Remove unused #[allow(...)] statements from compiler/

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -32,6 +32,7 @@ pub enum AutoTraitResult<A> {
     NegativeImpl,
 }
 
+#[allow(dead_code)]
 impl<A> AutoTraitResult<A> {
     fn is_auto(&self) -> bool {
         match *self {

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -2,7 +2,6 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html
 
-#[allow(dead_code)]
 pub mod auto_trait;
 mod chalk_fulfill;
 pub mod codegen;

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -2148,7 +2148,6 @@ trait TraitObligationExt<'tcx> {
 }
 
 impl<'tcx> TraitObligationExt<'tcx> for TraitObligation<'tcx> {
-    #[allow(unused_comparisons)]
     fn derived_cause(
         &self,
         variant: fn(DerivedObligationCause<'tcx>) -> ObligationCauseCode<'tcx>,