Update 'inactive_overload_cache' key

Instead of just the function name, use '__qualname__.name'.

include/pybind11/detail/internals.h

@@ -83,10 +83,10 @@ template <typename value_type>
 using type_map = std::unordered_map<std::type_index, value_type, type_hash, type_equal_to>;
 
 struct overload_hash {
-    inline size_t operator()(const std::pair<const PyObject *, const char *>& v) const {
-        size_t value = std::hash<const void *>()(v.first);
-        value ^= std::hash<const void *>()(v.second)  + 0x9e3779b9 + (value<<6) + (value>>2);
-        return value;
+    inline size_t operator()(const std::pair<const PyObject *, std::string>& v) const {
+        size_t h1 = std::hash<const void *>()(v.first);
+        size_t h2 = std::hash<std::string>()(v.second);
+        return h1^h2;
     }
 };
 
@@ -97,7 +97,7 @@ struct internals {
     type_map<type_info *> registered_types_cpp; // std::type_index -> pybind11's type information
     std::unordered_map<PyTypeObject *, std::vector<type_info *>> registered_types_py; // PyTypeObject* -> base type_info(s)
     std::unordered_multimap<const void *, instance*> registered_instances; // void * -> instance*
-    std::unordered_set<std::pair<const PyObject *, const char *>, overload_hash> inactive_overload_cache;
+    std::unordered_set<std::pair<const PyObject *, std::string>, overload_hash> inactive_overload_cache;
     type_map<std::vector<bool (*)(PyObject *, void *&)>> direct_conversions;
     std::unordered_map<const PyObject *, std::vector<PyObject *>> patients;
     std::forward_list<void (*) (std::exception_ptr)> registered_exception_translators;

include/pybind11/pybind11.h

@@ -2426,7 +2426,10 @@ inline function get_type_overload(const void *this_ptr, const detail::type_info
     if (!self)
         return function();
     handle type = self.get_type();
-    auto key = std::make_pair(type.ptr(), name);
+    /* N.B. This uses `__qualname__.name` instead of `name`
+       to resolve pybind11#1922. */
+    auto full_name = type.attr("__qualname__").cast<std::string>() + "." + name;
+    auto key = std::make_pair(type.ptr(), full_name);
 
     /* Cache functions that aren't overloaded in Python to avoid
        many costly Python dictionary lookups below */