Auto merge of #132027 - RalfJung:lang-feature-bool-fields, r=nnethercote

nightly feature tracking: get rid of the per-feature bool fields

The `struct Features` that tracks which features are enabled has a ton of public `bool`-typed fields that are basically caching the result of looking up the corresponding feature in `enabled_lang_features`. Having public fields with an invariant is not great, so at least they should be made private. However, it turns out caching these lookups is actually [not worth it](https://github.com/rust-lang/rust/pull/131321#issuecomment-2402068336), so this PR just entirely gets rid of these fields. (The alternative would be to make them private and have a method for each of them to expose them in a read-only way. Most of the diff of this PR would be the same in that case.)

r? `@nnethercote`

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

@@ -116,7 +116,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     // @lcnr believes that successfully evaluating even though there are
                     // used generic parameters is a bug of evaluation, so checking for it
                     // here does feel somewhat sensible.
-                    if !self.features().generic_const_exprs && ct.args.has_non_region_param() {
+                    if !self.features().generic_const_exprs() && ct.args.has_non_region_param() {
                         let def_kind = self.def_kind(instance.def_id());
                         assert!(
                             matches!(

compiler/rustc_middle/src/traits/specialization_graph.rs

@@ -61,7 +61,7 @@ pub enum OverlapMode {
 
 impl OverlapMode {
     pub fn get(tcx: TyCtxt<'_>, trait_id: DefId) -> OverlapMode {
-        let with_negative_coherence = tcx.features().with_negative_coherence;
+        let with_negative_coherence = tcx.features().with_negative_coherence();
         let strict_coherence = tcx.has_attr(trait_id, sym::rustc_strict_coherence);
 
         if with_negative_coherence {

compiler/rustc_middle/src/ty/context.rs

@@ -710,15 +710,15 @@ impl<'tcx> rustc_type_ir::inherent::Safety<TyCtxt<'tcx>> for hir::Safety {
 
 impl<'tcx> rustc_type_ir::inherent::Features<TyCtxt<'tcx>> for &'tcx rustc_feature::Features {
     fn generic_const_exprs(self) -> bool {
-        self.generic_const_exprs
+        self.generic_const_exprs()
     }
 
     fn coroutine_clone(self) -> bool {
-        self.coroutine_clone
+        self.coroutine_clone()
     }
 
     fn associated_const_equality(self) -> bool {
-        self.associated_const_equality
+        self.associated_const_equality()
     }
 }
 

compiler/rustc_middle/src/ty/layout.rs

@@ -398,7 +398,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
                     ),
                 }
             }
-            ty::Array(inner, len) if tcx.features().transmute_generic_consts => {
+            ty::Array(inner, len) if tcx.features().transmute_generic_consts() => {
                 let len_eval = len.try_to_target_usize(tcx);
                 if len_eval == Some(0) {
                     return Ok(SizeSkeleton::Known(Size::from_bytes(0), None));

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1208,7 +1208,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             }
         }
 
-        if self.tcx().features().return_type_notation
+        if self.tcx().features().return_type_notation()
             && let Some(ty::ImplTraitInTraitData::Trait { fn_def_id, .. }) =
                 self.tcx().opt_rpitit_info(def_id)
             && let ty::Alias(_, alias_ty) =

compiler/rustc_middle/src/ty/sty.rs

@@ -750,7 +750,7 @@ impl<'tcx> Ty<'tcx> {
 
     #[inline]
     pub fn new_diverging_default(tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
-        if tcx.features().never_type_fallback { tcx.types.never } else { tcx.types.unit }
+        if tcx.features().never_type_fallback() { tcx.types.never } else { tcx.types.unit }
     }
 
     // lang and diagnostic tys

compiler/rustc_middle/src/ty/util.rs

@@ -877,8 +877,8 @@ impl<'tcx> TyCtxt<'tcx> {
         // FIXME(effects): This is suspicious and should probably not be done,
         // especially now that we enforce host effects and then properly handle
         // effect vars during fallback.
-        let mut host_always_on =
-            !self.features().effects || self.sess.opts.unstable_opts.unleash_the_miri_inside_of_you;
+        let mut host_always_on = !self.features().effects()
+            || self.sess.opts.unstable_opts.unleash_the_miri_inside_of_you;
 
         // Compute the constness required by the context.
         let const_context = self.hir().body_const_context(def_id);
@@ -1826,8 +1826,8 @@ pub fn is_doc_notable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
 /// cause an ICE that we otherwise may want to prevent.
 pub fn intrinsic_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<ty::IntrinsicDef> {
     if (matches!(tcx.fn_sig(def_id).skip_binder().abi(), Abi::RustIntrinsic)
-        && tcx.features().intrinsics)
-        || (tcx.has_attr(def_id, sym::rustc_intrinsic) && tcx.features().rustc_attrs)
+        && tcx.features().intrinsics())
+        || (tcx.has_attr(def_id, sym::rustc_intrinsic) && tcx.features().rustc_attrs())
     {
         Some(ty::IntrinsicDef {
             name: tcx.item_name(def_id.into()),