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.
## Summary
Follow-up from #13268, this PR updates the test case to use
`assert_snapshot` now that the output is limited to only include the
rules with diagnostics.
## Test Plan
`cargo insta test`
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
