[red-knot] Special case @final, @override (#17608)

## Summary

This PR adds special-casing for `@final` and `@override` decorator for a
similar reason as https://github.com/astral-sh/ruff/pull/17591 to
support the invalid overload check.

Both `final` and `override` are identity functions which can be removed
once `TypeVar` support is added.

crates/red_knot_python_semantic/resources/primer/bad.txt

@@ -1,3 +1,4 @@
+Expression  # cycle panic (signature_)
 Tanjun  # cycle panic (signature_)
 aiohttp  # missing expression ID
 alerta  # missing expression ID

crates/red_knot_python_semantic/resources/primer/good.txt

@@ -1,5 +1,4 @@
 AutoSplit
-Expression
 PyGithub
 PyWinCtl
 SinbadCogs

crates/red_knot_python_semantic/src/types.rs

@@ -6027,6 +6027,10 @@ bitflags! {
         const OVERLOAD = 1 << 2;
         /// `@abc.abstractmethod`
         const ABSTRACT_METHOD = 1 << 3;
+        /// `@typing.final`
+        const FINAL = 1 << 4;
+        /// `@typing.override`
+        const OVERRIDE = 1 << 6;
     }
 }
 
@@ -6400,6 +6404,8 @@ pub enum KnownFunction {
     Cast,
     /// `typing(_extensions).overload`
     Overload,
+    /// `typing(_extensions).override`
+    Override,
     /// `typing(_extensions).is_protocol`
     IsProtocol,
     /// `typing(_extensions).get_protocol_members`
@@ -6467,6 +6473,7 @@ impl KnownFunction {
             | Self::AssertNever
             | Self::Cast
             | Self::Overload
+            | Self::Override
             | Self::RevealType
             | Self::Final
             | Self::IsProtocol
@@ -7844,6 +7851,7 @@ pub(crate) mod tests {
                 KnownFunction::Cast
                 | KnownFunction::Final
                 | KnownFunction::Overload
+                | KnownFunction::Override
                 | KnownFunction::RevealType
                 | KnownFunction::AssertType
                 | KnownFunction::AssertNever

crates/red_knot_python_semantic/src/types/call/bind.rs

@@ -584,6 +584,14 @@ impl<'db> Bindings<'db> {
                         }
                     }
 
+                    Some(KnownFunction::Override) => {
+                        // TODO: This can be removed once we understand legacy generics because the
+                        // typeshed definition for `typing.overload` is an identity function.
+                        if let [Some(ty)] = overload.parameter_types() {
+                            overload.set_return_type(*ty);
+                        }
+                    }
+
                     Some(KnownFunction::AbstractMethod) => {
                         // TODO: This can be removed once we understand legacy generics because the
                         // typeshed definition for `abc.abstractmethod` is an identity function.
@@ -592,6 +600,14 @@ impl<'db> Bindings<'db> {
                         }
                     }
 
+                    Some(KnownFunction::Final) => {
+                        // TODO: This can be removed once we understand legacy generics because the
+                        // typeshed definition for `abc.abstractmethod` is an identity function.
+                        if let [Some(ty)] = overload.parameter_types() {
+                            overload.set_return_type(*ty);
+                        }
+                    }
+
                     Some(KnownFunction::GetattrStatic) => {
                         let [Some(instance_ty), Some(attr_name), default] =
                             overload.parameter_types()

crates/red_knot_python_semantic/src/types/infer.rs

@@ -1500,6 +1500,14 @@ impl<'db> TypeInferenceBuilder<'db> {
                             function_decorators |= FunctionDecorators::ABSTRACT_METHOD;
                             continue;
                         }
+                        Some(KnownFunction::Final) => {
+                            function_decorators |= FunctionDecorators::FINAL;
+                            continue;
+                        }
+                        Some(KnownFunction::Override) => {
+                            function_decorators |= FunctionDecorators::OVERRIDE;
+                            continue;
+                        }
                         _ => {}
                     }
                 }