clean up target feature system; most of the toggleability is now handled by the ABI target feature check

Author: RalfJung

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -728,7 +728,7 @@ pub(crate) fn global_llvm_features(
  sess.dcx().emit_warn(unknown_feature);
 }
 Some((_, stability, _)) => {
-ifletErr(reason) = stability.toggle_allowed(&sess.target, enable){
+ifletErr(reason) = stability.toggle_allowed(){
  sess.dcx().emit_warn(ForbiddenCTargetFeature{
  feature,
 enabled:if enable {"enabled"}else{"disabled"},

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -19,7 +19,7 @@ use crate::errors;
 pub(crate)fnfrom_target_feature_attr(
 tcx:TyCtxt<'_>,
 attr:&hir::Attribute,
-rust_target_features:&UnordMap<String, target_features::StabilityComputed>,
+rust_target_features:&UnordMap<String, target_features::Stability>,
 target_features:&mutVec<TargetFeature>,
 ){
 letSome(list) = attr.meta_item_list()else{return};
@@ -64,7 +64,7 @@ pub(crate) fn from_target_feature_attr(
 
 // Only allow target features whose feature gates have been enabled
 // and which are permitted to be toggled.
-ifletErr(reason) = stability.toggle_allowed(/*enable*/true){
+ifletErr(reason) = stability.toggle_allowed(){
  tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr{
 span: item.span(),
  feature,
@@ -141,19 +141,18 @@ pub(crate) fn provide(providers: &mut Providers) {
 *providers = Providers{
 rust_target_features: |tcx, cnum| {
 assert_eq!(cnum,LOCAL_CRATE);
-let target = &tcx.sess.target;
 if tcx.sess.opts.actually_rustdoc{
 // rustdoc needs to be able to document functions that use all the features, so
 // whitelist them all
  rustc_target::target_features::all_rust_features()
-.map(|(a, b)| (a.to_string(), b.compute_toggleability(target)))
+.map(|(a, b)| (a.to_string(), b))
 .collect()
 }else{
  tcx.sess
 .target
 .rust_target_features()
 .iter()
-.map(|(a, b, _)| (a.to_string(),b.compute_toggleability(target)))
+.map(|(a, b, _)| (a.to_string(),*b))
 .collect()
 }
 },

compiler/rustc_middle/src/query/mod.rs

@@ -2355,7 +2355,7 @@ rustc_queries! {
 }
 
 /// Returns the Rust target features for the current target. These are not always the same as LLVM target features!
- query rust_target_features(_:CrateNum) -> &'tcx UnordMap<String, rustc_target::target_features::StabilityComputed> {
+ query rust_target_features(_:CrateNum) -> &'tcx UnordMap<String, rustc_target::target_features::Stability> {
  arena_cache
  eval_always
  desc {"looking up Rust target features"}