Remove needless allows

compiler/rustc_middle/src/ty/print/mod.rs

@@ -12,8 +12,6 @@
 
 pub type PrintError = std::fmt::Error;
 
-// FIXME(eddyb) false positive, the lifetime parameters are used with `P:  Printer<...>`.
-#[allow(unused_lifetimes)]
 pub trait Print<'tcx, P> {
     fn print(&self, cx: &mut P) -> Result<(), PrintError>;
 }

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -2719,11 +2719,8 @@ macro_rules! define_print {
     (($self:ident, $cx:ident): $($ty:ty $print:block)+) => {
         $(impl<'tcx, P: PrettyPrinter<'tcx>> Print<'tcx, P> for $ty {
             fn print(&$self, $cx: &mut P) -> Result<(), PrintError> {
-                #[allow(unused_mut)]
-                let mut $cx = $cx;
                 define_scoped_cx!($cx);
                 let _: () = $print;
-                #[allow(unreachable_code)]
                 Ok(())
             }
         })+