Revert "slot, signal: Avoid compiler warnings from function pointer conversions"

kjellahl · kjellahl · commit 1aabb8971321 · 2018-07-16T12:58:17.000+02:00
This reverts commit c7dbcd5. This can be done in a better way by keeping the union in a template function.
diff --git a/sigc++/functors/slot.h b/sigc++/functors/slot.h
@@ -134,18 +134,7 @@ struct slot_call
   /** Forms a function pointer from call_it().
    * @return A function pointer formed from call_it().
    */
-  static hook address()
-  {
-    // Conversion between different types of function pointers with
-    // reinterpret_cast can make gcc8 print a warning.
-    // https://github.com/libsigcplusplus/libsigcplusplus/issues/1
-    union {
-      hook ph;
-      decltype(&call_it) pc;
-    } u;
-    u.pc = &call_it;
-    return u.ph;
-  }
+  static hook address() { return reinterpret_cast<hook>(&call_it); }
 };
 
 } /* namespace internal */
@@ -202,17 +191,8 @@ class slot<T_return(T_arg...)> : public slot_base
    */
   inline T_return operator()(type_trait_take_t<T_arg>... a) const
   {
-    if (!empty() && !blocked())
-    {
-      // Conversion between different types of function pointers with
-      // reinterpret_cast can make gcc8 print a warning.
-      // https://github.com/libsigcplusplus/libsigcplusplus/issues/1
-      union {
-        internal::hook ph;
-        call_type pc;
-      } u;
-      u.ph = slot_base::rep_->call_;
-      return std::invoke(u.pc, slot_base::rep_, a...);
+    if (!empty() && !blocked()) {
+      return std::invoke(reinterpret_cast<call_type>(slot_base::rep_->call_), slot_base::rep_, a...);
     }
 
     return T_return();
diff --git a/sigc++/signal.h b/sigc++/signal.h
@@ -322,21 +322,12 @@ struct signal_emit<T_return, void, T_arg...>
         return T_return();
       }
 
-      // Conversion between different types of function pointers with
-      // reinterpret_cast can make gcc8 print a warning.
-      // https://github.com/libsigcplusplus/libsigcplusplus/issues/1
-      union {
-        internal::hook ph;
-        call_type pc;
-      } u;
-      u.ph = it->rep_->call_;
-      r_ = (u.pc)(it->rep_, a...);
+      r_ = (reinterpret_cast<call_type>(it->rep_->call_))(it->rep_, a...);
       for (++it; it != slots.end(); ++it)
       {
         if (it->empty() || it->blocked())
           continue;
-        u.ph = it->rep_->call_;
-        r_ = (u.pc)(it->rep_, a...);
+        r_ = (reinterpret_cast<call_type>(it->rep_->call_))(it->rep_, a...);
       }
     }
 
@@ -369,20 +360,12 @@ struct signal_emit<void, void, T_arg...>
     signal_impl_holder exec(impl);
     const temp_slot_list slots(impl->slots_);
 
-    // Conversion between different types of function pointers with
-    // reinterpret_cast can make gcc8 print a warning.
-    // https://github.com/libsigcplusplus/libsigcplusplus/issues/1
-    union {
-      internal::hook ph;
-      call_type pc;
-    } u;
     for (const auto& slot : slots)
     {
       if (slot.empty() || slot.blocked())
         continue;
 
-      u.ph = slot.rep_->call_;
-      (u.pc)(slot.rep_, a...);
+      (reinterpret_cast<call_type>(slot.rep_->call_))(slot.rep_, a...);
     }
   }
 };
