diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
index 8344ddb2a6967..641a31b6d2179 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
@@ -61,7 +61,7 @@ use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
 use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
-use rustc_target::abi::{FieldIdx, Integer, Primitive, Size, VariantIdx, FIRST_VARIANT};
+use rustc_target::abi::{FieldIdx, Integer, VariantIdx, FIRST_VARIANT};
 
 use self::Constructor::*;
 use self::SliceKind::*;
@@ -93,26 +93,27 @@ fn fast_try_eval_bits<'tcx>(
     param_env: ty::ParamEnv<'tcx>,
     value: &mir::Const<'tcx>,
 ) -> Option<u128> {
-    let int  = match value {
-        // If the constant is already evaluated, we shortcut here.
-        mir::Const::Ty(c) if let ty::ConstKind::Value(valtree) = c.kind() => {
-            valtree.unwrap_leaf()
-        },
-        // This is a more general form of the previous case.
-        _ => {
-            value.try_eval_scalar_int(tcx, param_env)?
-        },
-    };
-    let size = match value.ty().kind() {
-        ty::Bool => Size::from_bytes(1),
-        ty::Char => Size::from_bytes(4),
-        ty::Int(ity) => Integer::from_int_ty(&tcx, *ity).size(),
-        ty::Uint(uty) => Integer::from_uint_ty(&tcx, *uty).size(),
-        ty::Float(ty::FloatTy::F32) => Primitive::F32.size(&tcx),
-        ty::Float(ty::FloatTy::F64) => Primitive::F64.size(&tcx),
-        _ => return None,
-    };
-    int.to_bits(size).ok()
+    value.try_eval_bits(tcx, param_env)
+    // let int  = match value {
+    //     // If the constant is already evaluated, we shortcut here.
+    //     mir::Const::Ty(c) if let ty::ConstKind::Value(valtree) = c.kind() => {
+    //         valtree.unwrap_leaf()
+    //     },
+    //     // This is a more general form of the previous case.
+    //     _ => {
+    //         value.try_eval_scalar_int(tcx, param_env)?
+    //     },
+    // };
+    // let size = match value.ty().kind() {
+    //     ty::Bool => Size::from_bytes(1),
+    //     ty::Char => Size::from_bytes(4),
+    //     ty::Int(ity) => Integer::from_int_ty(&tcx, *ity).size(),
+    //     ty::Uint(uty) => Integer::from_uint_ty(&tcx, *uty).size(),
+    //     ty::Float(ty::FloatTy::F32) => Primitive::F32.size(&tcx),
+    //     ty::Float(ty::FloatTy::F64) => Primitive::F64.size(&tcx),
+    //     _ => return None,
+    // };
+    // int.to_bits(size).ok()
 }
 
 /// An inclusive interval, used for precise integer exhaustiveness checking.