[ty] Improve invalid-argument-type diagnostics where a union type was provided (#21044)

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Alex Waygood 2025-10-23 14:16:21 +01:00 committed by GitHub
parent 01695513ce
commit dab3d4e917
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@ -820,6 +820,30 @@ def f(x: int = 1, y: str = "foo") -> int:
reveal_type(f(y=2, x="bar")) # revealed: int
```
### Diagnostics for union types where the union is not assignable
<!-- snapshot-diagnostics -->
```py
from typing import Sized
class Foo: ...
class Bar: ...
class Baz: ...
def f(x: Sized): ...
def g(
a: str | Foo,
b: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo,
c: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo | Bar,
d: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo | Bar | Baz,
):
f(a) # error: [invalid-argument-type]
f(b) # error: [invalid-argument-type]
f(c) # error: [invalid-argument-type]
f(d) # error: [invalid-argument-type]
```
## Too many positional arguments
### One too many

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@ -0,0 +1,135 @@
---
source: crates/ty_test/src/lib.rs
expression: snapshot
---
---
mdtest name: function.md - Call expression - Wrong argument type - Diagnostics for union types where the union is not assignable
mdtest path: crates/ty_python_semantic/resources/mdtest/call/function.md
---
# Python source files
## mdtest_snippet.py
```
1 | from typing import Sized
2 |
3 | class Foo: ...
4 | class Bar: ...
5 | class Baz: ...
6 |
7 | def f(x: Sized): ...
8 | def g(
9 | a: str | Foo,
10 | b: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo,
11 | c: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo | Bar,
12 | d: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo | Bar | Baz,
13 | ):
14 | f(a) # error: [invalid-argument-type]
15 | f(b) # error: [invalid-argument-type]
16 | f(c) # error: [invalid-argument-type]
17 | f(d) # error: [invalid-argument-type]
```
# Diagnostics
```
error[invalid-argument-type]: Argument to function `f` is incorrect
--> src/mdtest_snippet.py:14:7
|
12 | d: list[str] | str | dict[str, str] | tuple[str, ...] | bytes | frozenset[str] | set[str] | Foo | Bar | Baz,
13 | ):
14 | f(a) # error: [invalid-argument-type]
| ^ Expected `Sized`, found `str | Foo`
15 | f(b) # error: [invalid-argument-type]
16 | f(c) # error: [invalid-argument-type]
|
info: Element `Foo` of this union is not assignable to `Sized`
info: Function defined here
--> src/mdtest_snippet.py:7:5
|
5 | class Baz: ...
6 |
7 | def f(x: Sized): ...
| ^ -------- Parameter declared here
8 | def g(
9 | a: str | Foo,
|
info: rule `invalid-argument-type` is enabled by default
```
```
error[invalid-argument-type]: Argument to function `f` is incorrect
--> src/mdtest_snippet.py:15:7
|
13 | ):
14 | f(a) # error: [invalid-argument-type]
15 | f(b) # error: [invalid-argument-type]
| ^ Expected `Sized`, found `list[str] | str | dict[str, str] | ... omitted 5 union elements`
16 | f(c) # error: [invalid-argument-type]
17 | f(d) # error: [invalid-argument-type]
|
info: Element `Foo` of this union is not assignable to `Sized`
info: Function defined here
--> src/mdtest_snippet.py:7:5
|
5 | class Baz: ...
6 |
7 | def f(x: Sized): ...
| ^ -------- Parameter declared here
8 | def g(
9 | a: str | Foo,
|
info: rule `invalid-argument-type` is enabled by default
```
```
error[invalid-argument-type]: Argument to function `f` is incorrect
--> src/mdtest_snippet.py:16:7
|
14 | f(a) # error: [invalid-argument-type]
15 | f(b) # error: [invalid-argument-type]
16 | f(c) # error: [invalid-argument-type]
| ^ Expected `Sized`, found `list[str] | str | dict[str, str] | ... omitted 6 union elements`
17 | f(d) # error: [invalid-argument-type]
|
info: Union elements `Foo` and `Bar` are not assignable to `Sized`
info: Function defined here
--> src/mdtest_snippet.py:7:5
|
5 | class Baz: ...
6 |
7 | def f(x: Sized): ...
| ^ -------- Parameter declared here
8 | def g(
9 | a: str | Foo,
|
info: rule `invalid-argument-type` is enabled by default
```
```
error[invalid-argument-type]: Argument to function `f` is incorrect
--> src/mdtest_snippet.py:17:7
|
15 | f(b) # error: [invalid-argument-type]
16 | f(c) # error: [invalid-argument-type]
17 | f(d) # error: [invalid-argument-type]
| ^ Expected `Sized`, found `list[str] | str | dict[str, str] | ... omitted 7 union elements`
|
info: Union element `Foo`, and 2 more union elements, are not assignable to `Sized`
info: Function defined here
--> src/mdtest_snippet.py:7:5
|
5 | class Baz: ...
6 |
7 | def f(x: Sized): ...
| ^ -------- Parameter declared here
8 | def g(
9 | a: str | Foo,
|
info: rule `invalid-argument-type` is enabled by default
```

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@ -3519,6 +3519,36 @@ impl<'db> BindingError<'db> {
"Expected `{expected_ty_display}`, found `{provided_ty_display}`"
));
if let Type::Union(union) = provided_ty {
let union_elements = union.elements(context.db());
let invalid_elements: Vec<Type<'db>> = union
.elements(context.db())
.iter()
.filter(|element| !element.is_assignable_to(context.db(), *expected_ty))
.copied()
.collect();
let first_invalid_element = invalid_elements[0].display(context.db());
if invalid_elements.len() < union_elements.len() {
match &invalid_elements[1..] {
[] => diag.info(format_args!(
"Element `{first_invalid_element}` of this union \
is not assignable to `{expected_ty_display}`",
)),
[single] => diag.info(format_args!(
"Union elements `{first_invalid_element}` and `{}` \
are not assignable to `{expected_ty_display}`",
single.display(context.db()),
)),
rest => diag.info(format_args!(
"Union element `{first_invalid_element}`, \
and {} more union elements, \
are not assignable to `{expected_ty_display}`",
rest.len(),
)),
}
}
}
if let Some(matching_overload) = matching_overload {
if let Some((name_span, parameter_span)) =
matching_overload.get(context.db()).and_then(|overload| {