[ty] Use the return type of `__get__` for descriptor lookups even when `__get__` is called with incorrect arguments (#21424)

crates/ty_python_semantic/resources/mdtest/descriptor_protocol.md

@@ -696,8 +696,16 @@ reveal_type(C().instance_access)  # revealed: str
 reveal_type(C.metaclass_access)  # revealed: bytes
 
 # TODO: These should emit a diagnostic
-reveal_type(C().class_object_access)  # revealed: TailoredForClassObjectAccess
-reveal_type(C.instance_access)  # revealed: TailoredForInstanceAccess
+#
+# However, we use the return-type of `__get__` as the inferred type anyway:
+# the way to specify that the descriptor object itself is returned when the
+# attribute is accessed on the instance or the class is by overloading `__get__`.
+#
+# Using the return type of `__get__` even for `__get__` calls that have invalid
+# arguments passed to them avoids false positives in situations where there are
+# `__get__` calls that we don't sufficiently understand.
+reveal_type(C().class_object_access)  # revealed: int
+reveal_type(C.instance_access)  # revealed: str
 ```
 
 ### Descriptors with incorrect `__get__` signature
@@ -712,10 +720,28 @@ class C:
     descriptor: Descriptor = Descriptor()
 
 # TODO: This should be an error
-reveal_type(C.descriptor)  # revealed: Descriptor
+reveal_type(C.descriptor)  # revealed: int
 
 # TODO: This should be an error
-reveal_type(C().descriptor)  # revealed: Descriptor
+reveal_type(C().descriptor)  # revealed: int
+```
+
+### "Descriptors" with non-callable `__get__` attributes
+
+If `__get__` is not callable at all, the interpreter will still attempt to call the method at
+runtime, and this will raise an exception. As such, even for `__get__ = None`, we still "attempt to
+call `__get__`" on the descriptor object (leading us to infer `Unknown`):
+
+```py
+class BrokenDescriptor:
+    __get__: None = None
+
+class Foo:
+    desc: BrokenDescriptor = BrokenDescriptor()
+
+# TODO: this raises `TypeError` at runtime due to the implicit call to `__get__`;
+# we should emit a diagnostic
+reveal_type(Foo().desc)  # revealed: Unknown
 ```
 
 ### Undeclared descriptor arguments

crates/ty_python_semantic/resources/mdtest/properties.md

@@ -167,10 +167,9 @@ class C:
 c = C()
 c.attr = 1
 
-# TODO: An error should be emitted here, and the type should be `Unknown`
-# or `Never`. See https://github.com/astral-sh/ruff/issues/16298 for more
-# details.
-reveal_type(c.attr)  # revealed: Unknown | property
+# TODO: An error should be emitted here.
+# See https://github.com/astral-sh/ruff/issues/16298 for more details.
+reveal_type(c.attr)  # revealed: Unknown
 ```
 
 ### Wrong setter signature

crates/ty_python_semantic/src/types.rs

@@ -3963,7 +3963,9 @@ impl<'db> Type<'db> {
                         UnionType::from_elements(db, [bindings.return_type(db), self])
                     }
                 })
-                .ok()?;
+                // TODO: an error when calling `__get__` will lead to a `TypeError` or similar at runtime;
+                // we should emit a diagnostic here instead of silently ignoring the error.
+                .unwrap_or_else(|CallError(_, bindings)| bindings.return_type(db));
 
             let descriptor_kind = if self.is_data_descriptor(db) {
                 AttributeKind::DataDescriptor