Introduce EnabledLibFeature

Instead of passing around 2-tuples of `(gate_name, attr_sp)`.

Author: jieyouxu

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -649,11 +649,11 @@ fn maybe_stage_features(sess: &Session, features: &Features, krate: &ast::Crate)
 }
 
 fn check_incompatible_features(sess: &Session, features: &Features) {
-    let enabled_features = features
-        .enabled_lang_features()
-        .iter()
-        .map(|feat| (feat.gate_name, feat.attr_sp))
-        .chain(features.enabled_lib_features().iter().copied());
+    let enabled_lang_features =
+        features.enabled_lang_features().iter().map(|feat| (feat.gate_name, feat.attr_sp));
+    let enabled_lib_features =
+        features.enabled_lib_features().iter().map(|feat| (feat.gate_name, feat.attr_sp));
+    let enabled_features = enabled_lang_features.chain(enabled_lib_features);
 
     for (f1, f2) in rustc_feature::INCOMPATIBLE_FEATURES
         .iter()

compiler/rustc_expand/src/config.rs

@@ -11,8 +11,8 @@ use rustc_ast::{
 use rustc_attr as attr;
 use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
 use rustc_feature::{
-    ACCEPTED_LANG_FEATURES, AttributeSafety, EnabledLangFeature, Features, LangFeatureStability,
-    REMOVED_LANG_FEATURES, UNSTABLE_LANG_FEATURES,
+    ACCEPTED_LANG_FEATURES, AttributeSafety, EnabledLangFeature, EnabledLibFeature, Features,
+    LangFeatureStability, REMOVED_LANG_FEATURES, UNSTABLE_LANG_FEATURES,
 };
 use rustc_lint_defs::BuiltinLintDiag;
 use rustc_parse::validate_attr;
@@ -131,7 +131,8 @@ pub fn features(sess: &Session, krate_attrs: &[Attribute], crate_name: Symbol) -
 
             // Otherwise, the feature is unknown. Enable it as a lib feature.
             // It will be checked later whether the feature really exists.
-            features.set_enabled_lib_feature(name, mi.span());
+            features
+                .set_enabled_lib_feature(EnabledLibFeature { gate_name: name, attr_sp: mi.span() });
 
             // Similar to above, detect internal lib features to suppress
             // the ICE message that asks for a report.

compiler/rustc_feature/src/lib.rs

@@ -136,6 +136,6 @@ pub use builtin_attrs::{
 };
 pub use removed::REMOVED_LANG_FEATURES;
 pub use unstable::{
-    EnabledLangFeature, Features, INCOMPATIBLE_FEATURES, LangFeatureStability,
+    EnabledLangFeature, EnabledLibFeature, Features, INCOMPATIBLE_FEATURES, LangFeatureStability,
     UNSTABLE_LANG_FEATURES,
 };

compiler/rustc_feature/src/unstable.rs

@@ -38,7 +38,7 @@ pub struct Features {
     /// `#![feature]` attrs for language features, for error reporting.
     enabled_lang_features: Vec<EnabledLangFeature>,
     /// `#![feature]` attrs for non-language (library) features.
-    enabled_lib_features: Vec<(Symbol, Span)>,
+    enabled_lib_features: Vec<EnabledLibFeature>,
     /// `enabled_lang_features` + `enabled_lib_features`.
     enabled_features: FxHashSet<Symbol>,
 }
@@ -63,17 +63,24 @@ pub enum LangFeatureStability {
     StableSince { version: Symbol },
 }
 
+/// Information abhout an enabled library feature.
+#[derive(Debug, Copy, Clone)]
+pub struct EnabledLibFeature {
+    pub gate_name: Symbol,
+    pub attr_sp: Span,
+}
+
 impl Features {
     /// `since` should be set for stable features that are nevertheless enabled with a `#[feature]`
     /// attribute, indicating since when they are stable.
-    pub fn set_enabled_lang_feature(&mut self, feat: EnabledLangFeature) {
-        self.enabled_lang_features.push(feat);
-        self.enabled_features.insert(feat.gate_name);
+    pub fn set_enabled_lang_feature(&mut self, lang_feat: EnabledLangFeature) {
+        self.enabled_lang_features.push(lang_feat);
+        self.enabled_features.insert(lang_feat.gate_name);
     }
 
-    pub fn set_enabled_lib_feature(&mut self, name: Symbol, span: Span) {
-        self.enabled_lib_features.push((name, span));
-        self.enabled_features.insert(name);
+    pub fn set_enabled_lib_feature(&mut self, lib_feat: EnabledLibFeature) {
+        self.enabled_lib_features.push(lib_feat);
+        self.enabled_features.insert(lib_feat.gate_name);
     }
 
     /// Returns a list of [`EnabledLangFeature`] with info about:
@@ -86,7 +93,7 @@ impl Features {
         &self.enabled_lang_features
     }
 
-    pub fn enabled_lib_features(&self) -> &Vec<(Symbol, Span)> {
+    pub fn enabled_lib_features(&self) -> &Vec<EnabledLibFeature> {
         &self.enabled_lib_features
     }
 

compiler/rustc_lint/src/builtin.rs

@@ -2287,11 +2287,13 @@ declare_lint_pass!(
 impl EarlyLintPass for IncompleteInternalFeatures {
     fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
         let features = cx.builder.features();
-        features
-            .enabled_lang_features()
-            .iter()
-            .map(|feat| (feat.gate_name, feat.attr_sp))
-            .chain(features.enabled_lib_features().into_iter().copied())
+        let lang_features =
+            features.enabled_lang_features().iter().map(|feat| (feat.gate_name, feat.attr_sp));
+        let lib_features =
+            features.enabled_lib_features().iter().map(|feat| (feat.gate_name, feat.attr_sp));
+
+        lang_features
+            .chain(lib_features)
             .filter(|(name, _)| features.incomplete(*name) || features.internal(*name))
             .for_each(|(name, span)| {
                 if features.incomplete(name) {

compiler/rustc_passes/src/stability.rs

@@ -10,7 +10,9 @@ use rustc_attr::{
 };
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::unord::{ExtendUnord, UnordMap, UnordSet};
-use rustc_feature::{ACCEPTED_LANG_FEATURES, EnabledLangFeature, LangFeatureStability};
+use rustc_feature::{
+    ACCEPTED_LANG_FEATURES, EnabledLangFeature, EnabledLibFeature, LangFeatureStability,
+};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId, LocalModDefId};
@@ -950,12 +952,12 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
 
     let enabled_lib_features = tcx.features().enabled_lib_features();
     let mut remaining_lib_features = FxIndexMap::default();
-    for (feature, span) in enabled_lib_features {
-        if remaining_lib_features.contains_key(&feature) {
+    for EnabledLibFeature { gate_name, attr_sp } in enabled_lib_features {
+        if remaining_lib_features.contains_key(gate_name) {
             // Warn if the user enables a lib feature multiple times.
-            tcx.dcx().emit_err(errors::DuplicateFeatureErr { span: *span, feature: *feature });
+            tcx.dcx().emit_err(errors::DuplicateFeatureErr { span: *attr_sp, feature: *gate_name });
         }
-        remaining_lib_features.insert(feature, *span);
+        remaining_lib_features.insert(*gate_name, *attr_sp);
     }
     // `stdbuild` has special handling for `libc`, so we need to
     // recognise the feature when building std.
@@ -987,7 +989,7 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
     /// time, less loading from metadata is performed and thus compiler performance is improved.
     fn check_features<'tcx>(
         tcx: TyCtxt<'tcx>,
-        remaining_lib_features: &mut FxIndexMap<&Symbol, Span>,
+        remaining_lib_features: &mut FxIndexMap<Symbol, Span>,
         remaining_implications: &mut UnordMap<Symbol, Symbol>,
         defined_features: &LibFeatures,
         all_implications: &UnordMap<Symbol, Symbol>,
@@ -1057,7 +1059,7 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
     }
 
     for (feature, span) in remaining_lib_features {
-        tcx.dcx().emit_err(errors::UnknownFeature { span, feature: *feature });
+        tcx.dcx().emit_err(errors::UnknownFeature { span, feature });
     }
 
     for (&implied_by, &feature) in remaining_implications.to_sorted_stable_ord() {

compiler/rustc_query_system/src/ich/impls_syntax.rs

@@ -137,3 +137,11 @@ impl<'tcx> HashStable<StableHashingContext<'tcx>> for rustc_feature::LangFeature
         }
     }
 }
+
+impl<'tcx> HashStable<StableHashingContext<'tcx>> for rustc_feature::EnabledLibFeature {
+    fn hash_stable(&self, hcx: &mut StableHashingContext<'tcx>, hasher: &mut StableHasher) {
+        let rustc_feature::EnabledLibFeature { gate_name, attr_sp } = self;
+        gate_name.hash_stable(hcx, hasher);
+        attr_sp.hash_stable(hcx, hasher);
+    }
+}