Switch rustdoc from clean::Stability to rustc_attr::Stability

This gives greater type safety and is less work to maintain on the
rustdoc end.

compiler/rustc_attr/src/builtin.rs

@@ -9,6 +9,7 @@ use rustc_session::parse::{feature_err, ParseSess};
 use rustc_session::Session;
 use rustc_span::hygiene::Transparency;
 use rustc_span::{symbol::sym, symbol::Symbol, Span};
+use std::cmp;
 use std::num::NonZeroU32;
 use version_check::Version;
 
@@ -154,14 +155,27 @@ pub struct ConstStability {
 }
 
 /// The available stability levels.
-#[derive(Encodable, Decodable, PartialEq, PartialOrd, Copy, Clone, Debug, Eq, Hash)]
+#[derive(Encodable, Decodable, PartialEq, Copy, Clone, Debug, Eq, Hash)]
 #[derive(HashStable_Generic)]
 pub enum StabilityLevel {
     // Reason for the current stability level and the relevant rust-lang issue
     Unstable { reason: Option<Symbol>, issue: Option<NonZeroU32>, is_soft: bool },
     Stable { since: Symbol },
 }
 
+impl cmp::PartialOrd for StabilityLevel {
+    // This only take into account stability, not any fields.
+    // Therefore it is only `PartialOrd` and not `Ord`.
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
+        match (self, other) {
+            (Self::Unstable { .. }, Self::Unstable { .. }) => Some(cmp::Ordering::Equal),
+            (Self::Stable { .. }, Self::Stable { .. }) => Some(cmp::Ordering::Equal),
+            (Self::Unstable { .. }, Self::Stable { .. }) => Some(cmp::Ordering::Less),
+            (Self::Stable { .. }, Self::Unstable { .. }) => Some(cmp::Ordering::Greater),
+        }
+    }
+}
+
 impl StabilityLevel {
     pub fn is_unstable(&self) -> bool {
         matches!(self, StabilityLevel::Unstable { .. })

src/librustdoc/clean/mod.rs

@@ -19,7 +19,6 @@ use rustc_index::vec::{Idx, IndexVec};
 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
 use rustc_middle::bug;
 use rustc_middle::middle::resolve_lifetime as rl;
-use rustc_middle::middle::stability;
 use rustc_middle::ty::fold::TypeFolder;
 use rustc_middle::ty::subst::{InternalSubsts, Subst};
 use rustc_middle::ty::{self, AdtKind, Lift, Ty, TyCtxt};
@@ -274,7 +273,7 @@ impl Clean<Item> for doctree::Module<'_> {
             attrs,
             source: span.clean(cx),
             visibility: self.vis.clean(cx),
-            stability: cx.stability(self.id).clean(cx),
+            stability: cx.stability(self.id),
             deprecation: cx.deprecation(self.id).clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             inner: ModuleItem(Module { is_crate: self.is_crate, items }),
@@ -2397,24 +2396,9 @@ impl Clean<Item> for doctree::ProcMacro<'_> {
     }
 }
 
-impl Clean<Stability> for attr::Stability {
-    fn clean(&self, _: &DocContext<'_>) -> Stability {
-        Stability {
-            level: stability::StabilityLevel::from_attr_level(&self.level),
-            feature: self.feature.to_string(),
-            since: match self.level {
-                attr::Stable { ref since } => since.to_string(),
-                _ => String::new(),
-            },
-            unstable_reason: match self.level {
-                attr::Unstable { reason: Some(ref reason), .. } => Some(reason.to_string()),
-                _ => None,
-            },
-            issue: match self.level {
-                attr::Unstable { issue, .. } => issue,
-                _ => None,
-            },
-        }
+impl Clean<attr::Stability> for attr::Stability {
+    fn clean(&self, _: &DocContext<'_>) -> attr::Stability {
+        self.clone()
     }
 }
 

src/librustdoc/clean/types.rs

@@ -4,7 +4,6 @@ use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::iter::FromIterator;
 use std::lazy::SyncOnceCell as OnceCell;
-use std::num::NonZeroU32;
 use std::rc::Rc;
 use std::sync::Arc;
 use std::{slice, vec};
@@ -13,18 +12,18 @@ use rustc_ast::attr;
 use rustc_ast::util::comments::beautify_doc_string;
 use rustc_ast::{self as ast, AttrStyle};
 use rustc_ast::{FloatTy, IntTy, UintTy};
+use rustc_attr::{Stability, StabilityLevel};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::Mutability;
 use rustc_index::vec::IndexVec;
-use rustc_middle::middle::stability;
 use rustc_middle::ty::{AssocKind, TyCtxt};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::DUMMY_SP;
-use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_span::symbol::{kw, sym, Ident, Symbol, SymbolStr};
 use rustc_span::{self, FileName};
 use rustc_target::abi::VariantIdx;
 use rustc_target::spec::abi::Abi;
@@ -197,7 +196,7 @@ impl Item {
         self.stability.as_ref().and_then(|ref s| {
             let mut classes = Vec::with_capacity(2);
 
-            if s.level == stability::Unstable {
+            if s.level.is_unstable() {
                 classes.push("unstable");
             }
 
@@ -210,8 +209,11 @@ impl Item {
         })
     }
 
-    pub fn stable_since(&self) -> Option<&str> {
-        self.stability.as_ref().map(|s| &s.since[..])
+    pub fn stable_since(&self) -> Option<SymbolStr> {
+        match self.stability?.level {
+            StabilityLevel::Stable { since, .. } => Some(since.as_str()),
+            StabilityLevel::Unstable { .. } => None,
+        }
     }
 
     pub fn is_non_exhaustive(&self) -> bool {
@@ -1719,15 +1721,6 @@ pub struct ProcMacro {
     pub helpers: Vec<String>,
 }
 
-#[derive(Clone, Debug)]
-pub struct Stability {
-    pub level: stability::StabilityLevel,
-    pub feature: String,
-    pub since: String,
-    pub unstable_reason: Option<String>,
-    pub issue: Option<NonZeroU32>,
-}
-
 #[derive(Clone, Debug)]
 pub struct Deprecation {
     pub since: Option<String>,

src/librustdoc/clean/utils.rs

@@ -3,12 +3,13 @@ use crate::clean::blanket_impl::BlanketImplFinder;
 use crate::clean::{
     inline, Clean, Crate, Deprecation, ExternalCrate, FnDecl, FnRetTy, Generic, GenericArg,
     GenericArgs, GenericBound, Generics, GetDefId, ImportSource, Item, ItemEnum, Lifetime,
-    MacroKind, Path, PathSegment, Primitive, PrimitiveType, ResolvedPath, Span, Stability, Type,
-    TypeBinding, TypeKind, Visibility, WherePredicate,
+    MacroKind, Path, PathSegment, Primitive, PrimitiveType, ResolvedPath, Span, Type, TypeBinding,
+    TypeKind, Visibility, WherePredicate,
 };
 use crate::core::DocContext;
 
 use itertools::Itertools;
+use rustc_attr::Stability;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};

src/librustdoc/html/render/mod.rs

@@ -49,6 +49,7 @@ use std::sync::Arc;
 
 use itertools::Itertools;
 use rustc_ast_pretty::pprust;
+use rustc_attr::StabilityLevel;
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_feature::UnstableFeatures;
@@ -1984,8 +1985,10 @@ fn item_module(w: &mut Buffer, cx: &Context, item: &clean::Item, items: &[clean:
         let s1 = i1.stability.as_ref().map(|s| s.level);
         let s2 = i2.stability.as_ref().map(|s| s.level);
         match (s1, s2) {
-            (Some(stability::Unstable), Some(stability::Stable)) => return Ordering::Greater,
-            (Some(stability::Stable), Some(stability::Unstable)) => return Ordering::Less,
+            (Some(a), Some(b)) => match a.partial_cmp(&b) {
+                Some(Ordering::Equal) | None => {}
+                Some(other) => return other,
+            },
             _ => {}
         }
         let lhs = i1.name.as_ref().map_or("", |s| &**s);
@@ -2150,10 +2153,7 @@ fn stability_tags(item: &clean::Item) -> String {
 
     // The "rustc_private" crates are permanently unstable so it makes no sense
     // to render "unstable" everywhere.
-    if item
-        .stability
-        .as_ref()
-        .map(|s| s.level == stability::Unstable && s.feature != "rustc_private")
+    if item.stability.as_ref().map(|s| s.level.is_unstable() && s.feature != sym::rustc_private)
         == Some(true)
     {
         tags += &tag_html("unstable", "", "Experimental");
@@ -2204,16 +2204,17 @@ fn short_stability(item: &clean::Item, cx: &Context) -> Vec<String> {
 
     // Render unstable items. But don't render "rustc_private" crates (internal compiler crates).
     // Those crates are permanently unstable so it makes no sense to render "unstable" everywhere.
-    if let Some(stab) = item
+    if let Some((StabilityLevel::Unstable { reason, issue, .. }, feature)) = item
         .stability
         .as_ref()
-        .filter(|stab| stab.level == stability::Unstable && stab.feature != "rustc_private")
+        .filter(|stab| stab.feature != sym::rustc_private)
+        .map(|stab| (stab.level, stab.feature))
     {
         let mut message =
             "<span class='emoji'>🔬</span> This is a nightly-only experimental API.".to_owned();
 
-        let mut feature = format!("<code>{}</code>", Escape(&stab.feature));
-        if let (Some(url), Some(issue)) = (&cx.shared.issue_tracker_base_url, stab.issue) {
+        let mut feature = format!("<code>{}</code>", Escape(&feature.as_str()));
+        if let (Some(url), Some(issue)) = (&cx.shared.issue_tracker_base_url, issue) {
             feature.push_str(&format!(
                 "&nbsp;<a href=\"{url}{issue}\">#{issue}</a>",
                 url = url,
@@ -2223,13 +2224,13 @@ fn short_stability(item: &clean::Item, cx: &Context) -> Vec<String> {
 
         message.push_str(&format!(" ({})", feature));
 
-        if let Some(unstable_reason) = &stab.unstable_reason {
+        if let Some(unstable_reason) = reason {
             let mut ids = cx.id_map.borrow_mut();
             message = format!(
                 "<details><summary>{}</summary>{}</details>",
                 message,
                 MarkdownHtml(
-                    &unstable_reason,
+                    &unstable_reason.as_str(),
                     &mut ids,
                     error_codes,
                     cx.shared.edition,
@@ -2355,7 +2356,7 @@ fn render_implementor(
         implementor,
         AssocItemLink::Anchor(None),
         RenderMode::Normal,
-        implementor.impl_item.stable_since(),
+        implementor.impl_item.stable_since().as_deref(),
         false,
         Some(use_absolute),
         false,
@@ -2384,7 +2385,7 @@ fn render_impls(
                 i,
                 assoc_link,
                 RenderMode::Normal,
-                containing_item.stable_since(),
+                containing_item.stable_since().as_deref(),
                 true,
                 None,
                 false,
@@ -2629,7 +2630,7 @@ fn item_trait(w: &mut Buffer, cx: &Context, it: &clean::Item, t: &clean::Trait,
                     &implementor,
                     assoc_link,
                     RenderMode::Normal,
-                    implementor.impl_item.stable_since(),
+                    implementor.impl_item.stable_since().as_deref(),
                     false,
                     None,
                     true,
@@ -2780,7 +2781,11 @@ fn render_stability_since_raw(w: &mut Buffer, ver: Option<&str>, containing_ver:
 }
 
 fn render_stability_since(w: &mut Buffer, item: &clean::Item, containing_item: &clean::Item) {
-    render_stability_since_raw(w, item.stable_since(), containing_item.stable_since())
+    render_stability_since_raw(
+        w,
+        item.stable_since().as_deref(),
+        containing_item.stable_since().as_deref(),
+    )
 }
 
 fn render_assoc_item(
@@ -3324,7 +3329,7 @@ fn render_assoc_items(
                 i,
                 AssocItemLink::Anchor(None),
                 render_mode,
-                containing_item.stable_since(),
+                containing_item.stable_since().as_deref(),
                 true,
                 None,
                 false,
@@ -3564,8 +3569,11 @@ fn render_impl(
             );
         }
         write!(w, "<a href='#{}' class='anchor'></a>", id);
-        let since = i.impl_item.stability.as_ref().map(|s| &s.since[..]);
-        render_stability_since_raw(w, since, outer_version);
+        let since = i.impl_item.stability.as_ref().and_then(|s| match s.level {
+            StabilityLevel::Stable { since } => Some(since.as_str()),
+            StabilityLevel::Unstable { .. } => None,
+        });
+        render_stability_since_raw(w, since.as_deref(), outer_version);
         if let Some(l) = cx.src_href(&i.impl_item, cache) {
             write!(w, "<a class='srclink' href='{}' title='{}'>[src]</a>", l, "goto source code");
         }
@@ -3626,7 +3634,7 @@ fn render_impl(
                     write!(w, "<code>");
                     render_assoc_item(w, item, link.anchor(&id), ItemType::Impl);
                     write!(w, "</code>");
-                    render_stability_since_raw(w, item.stable_since(), outer_version);
+                    render_stability_since_raw(w, item.stable_since().as_deref(), outer_version);
                     if let Some(l) = cx.src_href(item, cache) {
                         write!(
                             w,
@@ -3648,7 +3656,7 @@ fn render_impl(
                 write!(w, "<h4 id='{}' class=\"{}{}\"><code>", id, item_type, extra_class);
                 assoc_const(w, item, ty, default.as_ref(), link.anchor(&id), "");
                 write!(w, "</code>");
-                render_stability_since_raw(w, item.stable_since(), outer_version);
+                render_stability_since_raw(w, item.stable_since().as_deref(), outer_version);
                 if let Some(l) = cx.src_href(item, cache) {
                     write!(
                         w,