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[ty] Infer parameter specializations of generic aliases (#18021)

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This updates our function specialization inference to infer type
mappings from parameters that are generic aliases, e.g.:

```py
def f[T](x: list[T]) -> T: ...

reveal_type(f(["a", "b"]))  # revealed: str
```

Though note that we're still inferring the type of list literals as
`list[Unknown]`, so for now we actually need something like the
following in our tests:

```py
def _(x: list[str]):
    reveal_type(f(x))  # revealed: str
```
This commit is contained in:
Douglas Creager
2025-05-12 22:12:44 -04:00
committed by GitHub
parent 55df9271ba
commit 0fb94c052e
13 changed files with 98 additions and 85 deletions
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3
crates/ty_python_semantic/resources/mdtest/binary/tuples.md
View File

@@ -17,7 +17,6 @@ def _(x: tuple[int, str], y: tuple[None, tuple[int]]):
```py
def _(x: tuple[int, ...], y: tuple[str, ...]):
# TODO: should be `tuple[int | str, ...]`
reveal_type(x + y) # revealed: tuple[int | Unknown, ...]
reveal_type(x + y) # revealed: tuple[int | str, ...]
reveal_type(x + (1, 2)) # revealed: tuple[int, ...]
```

12
crates/ty_python_semantic/resources/mdtest/generics/legacy/functions.md
View File

@@ -88,14 +88,12 @@ def takes_in_protocol(x: CanIndex[T]) -> T:
return x[0]
def deep_list(x: list[str]) -> None:
# TODO: revealed: list[str]
reveal_type(takes_in_list(x)) # revealed: list[Unknown]
reveal_type(takes_in_list(x)) # revealed: list[str]
# TODO: revealed: str
reveal_type(takes_in_protocol(x)) # revealed: Unknown
def deeper_list(x: list[set[str]]) -> None:
# TODO: revealed: list[set[str]]
reveal_type(takes_in_list(x)) # revealed: list[Unknown]
reveal_type(takes_in_list(x)) # revealed: list[set[str]]
# TODO: revealed: set[str]
reveal_type(takes_in_protocol(x)) # revealed: Unknown
@@ -119,13 +117,11 @@ This also works when passing in arguments that are subclasses of the parameter t
class Sub(list[int]): ...
class GenericSub(list[T]): ...
# TODO: revealed: list[int]
reveal_type(takes_in_list(Sub())) # revealed: list[Unknown]
reveal_type(takes_in_list(Sub())) # revealed: list[int]
# TODO: revealed: int
reveal_type(takes_in_protocol(Sub())) # revealed: Unknown
# TODO: revealed: list[str]
reveal_type(takes_in_list(GenericSub[str]())) # revealed: list[Unknown]
reveal_type(takes_in_list(GenericSub[str]())) # revealed: list[str]
# TODO: revealed: str
reveal_type(takes_in_protocol(GenericSub[str]())) # revealed: Unknown

12
crates/ty_python_semantic/resources/mdtest/generics/pep695/functions.md
View File

@@ -83,14 +83,12 @@ def takes_in_protocol[T](x: CanIndex[T]) -> T:
return x[0]
def deep_list(x: list[str]) -> None:
# TODO: revealed: list[str]
reveal_type(takes_in_list(x)) # revealed: list[Unknown]
reveal_type(takes_in_list(x)) # revealed: list[str]
# TODO: revealed: str
reveal_type(takes_in_protocol(x)) # revealed: Unknown
def deeper_list(x: list[set[str]]) -> None:
# TODO: revealed: list[set[str]]
reveal_type(takes_in_list(x)) # revealed: list[Unknown]
reveal_type(takes_in_list(x)) # revealed: list[set[str]]
# TODO: revealed: set[str]
reveal_type(takes_in_protocol(x)) # revealed: Unknown
@@ -114,13 +112,11 @@ This also works when passing in arguments that are subclasses of the parameter t
class Sub(list[int]): ...
class GenericSub[T](list[T]): ...
# TODO: revealed: list[int]
reveal_type(takes_in_list(Sub())) # revealed: list[Unknown]
reveal_type(takes_in_list(Sub())) # revealed: list[int]
# TODO: revealed: int
reveal_type(takes_in_protocol(Sub())) # revealed: Unknown
# TODO: revealed: list[str]
reveal_type(takes_in_list(GenericSub[str]())) # revealed: list[Unknown]
reveal_type(takes_in_list(GenericSub[str]())) # revealed: list[str]
# TODO: revealed: str
reveal_type(takes_in_protocol(GenericSub[str]())) # revealed: Unknown