Technically incorrect comment

[haleyjd]

Background

Version of Chocolate Doom: Any/current

Operating System and version: All

Game: (Doom/Heretic/Hexen/Strife/other) Doom

Any loaded WADs and mods (please include full command line):

Bug description

The comment at

chocolate-doom/src/doom/p_mobj.c

Line 780 in 7f25bf6

// Thing type 0 is actually "player -1 start".

is describing vanilla Doom as "accepting/ignoring" negative doomednums in mapthing_t when that is not what happens. The original game will corrupt arbitrary memory with addresses computed backward from the start of playerstarts[] if given any doomednum between 0 and -32768, in chunks of sizeof(mapthing_t). Emulation of this would be nigh impossible for most cases and it is known to lead to crashing the game easily, but the comment here should be demystified to actually explain what really happens if the behavior is left unchecked.

[andwj]

I think the comment just means that a thing with type 0 in a map is accepted (and ignored) by Vanilla DOOM because it gets treated like a player start. I certainly don't interpret it as saying something about negative values of thing types.

I just tested a map with a thing of type 0 in it, and the Vanilla DOOM.EXE did play the map without any crash. Whatever memory is corrupted by a thing of type 0 does not seem critical to the game working.