Specialize `try_destructure_mir_constant` for its sole user

3 files changed, 9 insertions, 10 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/mod.rs b/compiler/rustc_const_eval/src/const_eval/mod.rs
index 5cc1fa2a497..900adb559bd 100644
--- a/compiler/rustc_const_eval/src/const_eval/mod.rs
+++ b/compiler/rustc_const_eval/src/const_eval/mod.rs
@@ -6,7 +6,7 @@ use crate::interpret::{
 };
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{EvalToValTreeResult, GlobalId};
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
 
 mod error;
@@ -89,14 +89,15 @@ pub(crate) fn eval_to_valtree<'tcx>(
 #[instrument(skip(tcx), level = "debug")]
 pub(crate) fn try_destructure_mir_constant<'tcx>(
     tcx: TyCtxt<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    val: mir::ConstantKind<'tcx>,
+    val: ConstValue<'tcx>,
+    ty: Ty<'tcx>,
 ) -> InterpResult<'tcx, mir::DestructuredConstant<'tcx>> {
+    let param_env = ty::ParamEnv::reveal_all();
     let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, CanAccessStatics::No);
-    let op = ecx.eval_mir_constant(&val, None, None)?;
+    let op = ecx.const_val_to_op(val, ty, None)?;
 
     // We go to `usize` as we cannot allocate anything bigger anyway.
-    let (field_count, variant, down) = match val.ty().kind() {
+    let (field_count, variant, down) = match ty.kind() {
         ty::Array(_, len) => (len.eval_target_usize(tcx, param_env) as usize, None, op),
         ty::Adt(def, _) if def.variants().is_empty() => {
             throw_ub!(Unreachable)
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index e30af165501..ba3be9083be 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -633,7 +633,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
-    pub(super) fn const_val_to_op(
+    pub(crate) fn const_val_to_op(
         &self,
         val_val: ConstValue<'tcx>,
         ty: Ty<'tcx>,
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index 8314f53ba57..826d2a15721 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -52,10 +52,8 @@ pub fn provide(providers: &mut Providers) {
         let (param_env, raw) = param_env_and_value.into_parts();
         const_eval::eval_to_valtree(tcx, param_env, raw)
     };
-    providers.try_destructure_mir_constant = |tcx, param_env_and_value| {
-        let (param_env, value) = param_env_and_value.into_parts();
-        const_eval::try_destructure_mir_constant(tcx, param_env, value).ok()
-    };
+    providers.try_destructure_mir_constant =
+        |tcx, (cv, ty)| const_eval::try_destructure_mir_constant(tcx, cv, ty).ok();
     providers.valtree_to_const_val = |tcx, (ty, valtree)| {
         const_eval::valtree_to_const_value(tcx, ty::ParamEnv::empty().and(ty), valtree)
     };