## Summary
This fixes an edge case that @carljm and I missed when implementing
https://github.com/astral-sh/ruff/pull/13800. Namely, if the left-hand
operand is the _exact same type_ as the right-hand operand, the
reflected dunder on the right-hand operand is never tried:
```pycon
>>> class Foo:
... def __radd__(self, other):
... return 42
...
>>> Foo() + Foo()
Traceback (most recent call last):
File "<python-input-1>", line 1, in <module>
Foo() + Foo()
~~~~~~^~~~~~~
TypeError: unsupported operand type(s) for +: 'Foo' and 'Foo'
```
This edge case _is_ covered in Brett's blog at
https://snarky.ca/unravelling-binary-arithmetic-operations-in-python/,
but I missed it amongst all the other subtleties of this algorithm. The
motivations and history behind it were discussed in
https://mail.python.org/archives/list/python-dev@python.org/thread/7NZUCODEAPQFMRFXYRMGJXDSIS3WJYIV/
## Test Plan
I added an mdtest for this cornercase.
## Summary
- Add `Type::is_disjoint_from` as a way to test whether two types
overlap
- Add a first set of simplification rules for intersection types
- `S & T = S` for `S <: T`
- `S & ~T = Never` for `S <: T`
- `~S & ~T = ~T` for `S <: T`
- `A & ~B = A` for `A` disjoint from `B`
- `A & B = Never` for `A` disjoint from `B`
- `bool & ~Literal[bool] = Literal[!bool]`
resolves one item in #12694
## Open questions:
- Can we somehow leverage the (anti) symmetry between `positive` and
`negative` contributions? I could imagine that there would be a way if
we had `Type::Not(type)`/`Type::Negative(type)`, but with the
`positive`/`negative` architecture, I'm not sure. Note that there is a
certain duplication in the `add_positive`/`add_negative` functions (e.g.
`S & ~T = Never` is implemented twice), but other rules are actually not
perfectly symmetric: `S & T = S` vs `~S & ~T = ~T`.
- I'm not particularly proud of the way `add_positive`/`add_negative`
turned out. They are long imperative-style functions with some
mutability mixed in (`to_remove`). I'm happy to look into ways to
improve this code *if we decide to go with this approach* of
implementing a set of ad-hoc rules for simplification.
- ~~Is it useful to perform simplifications eagerly in
`add_positive`/`add_negative`? (@carljm)~~ This is what I did for now.
## Test Plan
- Unit tests for `Type::is_disjoint_from`
- Observe changes in Markdown-based tests
- Unit tests for `IntersectionBuilder::build()`
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
Minor cleanup and consistent formatting of the Markdown-based tests.
- Removed lots of unnecessary `a`, `b`, `c`, … variables.
- Moved test assertions (`# revealed:` comments) closer to the tested
object.
- Always separate `# revealed` and `# error` comments from the code by
two spaces, according to the discussion
[here](https://github.com/astral-sh/ruff/pull/13746/files#r1799385758).
This trades readability for consistency in some cases.
- Fixed some headings
Summary
---------
PEP 695 Generics introduce a scope inside a class statement's arguments
and keywords.
```
class C[T](A[T]): # the T in A[T] is not from the global scope but from a type-param-specfic scope
...
```
When doing inference on the class bases, we currently have been doing
base class expression lookups in the global scope. Not an issue without
generics (since a scope is only created when generics are present).
This change instead makes sure to stop the global scope inference from
going into expressions within this sub-scope. Since there is a separate
scope, `check_file` and friends will trigger inference on these
expressions still.
Another change as a part of this is making sure that `ClassType` looks
up its bases in the right scope.
Test Plan
----------
`cargo test --package red_knot_python_semantic generics` will run the
markdown test that previously would panic due to scope lookup issues
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: Carl Meyer <carl@astral.sh>
This reverts https://github.com/astral-sh/ruff/pull/13799, and restores
the previous behavior, which I think was the most pragmatic and useful
version of the divide-by-zero error, if we will emit it at all.
In general, a type checker _does_ emit diagnostics when it can detect
something that will definitely be a problem for some inhabitants of a
type, but not others. For example, `x.foo` if `x` is typed as `object`
is a type error, even though some inhabitants of the type `object` will
have a `foo` attribute! The correct fix is to make your type annotations
more precise, so that `x` is assigned a type which definitely has the
`foo` attribute.
If we will emit it divide-by-zero errors, it should follow the same
logic. Dividing an inhabitant of the type `int` by zero may not emit an
error, if the inhabitant is an instance of a subclass of `builtins.int`
that overrides division. But it may emit an error (more likely it will).
If you don't want the diagnostic, you can clarify your type annotations
to require an instance of your safe subclass.
Because the Python type system doesn't have the ability to explicitly
reflect the fact that divide-by-zero is an error in type annotations
(e.g. for `int.__truediv__`), or conversely to declare a type as safe
from divide-by-zero, or include a "nonzero integer" type which it is
always safe to divide by, the analogy doesn't fully apply. You can't
explicitly mark your subclass of `int` as safe from divide-by-zero, we
just semi-arbitrarily choose to silence the diagnostic for subclasses,
to avoid false positives.
Also, if we fully followed the above logic, we'd have to error on every
`int / int` because the RHS `int` might be zero! But this would likely
cause too many false positives, because of the lack of a "nonzero
integer" type.
So this is just a pragmatic choice to emit the diagnostic when it is
very likely to be an error. It's unclear how useful this diagnostic is
in practice, but this version of it is at least very unlikely to cause
harm.
If the LHS is just `int` or `float` type, that type includes custom
subclasses which can arbitrarily override division behavior, so we
shouldn't emit a divide-by-zero error in those cases.
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
Add type inference for comparisons involving union types. For example:
```py
one_or_two = 1 if flag else 2
reveal_type(one_or_two <= 2) # revealed: Literal[True]
reveal_type(one_or_two <= 1) # revealed: bool
reveal_type(one_or_two <= 0) # revealed: Literal[False]
```
closes#13779
## Test Plan
See `resources/mdtest/comparison/unions.md`
## Summary
Fixes the bug described in #13514 where an unbound public type defaulted
to the type or `Unknown`, whereas it should only be the type if unbound.
## Test Plan
Added a new test case
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This PR adds a debug assertion that asserts that `TypeInference::extend`
is only called on results that have the same scope.
This is critical because `expressions` uses `ScopedExpressionId` that
are local and merging expressions from different
scopes would lead to incorrect expression types.
We could consider storing `scope` only on `TypeInference` for debug
builds. Doing so has the advantage that the `TypeInference` type is
smaller of which we'll have many. However, a `ScopeId` is a `u32`... so
it shouldn't matter that much and it avoids storing the `scope` both on
`TypeInference` and `TypeInferenceBuilder`
## Test Plan
`cargo test`
## Summary
This PR implements comparisons for (tuple, tuple).
It will close#13688 and complete an item in #13618 once merged.
## Test Plan
Basic tests are included for (tuple, tuple) comparisons.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
Just a small simplification to remove some unnecessary complexity here.
Rather than using separate branches for subscript expressions involving
boolean literals, we can simply convert them to integer literals and
reuse the logic in the `IntLiteral` branches.
## Test Plan
`cargo test -p red_knot_python_semantic`
## 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>
## Summary
Porting infer tests to new markdown tests framework.
Link to the corresponding issue: #13696
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
- Fix a bug with `… is not …` type guards.
Previously, in an example like
```py
x = [1]
y = [1]
if x is not y:
reveal_type(x)
```
we would infer a type of `list[int] & ~list[int] == Never` for `x`
inside the conditional (instead of `list[int]`), since we built a
(negative) intersection with the type of the right hand side (`y`).
However, as this example shows, this assumption can only be made for
singleton types (types with a single inhabitant) such as `None`.
- Add support for `… is …` type guards.
closes#13715
## Test Plan
Moved existing `narrow_…` tests to Markdown-based tests and added new
ones (including a regression test for the bug described above). Note
that will create some conflicts with
https://github.com/astral-sh/ruff/pull/13719. I tried to establish the
correct organizational structure as proposed in
https://github.com/astral-sh/ruff/pull/13719#discussion_r1800188105
This adds documentation for the new test framework.
I also added documentation for the planned design of features we haven't
built yet (clearly marked as such), so that this doc can become the sole
source of truth for the test framework design (we don't need to refer
back to the original internal design document.)
Also fixes a few issues in the test framework implementation that were
discovered in writing up the docs.
---------
Co-authored-by: T-256 <132141463+T-256@users.noreply.github.com>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>
## Summary
Adds a markdown-based test framework for writing tests of type inference
and type checking. Fixes#11664.
Implements the basic required features. A markdown test file is a suite
of tests, each test can contain one or more Python files, with
optionally specified path/name. The test writes all files to an
in-memory file system, runs red-knot, and matches the resulting
diagnostics against `Type: ` and `Error: ` assertions embedded in the
Python source as comments.
We will want to add features like incremental tests, setting custom
configuration for tests, writing non-Python files, testing syntax
errors, capturing full diagnostic output, etc. There's also plenty of
room for improved UX (colored output?).
## Test Plan
Lots of tests!
Sample of the current output when a test fails:
```
Running tests/inference.rs (target/debug/deps/inference-7c96590aa84de2a4)
running 1 test
test inference::path_1_resources_inference_numbers_md ... FAILED
failures:
---- inference::path_1_resources_inference_numbers_md stdout ----
inference/numbers.md - Numbers - Floats
/src/test.py
line 2: unexpected error: [invalid-assignment] "Object of type `Literal["str"]` is not assignable to `int`"
thread 'inference::path_1_resources_inference_numbers_md' panicked at crates/red_knot_test/src/lib.rs:60:5:
Some tests failed.
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
failures:
inference::path_1_resources_inference_numbers_md
test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.19s
error: test failed, to rerun pass `-p red_knot_test --test inference`
```
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Fixed a TODO by adding another TODO. It's the red-knot way!
## Summary
`builtins.type` can be subscripted at runtime on Python 3.9+, even
though it has no `__class_getitem__` method and its metaclass (which
is... itself) has no `__getitem__` method. The special case is
[hardcoded directly into `PyObject_GetItem` in
CPython](744caa8ef4/Objects/abstract.c (L181-L184)).
We just have to replicate the special case in our semantic model.
This will fail at runtime on Python <3.9. However, there's a bunch of
outstanding questions (detailed in the TODO comment I added) regarding
how we deal with subscriptions of other generic types on lower Python
versions. Since we want to avoid too many false positives for now, I
haven't tried to address this; I've just made `type` subscriptable on
all Python versions.
## Test Plan
`cargo test -p red_knot_python_semantic --lib`
## Summary
Implements string literal comparisons and fallbacks to `str` instance
for `LiteralString`.
Completes an item in #13618
## Test Plan
- Adds a dedicated test with non exhaustive cases
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
Implements the comparison operator for `[Type::IntLiteral]` and
`[Type::BooleanLiteral]` (as an artifact of special handling of `True` and
`False` in python).
Sets the framework to implement more comparison for types known at
static time (e.g. `BooleanLiteral`, `StringLiteral`), allowing us to only
implement cases of the triplet `<left> Type`, `<right> Type`, `CmpOp`.
Contributes to #12701 (without checking off an item yet).
## Test Plan
- Added a test for the comparison of literals that should include most
cases of note.
- Added a test for the comparison of int instances
Please note that the cases do not cover 100% of the branches as there
are many and the current testing strategy with variables make this
fairly confusing once we have too many in one test.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## 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).
## Summary
You can now call `return_ty_result` to operate on a `Result` directly
thereby using your own diagnostics, as in:
```rust
return dunder_getitem_method
.call(self.db, &[slice_ty])
.return_ty_result(self.db, value.as_ref().into(), self)
.unwrap_or_else(|err| {
self.add_diagnostic(
(&**value).into(),
"call-non-callable",
format_args!(
"Method `__getitem__` is not callable on object of type '{}'.",
value_ty.display(self.db),
),
);
err.return_ty()
});
```
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?
