remove some unused private trait impls

compiler/rustc_borrowck/src/polonius/legacy/facts.rs

@@ -184,22 +184,6 @@ where
     }
 }
 
-impl<A, B, C, D> FactRow for (A, B, C, D)
-where
-    A: FactCell,
-    B: FactCell,
-    C: FactCell,
-    D: FactCell,
-{
-    fn write(
-        &self,
-        out: &mut dyn Write,
-        location_table: &PoloniusLocationTable,
-    ) -> Result<(), Box<dyn Error>> {
-        write_row(out, location_table, &[&self.0, &self.1, &self.2, &self.3])
-    }
-}
-
 fn write_row(
     out: &mut dyn Write,
     location_table: &PoloniusLocationTable,

compiler/rustc_symbol_mangling/src/export.rs

@@ -21,7 +21,7 @@ macro_rules! default_hash_impl {
     };
 }
 
-default_hash_impl! { i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize, }
+default_hash_impl! { u8, u64, usize, }
 
 impl<'tcx> AbiHashStable<'tcx> for bool {
     #[inline]
@@ -37,13 +37,6 @@ impl<'tcx> AbiHashStable<'tcx> for str {
     }
 }
 
-impl<'tcx> AbiHashStable<'tcx> for String {
-    #[inline]
-    fn abi_hash(&self, tcx: TyCtxt<'tcx>, hasher: &mut StableHasher) {
-        self[..].abi_hash(tcx, hasher);
-    }
-}
-
 impl<'tcx> AbiHashStable<'tcx> for Symbol {
     #[inline]
     fn abi_hash(&self, tcx: TyCtxt<'tcx>, hasher: &mut StableHasher) {