## Summary
This PR updates the logic when raising conflicting declarations
diagnostic to avoid the undeclared path if present.
The conflicting declaration diagnostics is added when there are two or
more declarations in the control flow path of a definition whose type
isn't equivalent to each other. This can be seen in the following
example:
```py
if flag:
x: int
x = 1 # conflicting-declarations: Unknown, int
```
After this PR, we'd avoid considering "Unknown" as part of the
conflicting declarations. This means we'd still flag it for the
following case:
```py
if flag:
x: int
else:
x: str
x = 1 # conflicting-declarations: int, str
```
A solution that's local to the exception control flow was also explored
which required updating the logic for merging the flow snapshot to avoid
considering declarations using a flag. This is preserved here:
https://github.com/astral-sh/ruff/compare/dhruv/control-flow-no-declarations?expand=1.
The main motivation to avoid that is we don't really understand what the
user experience is w.r.t. the Unknown type and the
conflicting-declaration diagnostics. This makes us unsure on what the
right semantics are as to whether that diagnostics should be raised or
not and when to raise them. For now, we've decided to move forward with
this PR and could decide to adopt another solution or remove the
conflicting-declaration diagnostics in the future.
Closes: #13966
## Test Plan
Update the existing mdtest case. Add an additional case specific to
exception control flow to verify that the diagnostic is not being raised
now.
## Summary
This PR renames the `--custom-typeshed-dir`, `target-version`, and
`--current-directory` cli options to `--typeshed`,
`--python-version`, and `--project` as discussed in the CLI proposal
document.
I added aliases for `--target-version` (for Ruff compat) and
`--custom-typeshed-dir` (for Alex)
## Test Plan
Long help
```
An extremely fast Python type checker.
Usage: red_knot [OPTIONS] [COMMAND]
Commands:
server Start the language server
help Print this message or the help of the given subcommand(s)
Options:
--project <PROJECT>
Run the command within the given project directory.
All `pyproject.toml` files will be discovered by walking up the directory tree from the project root, as will the project's virtual environment (`.venv`).
Other command-line arguments (such as relative paths) will be resolved relative to the current working directory."#,
--venv-path <PATH>
Path to the virtual environment the project uses.
If provided, red-knot will use the `site-packages` directory of this virtual environment to resolve type information for the project's third-party dependencies.
--typeshed-path <PATH>
Custom directory to use for stdlib typeshed stubs
--extra-search-path <PATH>
Additional path to use as a module-resolution source (can be passed multiple times)
--python-version <VERSION>
Python version to assume when resolving types
[possible values: 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13]
-v, --verbose...
Use verbose output (or `-vv` and `-vvv` for more verbose output)
-W, --watch
Run in watch mode by re-running whenever files change
-h, --help
Print help (see a summary with '-h')
-V, --version
Print version
```
Short help
```
An extremely fast Python type checker.
Usage: red_knot [OPTIONS] [COMMAND]
Commands:
server Start the language server
help Print this message or the help of the given subcommand(s)
Options:
--project <PROJECT> Run the command within the given project directory
--venv-path <PATH> Path to the virtual environment the project uses
--typeshed-path <PATH> Custom directory to use for stdlib typeshed stubs
--extra-search-path <PATH> Additional path to use as a module-resolution source (can be passed multiple times)
--python-version <VERSION> Python version to assume when resolving types [possible values: 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13]
-v, --verbose... Use verbose output (or `-vv` and `-vvv` for more verbose output)
-W, --watch Run in watch mode by re-running whenever files change
-h, --help Print help (see more with '--help')
-V, --version Print version
```
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This is the second PR out of three that adds support for
enabling/disabling lint rules in Red Knot. You may want to take a look
at the [first PR](https://github.com/astral-sh/ruff/pull/14869) in this
stack to familiarize yourself with the used terminology.
This PR adds a new syntax to define a lint:
```rust
declare_lint! {
/// ## What it does
/// Checks for references to names that are not defined.
///
/// ## Why is this bad?
/// Using an undefined variable will raise a `NameError` at runtime.
///
/// ## Example
///
/// ```python
/// print(x) # NameError: name 'x' is not defined
/// ```
pub(crate) static UNRESOLVED_REFERENCE = {
summary: "detects references to names that are not defined",
status: LintStatus::preview("1.0.0"),
default_level: Level::Warn,
}
}
```
A lint has a name and metadata about its status (preview, stable,
removed, deprecated), the default diagnostic level (unless the
configuration changes), and documentation. I use a macro here to derive
the kebab-case name and extract the documentation automatically.
This PR doesn't yet add any mechanism to discover all known lints. This
will be added in the next and last PR in this stack.
## Documentation
I documented some rules but then decided that it's probably not my best
use of time if I document all of them now (it also means that I play
catch-up with all of you forever). That's why I left some rules
undocumented (marked with TODO)
## Where is the best place to define all lints?
I'm not sure. I think what I have in this PR is fine but I also don't
love it because most lints are in a single place but not all of them. If
you have ideas, let me know.
## Why is the message not part of the lint, unlike Ruff's `Violation`
I understand that the main motivation for defining `message` on
`Violation` in Ruff is to remove the need to repeat the same message
over and over again. I'm not sure if this is an actual problem. Most
rules only emit a diagnostic in a single place and they commonly use
different messages if they emit diagnostics in different code paths,
requiring extra fields on the `Violation` struct.
That's why I'm not convinced that there's an actual need for it and
there are alternatives that can reduce the repetition when creating a
diagnostic:
* Create a helper function. We already do this in red knot with the
`add_xy` methods
* Create a custom `Diagnostic` implementation that tailors the entire
diagnostic and pre-codes e.g. the message
Avoiding an extra field on the `Violation` also removes the need to
allocate intermediate strings as it is commonly the place in Ruff.
Instead, Red Knot can use a borrowed string with `format_args`
## Test Plan
`cargo test`
## Summary
This PR introduces a structured `DiagnosticId` instead of using a plain
`&'static str`. It is the first of three in a stack that implements a
basic rules infrastructure for Red Knot.
`DiagnosticId` is an enum over all known diagnostic codes. A closed enum
reduces the risk of accidentally introducing two identical diagnostic
codes. It also opens the possibility of generating reference
documentation from the enum in the future (not part of this PR).
The enum isn't *fully closed* because it uses a `&'static str` for lint
names. This is because we want the flexibility to define lints in
different crates, and all names are only known in `red_knot_linter` or
above. Still, lower-level crates must already reference the lint names
to emit diagnostics. We could define all lint-names in `DiagnosticId`
but I decided against it because:
* We probably want to share the `DiagnosticId` type between Ruff and Red
Knot to avoid extra complexity in the diagnostic crate, and both tools
use different lint names.
* Lints require a lot of extra metadata beyond just the name. That's why
I think defining them close to their implementation is important.
In the long term, we may also want to support plugins, which would make
it impossible to know all lint names at compile time. The next PR in the
stack introduces extra syntax for defining lints.
A closed enum does have a few disadvantages:
* rustc can't help us detect unused diagnostic codes because the enum is
public
* Adding a new diagnostic in the workspace crate now requires changes to
at least two crates: It requires changing the workspace crate to add the
diagnostic and the `ruff_db` crate to define the diagnostic ID. I
consider this an acceptable trade. We may want to move `DiagnosticId` to
its own crate or into a shared `red_knot_diagnostic` crate.
## Preventing duplicate diagnostic identifiers
One goal of this PR is to make it harder to introduce ambiguous
diagnostic IDs, which is achieved by defining a closed enum. However,
the enum isn't fully "closed" because it doesn't explicitly list the IDs
for all lint rules. That leaves the possibility that a lint rule and a
diagnostic ID share the same name.
I made the names unambiguous in this PR by separating them into
different namespaces by using `lint/<rule>` for lint rule codes. I don't
mind the `lint` prefix in a *Ruff next* context, but it is a bit weird
for a standalone type checker. I'd like to not overfocus on this for now
because I see a few different options:
* We remove the `lint` prefix and add a unit test in a top-level crate
that iterates over all known lint rules and diagnostic IDs to ensure the
names are non-overlapping.
* We only render `[lint]` as the error code and add a note to the
diagnostic mentioning the lint rule. This is similar to clippy and has
the advantage that the header line remains short
(`lint/some-long-rule-name` is very long ;))
* Any other form of adjusting the diagnostic rendering to make the
distinction clear
I think we can defer this decision for now because the `DiagnosticId`
contains all the relevant information to change the rendering
accordingly.
## Why `Lint` and not `LintRule`
I see three kinds of diagnostics in Red Knot:
* Non-suppressable: Reveal type, IO errors, configuration errors, etc.
(any `DiagnosticId`)
* Lints: code-related diagnostics that are suppressable.
* Lint rules: The same as lints, but they can be enabled or disabled in
the configuration. The majority of lints in Red Knot and the Ruff
linter.
Our current implementation doesn't distinguish between lints and Lint
rules because we aren't aware of a suppressible code-related lint that
can't be configured in the configuration. The only lint that comes to my
mind is maybe `division-by-zero` if we're 99.99% sure that it is always
right. However, I want to keep the door open to making this distinction
in the future if it proves useful.
Another reason why I chose lint over lint rule (or just rule) is that I
want to leave room for a future lint rule and lint phase concept:
* lint is the *what*: a specific code smell, pattern, or violation
* the lint rule is the *how*: I could see a future `LintRule` trait in
`red_knot_python_linter` that provides the necessary hooks to run as
part of the linter. A lint rule produces diagnostics for exactly one
lint. A lint rule differs from all lints in `red_knot_python_semantic`
because they don't run as "rules" in the Ruff sense. Instead, they're a
side-product of type inference.
* the lint phase is a different form of *how*: A lint phase can produce
many different lints in a single pass. This is a somewhat common pattern
in Ruff where running one analysis collects the necessary information
for finding many different lints
* diagnostic is the *presentation*: Unlike a lint, the diagnostic isn't
the what, but how a specific lint gets presented. I expect that many
lints can use one generic `LintDiagnostic`, but a few lints might need
more flexibility and implement their custom diagnostic rendering (at
least custom `Diagnostic` implementation).
## Test Plan
`cargo test`
## Summary
Add a typed representation of function signatures (parameters and return
type) and infer it correctly from a function.
Convert existing usage of function return types to use the signature
representation.
This does not yet add inferred types for parameters within function body
scopes based on the annotations, but it should be easy to add as a next
step.
Part of #14161 and #13693.
## Test Plan
Added tests.
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## Summary
- Remove `Type::Unbound`
- Handle (potential) unboundness as a concept orthogonal to the type
system (see new `Symbol` type)
- Improve existing and add new diagnostics related to (potential)
unboundness
closes#13671
## Test Plan
- Update existing markdown-based tests
- Add new tests for added/modified functionality
## Summary
I noticed that augmented assignments on floats were yielding "not
supported" diagnostics. If the dunder isn't bound at all, we should use
binary operator semantics, rather than treating it as not-callable.
## Summary
...and remove periods from messages that don't span more than a single
sentence.
This is more consistent with how we present user-facing messages in uv
(which has a defined style guide).
Use declared types in inference and checking. This means several things:
* Imports prefer declarations over inference, when declarations are
available.
* When we encounter a binding, we check that the bound value's inferred
type is assignable to the live declarations of the bound symbol, if any.
* When we encounter a declaration, we check that the declared type is
assignable from the inferred type of the symbol from previous bindings,
if any.
* When we encounter a binding+declaration, we check that the inferred
type of the bound value is assignable to the declared type.
My plan for handling declared types is to introduce a `Declaration` in
addition to `Definition`. A `Declaration` is an annotation of a name
with a type; a `Definition` is an actual runtime assignment of a value
to a name. A few things (an annotated function parameter, an
annotated-assignment with an RHS) are both a `Definition` and a
`Declaration`.
This more cleanly separates type inference (only cares about
`Definition`) from declared types (only impacted by a `Declaration`),
and I think it will work out better than trying to squeeze everything
into `Definition`. One of the tests in this PR
(`annotation_only_assignment_transparent_to_local_inference`)
demonstrates one reason why. The statement `x: int` should have no
effect on local inference of the type of `x`; whatever the locally
inferred type of `x` was before `x: int` should still be the inferred
type after `x: int`. This is actually quite hard to do if `x: int` is
considered a `Definition`, because a core assumption of the use-def map
is that a `Definition` replaces the previous value. To achieve this
would require some hackery to effectively treat `x: int` sort of as if
it were `x: int = x`, but it's not really even equivalent to that, so
this approach gets quite ugly.
As a first step in this plan, this PR stops treating AnnAssign with no
RHS as a `Definition`, which fixes behavior in a couple added tests.
This actually makes things temporarily worse for the ellipsis-type test,
since it is defined in typeshed only using annotated assignments with no
RHS. This will be fixed properly by the upcoming addition of
declarations, which should also treat a declared type as sufficient to
import a name, at least from a stub.
Add support for non-local name lookups.
There's one TODO around annotated assignments without a RHS; these need
a fair amount of attention, which they'll get in an upcoming PR about
declared vs inferred types.
Fixes#11663
## Summary
Adds basic support for inferring the type resulting from a call
expression. This only works for the *result* of call expressions; it
performs no inference on parameters. It also intentionally does nothing
with class instantiation, `__call__` implementors, or lambdas.
## Test Plan
Adds a test that it infers the right thing!
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This PR adds symbols introduced by `for` loops to red-knot:
- `x` in `for x in range(10): pass`
- `x` and `y` in `for x, y in d.items(): pass`
- `a`, `b`, `c` and `d` in `for [((a,), b), (c, d)] in foo: pass`
## Test Plan
Several tests added, and the assertion in the benchmarks has been
updated.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
This PR adds support for adding symbols and definitions for function and
lambda parameters to the semantic index.
### Notes
* The default expression of a parameter is evaluated in the enclosing
scope (not the type parameter or function scope).
* The annotation expression of a parameter is evaluated in the type
parameter scope if they're present other in the enclosing scope.
* The symbols and definitions are added in the function parameter scope.
### Type Inference
There are two definitions `Parameter` and `ParameterWithDefault` and
their respective `*_definition` methods on the type inference builder.
These methods are preferred and are re-used when checking from a
different region.
## Test Plan
Add test case for validating that the parameters are defined in the
function / lambda scope.
### Benchmark update
Validated the difference in diagnostics for benchmark code between
`main` and this branch. All of them are either directly or indirectly
referencing one of the function parameters. The diff is in the PR description.
## Summary
This PR adds scope and definition for comprehension nodes. This includes
the following nodes:
* List comprehension
* Dictionary comprehension
* Set comprehension
* Generator expression
### Scope
Each expression here adds it's own scope with one caveat - the `iter`
expression of the first generator is part of the parent scope. For
example, in the following code snippet the `iter1` variable is evaluated
in the outer scope.
```py
[x for x in iter1]
```
> The iterable expression in the leftmost for clause is evaluated
directly in the enclosing scope and then passed as an argument to the
implicitly nested scope.
>
> Reference:
https://docs.python.org/3/reference/expressions.html#displays-for-lists-sets-and-dictionaries
There's another special case for assignment expressions:
> There is one special case: an assignment expression occurring in a
list, set or dict comprehension or in a generator expression (below
collectively referred to as “comprehensions”) binds the target in the
containing scope, honoring a nonlocal or global declaration for the
target in that scope, if one exists.
>
> Reference: https://peps.python.org/pep-0572/#scope-of-the-target
For example, in the following code snippet, the variables `a` and `b`
are available after the comprehension while `x` isn't:
```py
[a := 1 for x in range(2) if (b := 2)]
```
### Definition
Each comprehension node adds a single definition, the "target" variable
(`[_ for target in iter]`). This has been accounted for and a new
variant has been added to `DefinitionKind`.
### Type Inference
Currently, type inference is limited to a single scope. It doesn't
_enter_ in another scope to infer the types of the remaining expressions
of a node. To accommodate this, the type inference for a **scope**
requires new methods which _doesn't_ infer the type of the `iter`
expression of the leftmost outer generator (that's defined in the
enclosing scope).
The type inference for the scope region is split into two parts:
* `infer_generator_expression` (similarly for comprehensions) infers the
type of the `iter` expression of the leftmost outer generator
* `infer_generator_expression_scope` (similarly for comprehension)
infers the type of the remaining expressions except for the one
mentioned in the previous point
The type inference for the **definition** also needs to account for this
special case of leftmost generator. This is done by defining a `first`
boolean parameter which indicates whether this comprehension definition
occurs first in the enclosing expression.
## Test Plan
New test cases were added to validate multiple scenarios. Refer to the
documentation for each test case which explains what is being tested.
Changes the red-knot benchmark to run on the stdlib "tomllib" library
(which is self-contained, four files, uses type annotations) instead of
on very small bits of handwritten code.
Also remove the `without_parse` benchmark: now that we are running on
real code that uses typeshed, we'd either have to pre-parse all of
typeshed (slow) or find some way to determine which typeshed modules
will be used by the benchmark (not feasible with reasonable complexity.)
## Test Plan
`cargo bench -p ruff_benchmark --bench red_knot`
