Function arg_attrs_for_rust_scalar 

fn arg_attrs_for_rust_scalar<'tcx>(
    cx: LayoutCx<'tcx>,
    scalar: Scalar,
    layout: TyAndLayout<'tcx>,
    offset: Size,
    is_return: bool,
    drop_target_pointee: Option<Ty<'tcx>>,
) -> ArgAttributes

Returns argument attributes for a scalar argument.

drop_target_pointee, if set, causes pointer-typed scalars to be treated like mutable references to the given type. This is used to special-case the argument of ptr::drop_in_place, interpreting it as &mut T instead of *mut T, for the purposes of attributes (which is valid as per its safety contract). If drop_target_pointee is set, offset must be 0 and layout.ty must be a pointer to the given type. Note that for wide pointers this function is called twice – once for the data pointer and once for the vtable pointer. drop_target_pointee must only be set for the data pointer.