diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 0d93e1478c420..df2412f446781 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -251,6 +251,10 @@ pub struct InferCtxt<'tcx> {
     /// Whether this inference context should care about region obligations in
     /// the root universe. Most notably, this is used during HIR typeck as region
     /// solving is left to borrowck instead.
+    ///
+    /// This is used in the old solver to enable the generation of regions constraints.
+    /// In the new solver its only used inside the InferCtxt's `Drop` implementation:
+    /// if we're considering regions, and new opaques are registered, we panic.
     pub considering_regions: bool,
     /// `-Znext-solver`: Whether this inference context is used by HIR typeck. If so, we
     /// need to make sure we don't rely on region identity in the trait solver or when
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 3d8ab41b37a31..10a5f380d4c80 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -118,7 +118,7 @@ pub use self::typeck_results::{
 use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason};
 use crate::metadata::{AmbigModChild, ModChild};
 use crate::middle::privacy::EffectiveVisibilities;
-use crate::mir::{Body, CoroutineLayout, CoroutineSavedLocal, SourceInfo};
+use crate::mir::{Body, CoroutineLayout, CoroutineSavedLocal, MirPhase, SourceInfo};
 use crate::query::{IntoQueryKey, Providers};
 use crate::ty;
 use crate::ty::codec::{TyDecoder, TyEncoder};
@@ -1777,7 +1777,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Returns the possibly-auto-generated MIR of a [`ty::InstanceKind`].
     #[instrument(skip(self), level = "debug")]
     pub fn instance_mir(self, instance: ty::InstanceKind<'tcx>) -> &'tcx Body<'tcx> {
-        match instance {
+        let body = match instance {
             ty::InstanceKind::Item(def) => {
                 debug!("calling def_kind on def: {:?}", def);
                 let def_kind = self.def_kind(def);
@@ -1816,7 +1816,15 @@ impl<'tcx> TyCtxt<'tcx> {
             | ty::InstanceKind::FnPtrAddrShim(..)
             | ty::InstanceKind::AsyncDropGlueCtorShim(..)
             | ty::InstanceKind::AsyncDropGlue(..) => self.mir_shims(instance),
-        }
+        };
+
+        assert!(
+            matches!(body.phase, MirPhase::Runtime(_)),
+            "body: {body:?} instance: {instance:?} {:?}",
+            if let ty::InstanceKind::Item(d) = instance { Some(self.def_kind(d)) } else { None },
+        );
+
+        body
     }
 
     /// Gets all attributes with the given name.
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index 50782c578f09f..6d9b8feea05f4 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -1074,7 +1074,12 @@ pub(super) fn build_adt_ctor(tcx: TyCtxt<'_>, ctor_id: DefId) -> Body<'_> {
     // so this would otherwise not get filled).
     body.set_mentioned_items(Vec::new());
 
-    crate::pass_manager::dump_mir_for_phase_change(tcx, &body);
+    pm::run_passes_no_validate(
+        tcx,
+        &mut body,
+        &[],
+        Some(MirPhase::Runtime(RuntimePhase::Optimized)),
+    );
 
     body
 }
diff --git a/compiler/rustc_traits/src/normalize_erasing_regions.rs b/compiler/rustc_traits/src/normalize_erasing_regions.rs
index d3a2c4d20f95d..1e6089dc37f95 100644
--- a/compiler/rustc_traits/src/normalize_erasing_regions.rs
+++ b/compiler/rustc_traits/src/normalize_erasing_regions.rs
@@ -22,7 +22,7 @@ fn try_normalize_after_erasing_regions<'tcx, T: TypeFoldable<TyCtxt<'tcx>> + Par
     goal: PseudoCanonicalInput<'tcx, T>,
 ) -> Result<T, NoSolution> {
     let PseudoCanonicalInput { typing_env, value } = goal;
-    let (infcx, param_env) = tcx.infer_ctxt().build_with_typing_env(typing_env);
+    let (infcx, param_env) = tcx.infer_ctxt().ignoring_regions().build_with_typing_env(typing_env);
     let cause = ObligationCause::dummy();
     match infcx.at(&cause, param_env).query_normalize(value) {
         Ok(Normalized { value: normalized_value, obligations: normalized_obligations }) => {
diff --git a/tests/mir-opt/unusual_item_types.Test-X-{constructor#0}.built.after.mir b/tests/mir-opt/unusual_item_types.Test-X-{constructor#0}.runtime-optimized.after.mir
similarity index 73%
rename from tests/mir-opt/unusual_item_types.Test-X-{constructor#0}.built.after.mir
rename to tests/mir-opt/unusual_item_types.Test-X-{constructor#0}.runtime-optimized.after.mir
index 1e497b412024c..527089e2b2cf0 100644
--- a/tests/mir-opt/unusual_item_types.Test-X-{constructor#0}.built.after.mir
+++ b/tests/mir-opt/unusual_item_types.Test-X-{constructor#0}.runtime-optimized.after.mir
@@ -1,4 +1,4 @@
-// MIR for `Test::X` after built
+// MIR for `Test::X` after runtime-optimized
 
 fn Test::X(_1: usize) -> Test {
     let mut _0: Test;
diff --git a/tests/mir-opt/unusual_item_types.rs b/tests/mir-opt/unusual_item_types.rs
index 8ec15b4014ae5..e547246bae5f5 100644
--- a/tests/mir-opt/unusual_item_types.rs
+++ b/tests/mir-opt/unusual_item_types.rs
@@ -11,7 +11,7 @@ impl A {
 }
 
 // See #59021
-// EMIT_MIR unusual_item_types.Test-X-{constructor#0}.built.after.mir
+// EMIT_MIR unusual_item_types.Test-X-{constructor#0}.runtime-optimized.after.mir
 enum Test {
     X(usize),
     Y { a: usize },