exhaustive matches are good

compiler/rustc_ty_utils/src/needs_drop.rs

@@ -172,7 +172,31 @@ where
                             queue_type(self, component);
                         }
                     }
-                    _ => return Some(Err(AlwaysRequiresDrop)),
+
+                    ty::Foreign(_) | ty::Dynamic(..) | ty::Placeholder(_) => {
+                        return Some(Err(AlwaysRequiresDrop));
+                    }
+
+                    ty::Bool
+                    | ty::Char
+                    | ty::Int(_)
+                    | ty::Uint(_)
+                    | ty::Float(_)
+                    | ty::Str
+                    | ty::Slice(_)
+                    | ty::Ref(..)
+                    | ty::RawPtr(..)
+                    | ty::FnDef(..)
+                    | ty::FnPtr(..)
+                    | ty::Tuple(_)
+                    | ty::Bound(..)
+                    | ty::GeneratorWitness(..)
+                    | ty::GeneratorWitnessMIR(..)
+                    | ty::Never
+                    | ty::Infer(_)
+                    | ty::Error(_) => {
+                        bug!("unexpected type returned by `needs_drop_components`: {component}")
+                    }
                 }
             }
         }