Adds a diagnostic for division by the integer zero in `//`, `/`, and
`%`.
Doesn't handle `<int> / 0.0` because we don't track the values of float
literals.
This variant shows inference that is not yet implemented..
## Summary
PR #13500 reopened the idea of adding a new type variant to keep track
of not-implemented features in Red Knot.
It was based off of #12986 with a more generic approach of keeping track
of different kind of unknowns. Discussion in #13500 agreed that keeping
track of different `Unknown` is complicated for now, and this feature is
better achieved through a new variant of `Type`.
### Requirements
Requirements for this implementation can be summed up with some extracts
of comment from @carljm on the previous PR
> So at the moment we are leaning towards simplifying this PR to just
use a new top-level variant, which behaves like Any and Unknown but
represents inference that is not yet implemented in red-knot.
> I think the general rule should be that Todo should propagate only
when the presence of the input Todo caused the output to be unknown.
>
> To take a specific example, the inferred result of addition must be
Unknown if either operand is Unknown. That is, Unknown + X will always
be Unknown regardless of what X is. (Same for X + Unknown.) In this
case, I believe that Unknown + Todo (or Todo + Unknown) should result in
Unknown, not result in Todo. If we fix the upstream source of the Todo,
the result would still be Unknown, so it's not useful to propagate the
Todo in this case: it wrongly suggests that the output is unknown
because of a todo item.
## Test Plan
This PR does not introduce new tests, but it did required to edit some
tests with the display of `[Type::Todo]` (currently `@Todo`), which
suggests that those test are placeholders requirements for features we
don't support yet.
While working on https://github.com/astral-sh/ruff/pull/13576 I noticed
that it was really hard to tell which assertion failed in some of these
test cases. This could be expanded to elsewhere, but I've heard this
test suite format won't be around for long?
## Summary
Following #13449, this PR adds custom handling for the bool constructor,
so when the input type has statically known truthiness value, it will be
used as the return value of the bool function.
For example, in the following snippet x will now be resolved to
`Literal[True]` instead of `bool`.
```python
x = bool(1)
```
## Test Plan
Some cargo tests were added.
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## Summary
Implement inference for `f-string`, contributes to #12701.
### First Implementation
When looking at the way `mypy` handles things, I noticed the following:
- No variables (e.g. `f"hello"`) ⇒ `LiteralString`
- Any variable (e.g. `f"number {1}"`) ⇒ `str`
My first commit (1ba5d0f13fdf70ed8b2b1a41433b32fc9085add2) implements
exactly this logic, except that we deal with string literals just like
`infer_string_literal_expression` (if below `MAX_STRING_LITERAL_SIZE`,
show `Literal["exact string"]`)
### Second Implementation
My second commit (90326ce9af5549af7b4efae89cd074ddf68ada14) pushes
things a bit further to handle cases where the expression within the
`f-string` are all literal values (string representation known at static
time).
Here's an example of when this could happen in code:
```python
BASE_URL = "https://httpbin.org"
VERSION = "v1"
endpoint = f"{BASE_URL}/{VERSION}/post" # Literal["https://httpbin.org/v1/post"]
```
As this can be sightly more costly (additional allocations), I don't
know if we want this feature.
## Test Plan
- Added a test `fstring_expression` covering all cases I can think of
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This PR changes removes the typeshed stubs from the vendored file system
shipped with ruff
and instead ships an empty "typeshed".
Making the typeshed files optional required extracting the typshed files
into a new `ruff_vendored` crate. I do like this even if all our builds
always include typeshed because it means `red_knot_python_semantic`
contains less code that needs compiling.
This also allows us to use deflate because the compression algorithm
doesn't matter for an archive containing a single, empty file.
## Test Plan
`cargo test`
I verified with ` cargo tree -f "{p} {f}" -p <package> ` that:
* red_knot_wasm: enables `deflate` compression
* red_knot: enables `zstd` compression
* `ruff`: uses stored
I'm not quiet sure how to build the binary that maturin builds but
comparing the release artifact size with `strip = true` shows a `1.5MB`
size reduction
---------
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
Avoid quadratic time in subsumed elements when adding a super-type of
existing union elements.
Reserve space in advance when adding multiple elements (from another
union) to a union.
Make union elements a `Box<[Type]>` instead of an `FxOrderSet`; the set
doesn't buy much since the rules of union uniqueness are defined in
terms of supertype/subtype, not in terms of simple type identity.
Move sealed-boolean handling out of a separate `UnionBuilder::simplify`
method and into `UnionBuilder::add`; now that `add` is iterating
existing elements anyway, this is more efficient.
Remove `UnionType::contains`, since it's now `O(n)` and we shouldn't
really need it, generally we care about subtype/supertype, not type
identity. (Right now it's used for `Type::Unbound`, which shouldn't even
be a type.)
Add support for `is_subtype_of` for the `object` type.
Addresses comments on https://github.com/astral-sh/ruff/pull/13401
This was mentioned in an earlier review, and seemed easy enough to just
do it. No need to repeat all the types twice when it gives no additional
information.
## Summary
This PR adds an experimental Ruff subcommand to generate dependency
graphs based on module resolution.
A few highlights:
- You can generate either dependency or dependent graphs via the
`--direction` command-line argument.
- Like Pants, we also provide an option to identify imports from string
literals (`--detect-string-imports`).
- Users can also provide additional dependency data via the
`include-dependencies` key under `[tool.ruff.import-map]`. This map uses
file paths as keys, and lists of strings as values. Those strings can be
file paths or globs.
The dependency resolution uses the red-knot module resolver which is
intended to be fully spec compliant, so it's also a chance to expose the
module resolver in a real-world setting.
The CLI is, e.g., `ruff graph build ../autobot`, which will output a
JSON map from file to files it depends on for the `autobot` project.
This fixes the last panic on checking pandas.
(Match statement became an `if let` because clippy decided it wanted
that once I added the additional line in the else case?)
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Support using `reveal_type` without importing it, as implied by the type
spec and supported by existing type checkers.
We use `typing_extensions.reveal_type` for the implicit built-in; this
way it exists on all Python versions. (It imports from `typing` on newer
Python versions.)
Emits an "undefined name" diagnostic whenever `reveal_type` is
referenced in this way (in addition to the revealed-type diagnostic when
it is called). This follows the mypy example (with `--enable-error-code
unimported-reveal`) and I think provides a good (and easily
understandable) balance for user experience. If you are using
`reveal_type` for quick temporary debugging, the additional
undefined-name diagnostic doesn't hinder that use case. If we make the
revealed-type diagnostic a non-failing one, the undefined-name
diagnostic can still be a failing diagnostic, helping prevent
accidentally leaving it in place. For any use cases where you want to
leave it in place, you can always import it to avoid the undefined-name
diagnostic.
In the future, we can easily provide configuration options to a) turn
off builtin-reveal_type altogether, and/or b) silence the undefined-name
diagnostic when using it, if we have users on either side (loving or
hating pseudo-builtin `reveal_type`) who are dissatisfied with this
compromise.
After looking at more cases (for example, the case in the added test in
this PR), I realized that our previous rule, "if a symbol has any
declarations, use only declarations for its public type" is not
adequate. Rather than using `Unknown` as fallback if the symbol is not
declared in some paths, we need to use the inferred type as fallback in
that case.
For the paths where the symbol _was_ declared, we know that any bindings
must be assignable to the declared type in that path, so this won't
change the overall declared type in those paths. But for paths where the
symbol wasn't declared, this will give us a better type in place of
`Unknown`.
Before `typing.reveal_type` existed, there was
`typing_extensions.reveal_type`. We should support both.
Also adds a test to verify that we can handle aliasing of `reveal_type`
to a different name.
Adds a bit of code to ensure that if we have a union of different
`reveal_type` functions (e.g. a union containing both
`typing_extensions.reveal_type` and `typing.reveal_type`) we still emit
the reveal-type diagnostic only once. This is probably unlikely in
practice, but it doesn't hurt to handle it smoothly. (It comes up now
because we don't support `version_info` checks yet, so
`typing_extensions.reveal_type` is actually that union.)
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
I noticed that this pattern sometimes occurs in typeshed:
```
if ...:
from foo import bar
else:
def bar(): ...
```
If we have the rule that symbols with declarations only use declarations
for the public type, then this ends up resolving as `Unknown |
Literal[bar]`, because we didn't consider the import to be a
declaration.
I think the most straightforward thing here is to also consider imports
as declarations. The same rationale applies as for function and class
definitions: if you shadow an import, you should have to explicitly
shadow with an annotation, rather than just doing it
implicitly/accidentally.
We may also ultimately need to re-evaluate the rule that public type
considers only declarations, if there are declarations.
Add support for the `typing.reveal_type` function, emitting a diagnostic
revealing the type of its single argument. This is a necessary piece for
the planned testing framework.
This puts the cart slightly in front of the horse, in that we don't yet
have proper support for validating call signatures / argument types. But
it's easy to do just enough to make `reveal_type` work.
This PR includes support for calling union types (this is necessary
because we don't yet support `sys.version_info` checks, so
`typing.reveal_type` itself is a union type), plus some nice
consolidated error messages for calls to unions where some elements are
not callable. This is mostly to demonstrate the flexibility in
diagnostics that we get from the `CallOutcome` enum.
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.
Add support for declared types to the semantic index. This involves a
lot of renaming to clarify the distinction between bindings and
declarations. The Definition (or more specifically, the DefinitionKind)
becomes responsible for determining which definitions are bindings,
which are declarations, and which are both, and the symbol table
building is refactored a bit so that the `IS_BOUND` (renamed from
`IS_DEFINED` for consistent terminology) flag is always set when a
binding is added, rather than being set separately (and requiring us to
ensure it is set properly).
The `SymbolState` is split into two parts, `SymbolBindings` and
`SymbolDeclarations`, because we need to store live bindings for every
declaration and live declarations for every binding; the split lets us
do this without storing more than we need.
The massive doc comment in `use_def.rs` is updated to reflect bindings
vs declarations.
The `UseDefMap` gains some new APIs which are allow-unused for now,
since this PR doesn't yet update type inference to take declarations
into account.
Add `::is_empty` and `::union` methods to the `BitSet` implementation.
Allowing unused for now, until these methods become used later with the
declared-types implementation.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
These are quite incomplete, but I needed to start stubbing them out in
order to build and test declared-types.
Allowing unused for now, until they are used later in the declared-types
PR.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This PR adds a new `Type` variant called `TupleType` which is used for
heterogeneous elements.
### Display notes
* For an empty tuple, I'm using `tuple[()]` as described in the docs:
https://docs.python.org/3/library/typing.html#annotating-tuples
* For nested elements, it'll use the literal type instead of builtin
type unlike Pyright which does `tuple[Literal[1], tuple[int, int]]`
instead of `tuple[Literal[1], tuple[Literal[2], Literal[3]]]`. Also,
mypy would give `tuple[builtins.int, builtins.int]` instead of
`tuple[Literal[1], Literal[2]]`
## Test Plan
Update test case to account for the display change and add cases for
multiple elements and nested tuple elements.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This PR adds support for control flow for match statement.
It also adds the necessary infrastructure required for narrowing
constraints in case blocks and implements the logic for
`PatternMatchSingleton` which is either `None` / `True` / `False`. Even
after this the inferred type doesn't get simplified completely, there's
a TODO for that in the test code.
## Test Plan
Add test cases for control flow for (a) when there's a wildcard pattern
and (b) when there isn't. There's also a test case to verify the
narrowing logic.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
When a type of the form `Literal["..."]` would be constructed with too
large of a string, this PR converts it to `LiteralString` instead.
We also extend inference for binary operations to include the case where
one of the operands is `LiteralString`.
Closes#13224
Pull the tests from `types.rs` into `infer.rs`.
All of these are integration tests with the same basic form: create a
code sample, run type inference or check on it, and make some assertions
about types and/or diagnostics. These are the sort of tests we will want
to move into a test framework with a low-boilerplate custom textual
format. In the meantime, having them together (and more importantly,
their helper utilities together) means that it's easy to keep tests for
related language features together (iterable tests with other iterable
tests, callable tests with other callable tests), without an artificial
split based on tests which test diagnostics vs tests which test
inference. And it allows a single test to more easily test both
diagnostics and inference. (Ultimately in the test framework, they will
likely all test diagnostics, just in some cases the diagnostics will
come from `reveal_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.
Initially I had deferred annotation name lookups reuse the "public
symbol type", since that gives the correct "from end of scope" view of
reaching definitions that we want. But there is a key difference; public
symbol types are based only on definitions in the queried scope (or
"name in the given namespace" in runtime terms), they don't ever look up
a name in nonlocal/global/builtin scopes. Deferred annotation resolution
should do this lookup.
Add a test, and fix deferred name resolution to support
nonlocal/global/builtin names.
Fixes#13176
## Summary
Part of #13085, this PR updates the comprehension definition to handle
multiple targets.
## Test Plan
Update existing semantic index test case for comprehension with multiple
targets. Running corpus tests shouldn't panic.
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
Test coverage for #13131 wasn't as good as I thought it was, because
although we infer a lot of types in stubs in typeshed, we don't check
typeshed, and therefore we don't do scope-level inference and pull all
types for a scope. So we didn't really have good test coverage for
scope-level inference in a stub. And because of this, I got the code for
supporting that wrong, meaning that if we did scope-level inference with
deferred types, we'd end up never populating the deferred types in the
scope's `TypeInference`, which causes panics like #13160.
Here I both add test coverage by running the corpus tests both as `.py`
and as `.pyi` (which reveals the panic), and I fix the code to support
deferred types in scope inference.
This also revealed a problem with deferred types in generic functions,
which effectively span two scopes. That problem will require a bit more
thought, and I don't want to block this PR on it, so for now I just
don't defer annotations on generic functions.
Fixes#13160.
## Summary
Follow-up to #13147, this PR implements the `AstNode` for `Identifier`.
This makes it easier to create the `NodeKey` in red knot because it uses
a generic method to construct the key from `AnyNodeRef` and is important
for definitions that are created only on identifiers instead of
`ExprName`.
## Test Plan
`cargo test` and `cargo clippy`
## Summary
This PR adds definition for match patterns.
## Test Plan
Update the existing test case for match statement symbols to verify that
the definitions are added as well.
The `UnionBuilder` builds `builtins.bool` when handed `Literal[True]`
and `Literal[False]`.
Caveat: If the builtins module is unfindable somehow, the builder falls
back to the union type of these two literals.
First task from #12694
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## 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
- Introduce methods for inferring annotation and type expressions.
- Correctly infer explicit return types from functions where they are
simple names that can be resolved in scope.
Contributes to #12701 by way of helping unlock call expressions (this
does not remotely finish that, as it stands, but it gets us moving that
direction).
## Test Plan
Added a test for function return types which use the name form of an
annotation expression, since this is aiming toward call expressions.
When we extend this to working for other annotation and type expression
positions, we should add explicit tests for those as well.
---------
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
Co-authored-by: Carl Meyer <carl@astral.sh>
Prototype deferred evaluation of type expressions by deferring
evaluation of class bases in a stub file. This allows self-referential
class definitions, as occur with the definition of `str` in typeshed
(which inherits `Sequence[str]`).
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
Just what it says on the tin: adds basic `EllipsisType` inference for
any time `...` appears in the AST.
## Test Plan
Test that `x = ...` produces exactly what we would expect.
---------
Co-authored-by: Carl Meyer <carl@oddbird.net>
## Summary
The resulting type when multiplying a string literal by an integer
literal is one of two types:
- `StringLiteral`, in the case where it is a reasonably small resulting
string (arbitrarily bounded here to 4096 bytes, roughly a page on many
operating systems), including the fully expanded string.
- `LiteralString`, matching Pyright etc., for strings larger than that.
Additionally:
- Switch to using `Box<str>` instead of `String` for the internal value
of `StringLiteral`, saving some non-trivial byte overhead (and keeping
the total number of allocations the same).
- Be clearer and more accurate about which types we ought to defer to in
`StringLiteral` and `LiteralString` member lookup.
## Test Plan
Added a test case covering multiplication times integers: positive,
negative, zero, and in and out of bounds.
---------
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This fixes the outstanding TODO and make it easier to work with new
cases. (Tidy first, *then* implement, basically!)
## Test Plan
After making this change all the existing tests still pass. A classic
refactor win. 🎉
# Summary
Add support for the first unary operator: negating integer literals. The
resulting type is another integer literal, with the value being the
negated value of the literal. All other types continue to return
`Type::Unknown` for the present, but this is designed to make it easy to
extend easily with other combinations of operator and operand.
Contributes to #12701.
## Test Plan
Add tests with basic negation, including of very large integers and
double negation.
## Summary
Introduce a `StringLiteralType` with corresponding `Display` type and a
relatively basic test that the resulting representation is as expected.
Note: we currently always allocate for `StringLiteral` types. This may
end up being a perf issue later, at which point we may want to look at
other ways of representing `value` here, i.e. with some kind of smarter
string structure which can reuse types. That is most likely to show up
with e.g. concatenation.
Contributes to #12701.
## Test Plan
Added a test for individual strings with both single and double quotes
as well as concatenated strings with both forms.
This PR has the `SemanticIndexBuilder` visit function definition
annotations before adding the function symbol/name to the builder.
For example, the following snippet no longer causes a panic:
```python
def bool(x) -> bool:
Return True
```
Note: This fix changes the ordering of the global symbol table.
Closes#13069
## 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 the `bytes` type to red-knot:
- Added the `bytes` type
- Added support for bytes literals
- Support for the `+` operator
Improves on #12701
Big TODO on supporting and normalizing r-prefixed bytestrings
(`rb"hello\n"`)
## Test Plan
Added a test for a bytes literals, concatenation, and corner values
The `SemanticIndexBuilder` was causing a cycle in a salsa query by
attempting to resolve the target before the value in a named expression
(e.g. `x := x+1`). This PR swaps the order, avoiding a panic.
Closes#13012.
## Summary
This PR adds symbols and definitions introduced by `with` statements.
The symbols and definitions are introduced for each with item. The type
inference is updated to call the definition region type inference
instead.
## Test Plan
Add test case to check for symbol table and definitions.
## Summary
This PR adds symbols introduced by `match` statements.
There are three patterns that introduces new symbols:
* `as` pattern
* Sequence pattern
* Mapping pattern
The recursive nature of the visitor makes sure that all symbols are
added.
## Test Plan
Add test case for all types of patterns that introduces a symbol.
## Summary
This PR adds definition for augmented assignment. This is similar to
annotated assignment in terms of implementation.
An augmented assignment should also record a use of the variable but
that's a TODO for now.
## Test Plan
Add test case to validate that a definition is added.
Extend the `UseDefMap` to also track which constraints (provided by e.g.
`if` tests) apply to each visible definition.
Uses a custom `BitSet` and `BitSetArray` to track which constraints
apply to which definitions, while keeping data inline as much as
possible.
## 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.
If a builtin is conditionally shadowed by a global, we didn't correctly
fall back to builtins for the not-defined-in-globals path (see added
test for an example.)
## 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.
Make `cargo doc -p red_knot_python_semantic --document-private-items`
run warning-free. I'd still like to do this for all of ruff and start
enforcing it in CI (https://github.com/astral-sh/ruff/issues/12372) but
haven't gotten to it yet. But in the meantime I'm trying to maintain it
for at least `red_knot_python_semantic`, as it helps to ensure our doc
comments stay up to date.
A few of the comments I just removed or shortened, as their continued
relevance wasn't clear to me; please object in review if you think some
of them are important to keep!
Also remove a no-longer-needed `allow` attribute.
For type narrowing, we'll need intersections (since applying type
narrowing is just a type intersection.)
Add `IntersectionBuilder`, along with some tests for it and
`UnionBuilder` (renamed from `UnionTypeBuilder`).
We use smart builders to ensure that we always keep these types in
disjunctive normal form (DNF). That means that we never have deeply
nested trees of unions and intersections: unions flatten into unions,
intersections flatten into intersections, and intersections distribute
over unions, so the most complex tree we can ever have is a union of
intersections. We also never have a single-element union or a
single-positive-element intersection; these both just simplify to the
contained type.
Maintaining these invariants means that `UnionBuilder` doesn't
necessarily end up building a `Type::Union` (e.g. if you only add a
single type to the union, it'll just return that type instead), and
`IntersectionBuilder` doesn't necessarily build a `Type::Intersection`
(if you add a union to the intersection, we distribute the intersection
over that union, and `IntersectionBuilder` will end up returning a
`Type::Union` of intersections).
We also simplify intersections by ensuring that if a type and its
negation are both in an intersection, they simplify out. (In future this
should also respect subtyping, not just type identity, but we don't have
subtyping yet.) We do implement subtyping of `Never` as a special case
for now.
Most of this PR is unused for now until type narrowing lands; I'm just
breaking it out to reduce the review fatigue of a single massive PR.
## Summary
I'm not sure if this is useful but this is a hacky implementation to add
the filename and row / column numbers to the current Red Knot
diagnostics.
I hit this `todo!` trying to run type inference over some real modules.
Since it's a one-liner to implement it, I just did that rather than
changing to `Type::Unknown`.
Now that we have builtins available, resolve some simple cases to the
right builtin type.
We should also adjust the display for types to include their module
name; that's not done yet here.
Extend red-knot type inference to cover all syntax, so that inferring
types for a scope gives all expressions a type. This means we can run
the red-knot semantic lint on all Python code without panics. It also
means we can infer types for `builtins.pyi` without panics.
To keep things simple, this PR intentionally doesn't add any new type
inference capabilities: the expanded coverage is all achieved with
`Type::Unknown`. But this puts the skeleton in place for adding better
inference of all these language features.
I also had to add basic Salsa cycle recovery (with just `Type::Unknown`
for now), because some `builtins.pyi` definitions are cyclic.
To test this, I added a comprehensive corpus of test snippets sourced
from Cinder under [MIT
license](https://github.com/facebookincubator/cinder/blob/cinder/3.10/cinderx/LICENSE),
which matches Ruff's license. I also added to this corpus some
additional snippets for newer language features: all the
`27_func_generic_*` and `73_class_generic_*` files, as well as
`20_lambda_default_arg.py`, and added a test which runs semantic-lint
over all these files. (The test doesn't assert the test-corpus files are
lint-free; just that they are able to lint without a panic.)
Add support for while-loop control flow.
This doesn't yet include general support for terminals and reachability;
that is wider than just while loops and belongs in its own PR.
This also doesn't yet add support for cyclic definitions in loops; that
comes with enough of its own complexity in Salsa that I want to handle
it separately.
Add a lint rule to detect if a name is definitely or possibly undefined
at a given usage.
If I create the file `undef/main.py` with contents:
```python
x = int
def foo():
z
return x
if flag:
y = x
y
```
And then run `cargo run --bin red_knot -- --current-directory
../ruff-examples/undef`, I get the output:
```
Name 'z' used when not defined.
Name 'flag' used when not defined.
Name 'y' used when possibly not defined.
```
If I modify the file to add `y = 0` at the top, red-knot re-checks it
and I get the new output:
```
Name 'z' used when not defined.
Name 'flag' used when not defined.
```
Note that `int` is not flagged, since it's a builtin, and `return x` in
the function scope is not flagged, since it refers to the global `x`.
When poring over traces, the ones that just include a definition or
symbol or expression ID aren't very useful, because you don't know which
file it comes from. This adds that information to the trace.
I guess the downside here is that if calling `.file(db)` on a
scope/definition/expression would execute other traced code, it would be
marked as outside the span? I don't think that's a concern, because I
don't think a simple field access on a tracked struct should ever
execute our code. If I'm wrong and this is a problem, it seems like the
tracing crate has this feature where you can record a field as
`tracing::field::Empty` and then fill in its value later with
`span.record(...)`, but when I tried this it wasn't working for me, not
sure why.
I think there's a lot more we can do to make our tracing output more
useful for debugging (e.g. record an event whenever a
definition/symbol/expression/use id is created with the details of that
definition/symbol/expression/use), this is just dipping my toes in the
water.
Per comments in https://github.com/astral-sh/ruff/pull/12269, "module
global" is kind of long, and arguably redundant.
I tried just using "module" but there were too many cases where I felt
this was ambiguous. I like the way "global" works out better, though it
does require an understanding that in Python "global" generally means
"module global" not "globally global" (though in a sense module globals
are also globally global since modules are singletons).
Support falling back to a global name lookup if a name isn't defined in
the local scope, in the cases where that is correct according to Python
semantics.
In class scopes, a name lookup checks the local namespace first, and if
the name isn't found there, looks it up in globals.
In function scopes (and type parameter scopes, which are function-like),
if a name has any definitions in the local scope, it is a local, and
accessing it when none of those definitions have executed yet just
results in an `UnboundLocalError`, it does not fall back to a global. If
the name does not have any definitions in the local scope, then it is an
implicit global.
Public symbol type lookups never include such a fall back. For example,
if a name is not defined in a class scope, it is not available as a
member on that class, even if a name lookup within the class scope would
have fallen back to a global lookup.
This PR makes the `@override` lint rule work again.
Not yet included/supported in this PR:
* Support for free variables / closures: a free symbol in a nested
function-like scope referring to a symbol in an outer function-like
scope.
* Support for `global` and `nonlocal` statements, which force a symbol
to be treated as global or nonlocal even if it has definitions in the
local scope.
* Module-global lookups should fall back to builtins if the name isn't
found in the module scope.
I would like to expose nicer APIs for the various kinds of symbols
(explicit global, implicit global, free, etc), but this will also wait
for a later PR, when more kinds of symbols are supported.
Adds inference tests sufficient to give full test coverage of the
`UseDefMapBuilder::merge` method.
In the process I realized that we could implement visiting of if
statements in `SemanticBuilder` with fewer `snapshot`, `restore`, and
`merge` operations, so I restructured that visit a bit.
I also found one correctness bug in the `merge` method (it failed to
extend the given snapshot with "unbound" for any missing symbols,
meaning we would just lose the fact that the symbol could be unbound in
the merged-in path), and two efficiency bugs (if one of the ranges to
merge is empty, we can just use the other one, no need for copies, and
if the ranges are overlapping -- which can occur with nested branches --
we can still just merge them with no copies), and fixed all three.
Improve semantic index tests with better assertions than just `.len()`,
and re-add use-definition test that was commented out in the switch to
Salsa initially.
Implements definition-level type inference, with basic control flow
(only if statements and if expressions so far) in Salsa.
There are a couple key ideas here:
1) We can do type inference queries at any of three region
granularities: an entire scope, a single definition, or a single
expression. These are represented by the `InferenceRegion` enum, and the
entry points are the salsa queries `infer_scope_types`,
`infer_definition_types`, and `infer_expression_types`. Generally
per-scope will be used for scopes that we are directly checking and
per-definition will be used anytime we are looking up symbol types from
another module/scope. Per-expression should be uncommon: used only for
the RHS of an unpacking or multi-target assignment (to avoid
re-inferring the RHS once per symbol defined in the assignment) and for
test nodes in type narrowing (e.g. the `test` of an `If` node). All
three queries return a `TypeInference` with a map of types for all
definitions and expressions within their region. If you do e.g.
scope-level inference, when it hits a definition, or an
independently-inferable expression, it should use the relevant query
(which may already be cached) to get all types within the smaller
region. This avoids double-inferring smaller regions, even though larger
regions encompass smaller ones.
2) Instead of building a control-flow graph and lazily traversing it to
find definitions which reach a use of a name (which is O(n^2) in the
worst case), instead semantic indexing builds a use-def map, where every
use of a name knows which definitions can reach that use. We also no
longer track all definitions of a symbol in the symbol itself; instead
the use-def map also records which defs remain visible at the end of the
scope, and considers these the publicly-visible definitions of the
symbol (see below).
Major items left as TODOs in this PR, to be done in follow-up PRs:
1) Free/global references aren't supported yet (only lookup based on
definitions in current scope), which means the override-check example
doesn't currently work. This is the first thing I'll fix as follow-up to
this PR.
2) Control flow outside of if statements and expressions.
3) Type narrowing.
There are also some smaller relevant changes here:
1) Eliminate `Option` in the return type of member lookups; instead
always return `Type::Unbound` for a name we can't find. Also use
`Type::Unbound` for modules we can't resolve (not 100% sure about this
one yet.)
2) Eliminate the use of the terms "public" and "root" to refer to
module-global scope or symbols. Instead consistently use the term
"module-global". It's longer, but it's the clearest, and the most
consistent with typical Python terminology. In particular I don't like
"public" for this use because it has other implications around author
intent (is an underscore-prefixed module-global symbol "public"?). And
"root" is just not commonly used for this in Python.
3) Eliminate the `PublicSymbol` Salsa ingredient. Many non-module-global
symbols can also be seen from other scopes (e.g. by a free var in a
nested scope, or by class attribute access), and thus need to have a
"public type" (that is, the type not as seen from a particular use in
the control flow of the same scope, but the type as seen from some other
scope.) So all symbols need to have a "public type" (here I want to keep
the use of the term "public", unless someone has a better term to
suggest -- since it's "public type of a symbol" and not "public symbol"
the confusion with e.g. initial underscores is less of an issue.) At
least initially, I would like to try not having special handling for
module-global symbols vs other symbols.
4) Switch to using "definitions that reach end of scope" rather than
"all definitions" in determining the public type of a symbol. I'm
convinced that in general this is the right way to go. We may want to
refine this further in future for some free-variable cases, but it can
be changed purely by making changes to the building of the use-def map
(the `public_definitions` index in it), without affecting any other
code. One consequence of combining this with no control-flow support
(just last-definition-wins) is that some inference tests now give more
wrong-looking results; I left TODO comments on these tests to fix them
when control flow is added.
And some potential areas for consideration in the future:
1) Should `symbol_ty` be a Salsa query? This would require making all
symbols a Salsa ingredient, and tracking even more dependencies. But it
would save some repeated reconstruction of unions, for symbols with
multiple public definitions. For now I'm not making it a query, but open
to changing this in future with actual perf evidence that it's better.
Intern types using Salsa interning instead of in the `TypeInference`
result.
This eliminates the need for `TypingContext`, and also paves the way for
finer-grained type inference queries.
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