librustc: De-`@mut` `IrMaps::num_live_nodes`
librustc: De-`@mut` `IrMaps::num_vars`
librustc: De-`@mut` `IrMaps::live_node_map`
librustc: De-`@mut` `IrMaps::variable_map`
librustc: De-`@mut` `IrMaps::capture_info_map`
librustc: De-`@mut` `IrMaps::var_kinds`
librustc: De-`@mut` `IrMaps::lnks`
librustc: De-`@mut` `IrMaps`
librustc: De-`@mut` `Rib::bindings`
librustc: De-`@mut` `Module::external_module_children`
librustc: De-`@mut` the write guard map
librustc: De-`@mut` `NameBindings::type_def`
librustc: De-`@mut` `NameBindings::value_def`
librustc: De-`@mut` `NameBindings`
librustc: De-`@mut` `Module::anonymous_children`
librustc: De-`@mut` the additional library search paths
librustc: De-`@mut` arrays of `entry` used in the encoder
librustc: De-`@mut` `Module::import_resolutions`
librustc: De-`@mut` several instances of `io::Writer`.

There are a few more related to pretty printing.
librustc: De-`@mut` the bindings list in pattern resolution