diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index ece61ff12520c..d0b4889b45fa9 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -237,23 +237,12 @@ impl<T: Idx> BitSet<T> {
         new_word != word
     }
 
-    /// Gets a slice of the underlying words.
-    pub fn words(&self) -> &[Word] {
-        &self.words
-    }
-
     /// Iterates over the indices of set bits in a sorted order.
     #[inline]
     pub fn iter(&self) -> BitIter<'_, T> {
         BitIter::new(&self.words)
     }
 
-    /// Duplicates the set as a hybrid set.
-    pub fn to_hybrid(&self) -> HybridBitSet<T> {
-        // Note: we currently don't bother trying to make a Sparse set.
-        HybridBitSet::Dense(self.to_owned())
-    }
-
     /// Set `self = self | other`. In contrast to `union` returns `true` if the set contains at
     /// least one bit that is not in `other` (i.e. `other` is not a superset of `self`).
     ///
@@ -1601,11 +1590,11 @@ impl<R: Idx, C: Idx> BitMatrix<R, C> {
     pub fn from_row_n(row: &BitSet<C>, num_rows: usize) -> BitMatrix<R, C> {
         let num_columns = row.domain_size();
         let words_per_row = num_words(num_columns);
-        assert_eq!(words_per_row, row.words().len());
+        assert_eq!(words_per_row, row.words.len());
         BitMatrix {
             num_rows,
             num_columns,
-            words: iter::repeat(row.words()).take(num_rows).flatten().cloned().collect(),
+            words: iter::repeat(&row.words).take(num_rows).flatten().cloned().collect(),
             marker: PhantomData,
         }
     }
@@ -1700,9 +1689,9 @@ impl<R: Idx, C: Idx> BitMatrix<R, C> {
         assert_eq!(with.domain_size(), self.num_columns);
         let (write_start, write_end) = self.range(write);
         let mut changed = false;
-        for (read_index, write_index) in iter::zip(0..with.words().len(), write_start..write_end) {
+        for (read_index, write_index) in iter::zip(0..with.words.len(), write_start..write_end) {
             let word = self.words[write_index];
-            let new_word = word | with.words()[read_index];
+            let new_word = word | with.words[read_index];
             self.words[write_index] = new_word;
             changed |= word != new_word;
         }
@@ -2002,54 +1991,6 @@ impl std::fmt::Debug for FiniteBitSet<u32> {
     }
 }
 
-impl FiniteBitSetTy for u64 {
-    const DOMAIN_SIZE: u32 = 64;
-
-    const FILLED: Self = Self::MAX;
-    const EMPTY: Self = Self::MIN;
-
-    const ONE: Self = 1u64;
-    const ZERO: Self = 0u64;
-
-    fn checked_shl(self, rhs: u32) -> Option<Self> {
-        self.checked_shl(rhs)
-    }
-
-    fn checked_shr(self, rhs: u32) -> Option<Self> {
-        self.checked_shr(rhs)
-    }
-}
-
-impl std::fmt::Debug for FiniteBitSet<u64> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:064b}", self.0)
-    }
-}
-
-impl FiniteBitSetTy for u128 {
-    const DOMAIN_SIZE: u32 = 128;
-
-    const FILLED: Self = Self::MAX;
-    const EMPTY: Self = Self::MIN;
-
-    const ONE: Self = 1u128;
-    const ZERO: Self = 0u128;
-
-    fn checked_shl(self, rhs: u32) -> Option<Self> {
-        self.checked_shl(rhs)
-    }
-
-    fn checked_shr(self, rhs: u32) -> Option<Self> {
-        self.checked_shr(rhs)
-    }
-}
-
-impl std::fmt::Debug for FiniteBitSet<u128> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:0128b}", self.0)
-    }
-}
-
 /// A fixed-sized bitset type represented by an integer type. Indices outwith than the range
 /// representable by `T` are considered set.
 #[derive(Copy, Clone, Eq, PartialEq, Decodable, Encodable)]
diff --git a/compiler/rustc_index/src/vec.rs b/compiler/rustc_index/src/vec.rs
index 99e72e49f8eb8..66c5cc774b224 100644
--- a/compiler/rustc_index/src/vec.rs
+++ b/compiler/rustc_index/src/vec.rs
@@ -137,10 +137,6 @@ impl<I: Idx, T> IndexVec<I, T> {
         self.raw.truncate(a)
     }
 
-    pub fn convert_index_type<Ix: Idx>(self) -> IndexVec<Ix, T> {
-        IndexVec::from_raw(self.raw)
-    }
-
     /// Grows the index vector so that it contains an entry for
     /// `elem`; if that is already true, then has no
     /// effect. Otherwise, inserts new values as needed by invoking
diff --git a/compiler/rustc_index/src/vec/tests.rs b/compiler/rustc_index/src/vec/tests.rs
index cb0f0db220d97..7e5e41bd2d19e 100644
--- a/compiler/rustc_index/src/vec/tests.rs
+++ b/compiler/rustc_index/src/vec/tests.rs
@@ -1,5 +1,3 @@
-#![allow(dead_code)]
-
 // Allows the macro invocation below to work
 use crate as rustc_index;