- moved the 'brainexplode' state to the rocket, which is the actor which actually uses it.

This appears to be the only case where an actor was set to a state owned by a completely unrelated actor which would present some problems with state owner checking in AActor::SetState, so let's better get rid of it ASAP.
I believe the only reason this wasn't changed when all actors were exported 8 years ago was that old binary DEHSUPP lump.

src/namedef.h

@@ -209,7 +209,6 @@ xx(XDeath)
 xx(Burn)
 //xx(Ice)			// already defined above
 xx(Disintegrate)
-xx(Brainexplode)
 
 // Weapon animator names.
 xx(Select)

src/scripting/decorate/thingdef_exp.cpp

@@ -476,6 +476,10 @@ static FxExpression *ParseExpression0 (FScanner &sc, PClassActor *cls)
 		{
 			exp = new FxRuntimeStateIndex(ParseExpressionM(sc, cls));
 		}
+		// The parsed expression is of type 'statelabel', but we want a real state here so we must convert it.
+		FArgumentList args;
+		args.Push(exp);
+		exp = new FxFunctionCall(NAME_ResolveState, NAME_None, args, sc);
 		sc.MustGetToken(')');
 		return exp;
 	}

wadsrc/static/dehsupp.txt

@@ -327,7 +327,7 @@ StateMap
 	BossEye,			Spawn, 3,	// S_BRAINEYE - S_BRAINEYE1
 	SpawnShot,			Spawn, 4,	// S_SPAWN1 - S_SPAWN4
 	SpawnFire,			Spawn, 8,	// S_SPAWNFIRE1 - S_SPAWNFIRE8
-	BossBrain,			BrainExplode, 3,	// S_BRAINEXPLODE1 - S_BRAINEXPLODE3
+	Rocket,				BrainExplode, 3,	// S_BRAINEXPLODE1 - S_BRAINEXPLODE3
 	GreenArmor,			Spawn, 2,	// S_ARM1 - S_ARM1A
 	BlueArmor,			Spawn, 2,	// S_ARM2 - S_ARM2A
 	ExplosiveBarrel,	Spawn, 7,	// S_BAR1 - S_BEXP5

wadsrc/static/zscript/doom/bossbrain.txt

@@ -20,10 +20,6 @@ class BossBrain : Actor
 	}
 	States
 	{
-	BrainExplode:
-		MISL BC 10 Bright;
-		MISL D 10 A_BrainExplode;
-		Stop;
 	Spawn:
 		BBRN A -1;
 		Stop;
@@ -162,7 +158,7 @@ extend class Actor
 			boom.DeathSound = "misc/brainexplode";
 			boom.Vel.z = random[BrainScream](0, 255)/128.;
 
-			boom.SetStateLabel ("BossBrain::Brainexplode");
+			boom.SetStateLabel ("Brainexplode");
 			boom.bRocketTrail = false;
 			boom.SetDamage(0);	// disables collision detection which is not wanted here
 			boom.tics -= random[BrainScream](0, 7);

wadsrc/static/zscript/doom/doomweapons.txt

@@ -357,6 +357,10 @@ class Rocket : Actor
 		MISL C 6 Bright;
 		MISL D 4 Bright;
 		Stop;
+	BrainExplode:
+		MISL BC 10 Bright;
+		MISL D 10 A_BrainExplode;
+		Stop;
 	}
 }