const_generics: Fix incorrect ty::ParamEnv::empty() usage

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -639,6 +639,10 @@ struct QueryTypeRelatingDelegate<'a, 'tcx> {
 }
 
 impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
+    fn param_env(&self) -> ty::ParamEnv<'tcx> {
+        self.param_env
+    }
+
     fn create_next_universe(&mut self) -> ty::UniverseIndex {
         self.infcx.create_next_universe()
     }

compiler/rustc_infer/src/infer/combine.rs

@@ -221,6 +221,7 @@ impl<'infcx, 'tcx> InferCtxt<'infcx, 'tcx> {
     /// As `3 + 4` contains `N` in its substs, this must not succeed.
     ///
     /// See `src/test/ui/const-generics/occurs-check/` for more examples where this is relevant.
+    #[instrument(level = "debug", skip(self))]
     fn unify_const_variable(
         &self,
         param_env: ty::ParamEnv<'tcx>,

compiler/rustc_infer/src/infer/nll_relate/mod.rs

@@ -72,6 +72,8 @@ where
 }
 
 pub trait TypeRelatingDelegate<'tcx> {
+    fn param_env(&self) -> ty::ParamEnv<'tcx>;
+
     /// Push a constraint `sup: sub` -- this constraint must be
     /// satisfied for the two types to be related. `sub` and `sup` may
     /// be regions from the type or new variables created through the
@@ -473,9 +475,8 @@ where
         self.infcx.tcx
     }
 
-    // FIXME(oli-obk): not sure how to get the correct ParamEnv
     fn param_env(&self) -> ty::ParamEnv<'tcx> {
-        ty::ParamEnv::empty()
+        self.delegate.param_env()
     }
 
     fn tag(&self) -> &'static str {
@@ -819,9 +820,8 @@ where
         self.infcx.tcx
     }
 
-    // FIXME(oli-obk): not sure how to get the correct ParamEnv
     fn param_env(&self) -> ty::ParamEnv<'tcx> {
-        ty::ParamEnv::empty()
+        self.delegate.param_env()
     }
 
     fn tag(&self) -> &'static str {

compiler/rustc_middle/src/mir/interpret/queries.rs

@@ -31,6 +31,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// constant `bar::<T>()` requires a substitution for `T`, if the substitution for `T` is still
     /// too generic for the constant to be evaluated then `Err(ErrorHandled::TooGeneric)` is
     /// returned.
+    #[instrument(level = "debug", skip(self))]
     pub fn const_eval_resolve(
         self,
         param_env: ty::ParamEnv<'tcx>,

compiler/rustc_middle/src/ty/instance.rs

@@ -347,6 +347,7 @@ impl<'tcx> Instance<'tcx> {
     }
 
     // This should be kept up to date with `resolve`.
+    #[instrument(level = "debug", skip(tcx))]
     pub fn resolve_opt_const_arg(
         tcx: TyCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,

compiler/rustc_mir/src/borrow_check/type_check/mod.rs

@@ -1098,6 +1098,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     ) -> Fallible<()> {
         relate_tys::relate_types(
             self.infcx,
+            self.param_env,
             a,
             v,
             b,

compiler/rustc_mir/src/borrow_check/type_check/relate_tys.rs

@@ -18,6 +18,7 @@ use crate::borrow_check::type_check::{BorrowCheckContext, Locations};
 /// variables, but not the type `b`.
 pub(super) fn relate_types<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
     a: Ty<'tcx>,
     v: ty::Variance,
     b: Ty<'tcx>,
@@ -28,7 +29,7 @@ pub(super) fn relate_types<'tcx>(
     debug!("relate_types(a={:?}, v={:?}, b={:?}, locations={:?})", a, v, b, locations);
     TypeRelating::new(
         infcx,
-        NllTypeRelatingDelegate::new(infcx, borrowck_context, locations, category),
+        NllTypeRelatingDelegate::new(infcx, borrowck_context, param_env, locations, category),
         v,
     )
     .relate(a, b)?;
@@ -39,6 +40,8 @@ struct NllTypeRelatingDelegate<'me, 'bccx, 'tcx> {
     infcx: &'me InferCtxt<'me, 'tcx>,
     borrowck_context: Option<&'me mut BorrowCheckContext<'bccx, 'tcx>>,
 
+    param_env: ty::ParamEnv<'tcx>,
+
     /// Where (and why) is this relation taking place?
     locations: Locations,
 
@@ -50,14 +53,19 @@ impl NllTypeRelatingDelegate<'me, 'bccx, 'tcx> {
     fn new(
         infcx: &'me InferCtxt<'me, 'tcx>,
         borrowck_context: Option<&'me mut BorrowCheckContext<'bccx, 'tcx>>,
+        param_env: ty::ParamEnv<'tcx>,
         locations: Locations,
         category: ConstraintCategory,
     ) -> Self {
-        Self { infcx, borrowck_context, locations, category }
+        Self { infcx, borrowck_context, param_env, locations, category }
     }
 }
 
 impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> {
+    fn param_env(&self) -> ty::ParamEnv<'tcx> {
+        self.param_env
+    }
+
     fn create_next_universe(&mut self) -> ty::UniverseIndex {
         self.infcx.create_next_universe()
     }

compiler/rustc_ty_utils/src/instance.rs

@@ -10,6 +10,7 @@ use traits::{translate_substs, Reveal};
 
 use tracing::debug;
 
+#[instrument(level = "debug", skip(tcx))]
 fn resolve_instance<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::ParamEnvAnd<'tcx, (DefId, SubstsRef<'tcx>)>,
@@ -38,13 +39,13 @@ fn resolve_instance_of_const_arg<'tcx>(
     )
 }
 
+#[instrument(level = "debug", skip(tcx))]
 fn inner_resolve_instance<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::ParamEnvAnd<'tcx, (ty::WithOptConstParam<DefId>, SubstsRef<'tcx>)>,
 ) -> Result<Option<Instance<'tcx>>, ErrorReported> {
     let (param_env, (def, substs)) = key.into_parts();
 
-    debug!("resolve(def={:?}, substs={:?})", def.did, substs);
     let result = if let Some(trait_def_id) = tcx.trait_of_item(def.did) {
         debug!(" => associated item, attempting to find impl in param_env {:#?}", param_env);
         let item = tcx.associated_item(def.did);
@@ -93,7 +94,7 @@ fn inner_resolve_instance<'tcx>(
         };
         Ok(Some(Instance { def, substs }))
     };
-    debug!("resolve(def.did={:?}, substs={:?}) = {:?}", def.did, substs, result);
+    debug!("inner_resolve_instance: result={:?}", result);
     result
 }
 

src/test/ui/const-generics/issue-80561-incorrect-param-env.rs

@@ -0,0 +1,24 @@
+// check-pass
+#![feature(const_generics, const_evaluatable_checked)]
+#![allow(incomplete_features)]
+
+// This tests that the correct `param_env` is used so that
+// attempting to normalize `Self::N` does not cause an ICE.
+
+pub struct Foo<const N: usize>;
+
+impl<const N: usize> Foo<N> {
+    pub fn foo() {}
+}
+
+pub trait Bar {
+    const N: usize;
+    fn bar()
+    where
+        [(); Self::N]: ,
+    {
+        Foo::<{ Self::N }>::foo();
+    }
+}
+
+fn main() {}