## Summary
This PR adds a new salsa query and an ingredient to resolve all the
variables involved in an unpacking assignment like `(a, b) = (1, 2)` at
once. Previously, we'd recursively try to match the correct type for
each definition individually which will result in creating duplicate
diagnostics.
This PR still doesn't solve the duplicate diagnostics issue because that
requires a different solution like using salsa accumulator or
de-duplicating the diagnostics manually.
Related: #13773
## Test Plan
Make sure that all unpack assignment test cases pass, there are no
panics in the corpus tests.
## Todo
- [x] Look at the performance regression
## Summary
This PR adds type narrowing in `and` and `or` expressions, for example:
```py
class A: ...
x: A | None = A() if bool_instance() else None
isinstance(x, A) or reveal_type(x) # revealed: None
```
## Test Plan
New mdtests 😍
## Summary
As python uses short-circuiting boolean operations in runtime, we should
mimic that logic in redknot as well.
For example, we should detect that in the following code `x` might be
undefined inside the block:
```py
if flag or (x := 1):
print(x)
```
## Test Plan
Added mdtest suit for boolean expressions.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
Add support for type narrowing in elif and else scopes as part of
#13694.
## Test Plan
- mdtest
- builder unit test for union negation.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
Remove unnecessary uses of `.as_ref()`, `.iter()`, `&**` and similar, mostly in situations when iterating over variables. Many of these changes are only possible following #13826, when we bumped our MSRV to 1.80: several useful implementations on `&Box<[T]>` were only stabilised in Rust 1.80. Some of these changes we could have done earlier, however.
## Summary
This PR adds support for unpacking tuple expression in an assignment
statement where the target expression can be a tuple or a list (the
allowed sequence targets).
The implementation introduces a new `infer_assignment_target` which can
then be used for other targets like the ones in for loops as well. This
delegates it to the `infer_definition`. The final implementation uses a
recursive function that visits the target expression in source order and
compares the variable node that corresponds to the definition. At the
same time, it keeps track of where it is on the assignment value type.
The logic also accounts for the number of elements on both sides such
that it matches even if there's a gap in between. For example, if
there's a starred expression like `(a, *b, c) = (1, 2, 3)`, then the
type of `a` will be `Literal[1]` and the type of `b` will be
`Literal[2]`.
There are a couple of follow-ups that can be done:
* Use this logic for other target positions like `for` loop
* Add diagnostics for mis-match length between LHS and RHS
## Test Plan
Add various test cases using the new markdown test framework.
Validate that existing test cases pass.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
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.
## 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>
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.
## 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.
## 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.
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>
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.
## 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.
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.
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.
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.
