remove Canonical::unchecked_rebind, it's unused

Author: lcnr

compiler/rustc_type_ir/src/canonical.rs

@@ -57,16 +57,6 @@ impl<I: Interner, V> Canonical<I, V> {
 letCanonical{ defining_opaque_types, max_universe, variables, value } = self;
 Canonical{ defining_opaque_types, max_universe, variables,value:map_op(value)}
 }
-
-/// Allows you to map the `value` of a canonical while keeping the same set of
-/// bound variables.
-///
-/// **WARNING:** This function is very easy to mis-use, hence the name! See
-/// the comment of [Canonical::unchecked_map] for more details.
-pubfnunchecked_rebind<W>(self,value:W) -> Canonical<I,W>{
-letCanonical{ defining_opaque_types, max_universe, variables,value: _ } = self;
-Canonical{ defining_opaque_types, max_universe, variables, value }
-}
 }
 
 impl<I:Interner,V: fmt::Display> fmt::DisplayforCanonical<I,V>{