the way pyright has a commit.txt file in its vendored copy of typeshed, to indicate which typeshed commit the vendored code corresponds to, I've also added a crates/red_knot/vendored_typeshed/source_commit.txt file in the third commit of this PR.
One open question is: should we vendor the stdlib and stubs directories, or just the stdlib directory? The stubs/ directory contains stubs for 162 third-party packages outside the stdlib. Mypy and typeshed_client1 only vendor the stdlib directory; pyright and pyre vendor both the stdlib and stubs directories; pytype vendors the entire typeshed repo (scripts/, tests/ and all).
In this PR, I've chosen to copy mypy and typeshed_client. Unlike vendoring the stdlib, which is unavoidable if we want to do typechecking of the stdlib, it's not strictly necessary to vendor the stubs directory: each subdirectory in stubs is published to PyPI as a standalone stubs distribution that can be (uv)-pip-installed into a virtual environment. It might be useful for our users if we vendored those stubs anyway, but there are costs as well as benefits to doing so (apart from just the sheer amount of vendored code in the ruff repository), so I'd rather consider it separately.
* Add `decorators: Vec<Type>` to `FunctionType` struct
* Thread decorators through two `add_function` definitions
* Populate decorators at the callsite in `infer_symbol_type`
* Small test
## Summary
This PR changes the `DebugStatistics` and `ReleaseStatistics` structs so
that they implement a common `StatisticsRecorder` trait, and makes the
`KeyValueCache` struct generic over a type parameter bound to that
trait. The advantage of this approach is that it's much harder for the
`DebugStatistics` and `ReleaseStatistics` structs to accidentally grow
out of sync in the methods that they implement, which was the cause of
the release-build failure recently fixed in #11177.
## Test Plan
`cargo test -p red_knot` and `cargo build --release` both continue to
pass for me locally
* Adds `Symbol.flag` bitfield. Populates it from (the three renamed)
`add_or_update_symbol*` methods.
* Currently there are these flags supported:
* `IS_DEFINED` is set in a scope where a variable is defined.
* `IS_USED` is set in a scope where a variable is referenced. (To have
both this and `IS_DEFINED` would require two separate appearances of a
variable in the same scope-- one def and one use.)
* `MARKED_GLOBAL` and `MARKED_NONLOCAL` are **not yet implemented**.
(*TODO: While traversing, if you find these declarations, add these
flags to the variable.*)
* Adds `Symbol.kind` field (commented) and the data structure which will
populate it: `Kind` which is an enum of freevar, cellvar,
implicit_global, and implicit_local. **Not yet populated**. (*TODO: a
second pass over the scope (or the ast?) will observe the
`MARKED_GLOBAL` and `MARKED_NONLOCAL` flags to populate this field. When
that's added, we'll uncomment the field.*)
* Adds a few tests that the `IS_DEFINED` and `IS_USED` fields are
correctly set and/or merged:
* Unit test that subsequent calls to `add_or_update_symbol` will merge
the flag arguments.
* Unit test that in the statement `x = foo`, the variable `foo` is
considered used but not defined.
* Unit test that in the statement `from bar import foo`, the variable
`foo` is considered defined but not used.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
`cargo build --release` currently fails to compile on `main`:
<details>
```
error[E0599]: no method named `hit` found for struct `ReleaseStatistics` in the current scope
--> crates/red_knot/src/cache.rs:22:29
|
22 | self.statistics.hit();
| ^^^ method not found in `ReleaseStatistics`
...
145 | pub struct ReleaseStatistics;
| ---------------------------- method `hit` not found for this struct
error[E0599]: no method named `miss` found for struct `ReleaseStatistics` in the current scope
--> crates/red_knot/src/cache.rs:25:29
|
25 | self.statistics.miss();
| ^^^^ method not found in `ReleaseStatistics`
...
145 | pub struct ReleaseStatistics;
| ---------------------------- method `miss` not found for this struct
error[E0599]: no method named `hit` found for struct `ReleaseStatistics` in the current scope
--> crates/red_knot/src/cache.rs:36:33
|
36 | self.statistics.hit();
| ^^^ method not found in `ReleaseStatistics`
...
145 | pub struct ReleaseStatistics;
| ---------------------------- method `hit` not found for this struct
error[E0599]: no method named `miss` found for struct `ReleaseStatistics` in the current scope
--> crates/red_knot/src/cache.rs:41:33
|
41 | self.statistics.miss();
| ^^^^ method not found in `ReleaseStatistics`
...
145 | pub struct ReleaseStatistics;
| ---------------------------- method `miss` not found for this struct
```
</details>
This is because in a release build, `CacheStatistics` is a type alias
for `ReleaseStatistics`, and `ReleaseStatistics` doesn't have `hit()` or
`miss()` methods. (In a debug build, `CacheStatistics` is a type alias
for `DebugStatistics`, which _does_ have those methods.)
Possibly we could make this less likely to happen in the future by
making both structs implement a common trait instead of using type
aliases that vary depending on whether it's a debug build or not? For
now, though, this PR just brings the two structs in sync w.r.t. the
methods they expose.
## Test Plan
`cargo build --release` now once again compiles for me locally
