You can now use subscript expressions in a type expression to explicitly
specialize generic classes, just like you could already do in value
expressions.
This still does not implement bidirectional checking, so a type
annotation on an assignment does not influence how we infer a
specialization for a (not explicitly specialized) constructor call. You
might get an `invalid-assignment` error if (a) we cannot infer a class
specialization from the constructor call (in which case you end up e.g.
trying to assign `C[Unknown]` to `C[int]`) or if (b) we can infer a
specialization, but it doesn't match the annotation.
Closes https://github.com/astral-sh/ruff/issues/17432
## Summary
This PR extends version-related syntax error detection to red-knot. The
main changes here are:
1. Passing `ParseOptions` specifying a `PythonVersion` to parser calls
2. Adding a `python_version` method to the `Db` trait to make this
possible
3. Converting `UnsupportedSyntaxError`s to `Diagnostic`s
4. Updating existing mdtests to avoid unrelated syntax errors
My initial draft of (1) and (2) in #16090 instead tried passing a
`PythonVersion` down to every parser call, but @MichaReiser suggested
the `Db` approach instead
[here](https://github.com/astral-sh/ruff/pull/16090#discussion_r1969198407),
and I think it turned out much nicer.
All of the new `python_version` methods look like this:
```rust
fn python_version(&self) -> ruff_python_ast::PythonVersion {
Program::get(self).python_version(self)
}
```
with the exception of the `TestDb` in `ruff_db`, which hard-codes
`PythonVersion::latest()`.
## Test Plan
Existing mdtests, plus a new mdtest to see at least one of the new
diagnostics.
This PR adds **_very_** basic inference of generic typevars at call
sites. It does not bring in a full unification algorithm, and there are
a few TODOs in the test suite that are not discharged by this. But it
handles a good number of useful cases! And the PR does not add anything
that would go away with a more sophisticated constraint solver.
In short, we just look for typevars in the formal parameters, and assume
that the inferred type of the corresponding argument is what that
typevar should map to. If a typevar appears more than once, we union
together the corresponding argument types.
Cases we are not yet handling:
- We are not widening literals.
- We are not recursing into parameters that are themselves generic
aliases.
- We are not being very clever with parameters that are union types.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
* Partial #17238
* Flyby from discord discussion - `todo_type!` now statically checks for
no parens in the message to avoid issues between debug & release build
tests
## Test Plan
many mdtests are changing
This is the first use of the new `lint()` reporter.
I somewhat skipped a step here and also modified the actual diagnostic
message itself. The snapshots should tell the story.
We couldn't do this before because we had no way of differentiating
between "message for the diagnostic as a whole" and "message for a
specific code annotation." Now we can, so we can write more precise
messages based on the assumption that users are also seeing the code
snippet.
The downside here is that the actual message text can become quite vague
in the absence of the code snippet. This occurs, for example, with
concise diagnostic formatting. It's unclear if we should do anything
about it. I don't really see a way to make it better that doesn't
involve creating diagnostics with messages for each mode, which I think
would be a major PITA.
The upside is that this code gets a bit simpler, and we very
specifically avoid doing extra work if this specific lint is disabled.
## Summary
There is a new official URL for the typing documentation:
https://typing.python.org/
Change all https://typing.readthedocs.io/ links to use the new sub
domain, which is slightly shorter and looks more official.
## Test Plan
Tested to see if each and every new URL is accessible. I noticed that
some links go to https://typing.python.org/en/latest/source/stubs.html
which seems to be outdated, but that is a separate issue. The same page
shows up for the old URL.
This PR lets you explicitly specialize a generic class using a subscript
expression. It introduces three new Rust types for representing classes:
- `NonGenericClass`
- `GenericClass` (not specialized)
- `GenericAlias` (specialized)
and two enum wrappers:
- `ClassType` (a non-generic class or generic alias, represents a class
_type_ at runtime)
- `ClassLiteralType` (a non-generic class or generic class, represents a
class body in the AST)
We also add internal support for specializing callables, in particular
function literals. (That is, the internal `Type` representation now
attaches an optional specialization to a function literal.) This is used
in this PR for the methods of a generic class, but should also give us
most of what we need for specializing generic _functions_ (which this PR
does not yet tackle).
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
Catch some Instances, but raise type error for the rest of them
Fixes#16851
## Test Plan
Extend invalid.md in annotations
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This PR closes#16248.
If the return type of the function isn't assignable to the one
specified, an `invalid-return-type` error occurs.
I thought it would be better to report this as a different kind of error
than the `invalid-assignment` error, so I defined this as a new error.
## Test Plan
All type inconsistencies in the test cases have been replaced with
appropriate ones.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
* Attributes/method are now properly looked up on metaclasses, when
called on class objects
* We properly distinguish between data descriptors and non-data
descriptors (but we do not yet support them in store-context, i.e.
`obj.data_descr = …`)
* The descriptor protocol is now implemented in a single unified place
for instances, classes and dunder-calls. Unions and possibly-unbound
symbols are supported in all possible stages of the process by creating
union types as results.
* In general, the handling of "possibly-unbound" symbols has been
improved in a lot of places: meta-class attributes, attributes,
descriptors with possibly-unbound `__get__` methods, instance
attributes, …
* We keep track of type qualifiers in a lot more places. I anticipate
that this will be useful if we import e.g. `Final` symbols from other
modules (see relevant change to typing spec:
https://github.com/python/typing/pull/1937).
* Detection and special-casing of the `typing.Protocol` special form in
order to avoid lots of changes in the test suite due to new `@Todo`
types when looking up attributes on builtin types which have `Protocol`
in their MRO. We previously
looked up attributes in a wrong way, which is why this didn't come up
before.
closes#16367closes#15966
## Context
The way attribute lookup in `Type::member` worked before was simply
wrong (mostly my own fault). The whole instance-attribute lookup should
probably never have been integrated into `Type::member`. And the
`Type::static_member` function that I introduced in my last descriptor
PR was the wrong abstraction. It's kind of fascinating how far this
approach took us, but I am pretty confident that the new approach
proposed here is what we need to model this correctly.
There are three key pieces that are required to implement attribute
lookups:
- **`Type::class_member`**/**`Type::find_in_mro`**: The
`Type::find_in_mro` method that can look up attributes on class bodies
(and corresponding bases). This is a partial function on types, as it
can not be called on instance types like`Type::Instance(…)` or
`Type::IntLiteral(…)`. For this reason, we usually call it through
`Type::class_member`, which is essentially just
`type.to_meta_type().find_in_mro(…)` plus union/intersection handling.
- **`Type::instance_member`**: This new function is basically the
type-level equivalent to `obj.__dict__[name]` when called on
`Type::Instance(…)`. We use this to discover instance attributes such as
those that we see as declarations on class bodies or as (annotated)
assignments to `self.attr` in methods of a class.
- The implementation of the descriptor protocol. It works slightly
different for instances and for class objects, but it can be described
by the general framework:
- Call `type.class_member("attribute")` to look up "attribute" in the
MRO of the meta type of `type`. Call the resulting `Symbol` `meta_attr`
(even if it's unbound).
- Use `meta_attr.class_member("__get__")` to look up `__get__` on the
*meta type* of `meta_attr`. Call it with `__get__(meta_attr, self,
self.to_meta_type())`. If this fails (either the lookup or the call),
just proceed with `meta_attr`. Otherwise, replace `meta_attr` in the
following with the return type of `__get__`. In this step, we also probe
if a `__set__` or `__delete__` method exists and store it in
`meta_attr_kind` (can be either "data descriptor" or "normal attribute
or non-data descriptor").
- Compute a `fallback` type.
- For instances, we use `self.instance_member("attribute")`
- For class objects, we use `class_attr =
self.find_in_mro("attribute")`, and then try to invoke the descriptor
protocol on `class_attr`, i.e. we look up `__get__` on the meta type of
`class_attr` and call it with `__get__(class_attr, None, self)`. This
additional invocation of the descriptor protocol on the fallback type is
one major asymmetry in the otherwise universal descriptor protocol
implementation.
- Finally, we look at `meta_attr`, `meta_attr_kind` and `fallback`, and
handle various cases of (possible) unboundness of these symbols.
- If `meta_attr` is bound and a data descriptor, just return `meta_attr`
- If `meta_attr` is not a data descriptor, and `fallback` is bound, just
return `fallback`
- If `meta_attr` is not a data descriptor, and `fallback` is unbound,
return `meta_attr`
- Return unions of these three possibilities for partially-bound
symbols.
This allows us to handle class objects and instances within the same
framework. There is a minor additional detail where for instances, we do
not allow the fallback type (the instance attribute) to completely
shadow the non-data descriptor. We do this because we (currently) don't
want to pretend that we can statically infer that an instance attribute
is always set.
Dunder method calls can also be embedded into this framework. The only
thing that changes is that *there is no fallback type*. If a dunder
method is called on an instance, we do not fall back to instance
variables. If a dunder method is called on a class object, we only look
it up on the meta class, never on the class itself.
## Test Plan
New Markdown tests.
To kick off the work of supporting generics, this adds many new
(currently failing) tests, showing the behavior we plan to support.
This is still missing a lot! Not included:
- typevar tuples
- param specs
- variance
- `Self`
But it's a good start! We can add more failing tests for those once we
tackle these.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
