param_env debugs are instrumental to rustc's success

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>,
@@ -228,7 +229,6 @@ impl<'infcx, 'tcx> InferCtxt<'infcx, 'tcx> {
         ct: &'tcx ty::Const<'tcx>,
         vid_is_expected: bool,
     ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
-        debug!("unify_const_variable: param_env={:?}", param_env);
         let (for_universe, span) = {
             let mut inner = self.inner.borrow_mut();
             let variable_table = &mut inner.const_unification_table();

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>,
@@ -39,7 +40,6 @@ impl<'tcx> TyCtxt<'tcx> {
         promoted: Option<mir::Promoted>,
         span: Option<Span>,
     ) -> EvalToConstValueResult<'tcx> {
-        debug!("const_eval_resolve: param_env={:?}", param_env);
         match ty::Instance::resolve_opt_const_arg(self, param_env, def, substs) {
             Ok(Some(instance)) => {
                 let cid = GlobalId { instance, promoted };

compiler/rustc_middle/src/ty/instance.rs

@@ -347,13 +347,13 @@ 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>,
         def: ty::WithOptConstParam<DefId>,
         substs: SubstsRef<'tcx>,
     ) -> Result<Option<Instance<'tcx>>, ErrorReported> {
-        debug!("resolve_opt_const_arg: param_env={:?},substs={:?}", param_env, substs);
         // All regions in the result of this query are erased, so it's
         // fine to erase all of the input regions.
 

compiler/rustc_ty_utils/src/instance.rs

@@ -10,11 +10,11 @@ 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>)>,
 ) -> Result<Option<Instance<'tcx>>, ErrorReported> {
-    debug!("resolve_instance: key = {:?}", key);
     let (param_env, (did, substs)) = key.into_parts();
     if let Some(did) = did.as_local() {
         if let Some(param_did) = tcx.opt_const_param_of(did) {
@@ -39,13 +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!("inner_resolve_instance: key={:?}", key);
     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);
@@ -94,10 +94,7 @@ fn inner_resolve_instance<'tcx>(
         };
         Ok(Some(Instance { def, substs }))
     };
-    debug!(
-        "inner_resolve_instance: resolve(def.did={:?}, substs={:?}) = {:?}",
-        def.did, substs, result
-    );
+    debug!("inner_resolve_instance: result={:?}", result);
     result
 }