added SWF_SELECTPRIORITY flag to A_SelectWeapon

src/thingdef/thingdef_codeptr.cpp

@@ -3103,12 +3103,19 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_Recoil)
 // A_SelectWeapon
 //
 //===========================================================================
+enum SW_Flags
+{
+	SWF_SELECTPRIORITY = 1,
+};
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SelectWeapon)
 {
 	PARAM_SELF_PROLOGUE(AActor);
 	PARAM_CLASS(cls, AWeapon);
+	PARAM_INT_OPT(flags) { flags = 0; }
 
-	if (cls == NULL || self->player == NULL) 
+	bool selectPriority = !!(flags & SWF_SELECTPRIORITY);
+
+	if ((!selectPriority && cls == NULL) || self->player == NULL)
 	{
 		ACTION_RETURN_BOOL(false);
 	}
@@ -3123,6 +3130,14 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SelectWeapon)
 		}
 		ACTION_RETURN_BOOL(true);
 	}
+	else if (selectPriority)
+	{
+		// [XA] if the named weapon cannot be found (or is a dummy like 'None'),
+		//      select the next highest priority weapon. This is basically
+		//      the same as A_CheckReload minus the ammo check. Handy.
+		self->player->mo->PickNewWeapon(NULL);
+		ACTION_RETURN_BOOL(true);
+	}
 	else
 	{
 		ACTION_RETURN_BOOL(false);

wadsrc/static/actors/actor.txt

@@ -265,7 +265,7 @@ ACTOR Actor native //: Thinker
 	native state A_CheckLOF(state jump, int flags = 0, float range = 0, float minrange = 0, float angle = 0, float pitch = 0, float offsetheight = 0, float offsetwidth = 0, int ptr_target = AAPTR_DEFAULT, float offsetforward = 0);
 	native state A_JumpIfTargetInLOS (state label, float/*angle*/ fov = 0, int flags = 0, float dist_max = 0, float dist_close = 0);
 	native state A_JumpIfInTargetLOS (state label, float/*angle*/ fov = 0, int flags = 0, float dist_max = 0, float dist_close = 0);
-	native bool A_SelectWeapon(class<Weapon> whichweapon);
+	native bool A_SelectWeapon(class<Weapon> whichweapon, int flags = 0);
 	action native A_Punch();
 	action native A_Feathers();
 	action native A_ClassBossHealth();

wadsrc/static/actors/constants.txt

@@ -150,6 +150,9 @@ const int WRF_ALLOWUSER2 = 256;
 const int WRF_ALLOWUSER3 = 512;
 const int WRF_ALLOWUSER4 = 1024;
 
+// Flags for A_SelectWeapon
+const int SWF_SELECTPRIORITY = 1;
+
 // Morph constants
 const int MRF_ADDSTAMINA = 1;
 const int MRF_FULLHEALTH = 2;