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[ty] Add hint if async context manager is used in non-async with statement (#18299)

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# Summary

Adds a subdiagnostic hint in the following scenario where a
synchronous `with` is used with an async context manager:
```py
class Manager:
    async def __aenter__(self): ...
    async def __aexit__(self, *args): ...

# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
# note: Objects of type `Manager` *can* be used as async context managers
# note: Consider using `async with` here
with Manager():
    ...
```

closes https://github.com/astral-sh/ty/issues/508

## Test Plan

New MD snapshot tests

---------

Co-authored-by: David Peter <mail@david-peter.de>
This commit is contained in:
lipefree
2025-05-26 21:34:47 +02:00
committed by GitHub
parent 62ef96f51e
commit 1d20cf9570
3 changed files with 147 additions and 1 deletions
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85
crates/ty_python_semantic/resources/mdtest/snapshots/sync.md_-_With_statements_-_Accidental_use_of_no…_(b07503f9b773ea61).snap Normal file
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@@ -0,0 +1,85 @@
---
source: crates/ty_test/src/lib.rs
expression: snapshot
---
---
mdtest name: sync.md - With statements - Accidental use of non-async `with`
mdtest path: crates/ty_python_semantic/resources/mdtest/with/sync.md
---
# Python source files
## mdtest_snippet.py
```
1 | class Manager:
2 | async def __aenter__(self): ...
3 | async def __aexit__(self, *args): ...
4 |
5 | # error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
6 | with Manager():
7 | ...
8 | class Manager:
9 | async def __aenter__(self): ...
10 | async def __aexit__(self, typ: str, exc, traceback): ...
11 |
12 | # error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
13 | with Manager():
14 | ...
15 | class Manager:
16 | async def __aenter__(self, wrong_extra_arg): ...
17 | async def __aexit__(self, typ, exc, traceback, wrong_extra_arg): ...
18 |
19 | # error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
20 | with Manager():
21 | ...
```
# Diagnostics
```
error[invalid-context-manager]: Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`
--> src/mdtest_snippet.py:6:6
|
5 | # error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and...
6 | with Manager():
| ^^^^^^^^^
7 | ...
8 | class Manager:
|
info: Objects of type `Manager` can be used as async context managers
info: Consider using `async with` here
info: rule `invalid-context-manager` is enabled by default
```
```
error[invalid-context-manager]: Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`
--> src/mdtest_snippet.py:13:6
|
12 | # error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` an...
13 | with Manager():
| ^^^^^^^^^
14 | ...
15 | class Manager:
|
info: Objects of type `Manager` can be used as async context managers
info: Consider using `async with` here
info: rule `invalid-context-manager` is enabled by default
```
```
error[invalid-context-manager]: Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`
--> src/mdtest_snippet.py:20:6
|
19 | # error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` an...
20 | with Manager():
| ^^^^^^^^^
21 | ...
|
info: Objects of type `Manager` can be used as async context managers
info: Consider using `async with` here
info: rule `invalid-context-manager` is enabled by default
```

42
crates/ty_python_semantic/resources/mdtest/with/sync.md
View File

@@ -149,3 +149,45 @@ context_expr = Manager()
with context_expr as f:
reveal_type(f) # revealed: str
```
## Accidental use of non-async `with`
<!-- snapshot-diagnostics -->
If a synchronous `with` statement is used on a type with `__aenter__` and `__aexit__`, we show a
diagnostic hint that the user might have intended to use `asnyc with` instead.
```py
class Manager:
async def __aenter__(self): ...
async def __aexit__(self, *args): ...
# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
with Manager():
...
```
The sub-diagnostic is also provided if the signatures of `__aenter__` and `__aexit__` do not match
the expected signatures for a context manager:
```py
class Manager:
async def __aenter__(self): ...
async def __aexit__(self, typ: str, exc, traceback): ...
# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
with Manager():
...
```
Similarly, we also show the hint if the functions have the wrong number of arguments:
```py
class Manager:
async def __aenter__(self, wrong_extra_arg): ...
async def __aexit__(self, typ, exc, traceback, wrong_extra_arg): ...
# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it does not implement `__enter__` and `__exit__`"
with Manager():
...
```