`MethodSig` -> `FnSig` & Use it in `ItemKind::Fn` In both AST & HIR, rename `MethodSig` to `FnSig` and then proceed to use it in `ItemKind::Fn` so that the overall structure is more regular. r? @davidtwco
`MethodSig` -> `FnSig` & Use it in `ItemKind::Fn` In both AST & HIR, rename `MethodSig` to `FnSig` and then proceed to use it in `ItemKind::Fn` so that the overall structure is more regular. r? @davidtwco