Clean up and add comment

Author: tiif

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -820,8 +820,6 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &ty::GenericParamDef) -> Result<(), Er
             let def_id = param.def_id.expect_local();
 
             if tcx.features().adt_const_params() {
-                // fixme: should we get rid of the check for LangItem::ConstParamTy? If yes, how should we check
-                // if the trait is implemented.
                 enter_wf_checking_ctxt(tcx, tcx.local_parent(def_id), |wfcx| {
                     wfcx.register_bound(
                         ObligationCause::new(span, def_id, ObligationCauseCode::ConstParam(ty)),

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -102,7 +102,6 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
     lang_item: LangItem,
     parent_cause: ObligationCause<'tcx>,
 ) -> Result<(), ConstParamTyImplementationError<'tcx>> {
-    // FIXME: core panics if remove unsizedconstparamty, figure out why
     assert_matches!(lang_item, LangItem::ConstParamTy);
     let mut need_unstable_feature_bound = false;
 
@@ -152,7 +151,7 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
         let infcx = tcx.infer_ctxt().build(TypingMode::non_body_analysis());
         let ocx = traits::ObligationCtxt::new_with_diagnostics(&infcx);
 
-        // FIXME: add a comment here
+        // Make sure certain types are gated with #[unstable_feature_bound(unsized_const_params)]
         if need_unstable_feature_bound {
             ocx.register_obligation(Obligation::new(
                 tcx,

library/core/src/marker.rs

@@ -1088,7 +1088,7 @@ pub trait ConstParamTy_: StructuralPartialEq + Eq {}
 
 /// Derive macro generating an impl of the trait `ConstParamTy`.
 #[rustc_builtin_macro]
-#[allow_internal_unstable(unsized_const_params)] // todo: remove this?
+#[allow_internal_unstable(unsized_const_params)]
 #[unstable(feature = "adt_const_params", issue = "95174")]
 pub macro ConstParamTy($item:item) {
     /* compiler built-in */