Iterate over values, not references

We're just iterating over pointer values; it simpler just to iterate
over pointer values rather than const pointer references.

Author: jagerman

include/pybind11/cast.h

@@ -139,12 +139,9 @@ struct all_type_info {
         iterator(vec_iter &&it, detail::type_info *single_base)
             : all_it{std::move(it)}, single{single_base} {}
 
-        using value_type = detail::type_info *;
-        using reference = const value_type &;
-
         bool operator==(const iterator &it) { return single ? single == it.single : all_it == it.all_it; }
         bool operator!=(const iterator &it) { return !(*this == it); }
-        reference operator*() { return single ? single : *all_it; }
+        detail::type_info *operator*() { return single ? single : *all_it; }
         iterator &operator ++() {
             if (single) single = nullptr;
             else ++all_it;
@@ -382,7 +379,7 @@ PYBIND11_NOINLINE inline handle get_object_handle(const void *ptr, const detail:
     auto &instances = get_internals().registered_instances;
     auto range = instances.equal_range(ptr);
     for (auto it = range.first; it != range.second; ++it) {
-        for (const auto &instance_type : detail::all_type_info(Py_TYPE(it->second))) {
+        for (auto instance_type : detail::all_type_info(Py_TYPE(it->second))) {
             if (instance_type && instance_type == type)
                 return handle((PyObject *) it->second);
         }
@@ -485,7 +482,7 @@ class type_caster_generic {
 
         auto it_instances = internals.registered_instances.equal_range(src);
         for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
-            for (auto &instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
+            for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
                 if (instance_type && instance_type == tinfo)
                     return handle((PyObject *) it_i->second).inc_ref();
             }