World|SaveGame: Restore and check state of as many objects as possible

A discrepancy during object state restoration does not halt the entire
process, but only causes a warning to be logged.

Fixes a crash in Hexen where the Mage's lightning weapon mobjs had their
lastEnemy pointer restored to an unmangled pointer value (that had been
truncated from 64 to 32 bits, no less), causing illegal memory access
when switching maps.

Suspiciously, some objects are still being reported as having lost their
targets, which does warrant further investigation.

IssueID #2275

doomsday/apps/client/src/world/base/map.cpp

@@ -3135,9 +3135,12 @@ String Map::objectsDescription() const
 void Map::restoreObjects(Info const &objState, IThinkerMapping const &thinkerMapping) const
 {
     /// @todo Generalize from mobjs to all thinkers?
+    LOG_AS("Map::restoreObjects");
 
     if (!gx.MobjStateAsInfo || !gx.MobjRestoreState) return;
 
+    bool problemsDetected = false;
+
     // Look up all the mobjs.
     QList<thinker_t const *> mobjs;
     thinkers().forAll(0x3, [&mobjs] (thinker_t *th) {
@@ -3148,10 +3151,9 @@ void Map::restoreObjects(Info const &objState, IThinkerMapping const &thinkerMap
     // Check that all objects are found in the state description.
     if (objState.root().contents().size() != mobjs.size())
     {
-        throw Error("Map::restoreObjects",
-                    String::format("Incorrect number of objects: %i in map, %i in description",
-                                   mobjs.size(),
-                                   objState.root().contents().size()));
+        LOGDEV_MAP_WARNING("Different number of objects: %i in map, but got %i in restore data")
+                        << mobjs.size()
+                        << objState.root().contents().size();
     }
 
     // Check the cross-references.
@@ -3172,9 +3174,8 @@ void Map::restoreObjects(Info const &objState, IThinkerMapping const &thinkerMap
             // Restore the state according to the serialized info.
             gx.MobjRestoreState(found->as<MobjThinkerData>().mobj(), state);
 
-            #if defined (DENG2_DEBUG)
+            // Verify that the state is now correct.
             {
-                // Verify that the state is now correct.
                 Info const currentDesc(gx.MobjStateAsInfo(found->as<MobjThinkerData>().mobj()));
                 Info::BlockElement const &currentState = currentDesc.root().contentsInOrder()
                         .first()->as<Info::BlockElement>();
@@ -3183,25 +3184,32 @@ void Map::restoreObjects(Info const &objState, IThinkerMapping const &thinkerMap
                 {
                     if (state.keyValue(key).text != currentState.keyValue(key).text)
                     {
-                        throw Error("Map::restoreObjects",
-                                    String("Object %1 has mismatching '%2' (current:%3 != arch:%4)")
-                                    .arg(privateId)
-                                    .arg(key)
-                                    .arg(currentState.keyValue(key).text)
-                                    .arg(state.keyValue(key).text));
+                        problemsDetected = true;
+                        const String msg = String("Object %1 has mismatching '%2' (current:%3 != arch:%4)")
+                                .arg(privateId)
+                                .arg(key)
+                                .arg(currentState.keyValue(key).text)
+                                .arg(state.keyValue(key).text);
+                        LOGDEV_MAP_WARNING("%s") << msg;
                     }
                 }
             }
-            #endif
         }
         else
         {
-            throw Error("Map::restoreObjects",
-                        String::format("Failed to find thinker matching ID 0x%x", privateId));
+            LOGDEV_MAP_ERROR("Failed to find thinker matching ID 0x%x") << privateId;
         }
     }
 
-    LOGDEV_MSG("State of map objects has been restored");
+    if (problemsDetected)
+    {
+        LOG_MAP_WARNING("Map objects were not fully restored " DENG2_CHAR_MDASH
+                        " gameplay may be affected (enable Developer log entries for details)");
+    }
+    else
+    {
+        LOGDEV_MAP_MSG("State of map objects has been restored");
+    }
 }
 
 void Map::serializeInternalState(Writer &to) const

doomsday/apps/plugins/common/src/world/mobj.cpp

@@ -648,7 +648,7 @@ void mobj_s::write(MapStateWriter *msw) const
         break;
     }
 
-    Writer_WriteInt32(writer, PTR2INT(mo->lastEnemy));
+    Writer_WriteInt32(writer, 0); //PTR2INT(mo->lastEnemy));
 #elif __JHERETIC__
     Writer_WriteInt16(writer, msw->serialIdFor(mo->generator));
 #endif
@@ -887,12 +887,16 @@ int mobj_s::read(MapStateReader *msr)
 #if __JHEXEN__
     if(ver >= 4)
     {
-        tracer    = INT2PTR(mobj_t, Reader_ReadInt32(reader));
+        // This value has not been mangled properly.
+        /*tracer = */INT2PTR(mobj_t, Reader_ReadInt32(reader));
+        tracer = nullptr;
     }
 
     if(ver >= 4)
     {
-        lastEnemy = INT2PTR(mobj_t, Reader_ReadInt32(reader));
+        // This value has not been mangled properly.
+        /*lastEnemy =*/ INT2PTR(mobj_t, Reader_ReadInt32(reader));
+        lastEnemy = nullptr;
     }
 #else
     if(ver >= 5)