Commit 4e9f5f25c8

@@ -4000,7 +4000,7 @@ fn resolveComptimeKnownAllocValue(sema: *Sema, block: *Block, alloc: Air.Inst.Re
                 const air_ptr_inst = Air.refToIndex(bin_op.lhs).?;
                 const tag_val = (try sema.resolveMaybeUndefVal(bin_op.rhs)).?;
                 const union_ty = sema.typeOf(bin_op.lhs).childType(mod);
-                const payload_ty = union_ty.unionFieldType(tag_val, mod);
+                const payload_ty = union_ty.unionFieldType(tag_val, mod).?;
                 if (try sema.typeHasOnePossibleValue(payload_ty)) |payload_val| {
                     const new_ptr = ptr_mapping.get(air_ptr_inst).?;
                     const store_val = try mod.unionValue(union_ty, tag_val, payload_val);

@@ -1646,8 +1646,12 @@ pub const Type = struct {
             },
 
             .union_type => |union_type| {
-                if (opt_sema) |sema| try sema.resolveTypeFields(ty);
-                if (ty.containerLayout(mod) != .Packed) {
+                const is_packed = ty.containerLayout(mod) == .Packed;
+                if (opt_sema) |sema| {
+                    try sema.resolveTypeFields(ty);
+                    if (is_packed) try sema.resolveTypeLayout(ty);
+                }
+                if (!is_packed) {
                     return (try ty.abiSizeAdvanced(mod, strat)).scalar * 8;
                 }
                 const union_obj = ip.loadUnionType(union_type);

@@ -417,7 +417,7 @@ pub fn print(
                         try print(.{
                             .ty = field_ty,
                             .val = un.val.toValue(),
-                            }, writer, level - 1, mod);
+                        }, writer, level - 1, mod);
                     } else {
                         try writer.writeAll("(no tag)");
                     }