diff --git a/src/librustc_mir/transform/check_consts/qualifs.rs b/src/librustc_mir/transform/check_consts/qualifs.rs
index 595ef2aad49d9..367e0e710c834 100644
--- a/src/librustc_mir/transform/check_consts/qualifs.rs
+++ b/src/librustc_mir/transform/check_consts/qualifs.rs
@@ -6,12 +6,10 @@ use syntax_pos::DUMMY_SP;
 
 use super::{ConstKind, Item as ConstCx};
 
-#[derive(Clone, Copy)]
-pub struct QualifSet(u8);
-
-impl QualifSet {
-    fn contains<Q: ?Sized + Qualif>(self) -> bool {
-        self.0 & (1 << Q::IDX) != 0
+pub fn in_any_value_of_ty(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> QualifSet {
+    QualifSet {
+        has_mut_interior: HasMutInterior::in_any_value_of_ty(cx, ty),
+        needs_drop: NeedsDrop::in_any_value_of_ty(cx, ty),
     }
 }
 
@@ -22,14 +20,14 @@ impl QualifSet {
 ///
 /// The default implementations proceed structurally.
 pub trait Qualif {
-    const IDX: usize;
-
     /// The name of the file used to debug the dataflow analysis that computes this qualif.
     const ANALYSIS_NAME: &'static str;
 
     /// Whether this `Qualif` is cleared when a local is moved from.
     const IS_CLEARED_ON_MOVE: bool = false;
 
+    fn in_qualif_set(set: &QualifSet) -> bool;
+
     /// Return the qualification that is (conservatively) correct for any value
     /// of the type.
     fn in_any_value_of_ty(_cx: &ConstCx<'_, 'tcx>, _ty: Ty<'tcx>) -> bool;
@@ -122,9 +120,8 @@ pub trait Qualif {
                     if cx.tcx.trait_of_item(def_id).is_some() {
                         Self::in_any_value_of_ty(cx, constant.literal.ty)
                     } else {
-                        let bits = cx.tcx.at(constant.span).mir_const_qualif(def_id);
-
-                        let qualif = QualifSet(bits).contains::<Self>();
+                        let qualifs = cx.tcx.at(constant.span).mir_const_qualif(def_id);
+                        let qualif = Self::in_qualif_set(&qualifs);
 
                         // Just in case the type is more specific than
                         // the definition, e.g., impl associated const
@@ -210,9 +207,12 @@ pub trait Qualif {
 pub struct HasMutInterior;
 
 impl Qualif for HasMutInterior {
-    const IDX: usize = 0;
     const ANALYSIS_NAME: &'static str = "flow_has_mut_interior";
 
+    fn in_qualif_set(set: &QualifSet) -> bool {
+        set.has_mut_interior
+    }
+
     fn in_any_value_of_ty(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> bool {
         !ty.is_freeze(cx.tcx, cx.param_env, DUMMY_SP)
     }
@@ -275,10 +275,13 @@ impl Qualif for HasMutInterior {
 pub struct NeedsDrop;
 
 impl Qualif for NeedsDrop {
-    const IDX: usize = 1;
     const ANALYSIS_NAME: &'static str = "flow_needs_drop";
     const IS_CLEARED_ON_MOVE: bool = true;
 
+    fn in_qualif_set(set: &QualifSet) -> bool {
+        set.needs_drop
+    }
+
     fn in_any_value_of_ty(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> bool {
         ty.needs_drop(cx.tcx, cx.param_env)
     }
diff --git a/src/librustc_mir/transform/check_consts/validation.rs b/src/librustc_mir/transform/check_consts/validation.rs
index 022f2bcd88144..2f2c65b8469a3 100644
--- a/src/librustc_mir/transform/check_consts/validation.rs
+++ b/src/librustc_mir/transform/check_consts/validation.rs
@@ -19,9 +19,9 @@ use std::ops::Deref;
 use crate::dataflow::{self as old_dataflow, generic as dataflow};
 use self::old_dataflow::IndirectlyMutableLocals;
 use super::ops::{self, NonConstOp};
-use super::qualifs::{HasMutInterior, NeedsDrop};
+use super::qualifs::{self, HasMutInterior, NeedsDrop};
 use super::resolver::FlowSensitiveAnalysis;
-use super::{ConstKind, Item, Qualif, QualifSet, is_lang_panic_fn};
+use super::{ConstKind, Item, Qualif, is_lang_panic_fn};
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum CheckOpResult {
@@ -130,18 +130,16 @@ impl Qualifs<'a, 'mir, 'tcx> {
             .map(|(bb, _)| bb);
 
         let return_block = match return_block {
-            None => return QualifSet::in_any_value_of_ty(item, item.body.return_ty()),
+            None => return qualifs::in_any_value_of_ty(item, item.body.return_ty()),
             Some(bb) => bb,
         };
 
         let return_loc = item.body.terminator_loc(return_block);
 
-        let mut qualifs = QualifSet::default();
-
-        qualifs.set::<NeedsDrop>(self.needs_drop_lazy_seek(RETURN_PLACE, return_loc));
-        qualifs.set::<HasMutInterior>(self.has_mut_interior_lazy_seek(RETURN_PLACE, return_loc));
-
-        qualifs
+        QualifSet {
+            needs_drop: self.needs_drop_lazy_seek(RETURN_PLACE, return_loc),
+            has_mut_interior: self.has_mut_interior_lazy_seek(RETURN_PLACE, return_loc),
+        }
     }
 }