ModMain.cs

    // WTF, why there no kitchen?
    [HarmonyPatch(typeof(RoomRoleWorker_Kitchen), "GetScore")]
    internal static class RoomRoleWorker_Kitchen__HandleDesignationCategoryChanges {
        public static IEnumerable<CodeInstruction> Transpiler(
            IEnumerable<CodeInstruction> code,
            ILGenerator generator,
            MethodBase original
        ) {
            string name = original.ShortDescription();
            try {
                Log.Message($"[SlippyCheeze] {name}: patching out the DesignationCategory check…");

                CodeMatch[] to_be_removed = new CodeMatch[]{
                    // IL_0018: ldloc.3      // thing
                    new CodeMatch(i => i.IsLdloc()),
                    // IL_0019: ldfld        class Verse.ThingDef Verse.Thing::def
                    new CodeMatch(i => i.LoadsField(AccessTools.Field(typeof(Thing), "def"))),
                    // IL_001e: ldfld        class Verse.DesignationCategoryDef Verse.BuildableDef::designationCategory
                    new CodeMatch(i => i.LoadsField(AccessTools.Field(typeof(BuildableDef), "designationCategory"))),
                    // IL_0023: ldsfld       class Verse.DesignationCategoryDef RimWorld.DesignationCategoryDefOf::Production
                    new CodeMatch(i => i.LoadsField(AccessTools.Field(typeof(DesignationCategoryDefOf), "Production"))),
                    // IL_0028: bne.un       IL_00ad
                    new CodeMatch(i => i.Branches(out Label? _))
                };

                return new CodeMatcher(code, generator)
                    .Start()
                    .MatchStartForward(to_be_removed)
                    .ThrowIfInvalid("finding the designation category check")
                    .RemoveInstructions(to_be_removed.Count())
                    .InstructionEnumeration();
            } catch (Exception ex) {
                Log.Error($"[SlippyCheeze] {name}: {ex}");
                code.ForEach((i, n) => Log.Message($"  {n:###}  {i}"));
                return code;
            }
        }
    }