Remove allow(dead_code) attributes.

By either removing the function, or change the attribute to something
more precise.

Author: nnethercote

compiler/rustc_transmute/src/layout/dfa.rs

@@ -38,7 +38,7 @@ impl<R> Transitions<R>
 where
     R: Ref,
 {
-    #[allow(dead_code)]
+    #[cfg(test)]
     fn insert(&mut self, transition: Transition<R>, state: State) {
         match transition {
             Transition::Byte(b) => {
@@ -86,15 +86,6 @@ impl<R> Dfa<R>
 where
     R: Ref,
 {
-    #[allow(dead_code)]
-    pub(crate) fn unit() -> Self {
-        let transitions: Map<State, Transitions<R>> = Map::default();
-        let start = State::new();
-        let accepting = start;
-
-        Self { transitions, start, accepting }
-    }
-
     #[cfg(test)]
     pub(crate) fn bool() -> Self {
         let mut transitions: Map<State, Transitions<R>> = Map::default();

compiler/rustc_transmute/src/layout/nfa.rs

@@ -159,11 +159,6 @@ where
         }
         Self { transitions, start, accepting }
     }
-
-    #[allow(dead_code)]
-    pub(crate) fn edges_from(&self, start: State) -> Option<&Map<Transition<R>, Set<State>>> {
-        self.transitions.get(&start)
-    }
 }
 
 impl State {