Codechange: mark chunks that are not stored as CH_READONLY

This makes it easier to spot chunks that have a save_proc that
is a nullptr, but also prevents confusion, where it looks like
the CH_ type of a chunk has influence on how it is being read.
It is not, it is only used for saving.

src/saveload/economy_sl.cpp

@@ -100,8 +100,8 @@ static void Ptrs_CAPY()
 
 static const ChunkHandler economy_chunk_handlers[] = {
 	{ 'CAPY', Save_CAPY, Load_CAPY, Ptrs_CAPY, nullptr, CH_ARRAY },
-	{ 'PRIC', nullptr,   Load_PRIC, nullptr,   nullptr, CH_RIFF  },
-	{ 'CAPR', nullptr,   Load_CAPR, nullptr,   nullptr, CH_RIFF  },
+	{ 'PRIC', nullptr,   Load_PRIC, nullptr,   nullptr, CH_READONLY  },
+	{ 'CAPR', nullptr,   Load_CAPR, nullptr,   nullptr, CH_READONLY  },
 	{ 'ECMY', Save_ECMY, Load_ECMY, nullptr,   nullptr, CH_ARRAY },
 };
 

src/saveload/engine_sl.cpp

@@ -196,7 +196,7 @@ static void Load_EIDS()
 static const ChunkHandler engine_chunk_handlers[] = {
 	{ 'EIDS', Save_EIDS, Load_EIDS, nullptr, nullptr, CH_ARRAY },
 	{ 'ENGN', Save_ENGN, Load_ENGN, nullptr, nullptr, CH_ARRAY },
-	{ 'ENGS', nullptr,   Load_ENGS, nullptr, nullptr, CH_RIFF  },
+	{ 'ENGS', nullptr,   Load_ENGS, nullptr, nullptr, CH_READONLY  },
 };
 
 extern const ChunkHandlerTable _engine_chunk_handlers(engine_chunk_handlers);

src/saveload/saveload.cpp

@@ -1897,10 +1897,10 @@ static void SlLoadCheckChunk(const ChunkHandler &ch)
  */
 static void SlSaveChunk(const ChunkHandler &ch)
 {
-	ChunkSaveLoadProc *proc = ch.save_proc;
+	if (ch.type == CH_READONLY) return;
 
-	/* Don't save any chunk information if there is no save handler. */
-	if (proc == nullptr) return;
+	ChunkSaveLoadProc *proc = ch.save_proc;
+	assert(proc != nullptr);
 
 	SlWriteUint32(ch.id);
 	Debug(sl, 2, "Saving chunk {:c}{:c}{:c}{:c}", ch.id >> 24, ch.id >> 16, ch.id >> 8, ch.id);

src/saveload/saveload.h

@@ -388,6 +388,7 @@ enum ChunkType {
 	CH_RIFF = 0,
 	CH_ARRAY = 1,
 	CH_SPARSE_ARRAY = 2,
+	CH_READONLY, ///< Chunk is never saved.
 };
 
 /** Handlers and description of chunk. */

src/saveload/station_sl.cpp

@@ -703,7 +703,7 @@ static void Ptrs_ROADSTOP()
 }
 
 static const ChunkHandler station_chunk_handlers[] = {
-	{ 'STNS', nullptr,       Load_STNS,     Ptrs_STNS,     nullptr, CH_ARRAY },
+	{ 'STNS', nullptr,       Load_STNS,     Ptrs_STNS,     nullptr, CH_READONLY },
 	{ 'STNN', Save_STNN,     Load_STNN,     Ptrs_STNN,     nullptr, CH_ARRAY },
 	{ 'ROAD', Save_ROADSTOP, Load_ROADSTOP, Ptrs_ROADSTOP, nullptr, CH_ARRAY },
 };

src/saveload/strings_sl.cpp

@@ -132,7 +132,7 @@ static void Load_NAME()
 
 /** Chunk handlers related to strings. */
 static const ChunkHandler name_chunk_handlers[] = {
-	{ 'NAME', nullptr, Load_NAME, nullptr, nullptr, CH_ARRAY },
+	{ 'NAME', nullptr, Load_NAME, nullptr, nullptr, CH_READONLY },
 };
 
 extern const ChunkHandlerTable _name_chunk_handlers(name_chunk_handlers);

src/saveload/waypoint_sl.cpp

@@ -225,7 +225,7 @@ static void Ptrs_WAYP()
 }
 
 static const ChunkHandler waypoint_chunk_handlers[] = {
-	{ 'CHKP', nullptr, Load_WAYP, Ptrs_WAYP, nullptr, CH_ARRAY },
+	{ 'CHKP', nullptr, Load_WAYP, Ptrs_WAYP, nullptr, CH_READONLY },
 };
 
 extern const ChunkHandlerTable _waypoint_chunk_handlers(waypoint_chunk_handlers);

src/settings.cpp

@@ -2105,7 +2105,7 @@ static void Save_PATS()
 }
 
 static const ChunkHandler setting_chunk_handlers[] = {
-	{ 'OPTS', nullptr,   Load_OPTS, nullptr, nullptr,    CH_RIFF  },
+	{ 'OPTS', nullptr,   Load_OPTS, nullptr, nullptr,    CH_READONLY },
 	{ 'PATS', Save_PATS, Load_PATS, nullptr, Check_PATS, CH_ARRAY },
 };