it's a start

Author: dcreager

crates/ty_python_semantic/resources/mdtest/async.md

@@ -43,9 +43,7 @@ async def main():
     loop = asyncio.get_event_loop()
     with concurrent.futures.ThreadPoolExecutor() as pool:
         result = await loop.run_in_executor(pool, blocking_function)
-
-        # TODO: should be `int`
-        reveal_type(result)  # revealed: Unknown
+        reveal_type(result)  # revealed: int
 ```
 
 ### `asyncio.Task`

crates/ty_python_semantic/resources/mdtest/dataclasses/fields.md

@@ -82,8 +82,7 @@ def get_default() -> str:
 
 reveal_type(field(default=1))  # revealed: dataclasses.Field[Literal[1]]
 reveal_type(field(default=None))  # revealed: dataclasses.Field[None]
-# TODO: this could ideally be `dataclasses.Field[str]` with a better generics solver
-reveal_type(field(default_factory=get_default))  # revealed: dataclasses.Field[Unknown]
+reveal_type(field(default_factory=get_default))  # revealed: dataclasses.Field[str]
 ```
 
 ## dataclass_transform field_specifiers

crates/ty_python_semantic/resources/mdtest/decorators.md

@@ -144,11 +144,8 @@ from functools import cache
 def f(x: int) -> int:
     return x**2
 
-# TODO: Should be `_lru_cache_wrapper[int]`
-reveal_type(f)  # revealed: _lru_cache_wrapper[Unknown]
-
-# TODO: Should be `int`
-reveal_type(f(1))  # revealed: Unknown
+reveal_type(f)  # revealed: _lru_cache_wrapper[int]
+reveal_type(f(1))  # revealed: int
 ```
 
 ## Lambdas as decorators

crates/ty_python_semantic/src/types/generics.rs

@@ -1647,6 +1647,27 @@ impl<'db> SpecializationBuilder<'db> {
                 }
             }
 
+            (Type::Callable(formal_callable), _) => {
+                if let Some(Type::Callable(actual_callable)) =
+                    actual.try_upcast_to_callable(self.db)
+                {
+                    for formal_signature in &formal_callable.signatures(self.db).overloads {
+                        for actual_signature in &actual_callable.signatures(self.db).overloads {
+                            if let Some(formal_return_ty) = formal_signature.return_ty
+                                && let Some(actual_return_ty) = actual_signature.return_ty
+                            {
+                                self.infer_map_impl(
+                                    formal_return_ty,
+                                    actual_return_ty,
+                                    polarity,
+                                    &mut f,
+                                )?;
+                            }
+                        }
+                    }
+                }
+            }
+
             // TODO: Add more forms that we can structurally induct into: type[C], callables
             _ => {}
         }