This PR updates our iterator protocol machinery to return a tuple spec
describing the elements that are returned, instead of a type. That
allows us to track heterogeneous iterators more precisely, and
consolidates the logic in unpacking and splatting, which are the two
places where we can take advantage of that more precise information.
(Other iterator consumers, like `for` loops, have to collapse the
iterated elements down to a single type regardless, and we provide a new
helper method on `TupleSpec` to perform that summarization.)
## Summary
Implements proper reachability analysis and — in effect — exhaustiveness
checking for `match` statements. This allows us to check the following
code without any errors (leads to *"can implicitly return `None`"* on
`main`):
```py
from enum import Enum, auto
class Color(Enum):
RED = auto()
GREEN = auto()
BLUE = auto()
def hex(color: Color) -> str:
match color:
case Color.RED:
return "#ff0000"
case Color.GREEN:
return "#00ff00"
case Color.BLUE:
return "#0000ff"
```
Note that code like this already worked fine if there was a
`assert_never(color)` statement in a catch-all case, because we would
then consider that `assert_never` call terminal. But now this also works
without the wildcard case. Adding a member to the enum would still lead
to an error here, if that case would not be handled in `hex`.
What needed to happen to support this is a new way of evaluating match
pattern constraints. Previously, we would simply compare the type of the
subject expression against the patterns. For the last case here, the
subject type would still be `Color` and the value type would be
`Literal[Color.BLUE]`, so we would infer an ambiguous truthiness.
Now, before we compare the subject type against the pattern, we first
generate a union type that corresponds to the set of all values that
would have *definitely been matched* by previous patterns. Then, we
build a "narrowed" subject type by computing `subject_type &
~already_matched_type`, and compare *that* against the pattern type. For
the example here, `already_matched_type = Literal[Color.RED] |
Literal[Color.GREEN]`, and so we have a narrowed subject type of `Color
& ~(Literal[Color.RED] | Literal[Color.GREEN]) = Literal[Color.BLUE]`,
which allows us to infer a reachability of `AlwaysTrue`.
<details>
<summary>A note on negated reachability constraints</summary>
It might seem that we now perform duplicate work, because we also record
*negated* reachability constraints. But that is still important for
cases like the following (and possibly also for more realistic
scenarios):
```py
from typing import Literal
def _(x: int | str):
match x:
case None:
pass # never reachable
case _:
y = 1
y
```
</details>
closes https://github.com/astral-sh/ty/issues/99
## Test Plan
* I verified that this solves all examples from the linked ticket (the
first example needs a PEP 695 type alias, because we don't support
legacy type aliases yet)
* Verified that the ecosystem changes are all because of removed false
positives
* Updated tests
## Summary
I noticed that our type narrowing and reachability analysis was
incorrect for class patterns that are not irrefutable. The test cases
below compare the old and the new behavior:
```py
from dataclasses import dataclass
@dataclass
class Point:
x: int
y: int
class Other: ...
def _(target: Point):
y = 1
match target:
case Point(0, 0):
y = 2
case Point(x=0, y=1):
y = 3
case Point(x=1, y=0):
y = 4
reveal_type(y) # revealed: Literal[1, 2, 3, 4] (previously: Literal[2])
def _(target: Point | Other):
match target:
case Point(0, 0):
reveal_type(target) # revealed: Point
case Point(x=0, y=1):
reveal_type(target) # revealed: Point (previously: Never)
case Point(x=1, y=0):
reveal_type(target) # revealed: Point (previously: Never)
case Other():
reveal_type(target) # revealed: Other (previously: Other & ~Point)
```
## Test Plan
New Markdown test
## Summary
closes#19204
## Test Plan
1. test case is added in dedicated file
2. locally tested the code manually
---------
Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>
Co-authored-by: CodeMan62 <sharmahimanshu150082007@gmail.com>
## Summary
This PR moves most of the work of rendering concise diagnostics in Ruff
into `ruff_db`, where the code is shared with ty. To accomplish this
without breaking backwards compatibility in Ruff, there are two main
changes on the `ruff_db`/ty side:
- Added the logic from Ruff for remapping notebook line numbers to cells
- Reordered the fields in the diagnostic to match Ruff and rustc
```text
# old
error[invalid-assignment] try.py:3:1: Object of type `Literal[1]` is not
assignable to `str`
# new
try.py:3:1: error[invalid-assignment]: Object of type `Literal[1]` is
not assignable to `str`
```
I don't think the notebook change failed any tests on its own, and only
a handful of snaphots changed in ty after reordering the fields, but
this will obviously affect any other uses of the concise format, outside
of tests, too.
The other big change should only affect Ruff:
- Added three new `DisplayDiagnosticConfig` options
Micha and I hoped that we could get by with one option
(`hide_severity`), but Ruff also toggles `show_fix_status` itself,
independently (there are cases where we want neither severity nor the
fix status), and during the implementation I realized we also needed
access to an `Applicability`. The main goal here is to suppress the
severity (`error` above) because ruff only uses the `error` severity and
to use the secondary/noqa code instead of the line name
(`invalid-assignment` above).
```text
# ty - same as "new" above
try.py:3:1: error[invalid-assignment]: Object of type `Literal[1]` is
not assignable to `str`
# ruff
try.py:3:1: RUF123 [*] Object of type `Literal[1]` is not assignable to
`str`
```
This part of the concise diagnostic is actually shared with the `full`
output format in Ruff, but with the settings above, there are no
snapshot changes to either format.
## Test Plan
Existing tests with the handful of updates mentioned above, as well as
some new tests in the `concise` module.
Also this PR. Swapping the fields might have broken mypy_primer, unless
it occasionally times out on its own.
I also ran this script in the root of my Ruff checkout, which also has
CPython in it:
```shell
flags=(--isolated --no-cache --no-respect-gitignore --output-format concise .)
diff <(target/release/ruff check ${flags[@]} 2> /dev/null) \
<(ruff check ${flags[@]} 2> /dev/null)
```
This yielded an expected diff due to some t-string error changes on main
since 0.12.4:
```diff
33622c33622
< crates/ruff_python_parser/resources/inline/err/f_string_lambda_without_parentheses.py:1:15: SyntaxError: Expected an element of or the end of the f-string
---
> crates/ruff_python_parser/resources/inline/err/f_string_lambda_without_parentheses.py:1:15: SyntaxError: Expected an f-string or t-string element or the end of the f-string or t-string
33742c33742
< crates/ruff_python_parser/resources/inline/err/implicitly_concatenated_unterminated_string_multiline.py:4:1: SyntaxError: Expected an element of or the end of the f-string
---
> crates/ruff_python_parser/resources/inline/err/implicitly_concatenated_unterminated_string_multiline.py:4:1: SyntaxError: Expected an f-string or t-string element or the end of the f-string or t-string
34131c34131
< crates/ruff_python_parser/resources/inline/err/t_string_lambda_without_parentheses.py:2:15: SyntaxError: Expected an element of or the end of the t-string
---
> crates/ruff_python_parser/resources/inline/err/t_string_lambda_without_parentheses.py:2:15: SyntaxError: Expected an f-string or t-string element or the end of the f-string or t-string
```
So modulo color, the results are identical on 38,186 errors in our test
suite and CPython 3.10.
---------
Co-authored-by: David Peter <mail@david-peter.de>
## Summary
We previously didn't recognize `Literal[Color.RED]` as single-valued, if
the enum also derived from `str` or `int`:
```py
from enum import Enum
class Color(str, Enum):
RED = "red"
GREEN = "green"
BLUE = "blue"
def _(color: Color):
if color == Color.RED:
reveal_type(color) # previously: Color, now: Literal[Color.RED]
```
The reason for that was that `int` and `str` have "custom" `__eq__` and
`__ne__` implementations that return `bool`. We do not treat enum
literals from classes with custom `__eq__` and `__ne__` implementations
as single-valued, but of course we know that `int.__eq__` and
`str.__eq__` are well-behaved.
## Test Plan
New Markdown tests.
This makes caching of submodules independent of whether `Module`
is itself a Salsa ingredient. In fact, this makes the work done in
the prior commit superfluous. But we're possibly keeping it as an
ingredient for now since it's a bit of a tedious change and we might
need it in the near future.
Ref https://github.com/astral-sh/ruff/pull/19495#pullrequestreview-3045736715
## Summary
Add more precise type inference for a limited set of `isinstance(…)`
calls, i.e. return `Literal[True]` if we can be sure that this is the
correct result. This improves exhaustiveness checking / reachability
analysis for if-elif-else chains with `isinstance` checks. For example:
```py
def is_number(x: int | str) -> bool: # no "can implicitly return `None` error here anymore
if isinstance(x, int):
return True
elif isinstance(x, str):
return False
# code here is now detected as being unreachable
```
This PR also adds a new test suite for exhaustiveness checking.
## Test Plan
New Markdown tests
### Ecosystem analysis
The removed diagnostics look good. There's [one
case](f52c4f1afd/torchvision/io/video_reader.py (L125-L143))
where a "true positive" is removed in unreachable code. `src` is
annotated as being of type `str`, but there is an `elif isinstance(src,
bytes)` branch, which we now detect as unreachable. And so the
diagnostic inside that branch is silenced. I don't think this is a
problem, especially once we have a "graying out" feature, or a lint that
warns about unreachable code.
## Summary
Fixes https://github.com/astral-sh/ty/issues/874
Labeling this as `internal`, since we haven't released the
enum-expansion feature.
## Test Plan
New Markdown tests
## Summary
Closes: astral-sh/ty#88
This PR implements an initial version of a mock language server that can
be used to write e2e tests using the real server running in the
background.
The way it works is that you'd use the `TestServerBuilder` to help
construct the `TestServer` with the setup data. This could be the
workspace folders, populating the file and it's content in the memory
file system, setting the right client capabilities to make the server
respond correctly, etc. This can be expanded as we write more test
cases.
There are still a few things to follow-up on:
- ~In the `Drop` implementation, we should assert that there are no
pending notification, request and responses from the server that the
test code hasn't handled yet~ Implemented in [`afd1f82`
(#19391)](afd1f82bde)
- Reduce the setup boilerplate in any way we can
- Improve the final assertion, currently I'm just snapshotting the final
output
## Test Plan
Written a few test cases.
## Summary
This PR implements the following section from the [typing spec on
enums](https://typing.python.org/en/latest/spec/enums.html#enum-definition):
> Enum classes can also be defined using a subclass of `enum.Enum` **or
any class that uses `enum.EnumType` (or a subclass thereof) as a
metaclass**. Note that `enum.EnumType` was named `enum.EnumMeta` prior
to Python 3.11.
part of https://github.com/astral-sh/ty/issues/183
## Test Plan
New Markdown tests
This PR updates our call binding logic to handle splatted arguments.
Complicating matters is that we have separated call bind analysis into
two phases: parameter matching and type checking. Parameter matching
looks at the arity of the function signature and call site, and assigns
arguments to parameters. Importantly, we don't yet know the type of each
argument! This is needed so that we can decide whether to infer the type
of each argument as a type form or value form, depending on the
requirements of the parameter that the argument was matched to.
This is an issue when splatting an argument, since we need to know how
many elements the splatted argument contains to know how many positional
parameters to match it against. And to know how many elements the
splatted argument has, we need to know its type.
To get around this, we now make the assumption that splatted arguments
can only be used with value-form parameters. (If you end up splatting an
argument into a type-form parameter, we will silently pass in its
value-form type instead.) That allows us to preemptively infer the
(value-form) type of any splatted argument, so that we have its arity
available during parameter matching. We defer inference of non-splatted
arguments until after parameter matching has finished, as before.
We reuse a lot of the new tuple machinery to make this happen — in
particular resizing the tuple spec representing the number of arguments
passed in with the tuple length representing the number of parameters
the splat was matched with.
This work also shows that we might need to change how we are performing
argument expansion during overload resolution. At the moment, when we
expand parameters, we assume that each argument will still be matched to
the same parameters as before, and only retry the type-checking phase.
With splatted arguments, this is no longer the case, since the inferred
arity of each union element might be different than the arity of the
union as a whole, which can affect how many parameters the splatted
argument is matched to. See the regression test case in
`mdtest/call/function.md` for more details.
## Summary
Infer the correct type in a scenario like this:
```py
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
for color in Color:
reveal_type(color) # revealed: Color
```
We should eventually support this out-of-the-box when
https://github.com/astral-sh/ty/issues/501 is implemented. For this
reason, @AlexWaygood would prefer to keep things as they are (we
currently infer `Unknown`, so false positives seem unlikely). But it
seemed relatively easy to support, so I'm opening this for discussion.
part of https://github.com/astral-sh/ty/issues/183
## Test Plan
Adapted existing test.
## Ecosystem analysis
```diff
- warning[unused-ignore-comment] rotkehlchen/chain/aggregator.py:591:82: Unused blanket `type: ignore` directive
```
This `unused-ignore-comment` goes away due to a new true positive.
## Summary
Fixes pull-types panics for illegal annotations like
`Literal[object[index]]`.
Originally reported by @AlexWaygood
## Test Plan
* Verified that this caused panics in the playground, when typing (and
potentially hovering over) `x: Literal[obj[0]]`.
* Added a regression test
Summary
--
This PR tweaks Ruff's internal usage of the new diagnostic model to more
closely
match the intended use, as I understand it. Specifically, it moves the
fix/help
suggestion from the primary annotation's message to a subdiagnostic. In
turn, it
adds the secondary/noqa code as the new primary annotation message. As
shown in
the new `ruff_db` tests, this more closely mirrors Ruff's current
diagnostic
output.
I also added `Severity::Help` to render the fix suggestion with a
`help:` prefix
instead of `info:`.
These changes don't have any external impact now but should help a bit
with #19415.
Test Plan
--
New full output format tests in `ruff_db`
Rendered Diagnostics
--
Full diagnostic output from `annotate-snippets` in this PR:
```
error[unused-import]: `os` imported but unused
--> fib.py:1:8
|
1 | import os
| ^^
|
help: Remove unused import: `os`
```
Current Ruff output for the same code:
```
fib.py:1:8: F401 [*] `os` imported but unused
|
1 | import os
| ^^ F401
|
= help: Remove unused import: `os`
```
Proposed final output after #19415:
```
F401 [*] `os` imported but unused
--> fib.py:1:8
|
1 | import os
| ^^
|
help: Remove unused import: `os`
```
These are slightly updated from
https://github.com/astral-sh/ruff/pull/19464#issuecomment-3097377634
below to remove the extra noqa codes in the primary annotation messages
for the first and third cases.
This implements mapping of definitions in stubs to definitions in the
"real" implementation using the approach described in
https://github.com/astral-sh/ty/issues/788#issuecomment-3097000287
I've tested this with goto-definition in vscode with code that uses
`colorama` and `types-colorama`.
Notably this implementation does not add support for stub-mapping stdlib
modules, which can be done as an essentially orthogonal followup in the
implementation of `resolve_real_module`.
Part of https://github.com/astral-sh/ty/issues/788
## Summary
It was faster to implement this then to write the ticket: Disallow
`ClassVar` annotations almost everywhere outside of class body scopes.
## Test Plan
New Markdown tests
## Summary
Disallow `Final` in function parameter- and return-type annotations.
[Typing
spec](https://typing.python.org/en/latest/spec/qualifiers.html#uppercase-final):
> `Final` may only be used in assignments or variable annotations. Using
it in any other position is an error. In particular, `Final` can’t be
used in annotations for function arguments
## Test Plan
Updated MD test
I noticed that the semantic token implementation was not handling
identifiers in a few cases. This adds support for identifiers that
appear in `except`, `case`, `nonlocal`, and `global` statements.
Co-authored-by: UnboundVariable <unbound@gmail.com>
This is a follow-on to #19410 that further reduces the memory usage of
our reachability constraints. When finishing the building of a use-def
map, we walk through all of the "final" states and mark only those
reachability constraints as "used". We then throw away the interior TDD
nodes of any reachability constraints that weren't marked as used.
(This helps because we build up quite a few intermediate TDD nodes when
constructing complex reachability constraints. These nodes can never be
accessed if they were _only_ used as an intermediate TDD node. The
marking step ensures that we keep any nodes that ended up being referred
to in some accessible use-def map state.)
## Summary
Adds proper type inference for implicit instance attributes that are
declared with a "bare" `Final` and adds `invalid-assignment` diagnostics
for all implicit instance attributes that are declared `Final` or
`Final[…]`.
## Test Plan
New and updated MD tests.
## Ecosystem analysis
```diff
pytest (https://github.com/pytest-dev/pytest)
+ error[invalid-return-type] src/_pytest/fixtures.py:1662:24: Return type does not match returned value: expected `Scope`, found `Scope | (Unknown & ~None & ~((...) -> object) & ~str) | (((str, Config, /) -> Unknown) & ~((...) -> object) & ~str) | (Unknown & ~str)
```
The definition of the `scope` attribute is [here](
5f99385635/src/_pytest/fixtures.py (L1020-L1028)).
Looks like this is a new false positive due to missing `TypeAlias`
support that is surfaced here because we now infer a more precise type
for `FixtureDef._scope`.
## Summary
Implement expansion of enums into unions of enum literals (and the
reverse operation). For the enum below, this allows us to understand
that `Color = Literal[Color.RED, Color.GREEN, Color.BLUE]`, or that
`Color & ~Literal[Color.RED] = Literal[Color.GREEN, Color.BLUE]`. This
helps in exhaustiveness checking, which is why we see some removed
`assert_never` false positives. And since exhaustiveness checking also
helps with understanding terminal control flow, we also see a few
removed `invalid-return-type` and `possibly-unresolved-reference` false
positives. This PR also adds expansion of enums in overload resolution
and type narrowing constructs.
```py
from enum import Enum
from typing_extensions import Literal, assert_never
from ty_extensions import Intersection, Not, static_assert, is_equivalent_to
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
type Red = Literal[Color.RED]
type Green = Literal[Color.GREEN]
type Blue = Literal[Color.BLUE]
static_assert(is_equivalent_to(Red | Green | Blue, Color))
static_assert(is_equivalent_to(Intersection[Color, Not[Red]], Green | Blue))
def color_name(color: Color) -> str: # no error here (we detect that this can not implicitly return None)
if color is Color.RED:
return "Red"
elif color is Color.GREEN:
return "Green"
elif color is Color.BLUE:
return "Blue"
else:
assert_never(color) # no error here
```
## Performance
I avoided an initial regression here for large enums, but the
`UnionBuilder` and `IntersectionBuilder` parts can certainly still be
optimized. We might want to use the same technique that we also use for
unions of other literals. I didn't see any problems in our benchmarks so
far, so this is not included yet.
## Test Plan
Many new Markdown tests
## Summary
Emit errors for the following assignments:
```py
class C:
CLASS_LEVEL_CONSTANT: Final[int] = 1
C.CLASS_LEVEL_CONSTANT = 2
C().CLASS_LEVEL_CONSTANT = 2
```
## Test Plan
Updated and new MD tests
Parsing the (invalid) expression `f"{\t"i}"` caused a panic because the
`TStringMiddle` character was "unreachable" due the way the parser
recovered from the line continuation (it ate the t-string start).
The cause of the issue is as follows:
The parser begins parsing the f-string and expects to see a list of
objects, essentially alternating between _interpolated elements_ and
ordinary strings. It is happy to see the first left brace, but then
there is a lexical error caused by the line-continuation character. So
instead of the parser seeing a list of elements with just one member, it
sees a list that starts like this:
- Interpolated element with an invalid token, stored as a `Name`
- Something else built from tokens beginning with `TStringStart` and
`TStringMiddle`
When it sees the `TStringStart` error recovery says "that's a list
element I don't know what to do with, let's skip it". When it sees
`TStringMiddle` it says "oh, that looks like the middle of _some
interpolated string_ so let's try to parse it as one of the literal
elements of my `FString`". Unfortunately, the function being used to
parse individual list elements thinks (arguably correctly) that it's not
possible to have a `TStringMiddle` sitting in your `FString`, and hits
`unreachable`.
Two potential ways (among many) to solve this issue are:
1. Allow a `TStringMiddle` as a valid "literal" part of an f-string
during parsing (with the hope/understanding that this would only occur
in an invalid context)
2. Skip the `TStringMiddle` as an "unexpected/invalid list item" in the
same way that we skipped `TStringStart`.
I have opted for the second approach since it seems somehow more morally
correct, even though it loses more information. To implement this, the
recovery context needs to know whether we are in an f-string or t-string
- hence the changes to that enum. As a bonus we get slightly more
specific error messages in some cases.
Closes#18860
