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-rw-r--r--compiler/rustc_feature/src/active.rs69
-rw-r--r--compiler/rustc_feature/src/lib.rs36
-rw-r--r--compiler/rustc_feature/src/removed.rs27
3 files changed, 62 insertions, 70 deletions
diff --git a/compiler/rustc_feature/src/active.rs b/compiler/rustc_feature/src/active.rs
index a02c04ecd3e..83961647bd4 100644
--- a/compiler/rustc_feature/src/active.rs
+++ b/compiler/rustc_feature/src/active.rs
@@ -7,15 +7,6 @@ use rustc_span::edition::Edition;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 
-macro_rules! set {
-    ($field: ident) => {{
-        fn f(features: &mut Features, _: Span) {
-            features.$field = true;
-        }
-        f as fn(&mut Features, Span)
-    }};
-}
-
 #[derive(PartialEq)]
 enum FeatureStatus {
     Default,
@@ -23,16 +14,19 @@ enum FeatureStatus {
     Internal,
 }
 
-macro_rules! declare_features {
-    (__status_to_enum active) => {
+macro_rules! status_to_enum {
+    (active) => {
         FeatureStatus::Default
     };
-    (__status_to_enum incomplete) => {
+    (incomplete) => {
         FeatureStatus::Incomplete
     };
-    (__status_to_enum internal) => {
+    (internal) => {
         FeatureStatus::Internal
     };
+}
+
+macro_rules! declare_features {
     ($(
         $(#[doc = $doc:tt])* ($status:ident, $feature:ident, $ver:expr, $issue:expr, $edition:expr),
     )+) => {
@@ -43,7 +37,10 @@ macro_rules! declare_features {
             &[$(
                 // (sym::$feature, $ver, $issue, $edition, set!($feature))
                 Feature {
-                    state: State::Active { set: set!($feature) },
+                    state: State::Active {
+                        // Sets this feature's corresponding bool within `features`.
+                        set: |features| features.$feature = true,
+                    },
                     name: sym::$feature,
                     since: $ver,
                     issue: to_nonzero($issue),
@@ -58,8 +55,9 @@ macro_rules! declare_features {
             pub declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>,
             /// `#![feature]` attrs for non-language (library) features.
             pub declared_lib_features: Vec<(Symbol, Span)>,
-            /// Features enabled for this crate.
-            pub active_features: FxHashSet<Symbol>,
+            /// `declared_lang_features` + `declared_lib_features`.
+            pub declared_features: FxHashSet<Symbol>,
+            /// Individual features (unstable only).
             $(
                 $(#[doc = $doc])*
                 pub $feature: bool
@@ -67,16 +65,33 @@ macro_rules! declare_features {
         }
 
         impl Features {
+            pub fn set_declared_lang_feature(
+                &mut self,
+                symbol: Symbol,
+                span: Span,
+                since: Option<Symbol>
+            ) {
+                self.declared_lang_features.push((symbol, span, since));
+                self.declared_features.insert(symbol);
+            }
+
+            pub fn set_declared_lib_feature(&mut self, symbol: Symbol, span: Span) {
+                self.declared_lib_features.push((symbol, span));
+                self.declared_features.insert(symbol);
+            }
+
             pub fn walk_feature_fields(&self, mut f: impl FnMut(&str, bool)) {
                 $(f(stringify!($feature), self.$feature);)+
             }
 
-            /// Is the given feature active?
-            pub fn active(&self, feature: Symbol) -> bool {
-                self.active_features.contains(&feature)
+            /// Is the given feature explicitly declared, i.e. named in a
+            /// `#![feature(...)]` within the code?
+            pub fn declared(&self, feature: Symbol) -> bool {
+                self.declared_features.contains(&feature)
             }
 
-            /// Is the given feature enabled?
+            /// Is the given feature enabled, i.e. declared or automatically
+            /// enabled due to the edition?
             ///
             /// Panics if the symbol doesn't correspond to a declared feature.
             pub fn enabled(&self, feature: Symbol) -> bool {
@@ -93,11 +108,10 @@ macro_rules! declare_features {
             pub fn incomplete(&self, feature: Symbol) -> bool {
                 match feature {
                     $(
-                        sym::$feature => declare_features!(__status_to_enum $status) == FeatureStatus::Incomplete,
+                        sym::$feature => status_to_enum!($status) == FeatureStatus::Incomplete,
                     )*
                     // accepted and removed features aren't in this file but are never incomplete
-                    _ if self.declared_lang_features.iter().any(|f| f.0 == feature) => false,
-                    _ if self.declared_lib_features.iter().any(|f| f.0 == feature) => false,
+                    _ if self.declared_features.contains(&feature) => false,
                     _ => panic!("`{}` was not listed in `declare_features`", feature),
                 }
             }
@@ -108,12 +122,11 @@ macro_rules! declare_features {
             pub fn internal(&self, feature: Symbol) -> bool {
                 match feature {
                     $(
-                        sym::$feature => declare_features!(__status_to_enum $status) == FeatureStatus::Internal,
+                        sym::$feature => status_to_enum!($status) == FeatureStatus::Internal,
                     )*
                     // accepted and removed features aren't in this file but are never internal
                     // (a removed feature might have been internal, but it doesn't matter anymore)
-                    _ if self.declared_lang_features.iter().any(|f| f.0 == feature) => false,
-                    _ if self.declared_lib_features.iter().any(|f| f.0 == feature) => false,
+                    _ if self.declared_features.contains(&feature) => false,
                     _ => panic!("`{}` was not listed in `declare_features`", feature),
                 }
             }
@@ -123,9 +136,9 @@ macro_rules! declare_features {
 
 impl Feature {
     /// Sets this feature in `Features`. Panics if called on a non-active feature.
-    pub fn set(&self, features: &mut Features, span: Span) {
+    pub fn set(&self, features: &mut Features) {
         match self.state {
-            State::Active { set } => set(features, span),
+            State::Active { set } => set(features),
             _ => panic!("called `set` on feature `{}` which is not `active`", self.name),
         }
     }
diff --git a/compiler/rustc_feature/src/lib.rs b/compiler/rustc_feature/src/lib.rs
index 69e33115922..4721bff0ec7 100644
--- a/compiler/rustc_feature/src/lib.rs
+++ b/compiler/rustc_feature/src/lib.rs
@@ -23,16 +23,15 @@ mod removed;
 #[cfg(test)]
 mod tests;
 
-use rustc_span::{edition::Edition, symbol::Symbol, Span};
+use rustc_span::{edition::Edition, symbol::Symbol};
 use std::fmt;
 use std::num::NonZeroU32;
 
 #[derive(Clone, Copy)]
 pub enum State {
     Accepted,
-    Active { set: fn(&mut Features, Span) },
+    Active { set: fn(&mut Features) },
     Removed { reason: Option<&'static str> },
-    Stabilized { reason: Option<&'static str> },
 }
 
 impl fmt::Debug for State {
@@ -41,7 +40,6 @@ impl fmt::Debug for State {
             State::Accepted { .. } => write!(f, "accepted"),
             State::Active { .. } => write!(f, "active"),
             State::Removed { .. } => write!(f, "removed"),
-            State::Stabilized { .. } => write!(f, "stabilized"),
         }
     }
 }
@@ -79,8 +77,8 @@ pub enum UnstableFeatures {
 impl UnstableFeatures {
     /// This takes into account `RUSTC_BOOTSTRAP`.
     ///
-    /// If `krate` is [`Some`], then setting `RUSTC_BOOTSTRAP=krate` will enable the nightly features.
-    /// Otherwise, only `RUSTC_BOOTSTRAP=1` will work.
+    /// If `krate` is [`Some`], then setting `RUSTC_BOOTSTRAP=krate` will enable the nightly
+    /// features. Otherwise, only `RUSTC_BOOTSTRAP=1` will work.
     pub fn from_environment(krate: Option<&str>) -> Self {
         // `true` if this is a feature-staged build, i.e., on the beta or stable channel.
         let disable_unstable_features =
@@ -107,19 +105,17 @@ impl UnstableFeatures {
 }
 
 fn find_lang_feature_issue(feature: Symbol) -> Option<NonZeroU32> {
-    if let Some(info) = ACTIVE_FEATURES.iter().find(|t| t.name == feature) {
-        info.issue
-    } else {
-        // search in Accepted, Removed, or Stable Removed features
-        let found = ACCEPTED_FEATURES
-            .iter()
-            .chain(REMOVED_FEATURES)
-            .chain(STABLE_REMOVED_FEATURES)
-            .find(|t| t.name == feature);
-        match found {
-            Some(found) => found.issue,
-            None => panic!("feature `{feature}` is not declared anywhere"),
-        }
+    // Search in all the feature lists.
+    let found = []
+        .iter()
+        .chain(ACTIVE_FEATURES)
+        .chain(ACCEPTED_FEATURES)
+        .chain(REMOVED_FEATURES)
+        .find(|t| t.name == feature);
+
+    match found {
+        Some(found) => found.issue,
+        None => panic!("feature `{feature}` is not declared anywhere"),
     }
 }
 
@@ -152,4 +148,4 @@ pub use builtin_attrs::{
     is_valid_for_get_attr, AttributeGate, AttributeTemplate, AttributeType, BuiltinAttribute,
     GatedCfg, BUILTIN_ATTRIBUTES, BUILTIN_ATTRIBUTE_MAP,
 };
-pub use removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
+pub use removed::REMOVED_FEATURES;
diff --git a/compiler/rustc_feature/src/removed.rs b/compiler/rustc_feature/src/removed.rs
index da18cb2a239..de15deef178 100644
--- a/compiler/rustc_feature/src/removed.rs
+++ b/compiler/rustc_feature/src/removed.rs
@@ -20,23 +20,6 @@ macro_rules! declare_features {
             ),+
         ];
     };
-
-    ($(
-        $(#[doc = $doc:tt])* (stable_removed, $feature:ident, $ver:expr, $issue:expr, None),
-    )+) => {
-        /// Represents stable features which have since been removed (it was once Accepted)
-        pub const STABLE_REMOVED_FEATURES: &[Feature] = &[
-            $(
-                Feature {
-                    state: State::Stabilized { reason: None },
-                    name: sym::$feature,
-                    since: $ver,
-                    issue: to_nonzero($issue),
-                    edition: None,
-                }
-            ),+
-        ];
-    };
 }
 
 #[rustfmt::skip]
@@ -141,6 +124,11 @@ declare_features! (
     (removed, no_coverage, "CURRENT_RUSTC_VERSION", Some(84605), None, Some("renamed to `coverage_attribute`")),
     /// Allows `#[no_debug]`.
     (removed, no_debug, "1.43.0", Some(29721), None, Some("removed due to lack of demand")),
+    /// Note: this feature was previously recorded in a separate
+    /// `STABLE_REMOVED` list because it, uniquely, was once stable but was
+    /// then removed. But there was no utility storing it separately, so now
+    /// it's in this list.
+    (removed, no_stack_check, "1.0.0", None, None, None),
     /// Allows using `#[on_unimplemented(..)]` on traits.
     /// (Moved to `rustc_attrs`.)
     (removed, on_unimplemented, "1.40.0", None, None, None),
@@ -208,8 +196,3 @@ declare_features! (
     // feature-group-end: removed features
     // -------------------------------------------------------------------------
 );
-
-#[rustfmt::skip]
-declare_features! (
-    (stable_removed, no_stack_check, "1.0.0", None, None),
-);