new solver: improve instrument annotations

compiler/rustc_trait_selection/src/solve/assembly/mod.rs

@@ -490,6 +490,7 @@ fn assemble_non_blanket_impl_candidates<G: GoalKind<'tcx>>(
         }
     }
 
+    #[instrument(level = "debug", skip_all)]
     fn assemble_unsize_to_dyn_candidate<G: GoalKind<'tcx>>(
         &mut self,
         goal: Goal<'tcx, G>,
@@ -507,6 +508,7 @@ fn assemble_unsize_to_dyn_candidate<G: GoalKind<'tcx>>(
         }
     }
 
+    #[instrument(level = "debug", skip_all)]
     fn assemble_blanket_impl_candidates<G: GoalKind<'tcx>>(
         &mut self,
         goal: Goal<'tcx, G>,

compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs

@@ -146,7 +146,7 @@ fn evaluate_root_goal(
 }
 
 impl<'tcx> InferCtxtEvalExt<'tcx> for InferCtxt<'tcx> {
-    #[instrument(level = "debug", skip(self), ret)]
+    #[instrument(level = "debug", skip(self))]
     fn evaluate_root_goal(
         &self,
         goal: Goal<'tcx, ty::Predicate<'tcx>>,

compiler/rustc_trait_selection/src/solve/mod.rs

@@ -288,6 +288,7 @@ fn flounder(&mut self, responses: &[CanonicalResponse<'tcx>]) -> QueryResult<'tc
     /// in [`EvalCtxt::assemble_candidates_via_self_ty`] does not have to normalize
     /// the self type. It is required when structurally matching on any other
     /// arguments of a trait goal, e.g. when assembling builtin unsize candidates.
+    #[instrument(level = "debug", skip(self), ret)]
     fn try_normalize_ty(
         &mut self,
         param_env: ty::ParamEnv<'tcx>,