From ddf9fffdd46e8ed9a4914dbf801ccc0d2bb1ed5b Mon Sep 17 00:00:00 2001
From: MrMelbert <51863163+MrMelbert@users.noreply.github.com>
Date: Thu, 25 Jan 2024 02:38:50 -0600
Subject: [PATCH] Fixes a hard delete with AI laws, adds a stack trace for law
 datums associating with mobs when already associated (#81065)

## About The Pull Request

- Adds a stack trace for law datums associating with mobs when already
associated.
- From what I can tell, any situation in which a law datum is attempting
to associate with another mob when it already has an owner assigned is
an error. So this might help track down similar bugs in the future.
- Fixes a hard delete involving AI laws.
- When a malf AI occupies an APC, it creates an APC copy of the AI. This
is an entirely separate mob.
- In creating this copy, it uses the malf AI's current laws for the new
copy's laws. Exactly. The same datum.
- So the copy attempts to associate with the datum, and nothing happens,
but it still assigns it to the copy's laws var.
- When the AI attempts to return to their core from the APC, it deletes
the copy. Which deletes the law datum, which our main Ai still has a
reference too, so hard delete. Womp womp.
- I fixed this by implementing a new proc, `copy_lawset`. The APC copy
now gets a copy of the laws when the shunt happens.
- This is imperfect, as they are two separate law datums now, it means
any law changes to the first will not directly affect the second... I
think. The whole "parent" AI system should cover this in theory? But I
don't know if it actually does? It's quite confusing.
- We should really codify methods of linking lawsets together rather
than the hackiness that cyborgs do currently.

## Changelog

:cl: Melbert
fix: Fixed AIs who shunt to APCs causing their laws to be deleted.
/:cl:
---
 code/datums/ai_laws/ai_laws.dm     | 20 +++++++++++++++++---
 code/modules/power/apc/apc_malf.dm |  2 +-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/code/datums/ai_laws/ai_laws.dm b/code/datums/ai_laws/ai_laws.dm
index 9b9f9c62841..971dc118f3a 100644
--- a/code/datums/ai_laws/ai_laws.dm
+++ b/code/datums/ai_laws/ai_laws.dm
@@ -139,7 +139,7 @@ GLOBAL_VAR(round_default_lawset)
 	/// These laws will go away when an AI is reset
 	var/list/hacked = list()
 
-/datum/ai_laws/Destroy(force = FALSE, ...)
+/datum/ai_laws/Destroy(force = FALSE)
 	if(!QDELETED(owner)) //Stopgap to help with laws randomly being lost. This stack_trace will hopefully help find the real issues.
 		if(force) //Unless we're forced...
 			stack_trace("AI law datum for [owner] has been forcefully destroyed incorrectly; the owner variable should be cleared first!")
@@ -149,6 +149,18 @@ GLOBAL_VAR(round_default_lawset)
 	owner = null
 	return ..()
 
+/// Makes a copy of the lawset and returns a new law datum.
+/datum/ai_laws/proc/copy_lawset()
+	var/datum/ai_laws/new_lawset = new type()
+	new_lawset.protected_zeroth = protected_zeroth
+	new_lawset.zeroth = zeroth
+	new_lawset.zeroth_borg = zeroth_borg
+	new_lawset.inherent = inherent.Copy()
+	new_lawset.supplied = supplied.Copy()
+	new_lawset.ion = ion.Copy()
+	new_lawset.hacked = hacked.Copy()
+	return new_lawset
+
 /datum/ai_laws/pai
 	name = "pAI Directives"
 	zeroth = ("Serve your master.")
@@ -429,8 +441,10 @@ GLOBAL_VAR(round_default_lawset)
 	to_chat(to_who, examine_block(jointext(printable_laws, "\n")))
 
 /datum/ai_laws/proc/associate(mob/living/silicon/M)
-	if(!owner)
-		owner = M
+	if(owner)
+		CRASH("AI law datum linked to [owner] attempted to associate with another mob [M]")
+
+	owner = M
 
 /**
  * Generates a list of all laws on this datum, including rendered HTML tags if required
diff --git a/code/modules/power/apc/apc_malf.dm b/code/modules/power/apc/apc_malf.dm
index 3b070368804..62134de146e 100644
--- a/code/modules/power/apc/apc_malf.dm
+++ b/code/modules/power/apc/apc_malf.dm
@@ -37,7 +37,7 @@
 	if(!is_station_level(z))
 		return
 	malf.ShutOffDoomsdayDevice()
-	occupier = new /mob/living/silicon/ai(src, malf.laws, malf) //DEAR GOD WHY? //IKR????
+	occupier = new /mob/living/silicon/ai(src, malf.laws.copy_lawset(), malf) //DEAR GOD WHY? //IKR????
 	occupier.adjustOxyLoss(malf.getOxyLoss())
 	if(!findtext(occupier.name, "APC Copy"))
 		occupier.name = "[malf.name] APC Copy"