From 1e30b5ae45ddf07fc7b6d233964e8eddebdc4ecd Mon Sep 17 00:00:00 2001
From: schvv31n <tim.kurdov@gmail.com>
Date: Mon, 9 Sep 2024 09:23:00 +0100
Subject: [PATCH 1/7] rustdoc-json: `Id(String)` -> `Id(u32)`

---
 src/librustdoc/json/conversions.rs           | 590 +++++++++----------
 src/librustdoc/json/mod.rs                   |  23 +-
 src/rustdoc-json-types/lib.rs                |   6 +-
 src/tools/jsondoclint/src/validator.rs       |   2 +-
 src/tools/jsondoclint/src/validator/tests.rs |  38 +-
 5 files changed, 326 insertions(+), 333 deletions(-)

diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index b411f9a1a52d0..b8791c9918b12 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -4,20 +4,17 @@
 
 #![allow(rustc::default_hash_types)]
 
-use std::fmt;
-
 use rustc_ast::ast;
 use rustc_attr::DeprecatedSince;
 use rustc_hir::def::{CtorKind, DefKind};
 use rustc_hir::def_id::DefId;
 use rustc_metadata::rendered_const;
-use rustc_middle::bug;
-use rustc_middle::ty::{self, TyCtxt};
-use rustc_span::symbol::sym;
-use rustc_span::{Pos, Symbol};
+use rustc_middle::{bug, ty};
+use rustc_span::{Pos, Symbol, sym};
 use rustc_target::spec::abi::Abi as RustcAbi;
 use rustdoc_json_types::*;
 
+use super::FullItemId;
 use crate::clean::{self, ItemId};
 use crate::formats::FormatRenderer;
 use crate::formats::item_type::ItemType;
@@ -40,7 +37,7 @@ impl JsonRenderer<'_> {
                     Some(UrlFragment::UserWritten(_)) | None => *page_id,
                 };
 
-                (String::from(&**link), id_from_item_default(id.into(), self.tcx))
+                (String::from(&**link), self.id_from_item_default(id.into()))
             })
             .collect();
         let docs = item.opt_doc_value();
@@ -48,7 +45,7 @@ impl JsonRenderer<'_> {
         let span = item.span(self.tcx);
         let visibility = item.visibility(self.tcx);
         let clean::Item { name, item_id, .. } = item;
-        let id = id_from_item(&item, self.tcx);
+        let id = self.id_from_item(&item);
         let inner = match item.kind {
             clean::KeywordItem => return None,
             clean::StrippedItem(ref inner) => {
@@ -59,12 +56,12 @@ impl JsonRenderer<'_> {
                     clean::ModuleItem(_)
                         if self.imported_items.contains(&item_id.expect_def_id()) =>
                     {
-                        from_clean_item(item, self.tcx)
+                        from_clean_item(item, self)
                     }
                     _ => return None,
                 }
             }
-            _ => from_clean_item(item, self.tcx),
+            _ => from_clean_item(item, self),
         };
         Some(Item {
             id,
@@ -105,37 +102,116 @@ impl JsonRenderer<'_> {
             Some(ty::Visibility::Public) => Visibility::Public,
             Some(ty::Visibility::Restricted(did)) if did.is_crate_root() => Visibility::Crate,
             Some(ty::Visibility::Restricted(did)) => Visibility::Restricted {
-                parent: id_from_item_default(did.into(), self.tcx),
+                parent: self.id_from_item_default(did.into()),
                 path: self.tcx.def_path(did).to_string_no_crate_verbose(),
             },
         }
     }
+
+    pub(crate) fn id_from_item_default(&self, item_id: ItemId) -> Id {
+        self.id_from_item_inner(item_id, None, None)
+    }
+
+    pub(crate) fn id_from_item_inner(
+        &self,
+        item_id: ItemId,
+        name: Option<Symbol>,
+        extra: Option<Id>,
+    ) -> Id {
+        let make_part = |def_id: DefId, name: Option<Symbol>, extra: Option<Id>| {
+            let name = match name {
+                Some(name) => Some(name),
+                None => {
+                    // We need this workaround because primitive types' DefId actually refers to
+                    // their parent module, which isn't present in the output JSON items. So
+                    // instead, we directly get the primitive symbol
+                    if matches!(self.tcx.def_kind(def_id), DefKind::Mod)
+                        && let Some(prim) = self
+                            .tcx
+                            .get_attrs(def_id, sym::rustc_doc_primitive)
+                            .find_map(|attr| attr.value_str())
+                    {
+                        Some(prim)
+                    } else {
+                        self.tcx.opt_item_name(def_id)
+                    }
+                }
+            };
+
+            FullItemId { def_id, name, extra }
+        };
+
+        let key = match item_id {
+            ItemId::DefId(did) => (make_part(did, name, extra), None),
+            ItemId::Blanket { for_, impl_id } => {
+                (make_part(impl_id, None, None), Some(make_part(for_, name, extra)))
+            }
+            ItemId::Auto { for_, trait_ } => {
+                (make_part(trait_, None, None), Some(make_part(for_, name, extra)))
+            }
+        };
+
+        let mut interner = self.id_interner.borrow_mut();
+        let len = interner.len();
+        *interner
+            .entry(key)
+            .or_insert_with(|| Id(len.try_into().expect("too many items in a crate")))
+    }
+
+    pub(crate) fn id_from_item(&self, item: &clean::Item) -> Id {
+        match item.kind {
+            clean::ItemKind::ImportItem(ref import) => {
+                let extra =
+                    import.source.did.map(ItemId::from).map(|i| self.id_from_item_default(i));
+                self.id_from_item_inner(item.item_id, item.name, extra)
+            }
+            _ => self.id_from_item_inner(item.item_id, item.name, None),
+        }
+    }
+
+    fn ids(&self, items: impl IntoIterator<Item = clean::Item>) -> Vec<Id> {
+        items
+            .into_iter()
+            .filter(|x| !x.is_stripped() && !x.is_keyword())
+            .map(|i| self.id_from_item(&i))
+            .collect()
+    }
+
+    fn ids_keeping_stripped(
+        &self,
+        items: impl IntoIterator<Item = clean::Item>,
+    ) -> Vec<Option<Id>> {
+        items
+            .into_iter()
+            .map(|i| (!i.is_stripped() && !i.is_keyword()).then(|| self.id_from_item(&i)))
+            .collect()
+    }
 }
 
-pub(crate) trait FromWithTcx<T> {
-    fn from_tcx(f: T, tcx: TyCtxt<'_>) -> Self;
+pub(crate) trait FromClean<T> {
+    fn from_clean(f: T, renderer: &JsonRenderer<'_>) -> Self;
 }
 
-pub(crate) trait IntoWithTcx<T> {
-    fn into_tcx(self, tcx: TyCtxt<'_>) -> T;
+pub(crate) trait IntoJson<T> {
+    fn into_json(self, renderer: &JsonRenderer<'_>) -> T;
 }
 
-impl<T, U> IntoWithTcx<U> for T
+impl<T, U> IntoJson<U> for T
 where
-    U: FromWithTcx<T>,
+    U: FromClean<T>,
 {
-    fn into_tcx(self, tcx: TyCtxt<'_>) -> U {
-        U::from_tcx(self, tcx)
+    fn into_json(self, renderer: &JsonRenderer<'_>) -> U {
+        U::from_clean(self, renderer)
     }
 }
 
-impl<I, T, U> FromWithTcx<I> for Vec<U>
+impl<I, T, U> FromClean<I> for Vec<U>
 where
     I: IntoIterator<Item = T>,
-    U: FromWithTcx<T>,
+    U: FromClean<T>,
 {
-    fn from_tcx(f: I, tcx: TyCtxt<'_>) -> Vec<U> {
-        f.into_iter().map(|x| x.into_tcx(tcx)).collect()
+    fn from_clean(f: I, renderer: &JsonRenderer<'_>) -> Vec<U> {
+        f.into_iter().map(|x| x.into_json(renderer)).collect()
     }
 }
 
@@ -150,37 +226,38 @@ pub(crate) fn from_deprecation(deprecation: rustc_attr::Deprecation) -> Deprecat
     Deprecation { since, note: note.map(|s| s.to_string()) }
 }
 
-impl FromWithTcx<clean::GenericArgs> for GenericArgs {
-    fn from_tcx(args: clean::GenericArgs, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::GenericArgs> for GenericArgs {
+    fn from_clean(args: clean::GenericArgs, renderer: &JsonRenderer<'_>) -> Self {
         use clean::GenericArgs::*;
         match args {
             AngleBracketed { args, constraints } => GenericArgs::AngleBracketed {
-                args: args.into_vec().into_tcx(tcx),
-                constraints: constraints.into_tcx(tcx),
+                args: args.into_vec().into_json(renderer),
+                constraints: constraints.into_json(renderer),
             },
             Parenthesized { inputs, output } => GenericArgs::Parenthesized {
-                inputs: inputs.into_vec().into_tcx(tcx),
-                output: output.map(|a| (*a).into_tcx(tcx)),
+                inputs: inputs.into_vec().into_json(renderer),
+                output: output.map(|a| (*a).into_json(renderer)),
             },
         }
     }
 }
 
-impl FromWithTcx<clean::GenericArg> for GenericArg {
-    fn from_tcx(arg: clean::GenericArg, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::GenericArg> for GenericArg {
+    fn from_clean(arg: clean::GenericArg, renderer: &JsonRenderer<'_>) -> Self {
         use clean::GenericArg::*;
         match arg {
             Lifetime(l) => GenericArg::Lifetime(convert_lifetime(l)),
-            Type(t) => GenericArg::Type(t.into_tcx(tcx)),
-            Const(box c) => GenericArg::Const(c.into_tcx(tcx)),
+            Type(t) => GenericArg::Type(t.into_json(renderer)),
+            Const(box c) => GenericArg::Const(c.into_json(renderer)),
             Infer => GenericArg::Infer,
         }
     }
 }
 
-impl FromWithTcx<clean::Constant> for Constant {
+impl FromClean<clean::Constant> for Constant {
     // FIXME(generic_const_items): Add support for generic const items.
-    fn from_tcx(constant: clean::Constant, tcx: TyCtxt<'_>) -> Self {
+    fn from_clean(constant: clean::Constant, renderer: &JsonRenderer<'_>) -> Self {
+        let tcx = renderer.tcx;
         let expr = constant.expr(tcx);
         let value = constant.value(tcx);
         let is_literal = constant.is_literal(tcx);
@@ -188,9 +265,10 @@ impl FromWithTcx<clean::Constant> for Constant {
     }
 }
 
-impl FromWithTcx<clean::ConstantKind> for Constant {
+impl FromClean<clean::ConstantKind> for Constant {
     // FIXME(generic_const_items): Add support for generic const items.
-    fn from_tcx(constant: clean::ConstantKind, tcx: TyCtxt<'_>) -> Self {
+    fn from_clean(constant: clean::ConstantKind, renderer: &JsonRenderer<'_>) -> Self {
+        let tcx = renderer.tcx;
         let expr = constant.expr(tcx);
         let value = constant.value(tcx);
         let is_literal = constant.is_literal(tcx);
@@ -198,147 +276,62 @@ impl FromWithTcx<clean::ConstantKind> for Constant {
     }
 }
 
-impl FromWithTcx<clean::AssocItemConstraint> for AssocItemConstraint {
-    fn from_tcx(constraint: clean::AssocItemConstraint, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::AssocItemConstraint> for AssocItemConstraint {
+    fn from_clean(constraint: clean::AssocItemConstraint, renderer: &JsonRenderer<'_>) -> Self {
         AssocItemConstraint {
             name: constraint.assoc.name.to_string(),
-            args: constraint.assoc.args.into_tcx(tcx),
-            binding: constraint.kind.into_tcx(tcx),
+            args: constraint.assoc.args.into_json(renderer),
+            binding: constraint.kind.into_json(renderer),
         }
     }
 }
 
-impl FromWithTcx<clean::AssocItemConstraintKind> for AssocItemConstraintKind {
-    fn from_tcx(kind: clean::AssocItemConstraintKind, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::AssocItemConstraintKind> for AssocItemConstraintKind {
+    fn from_clean(kind: clean::AssocItemConstraintKind, renderer: &JsonRenderer<'_>) -> Self {
         use clean::AssocItemConstraintKind::*;
         match kind {
-            Equality { term } => AssocItemConstraintKind::Equality(term.into_tcx(tcx)),
-            Bound { bounds } => AssocItemConstraintKind::Constraint(bounds.into_tcx(tcx)),
-        }
-    }
-}
-
-#[inline]
-pub(crate) fn id_from_item_default(item_id: ItemId, tcx: TyCtxt<'_>) -> Id {
-    id_from_item_inner(item_id, tcx, None, None)
-}
-
-/// It generates an ID as follows:
-///
-/// `CRATE_ID:ITEM_ID[:NAME_ID][-EXTRA]`:
-///   * If there is no `name`, `NAME_ID` is not generated.
-///   * If there is no `extra`, `EXTRA` is not generated.
-///
-/// * `name` is the item's name if available (it's not for impl blocks for example).
-/// * `extra` is used for reexports: it contains the ID of the reexported item. It is used to allow
-///   to have items with the same name but different types to both appear in the generated JSON.
-pub(crate) fn id_from_item_inner(
-    item_id: ItemId,
-    tcx: TyCtxt<'_>,
-    name: Option<Symbol>,
-    extra: Option<&Id>,
-) -> Id {
-    struct DisplayDefId<'a, 'b>(DefId, TyCtxt<'a>, Option<&'b Id>, Option<Symbol>);
-
-    impl<'a, 'b> fmt::Display for DisplayDefId<'a, 'b> {
-        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-            let DisplayDefId(def_id, tcx, extra, name) = self;
-            // We need this workaround because primitive types' DefId actually refers to
-            // their parent module, which isn't present in the output JSON items. So
-            // instead, we directly get the primitive symbol and convert it to u32 to
-            // generate the ID.
-            let s;
-            let extra = if let Some(e) = extra {
-                s = format!("-{}", e.0);
-                &s
-            } else {
-                ""
-            };
-            let name = match name {
-                Some(name) => format!(":{}", name.as_u32()),
-                None => {
-                    // We need this workaround because primitive types' DefId actually refers to
-                    // their parent module, which isn't present in the output JSON items. So
-                    // instead, we directly get the primitive symbol and convert it to u32 to
-                    // generate the ID.
-                    if matches!(tcx.def_kind(def_id), DefKind::Mod)
-                        && let Some(prim) = tcx
-                            .get_attrs(*def_id, sym::rustc_doc_primitive)
-                            .find_map(|attr| attr.value_str())
-                    {
-                        format!(":{}", prim.as_u32())
-                    } else {
-                        tcx.opt_item_name(*def_id)
-                            .map(|n| format!(":{}", n.as_u32()))
-                            .unwrap_or_default()
-                    }
-                }
-            };
-            write!(f, "{}:{}{name}{extra}", def_id.krate.as_u32(), u32::from(def_id.index))
-        }
-    }
-
-    match item_id {
-        ItemId::DefId(did) => Id(format!("{}", DisplayDefId(did, tcx, extra, name))),
-        ItemId::Blanket { for_, impl_id } => Id(format!(
-            "b:{}-{}",
-            DisplayDefId(impl_id, tcx, None, None),
-            DisplayDefId(for_, tcx, extra, name)
-        )),
-        ItemId::Auto { for_, trait_ } => Id(format!(
-            "a:{}-{}",
-            DisplayDefId(trait_, tcx, None, None),
-            DisplayDefId(for_, tcx, extra, name)
-        )),
-    }
-}
-
-pub(crate) fn id_from_item(item: &clean::Item, tcx: TyCtxt<'_>) -> Id {
-    match item.kind {
-        clean::ItemKind::ImportItem(ref import) => {
-            let extra =
-                import.source.did.map(ItemId::from).map(|i| id_from_item_inner(i, tcx, None, None));
-            id_from_item_inner(item.item_id, tcx, item.name, extra.as_ref())
+            Equality { term } => AssocItemConstraintKind::Equality(term.into_json(renderer)),
+            Bound { bounds } => AssocItemConstraintKind::Constraint(bounds.into_json(renderer)),
         }
-        _ => id_from_item_inner(item.item_id, tcx, item.name, None),
     }
 }
 
-fn from_clean_item(item: clean::Item, tcx: TyCtxt<'_>) -> ItemEnum {
+fn from_clean_item(item: clean::Item, renderer: &JsonRenderer<'_>) -> ItemEnum {
     use clean::ItemKind::*;
     let name = item.name;
     let is_crate = item.is_crate();
-    let header = item.fn_header(tcx);
+    let header = item.fn_header(renderer.tcx);
 
     match item.inner.kind {
         ModuleItem(m) => {
-            ItemEnum::Module(Module { is_crate, items: ids(m.items, tcx), is_stripped: false })
-        }
-        ImportItem(i) => ItemEnum::Use(i.into_tcx(tcx)),
-        StructItem(s) => ItemEnum::Struct(s.into_tcx(tcx)),
-        UnionItem(u) => ItemEnum::Union(u.into_tcx(tcx)),
-        StructFieldItem(f) => ItemEnum::StructField(f.into_tcx(tcx)),
-        EnumItem(e) => ItemEnum::Enum(e.into_tcx(tcx)),
-        VariantItem(v) => ItemEnum::Variant(v.into_tcx(tcx)),
-        FunctionItem(f) => ItemEnum::Function(from_function(f, true, header.unwrap(), tcx)),
+            ItemEnum::Module(Module { is_crate, items: renderer.ids(m.items), is_stripped: false })
+        }
+        ImportItem(i) => ItemEnum::Use(i.into_json(renderer)),
+        StructItem(s) => ItemEnum::Struct(s.into_json(renderer)),
+        UnionItem(u) => ItemEnum::Union(u.into_json(renderer)),
+        StructFieldItem(f) => ItemEnum::StructField(f.into_json(renderer)),
+        EnumItem(e) => ItemEnum::Enum(e.into_json(renderer)),
+        VariantItem(v) => ItemEnum::Variant(v.into_json(renderer)),
+        FunctionItem(f) => ItemEnum::Function(from_function(f, true, header.unwrap(), renderer)),
         ForeignFunctionItem(f, _) => {
-            ItemEnum::Function(from_function(f, false, header.unwrap(), tcx))
-        }
-        TraitItem(t) => ItemEnum::Trait((*t).into_tcx(tcx)),
-        TraitAliasItem(t) => ItemEnum::TraitAlias(t.into_tcx(tcx)),
-        MethodItem(m, _) => ItemEnum::Function(from_function(m, true, header.unwrap(), tcx)),
-        TyMethodItem(m) => ItemEnum::Function(from_function(m, false, header.unwrap(), tcx)),
-        ImplItem(i) => ItemEnum::Impl((*i).into_tcx(tcx)),
-        StaticItem(s) => ItemEnum::Static(s.into_tcx(tcx)),
-        ForeignStaticItem(s, _) => ItemEnum::Static(s.into_tcx(tcx)),
+            ItemEnum::Function(from_function(f, false, header.unwrap(), renderer))
+        }
+        TraitItem(t) => ItemEnum::Trait((*t).into_json(renderer)),
+        TraitAliasItem(t) => ItemEnum::TraitAlias(t.into_json(renderer)),
+        MethodItem(m, _) => ItemEnum::Function(from_function(m, true, header.unwrap(), renderer)),
+        TyMethodItem(m) => ItemEnum::Function(from_function(m, false, header.unwrap(), renderer)),
+        ImplItem(i) => ItemEnum::Impl((*i).into_json(renderer)),
+        StaticItem(s) => ItemEnum::Static(s.into_json(renderer)),
+        ForeignStaticItem(s, _) => ItemEnum::Static(s.into_json(renderer)),
         ForeignTypeItem => ItemEnum::ExternType,
-        TypeAliasItem(t) => ItemEnum::TypeAlias(t.into_tcx(tcx)),
+        TypeAliasItem(t) => ItemEnum::TypeAlias(t.into_json(renderer)),
         // FIXME(generic_const_items): Add support for generic free consts
-        ConstantItem(ci) => {
-            ItemEnum::Constant { type_: ci.type_.into_tcx(tcx), const_: ci.kind.into_tcx(tcx) }
-        }
+        ConstantItem(ci) => ItemEnum::Constant {
+            type_: ci.type_.into_json(renderer),
+            const_: ci.kind.into_json(renderer),
+        },
         MacroItem(m) => ItemEnum::Macro(m.source),
-        ProcMacroItem(m) => ItemEnum::ProcMacro(m.into_tcx(tcx)),
+        ProcMacroItem(m) => ItemEnum::ProcMacro(m.into_json(renderer)),
         PrimitiveItem(p) => {
             ItemEnum::Primitive(Primitive {
                 name: p.as_sym().to_string(),
@@ -347,19 +340,22 @@ fn from_clean_item(item: clean::Item, tcx: TyCtxt<'_>) -> ItemEnum {
         }
         // FIXME(generic_const_items): Add support for generic associated consts.
         TyAssocConstItem(_generics, ty) => {
-            ItemEnum::AssocConst { type_: (*ty).into_tcx(tcx), value: None }
+            ItemEnum::AssocConst { type_: (*ty).into_json(renderer), value: None }
         }
         // FIXME(generic_const_items): Add support for generic associated consts.
-        AssocConstItem(ci) => {
-            ItemEnum::AssocConst { type_: ci.type_.into_tcx(tcx), value: Some(ci.kind.expr(tcx)) }
-        }
-        TyAssocTypeItem(g, b) => {
-            ItemEnum::AssocType { generics: g.into_tcx(tcx), bounds: b.into_tcx(tcx), type_: None }
-        }
+        AssocConstItem(ci) => ItemEnum::AssocConst {
+            type_: ci.type_.into_json(renderer),
+            value: Some(ci.kind.expr(renderer.tcx)),
+        },
+        TyAssocTypeItem(g, b) => ItemEnum::AssocType {
+            generics: g.into_json(renderer),
+            bounds: b.into_json(renderer),
+            type_: None,
+        },
         AssocTypeItem(t, b) => ItemEnum::AssocType {
-            generics: t.generics.into_tcx(tcx),
-            bounds: b.into_tcx(tcx),
-            type_: Some(t.item_type.unwrap_or(t.type_).into_tcx(tcx)),
+            generics: t.generics.into_json(renderer),
+            bounds: b.into_json(renderer),
+            type_: Some(t.item_type.unwrap_or(t.type_).into_json(renderer)),
         },
         // `convert_item` early returns `None` for stripped items and keywords.
         KeywordItem => unreachable!(),
@@ -367,7 +363,7 @@ fn from_clean_item(item: clean::Item, tcx: TyCtxt<'_>) -> ItemEnum {
             match *inner {
                 ModuleItem(m) => ItemEnum::Module(Module {
                     is_crate,
-                    items: ids(m.items, tcx),
+                    items: renderer.ids(m.items),
                     is_stripped: true,
                 }),
                 // `convert_item` early returns `None` for stripped items we're not including
@@ -381,36 +377,36 @@ fn from_clean_item(item: clean::Item, tcx: TyCtxt<'_>) -> ItemEnum {
     }
 }
 
-impl FromWithTcx<clean::Struct> for Struct {
-    fn from_tcx(struct_: clean::Struct, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Struct> for Struct {
+    fn from_clean(struct_: clean::Struct, renderer: &JsonRenderer<'_>) -> Self {
         let has_stripped_fields = struct_.has_stripped_entries();
         let clean::Struct { ctor_kind, generics, fields } = struct_;
 
         let kind = match ctor_kind {
-            Some(CtorKind::Fn) => StructKind::Tuple(ids_keeping_stripped(fields, tcx)),
+            Some(CtorKind::Fn) => StructKind::Tuple(renderer.ids_keeping_stripped(fields)),
             Some(CtorKind::Const) => {
                 assert!(fields.is_empty());
                 StructKind::Unit
             }
-            None => StructKind::Plain { fields: ids(fields, tcx), has_stripped_fields },
+            None => StructKind::Plain { fields: renderer.ids(fields), has_stripped_fields },
         };
 
         Struct {
             kind,
-            generics: generics.into_tcx(tcx),
+            generics: generics.into_json(renderer),
             impls: Vec::new(), // Added in JsonRenderer::item
         }
     }
 }
 
-impl FromWithTcx<clean::Union> for Union {
-    fn from_tcx(union_: clean::Union, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Union> for Union {
+    fn from_clean(union_: clean::Union, renderer: &JsonRenderer<'_>) -> Self {
         let has_stripped_fields = union_.has_stripped_entries();
         let clean::Union { generics, fields } = union_;
         Union {
-            generics: generics.into_tcx(tcx),
+            generics: generics.into_json(renderer),
             has_stripped_fields,
-            fields: ids(fields, tcx),
+            fields: renderer.ids(fields),
             impls: Vec::new(), // Added in JsonRenderer::item
         }
     }
@@ -444,51 +440,51 @@ fn convert_lifetime(l: clean::Lifetime) -> String {
     l.0.to_string()
 }
 
-impl FromWithTcx<clean::Generics> for Generics {
-    fn from_tcx(generics: clean::Generics, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Generics> for Generics {
+    fn from_clean(generics: clean::Generics, renderer: &JsonRenderer<'_>) -> Self {
         Generics {
-            params: generics.params.into_tcx(tcx),
-            where_predicates: generics.where_predicates.into_tcx(tcx),
+            params: generics.params.into_json(renderer),
+            where_predicates: generics.where_predicates.into_json(renderer),
         }
     }
 }
 
-impl FromWithTcx<clean::GenericParamDef> for GenericParamDef {
-    fn from_tcx(generic_param: clean::GenericParamDef, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::GenericParamDef> for GenericParamDef {
+    fn from_clean(generic_param: clean::GenericParamDef, renderer: &JsonRenderer<'_>) -> Self {
         GenericParamDef {
             name: generic_param.name.to_string(),
-            kind: generic_param.kind.into_tcx(tcx),
+            kind: generic_param.kind.into_json(renderer),
         }
     }
 }
 
-impl FromWithTcx<clean::GenericParamDefKind> for GenericParamDefKind {
-    fn from_tcx(kind: clean::GenericParamDefKind, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::GenericParamDefKind> for GenericParamDefKind {
+    fn from_clean(kind: clean::GenericParamDefKind, renderer: &JsonRenderer<'_>) -> Self {
         use clean::GenericParamDefKind::*;
         match kind {
             Lifetime { outlives } => GenericParamDefKind::Lifetime {
                 outlives: outlives.into_iter().map(convert_lifetime).collect(),
             },
             Type { bounds, default, synthetic } => GenericParamDefKind::Type {
-                bounds: bounds.into_tcx(tcx),
-                default: default.map(|x| (*x).into_tcx(tcx)),
+                bounds: bounds.into_json(renderer),
+                default: default.map(|x| (*x).into_json(renderer)),
                 is_synthetic: synthetic,
             },
             Const { ty, default, synthetic: _ } => GenericParamDefKind::Const {
-                type_: (*ty).into_tcx(tcx),
+                type_: (*ty).into_json(renderer),
                 default: default.map(|x| *x),
             },
         }
     }
 }
 
-impl FromWithTcx<clean::WherePredicate> for WherePredicate {
-    fn from_tcx(predicate: clean::WherePredicate, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::WherePredicate> for WherePredicate {
+    fn from_clean(predicate: clean::WherePredicate, renderer: &JsonRenderer<'_>) -> Self {
         use clean::WherePredicate::*;
         match predicate {
             BoundPredicate { ty, bounds, bound_params } => WherePredicate::BoundPredicate {
-                type_: ty.into_tcx(tcx),
-                bounds: bounds.into_tcx(tcx),
+                type_: ty.into_json(renderer),
+                bounds: bounds.into_json(renderer),
                 generic_params: bound_params
                     .into_iter()
                     .map(|x| {
@@ -503,15 +499,15 @@ impl FromWithTcx<clean::WherePredicate> for WherePredicate {
                                 GenericParamDefKind::Type {
                                     bounds: bounds
                                         .into_iter()
-                                        .map(|bound| bound.into_tcx(tcx))
+                                        .map(|bound| bound.into_json(renderer))
                                         .collect(),
-                                    default: default.map(|ty| (*ty).into_tcx(tcx)),
+                                    default: default.map(|ty| (*ty).into_json(renderer)),
                                     is_synthetic: synthetic,
                                 }
                             }
                             clean::GenericParamDefKind::Const { ty, default, synthetic: _ } => {
                                 GenericParamDefKind::Const {
-                                    type_: (*ty).into_tcx(tcx),
+                                    type_: (*ty).into_json(renderer),
                                     default: default.map(|d| *d),
                                 }
                             }
@@ -530,21 +526,22 @@ impl FromWithTcx<clean::WherePredicate> for WherePredicate {
                     })
                     .collect(),
             },
-            EqPredicate { lhs, rhs } => {
-                WherePredicate::EqPredicate { lhs: lhs.into_tcx(tcx), rhs: rhs.into_tcx(tcx) }
-            }
+            EqPredicate { lhs, rhs } => WherePredicate::EqPredicate {
+                lhs: lhs.into_json(renderer),
+                rhs: rhs.into_json(renderer),
+            },
         }
     }
 }
 
-impl FromWithTcx<clean::GenericBound> for GenericBound {
-    fn from_tcx(bound: clean::GenericBound, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::GenericBound> for GenericBound {
+    fn from_clean(bound: clean::GenericBound, renderer: &JsonRenderer<'_>) -> Self {
         use clean::GenericBound::*;
         match bound {
             TraitBound(clean::PolyTrait { trait_, generic_params }, modifier) => {
                 GenericBound::TraitBound {
-                    trait_: trait_.into_tcx(tcx),
-                    generic_params: generic_params.into_tcx(tcx),
+                    trait_: trait_.into_json(renderer),
+                    generic_params: generic_params.into_json(renderer),
                     modifier: from_trait_bound_modifier(modifier),
                 }
             }
@@ -572,73 +569,75 @@ pub(crate) fn from_trait_bound_modifier(
     }
 }
 
-impl FromWithTcx<clean::Type> for Type {
-    fn from_tcx(ty: clean::Type, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Type> for Type {
+    fn from_clean(ty: clean::Type, renderer: &JsonRenderer<'_>) -> Self {
         use clean::Type::{
             Array, BareFunction, BorrowedRef, Generic, ImplTrait, Infer, Primitive, QPath,
             RawPointer, SelfTy, Slice, Tuple,
         };
 
         match ty {
-            clean::Type::Path { path } => Type::ResolvedPath(path.into_tcx(tcx)),
+            clean::Type::Path { path } => Type::ResolvedPath(path.into_json(renderer)),
             clean::Type::DynTrait(bounds, lt) => Type::DynTrait(DynTrait {
                 lifetime: lt.map(convert_lifetime),
-                traits: bounds.into_tcx(tcx),
+                traits: bounds.into_json(renderer),
             }),
             Generic(s) => Type::Generic(s.to_string()),
             // FIXME: add dedicated variant to json Type?
             SelfTy => Type::Generic("Self".to_owned()),
             Primitive(p) => Type::Primitive(p.as_sym().to_string()),
-            BareFunction(f) => Type::FunctionPointer(Box::new((*f).into_tcx(tcx))),
-            Tuple(t) => Type::Tuple(t.into_tcx(tcx)),
-            Slice(t) => Type::Slice(Box::new((*t).into_tcx(tcx))),
-            Array(t, s) => Type::Array { type_: Box::new((*t).into_tcx(tcx)), len: s.to_string() },
+            BareFunction(f) => Type::FunctionPointer(Box::new((*f).into_json(renderer))),
+            Tuple(t) => Type::Tuple(t.into_json(renderer)),
+            Slice(t) => Type::Slice(Box::new((*t).into_json(renderer))),
+            Array(t, s) => {
+                Type::Array { type_: Box::new((*t).into_json(renderer)), len: s.to_string() }
+            }
             clean::Type::Pat(t, p) => Type::Pat {
-                type_: Box::new((*t).into_tcx(tcx)),
+                type_: Box::new((*t).into_json(renderer)),
                 __pat_unstable_do_not_use: p.to_string(),
             },
-            ImplTrait(g) => Type::ImplTrait(g.into_tcx(tcx)),
+            ImplTrait(g) => Type::ImplTrait(g.into_json(renderer)),
             Infer => Type::Infer,
             RawPointer(mutability, type_) => Type::RawPointer {
                 is_mutable: mutability == ast::Mutability::Mut,
-                type_: Box::new((*type_).into_tcx(tcx)),
+                type_: Box::new((*type_).into_json(renderer)),
             },
             BorrowedRef { lifetime, mutability, type_ } => Type::BorrowedRef {
                 lifetime: lifetime.map(convert_lifetime),
                 is_mutable: mutability == ast::Mutability::Mut,
-                type_: Box::new((*type_).into_tcx(tcx)),
+                type_: Box::new((*type_).into_json(renderer)),
             },
             QPath(box clean::QPathData { assoc, self_type, trait_, .. }) => Type::QualifiedPath {
                 name: assoc.name.to_string(),
-                args: Box::new(assoc.args.into_tcx(tcx)),
-                self_type: Box::new(self_type.into_tcx(tcx)),
-                trait_: trait_.map(|trait_| trait_.into_tcx(tcx)),
+                args: Box::new(assoc.args.into_json(renderer)),
+                self_type: Box::new(self_type.into_json(renderer)),
+                trait_: trait_.map(|trait_| trait_.into_json(renderer)),
             },
         }
     }
 }
 
-impl FromWithTcx<clean::Path> for Path {
-    fn from_tcx(path: clean::Path, tcx: TyCtxt<'_>) -> Path {
+impl FromClean<clean::Path> for Path {
+    fn from_clean(path: clean::Path, renderer: &JsonRenderer<'_>) -> Path {
         Path {
             name: path.whole_name(),
-            id: id_from_item_default(path.def_id().into(), tcx),
-            args: path.segments.last().map(|args| Box::new(args.clone().args.into_tcx(tcx))),
+            id: renderer.id_from_item_default(path.def_id().into()),
+            args: path.segments.last().map(|args| Box::new(args.clone().args.into_json(renderer))),
         }
     }
 }
 
-impl FromWithTcx<clean::Term> for Term {
-    fn from_tcx(term: clean::Term, tcx: TyCtxt<'_>) -> Term {
+impl FromClean<clean::Term> for Term {
+    fn from_clean(term: clean::Term, renderer: &JsonRenderer<'_>) -> Term {
         match term {
-            clean::Term::Type(ty) => Term::Type(FromWithTcx::from_tcx(ty, tcx)),
-            clean::Term::Constant(c) => Term::Constant(FromWithTcx::from_tcx(c, tcx)),
+            clean::Term::Type(ty) => Term::Type(ty.into_json(renderer)),
+            clean::Term::Constant(c) => Term::Constant(c.into_json(renderer)),
         }
     }
 }
 
-impl FromWithTcx<clean::BareFunctionDecl> for FunctionPointer {
-    fn from_tcx(bare_decl: clean::BareFunctionDecl, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::BareFunctionDecl> for FunctionPointer {
+    fn from_clean(bare_decl: clean::BareFunctionDecl, renderer: &JsonRenderer<'_>) -> Self {
         let clean::BareFunctionDecl { safety, generic_params, decl, abi } = bare_decl;
         FunctionPointer {
             header: FunctionHeader {
@@ -647,29 +646,30 @@ impl FromWithTcx<clean::BareFunctionDecl> for FunctionPointer {
                 is_async: false,
                 abi: convert_abi(abi),
             },
-            generic_params: generic_params.into_tcx(tcx),
-            sig: decl.into_tcx(tcx),
+            generic_params: generic_params.into_json(renderer),
+            sig: decl.into_json(renderer),
         }
     }
 }
 
-impl FromWithTcx<clean::FnDecl> for FunctionSignature {
-    fn from_tcx(decl: clean::FnDecl, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::FnDecl> for FunctionSignature {
+    fn from_clean(decl: clean::FnDecl, renderer: &JsonRenderer<'_>) -> Self {
         let clean::FnDecl { inputs, output, c_variadic } = decl;
         FunctionSignature {
             inputs: inputs
                 .values
                 .into_iter()
-                .map(|arg| (arg.name.to_string(), arg.type_.into_tcx(tcx)))
+                .map(|arg| (arg.name.to_string(), arg.type_.into_json(renderer)))
                 .collect(),
-            output: if output.is_unit() { None } else { Some(output.into_tcx(tcx)) },
+            output: if output.is_unit() { None } else { Some(output.into_json(renderer)) },
             is_c_variadic: c_variadic,
         }
     }
 }
 
-impl FromWithTcx<clean::Trait> for Trait {
-    fn from_tcx(trait_: clean::Trait, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Trait> for Trait {
+    fn from_clean(trait_: clean::Trait, renderer: &JsonRenderer<'_>) -> Self {
+        let tcx = renderer.tcx;
         let is_auto = trait_.is_auto(tcx);
         let is_unsafe = trait_.safety(tcx) == rustc_hir::Safety::Unsafe;
         let is_object_safe = trait_.is_object_safe(tcx);
@@ -678,26 +678,29 @@ impl FromWithTcx<clean::Trait> for Trait {
             is_auto,
             is_unsafe,
             is_object_safe,
-            items: ids(items, tcx),
-            generics: generics.into_tcx(tcx),
-            bounds: bounds.into_tcx(tcx),
+            items: renderer.ids(items),
+            generics: generics.into_json(renderer),
+            bounds: bounds.into_json(renderer),
             implementations: Vec::new(), // Added in JsonRenderer::item
         }
     }
 }
 
-impl FromWithTcx<clean::PolyTrait> for PolyTrait {
-    fn from_tcx(
+impl FromClean<clean::PolyTrait> for PolyTrait {
+    fn from_clean(
         clean::PolyTrait { trait_, generic_params }: clean::PolyTrait,
-        tcx: TyCtxt<'_>,
+        renderer: &JsonRenderer<'_>,
     ) -> Self {
-        PolyTrait { trait_: trait_.into_tcx(tcx), generic_params: generic_params.into_tcx(tcx) }
+        PolyTrait {
+            trait_: trait_.into_json(renderer),
+            generic_params: generic_params.into_json(renderer),
+        }
     }
 }
 
-impl FromWithTcx<clean::Impl> for Impl {
-    fn from_tcx(impl_: clean::Impl, tcx: TyCtxt<'_>) -> Self {
-        let provided_trait_methods = impl_.provided_trait_methods(tcx);
+impl FromClean<clean::Impl> for Impl {
+    fn from_clean(impl_: clean::Impl, renderer: &JsonRenderer<'_>) -> Self {
+        let provided_trait_methods = impl_.provided_trait_methods(renderer.tcx);
         let clean::Impl { safety, generics, trait_, for_, items, polarity, kind } = impl_;
         // FIXME: use something like ImplKind in JSON?
         let (is_synthetic, blanket_impl) = match kind {
@@ -711,17 +714,17 @@ impl FromWithTcx<clean::Impl> for Impl {
         };
         Impl {
             is_unsafe: safety == rustc_hir::Safety::Unsafe,
-            generics: generics.into_tcx(tcx),
+            generics: generics.into_json(renderer),
             provided_trait_methods: provided_trait_methods
                 .into_iter()
                 .map(|x| x.to_string())
                 .collect(),
-            trait_: trait_.map(|path| path.into_tcx(tcx)),
-            for_: for_.into_tcx(tcx),
-            items: ids(items, tcx),
+            trait_: trait_.map(|path| path.into_json(renderer)),
+            for_: for_.into_json(renderer),
+            items: renderer.ids(items),
             is_negative,
             is_synthetic,
-            blanket_impl: blanket_impl.map(|x| x.into_tcx(tcx)),
+            blanket_impl: blanket_impl.map(|x| x.into_json(renderer)),
         }
     }
 }
@@ -730,42 +733,42 @@ pub(crate) fn from_function(
     function: Box<clean::Function>,
     has_body: bool,
     header: rustc_hir::FnHeader,
-    tcx: TyCtxt<'_>,
+    renderer: &JsonRenderer<'_>,
 ) -> Function {
     let clean::Function { decl, generics } = *function;
     Function {
-        sig: decl.into_tcx(tcx),
-        generics: generics.into_tcx(tcx),
+        sig: decl.into_json(renderer),
+        generics: generics.into_json(renderer),
         header: from_fn_header(&header),
         has_body,
     }
 }
 
-impl FromWithTcx<clean::Enum> for Enum {
-    fn from_tcx(enum_: clean::Enum, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Enum> for Enum {
+    fn from_clean(enum_: clean::Enum, renderer: &JsonRenderer<'_>) -> Self {
         let has_stripped_variants = enum_.has_stripped_entries();
         let clean::Enum { variants, generics } = enum_;
         Enum {
-            generics: generics.into_tcx(tcx),
+            generics: generics.into_json(renderer),
             has_stripped_variants,
-            variants: ids(variants, tcx),
+            variants: renderer.ids(variants),
             impls: Vec::new(), // Added in JsonRenderer::item
         }
     }
 }
 
-impl FromWithTcx<clean::Variant> for Variant {
-    fn from_tcx(variant: clean::Variant, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Variant> for Variant {
+    fn from_clean(variant: clean::Variant, renderer: &JsonRenderer<'_>) -> Self {
         use clean::VariantKind::*;
 
-        let discriminant = variant.discriminant.map(|d| d.into_tcx(tcx));
+        let discriminant = variant.discriminant.map(|d| d.into_json(renderer));
 
         let kind = match variant.kind {
             CLike => VariantKind::Plain,
-            Tuple(fields) => VariantKind::Tuple(ids_keeping_stripped(fields, tcx)),
+            Tuple(fields) => VariantKind::Tuple(renderer.ids_keeping_stripped(fields)),
             Struct(s) => VariantKind::Struct {
                 has_stripped_fields: s.has_stripped_entries(),
-                fields: ids(s.fields, tcx),
+                fields: renderer.ids(s.fields),
             },
         };
 
@@ -773,8 +776,9 @@ impl FromWithTcx<clean::Variant> for Variant {
     }
 }
 
-impl FromWithTcx<clean::Discriminant> for Discriminant {
-    fn from_tcx(disr: clean::Discriminant, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Discriminant> for Discriminant {
+    fn from_clean(disr: clean::Discriminant, renderer: &JsonRenderer<'_>) -> Self {
+        let tcx = renderer.tcx;
         Discriminant {
             // expr is only none if going through the inlining path, which gets
             // `rustc_middle` types, not `rustc_hir`, but because JSON never inlines
@@ -785,8 +789,8 @@ impl FromWithTcx<clean::Discriminant> for Discriminant {
     }
 }
 
-impl FromWithTcx<clean::Import> for Use {
-    fn from_tcx(import: clean::Import, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Import> for Use {
+    fn from_clean(import: clean::Import, renderer: &JsonRenderer<'_>) -> Self {
         use clean::ImportKind::*;
         let (name, is_glob) = match import.kind {
             Simple(s) => (s.to_string(), false),
@@ -798,14 +802,14 @@ impl FromWithTcx<clean::Import> for Use {
         Use {
             source: import.source.path.whole_name(),
             name,
-            id: import.source.did.map(ItemId::from).map(|i| id_from_item_default(i, tcx)),
+            id: import.source.did.map(ItemId::from).map(|i| renderer.id_from_item_default(i)),
             is_glob,
         }
     }
 }
 
-impl FromWithTcx<clean::ProcMacro> for ProcMacro {
-    fn from_tcx(mac: clean::ProcMacro, _tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::ProcMacro> for ProcMacro {
+    fn from_clean(mac: clean::ProcMacro, _renderer: &JsonRenderer<'_>) -> Self {
         ProcMacro {
             kind: from_macro_kind(mac.kind),
             helpers: mac.helpers.iter().map(|x| x.to_string()).collect(),
@@ -822,17 +826,18 @@ pub(crate) fn from_macro_kind(kind: rustc_span::hygiene::MacroKind) -> MacroKind
     }
 }
 
-impl FromWithTcx<Box<clean::TypeAlias>> for TypeAlias {
-    fn from_tcx(type_alias: Box<clean::TypeAlias>, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<Box<clean::TypeAlias>> for TypeAlias {
+    fn from_clean(type_alias: Box<clean::TypeAlias>, renderer: &JsonRenderer<'_>) -> Self {
         let clean::TypeAlias { type_, generics, item_type: _, inner_type: _ } = *type_alias;
-        TypeAlias { type_: type_.into_tcx(tcx), generics: generics.into_tcx(tcx) }
+        TypeAlias { type_: type_.into_json(renderer), generics: generics.into_json(renderer) }
     }
 }
 
-impl FromWithTcx<clean::Static> for Static {
-    fn from_tcx(stat: clean::Static, tcx: TyCtxt<'_>) -> Self {
+impl FromClean<clean::Static> for Static {
+    fn from_clean(stat: clean::Static, renderer: &JsonRenderer<'_>) -> Self {
+        let tcx = renderer.tcx;
         Static {
-            type_: (*stat.type_).into_tcx(tcx),
+            type_: (*stat.type_).into_json(renderer),
             is_mutable: stat.mutability == ast::Mutability::Mut,
             expr: stat
                 .expr
@@ -842,14 +847,17 @@ impl FromWithTcx<clean::Static> for Static {
     }
 }
 
-impl FromWithTcx<clean::TraitAlias> for TraitAlias {
-    fn from_tcx(alias: clean::TraitAlias, tcx: TyCtxt<'_>) -> Self {
-        TraitAlias { generics: alias.generics.into_tcx(tcx), params: alias.bounds.into_tcx(tcx) }
+impl FromClean<clean::TraitAlias> for TraitAlias {
+    fn from_clean(alias: clean::TraitAlias, renderer: &JsonRenderer<'_>) -> Self {
+        TraitAlias {
+            generics: alias.generics.into_json(renderer),
+            params: alias.bounds.into_json(renderer),
+        }
     }
 }
 
-impl FromWithTcx<ItemType> for ItemKind {
-    fn from_tcx(kind: ItemType, _tcx: TyCtxt<'_>) -> Self {
+impl FromClean<ItemType> for ItemKind {
+    fn from_clean(kind: ItemType, _renderer: &JsonRenderer<'_>) -> Self {
         use ItemType::*;
         match kind {
             Module => ItemKind::Module,
@@ -878,25 +886,3 @@ impl FromWithTcx<ItemType> for ItemKind {
         }
     }
 }
-
-fn ids(items: impl IntoIterator<Item = clean::Item>, tcx: TyCtxt<'_>) -> Vec<Id> {
-    items
-        .into_iter()
-        .filter(|x| !x.is_stripped() && !x.is_keyword())
-        .map(|i| id_from_item(&i, tcx))
-        .collect()
-}
-
-fn ids_keeping_stripped(
-    items: impl IntoIterator<Item = clean::Item>,
-    tcx: TyCtxt<'_>,
-) -> Vec<Option<Id>> {
-    items
-        .into_iter()
-        .map(
-            |i| {
-                if !i.is_stripped() && !i.is_keyword() { Some(id_from_item(&i, tcx)) } else { None }
-            },
-        )
-        .collect()
-}
diff --git a/src/librustdoc/json/mod.rs b/src/librustdoc/json/mod.rs
index b7a683eed1c2f..df97c5ea2634a 100644
--- a/src/librustdoc/json/mod.rs
+++ b/src/librustdoc/json/mod.rs
@@ -16,6 +16,7 @@ use std::rc::Rc;
 use rustc_hir::def_id::{DefId, DefIdSet};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
+use rustc_span::Symbol;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustdoc_json_types as types;
 // It's important to use the FxHashMap from rustdoc_json_types here, instead of
@@ -31,9 +32,17 @@ use crate::docfs::PathError;
 use crate::error::Error;
 use crate::formats::FormatRenderer;
 use crate::formats::cache::Cache;
-use crate::json::conversions::{IntoWithTcx, id_from_item, id_from_item_default};
+use crate::json::conversions::IntoJson;
 use crate::{clean, try_err};
 
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
+struct FullItemId {
+    def_id: DefId,
+    name: Option<Symbol>,
+    /// Used to distinguish imports of different items with the same name
+    extra: Option<types::Id>,
+}
+
 #[derive(Clone)]
 pub(crate) struct JsonRenderer<'tcx> {
     tcx: TyCtxt<'tcx>,
@@ -46,6 +55,7 @@ pub(crate) struct JsonRenderer<'tcx> {
     out_dir: Option<PathBuf>,
     cache: Rc<Cache>,
     imported_items: DefIdSet,
+    id_interner: Rc<RefCell<FxHashMap<(FullItemId, Option<FullItemId>), types::Id>>>,
 }
 
 impl<'tcx> JsonRenderer<'tcx> {
@@ -63,7 +73,7 @@ impl<'tcx> JsonRenderer<'tcx> {
                     .map(|i| {
                         let item = &i.impl_item;
                         self.item(item.clone()).unwrap();
-                        id_from_item(&item, self.tcx)
+                        self.id_from_item(&item)
                     })
                     .collect()
             })
@@ -94,7 +104,7 @@ impl<'tcx> JsonRenderer<'tcx> {
 
                         if item.item_id.is_local() || is_primitive_impl {
                             self.item(item.clone()).unwrap();
-                            Some(id_from_item(&item, self.tcx))
+                            Some(self.id_from_item(&item))
                         } else {
                             None
                         }
@@ -145,6 +155,7 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
                 out_dir: if options.output_to_stdout { None } else { Some(options.output) },
                 cache: Rc::new(cache),
                 imported_items,
+                id_interner: Default::default(),
             },
             krate,
         ))
@@ -243,7 +254,7 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
 
         debug!("Constructing Output");
         let output_crate = types::Crate {
-            root: types::Id(format!("0:0:{}", e.name(self.tcx).as_u32())),
+            root: self.id_from_item_default(e.def_id().into()),
             crate_version: self.cache.crate_version.clone(),
             includes_private: self.cache.document_private,
             index,
@@ -253,10 +264,10 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
                 .iter()
                 .chain(&self.cache.external_paths)
                 .map(|(&k, &(ref path, kind))| {
-                    (id_from_item_default(k.into(), self.tcx), types::ItemSummary {
+                    (self.id_from_item_default(k.into()), types::ItemSummary {
                         crate_id: k.krate.as_u32(),
                         path: path.iter().map(|s| s.to_string()).collect(),
-                        kind: kind.into_tcx(self.tcx),
+                        kind: kind.into_json(self),
                     })
                 })
                 .collect(),
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
index b3707cf615714..c94efafd5b79f 100644
--- a/src/rustdoc-json-types/lib.rs
+++ b/src/rustdoc-json-types/lib.rs
@@ -13,7 +13,7 @@ use serde::{Deserialize, Serialize};
 /// This integer is incremented with every breaking change to the API,
 /// and is returned along with the JSON blob as [`Crate::format_version`].
 /// Consuming code should assert that this value matches the format version(s) that it supports.
-pub const FORMAT_VERSION: u32 = 34;
+pub const FORMAT_VERSION: u32 = 35;
 
 /// The root of the emitted JSON blob.
 ///
@@ -296,9 +296,9 @@ pub enum AssocItemConstraintKind {
 /// Rustdoc makes no guarantees about the inner value of Id's. Applications
 /// should treat them as opaque keys to lookup items, and avoid attempting
 /// to parse them, or otherwise depend on any implementation details.
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
 // FIXME(aDotInTheVoid): Consider making this non-public in rustdoc-types.
-pub struct Id(pub String);
+pub struct Id(pub u32);
 
 /// The fundamental kind of an item. Unlike [`ItemEnum`], this does not carry any aditional info.
 ///
diff --git a/src/tools/jsondoclint/src/validator.rs b/src/tools/jsondoclint/src/validator.rs
index b04919bdd3edc..f7c752033c59e 100644
--- a/src/tools/jsondoclint/src/validator.rs
+++ b/src/tools/jsondoclint/src/validator.rs
@@ -418,7 +418,7 @@ impl<'a> Validator<'a> {
         } else if !self.missing_ids.contains(id) {
             self.missing_ids.insert(id);
 
-            let sels = json_find::find_selector(&self.krate_json, &Value::String(id.0.clone()));
+            let sels = json_find::find_selector(&self.krate_json, &Value::Number(id.0.into()));
             assert_ne!(sels.len(), 0);
 
             self.fail(id, ErrorKind::NotFound(sels))
diff --git a/src/tools/jsondoclint/src/validator/tests.rs b/src/tools/jsondoclint/src/validator/tests.rs
index d15aa7db31571..e842e1318db92 100644
--- a/src/tools/jsondoclint/src/validator/tests.rs
+++ b/src/tools/jsondoclint/src/validator/tests.rs
@@ -15,24 +15,20 @@ fn check(krate: &Crate, errs: &[Error]) {
     assert_eq!(errs, &validator.errs[..]);
 }
 
-fn id(s: &str) -> Id {
-    Id(s.to_owned())
-}
-
 #[test]
 fn errors_on_missing_links() {
     let k = Crate {
-        root: id("0"),
+        root: Id(0),
         crate_version: None,
         includes_private: false,
-        index: FxHashMap::from_iter([(id("0"), Item {
+        index: FxHashMap::from_iter([(Id(0), Item {
             name: Some("root".to_owned()),
-            id: id(""),
+            id: Id(0),
             crate_id: 0,
             span: None,
             visibility: Visibility::Public,
             docs: None,
-            links: FxHashMap::from_iter([("Not Found".to_owned(), id("1"))]),
+            links: FxHashMap::from_iter([("Not Found".to_owned(), Id(1))]),
             attrs: vec![],
             deprecation: None,
             inner: ItemEnum::Module(Module { is_crate: true, items: vec![], is_stripped: false }),
@@ -49,7 +45,7 @@ fn errors_on_missing_links() {
             SelectorPart::Field("links".to_owned()),
             SelectorPart::Field("Not Found".to_owned()),
         ]]),
-        id: id("1"),
+        id: Id(1),
     }]);
 }
 
@@ -58,28 +54,28 @@ fn errors_on_missing_links() {
 #[test]
 fn errors_on_local_in_paths_and_not_index() {
     let krate = Crate {
-        root: id("0:0:1572"),
+        root: Id(0),
         crate_version: None,
         includes_private: false,
         index: FxHashMap::from_iter([
-            (id("0:0:1572"), Item {
-                id: id("0:0:1572"),
+            (Id(0), Item {
+                id: Id(0),
                 crate_id: 0,
                 name: Some("microcore".to_owned()),
                 span: None,
                 visibility: Visibility::Public,
                 docs: None,
-                links: FxHashMap::from_iter([(("prim@i32".to_owned(), id("0:1:1571")))]),
+                links: FxHashMap::from_iter([(("prim@i32".to_owned(), Id(2)))]),
                 attrs: Vec::new(),
                 deprecation: None,
                 inner: ItemEnum::Module(Module {
                     is_crate: true,
-                    items: vec![id("0:1:717")],
+                    items: vec![Id(1)],
                     is_stripped: false,
                 }),
             }),
-            (id("0:1:717"), Item {
-                id: id("0:1:717"),
+            (Id(1), Item {
+                id: Id(1),
                 crate_id: 0,
                 name: Some("i32".to_owned()),
                 span: None,
@@ -91,7 +87,7 @@ fn errors_on_local_in_paths_and_not_index() {
                 inner: ItemEnum::Primitive(Primitive { name: "i32".to_owned(), impls: vec![] }),
             }),
         ]),
-        paths: FxHashMap::from_iter([(id("0:1:1571"), ItemSummary {
+        paths: FxHashMap::from_iter([(Id(2), ItemSummary {
             crate_id: 0,
             path: vec!["microcore".to_owned(), "i32".to_owned()],
             kind: ItemKind::Primitive,
@@ -101,7 +97,7 @@ fn errors_on_local_in_paths_and_not_index() {
     };
 
     check(&krate, &[Error {
-        id: id("0:1:1571"),
+        id: Id(2),
         kind: ErrorKind::Custom("Id for local item in `paths` but not in `index`".to_owned()),
     }]);
 }
@@ -110,11 +106,11 @@ fn errors_on_local_in_paths_and_not_index() {
 #[should_panic = "LOCAL_CRATE_ID is wrong"]
 fn checks_local_crate_id_is_correct() {
     let krate = Crate {
-        root: id("root"),
+        root: Id(0),
         crate_version: None,
         includes_private: false,
-        index: FxHashMap::from_iter([(id("root"), Item {
-            id: id("root"),
+        index: FxHashMap::from_iter([(Id(0), Item {
+            id: Id(0),
             crate_id: LOCAL_CRATE_ID.wrapping_add(1),
             name: Some("irrelavent".to_owned()),
             span: None,

From 71bb0e72ce837d8669b8662ffe6b07de395983f5 Mon Sep 17 00:00:00 2001
From: Lukas Bergdoll <lukas.bergdoll@gmail.com>
Date: Mon, 30 Sep 2024 10:54:23 +0200
Subject: [PATCH 2/7] Port sort-research-rs test suite Rust stdlib tests

This commit is a followup to https://github.com/rust-lang/rust/pull/124032. It
replaces the tests that test the various sort functions in the standard library
with a test-suite developed as part of
https://github.com/Voultapher/sort-research-rs. The current tests suffer a
couple of problems:

- They don't cover important real world patterns that the implementations take
  advantage of and execute special code for.
- The input lengths tested miss out on code paths. For example, important safety
  property tests never reach the quicksort part of the implementation.
- The miri side is often limited to `len <= 20` which means it very thoroughly
  tests the insertion sort, which accounts for 19 out of 1.5k LoC.
- They are split into to core and alloc, causing code duplication and uneven
  coverage.
- The randomness is not repeatable, as it
  relies on `std::hash::RandomState::new().build_hasher()`.

Most of these issues existed before
https://github.com/rust-lang/rust/pull/124032, but they are intensified by it.
One thing that is new and requires additional testing, is that the new sort
implementations specialize based on type properties. For example `Freeze` and
non `Freeze` execute different code paths.

Effectively there are three dimensions that matter:

- Input type
- Input length
- Input pattern

The ported test-suite tests various properties along all three dimensions,
greatly improving test coverage. It side-steps the miri issue by preferring
sampled approaches. For example the test that checks if after a panic the set of
elements is still the original one, doesn't do so for every single possible
panic opportunity but rather it picks one at random, and performs this test
across a range of input length, which varies the panic point across them. This
allows regular execution to easily test inputs of length 10k, and miri execution
up to 100 which covers significantly more code. The randomness used is tied to a
fixed - but random per process execution - seed. This allows for fully
repeatable tests and fuzzer like exploration across multiple runs.

Structure wise, the tests are previously found in the core integration tests for
`sort_unstable` and alloc unit tests for `sort`. The new test-suite was
developed to be a purely black-box approach, which makes integration testing the
better place, because it can't accidentally rely on internal access. Because
unwinding support is required the tests can't be in core, even if the
implementation is, so they are now part of the alloc integration tests. Are
there architectures that can only build and test core and not alloc? If so, do
such platforms require sort testing? For what it's worth the current
implementation state passes miri `--target mips64-unknown-linux-gnuabi64` which
is big endian.

The test-suite also contains tests for properties that were and are given by the
current and previous implementations, and likely relied upon by users but
weren't tested. For example `self_cmp` tests that the two parameters `a` and `b`
passed into the comparison function are never references to the same object,
which if the user is sorting for example a `&mut [Mutex<i32>]` could lead to a
deadlock.

Instead of using the hashed caller location as rand seed, it uses seconds since
unix epoch / 10, which given timestamps in the CI should be reasonably easy to
reproduce, but also allows fuzzer like space exploration.
---
 library/alloc/src/slice.rs                    |   24 +-
 library/alloc/src/slice/tests.rs              |  369 -----
 library/alloc/tests/lib.rs                    |    2 +
 library/alloc/tests/sort/ffi_types.rs         |   82 ++
 .../tests/sort/known_good_stable_sort.rs      |  192 +++
 library/alloc/tests/sort/mod.rs               |   17 +
 library/alloc/tests/sort/patterns.rs          |  211 +++
 library/alloc/tests/sort/tests.rs             | 1233 +++++++++++++++++
 library/alloc/tests/sort/zipf.rs              |  208 +++
 library/core/tests/slice.rs                   |   51 -
 10 files changed, 1955 insertions(+), 434 deletions(-)
 delete mode 100644 library/alloc/src/slice/tests.rs
 create mode 100644 library/alloc/tests/sort/ffi_types.rs
 create mode 100644 library/alloc/tests/sort/known_good_stable_sort.rs
 create mode 100644 library/alloc/tests/sort/mod.rs
 create mode 100644 library/alloc/tests/sort/patterns.rs
 create mode 100644 library/alloc/tests/sort/tests.rs
 create mode 100644 library/alloc/tests/sort/zipf.rs

diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs
index a92d22b1c309e..e3c7835f1d10b 100644
--- a/library/alloc/src/slice.rs
+++ b/library/alloc/src/slice.rs
@@ -19,20 +19,6 @@ use core::cmp::Ordering::{self, Less};
 use core::mem::{self, MaybeUninit};
 #[cfg(not(no_global_oom_handling))]
 use core::ptr;
-#[cfg(not(no_global_oom_handling))]
-use core::slice::sort;
-
-use crate::alloc::Allocator;
-#[cfg(not(no_global_oom_handling))]
-use crate::alloc::Global;
-#[cfg(not(no_global_oom_handling))]
-use crate::borrow::ToOwned;
-use crate::boxed::Box;
-use crate::vec::Vec;
-
-#[cfg(test)]
-mod tests;
-
 #[unstable(feature = "array_chunks", issue = "74985")]
 pub use core::slice::ArrayChunks;
 #[unstable(feature = "array_chunks", issue = "74985")]
@@ -43,6 +29,8 @@ pub use core::slice::ArrayWindows;
 pub use core::slice::EscapeAscii;
 #[stable(feature = "slice_get_slice", since = "1.28.0")]
 pub use core::slice::SliceIndex;
+#[cfg(not(no_global_oom_handling))]
+use core::slice::sort;
 #[stable(feature = "slice_group_by", since = "1.77.0")]
 pub use core::slice::{ChunkBy, ChunkByMut};
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -83,6 +71,14 @@ pub use hack::into_vec;
 #[cfg(test)]
 pub use hack::to_vec;
 
+use crate::alloc::Allocator;
+#[cfg(not(no_global_oom_handling))]
+use crate::alloc::Global;
+#[cfg(not(no_global_oom_handling))]
+use crate::borrow::ToOwned;
+use crate::boxed::Box;
+use crate::vec::Vec;
+
 // HACK(japaric): With cfg(test) `impl [T]` is not available, these three
 // functions are actually methods that are in `impl [T]` but not in
 // `core::slice::SliceExt` - we need to supply these functions for the
diff --git a/library/alloc/src/slice/tests.rs b/library/alloc/src/slice/tests.rs
deleted file mode 100644
index 786704caeb0ad..0000000000000
--- a/library/alloc/src/slice/tests.rs
+++ /dev/null
@@ -1,369 +0,0 @@
-use core::cell::Cell;
-use core::cmp::Ordering::{self, Equal, Greater, Less};
-use core::convert::identity;
-use core::sync::atomic::AtomicUsize;
-use core::sync::atomic::Ordering::Relaxed;
-use core::{fmt, mem};
-use std::panic;
-
-use rand::distributions::Standard;
-use rand::prelude::*;
-use rand::{Rng, RngCore};
-
-use crate::borrow::ToOwned;
-use crate::rc::Rc;
-use crate::string::ToString;
-use crate::test_helpers::test_rng;
-use crate::vec::Vec;
-
-macro_rules! do_test {
-    ($input:ident, $func:ident) => {
-        let len = $input.len();
-
-        // Work out the total number of comparisons required to sort
-        // this array...
-        let mut count = 0usize;
-        $input.to_owned().$func(|a, b| {
-            count += 1;
-            a.cmp(b)
-        });
-
-        // ... and then panic on each and every single one.
-        for panic_countdown in 0..count {
-            // Refresh the counters.
-            VERSIONS.store(0, Relaxed);
-            for i in 0..len {
-                DROP_COUNTS[i].store(0, Relaxed);
-            }
-
-            let v = $input.to_owned();
-            let _ = panic::catch_unwind(move || {
-                let mut v = v;
-                let mut panic_countdown = panic_countdown;
-                v.$func(|a, b| {
-                    if panic_countdown == 0 {
-                        SILENCE_PANIC.with(|s| s.set(true));
-                        panic!();
-                    }
-                    panic_countdown -= 1;
-                    a.cmp(b)
-                })
-            });
-
-            // Check that the number of things dropped is exactly
-            // what we expect (i.e., the contents of `v`).
-            for (i, c) in DROP_COUNTS.iter().enumerate().take(len) {
-                let count = c.load(Relaxed);
-                assert!(count == 1, "found drop count == {} for i == {}, len == {}", count, i, len);
-            }
-
-            // Check that the most recent versions of values were dropped.
-            assert_eq!(VERSIONS.load(Relaxed), 0);
-        }
-    };
-}
-
-const MAX_LEN: usize = 80;
-
-static DROP_COUNTS: [AtomicUsize; MAX_LEN] = [
-    // FIXME(RFC 1109): AtomicUsize is not Copy.
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-];
-
-static VERSIONS: AtomicUsize = AtomicUsize::new(0);
-
-#[derive(Clone, Eq)]
-struct DropCounter {
-    x: u32,
-    id: usize,
-    version: Cell<usize>,
-}
-
-impl PartialEq for DropCounter {
-    fn eq(&self, other: &Self) -> bool {
-        self.partial_cmp(other) == Some(Ordering::Equal)
-    }
-}
-
-impl PartialOrd for DropCounter {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        self.version.set(self.version.get() + 1);
-        other.version.set(other.version.get() + 1);
-        VERSIONS.fetch_add(2, Relaxed);
-        self.x.partial_cmp(&other.x)
-    }
-}
-
-impl Ord for DropCounter {
-    fn cmp(&self, other: &Self) -> Ordering {
-        self.partial_cmp(other).unwrap()
-    }
-}
-
-impl Drop for DropCounter {
-    fn drop(&mut self) {
-        DROP_COUNTS[self.id].fetch_add(1, Relaxed);
-        VERSIONS.fetch_sub(self.version.get(), Relaxed);
-    }
-}
-
-std::thread_local!(static SILENCE_PANIC: Cell<bool> = Cell::new(false));
-
-#[test]
-#[cfg_attr(target_os = "emscripten", ignore)] // no threads
-#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
-fn panic_safe() {
-    panic::update_hook(move |prev, info| {
-        if !SILENCE_PANIC.with(|s| s.get()) {
-            prev(info);
-        }
-    });
-
-    let mut rng = test_rng();
-
-    // Miri is too slow (but still need to `chain` to make the types match)
-    let lens = if cfg!(miri) { (1..10).chain(0..0) } else { (1..20).chain(70..MAX_LEN) };
-    let moduli: &[u32] = if cfg!(miri) { &[5] } else { &[5, 20, 50] };
-
-    for len in lens {
-        for &modulus in moduli {
-            for &has_runs in &[false, true] {
-                let mut input = (0..len)
-                    .map(|id| DropCounter {
-                        x: rng.next_u32() % modulus,
-                        id: id,
-                        version: Cell::new(0),
-                    })
-                    .collect::<Vec<_>>();
-
-                if has_runs {
-                    for c in &mut input {
-                        c.x = c.id as u32;
-                    }
-
-                    for _ in 0..5 {
-                        let a = rng.gen::<usize>() % len;
-                        let b = rng.gen::<usize>() % len;
-                        if a < b {
-                            input[a..b].reverse();
-                        } else {
-                            input.swap(a, b);
-                        }
-                    }
-                }
-
-                do_test!(input, sort_by);
-                do_test!(input, sort_unstable_by);
-            }
-        }
-    }
-
-    // Set default panic hook again.
-    drop(panic::take_hook());
-}
-
-#[test]
-#[cfg_attr(miri, ignore)] // Miri is too slow
-#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
-fn test_sort() {
-    let mut rng = test_rng();
-
-    for len in (2..25).chain(500..510) {
-        for &modulus in &[5, 10, 100, 1000] {
-            for _ in 0..10 {
-                let orig: Vec<_> = (&mut rng)
-                    .sample_iter::<i32, _>(&Standard)
-                    .map(|x| x % modulus)
-                    .take(len)
-                    .collect();
-
-                // Sort in default order.
-                let mut v = orig.clone();
-                v.sort();
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in ascending order.
-                let mut v = orig.clone();
-                v.sort_by(|a, b| a.cmp(b));
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in descending order.
-                let mut v = orig.clone();
-                v.sort_by(|a, b| b.cmp(a));
-                assert!(v.windows(2).all(|w| w[0] >= w[1]));
-
-                // Sort in lexicographic order.
-                let mut v1 = orig.clone();
-                let mut v2 = orig.clone();
-                v1.sort_by_key(|x| x.to_string());
-                v2.sort_by_cached_key(|x| x.to_string());
-                assert!(v1.windows(2).all(|w| w[0].to_string() <= w[1].to_string()));
-                assert!(v1 == v2);
-
-                // Sort with many pre-sorted runs.
-                let mut v = orig.clone();
-                v.sort();
-                v.reverse();
-                for _ in 0..5 {
-                    let a = rng.gen::<usize>() % len;
-                    let b = rng.gen::<usize>() % len;
-                    if a < b {
-                        v[a..b].reverse();
-                    } else {
-                        v.swap(a, b);
-                    }
-                }
-                v.sort();
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-            }
-        }
-    }
-
-    const ORD_VIOLATION_MAX_LEN: usize = 500;
-    let mut v = [0; ORD_VIOLATION_MAX_LEN];
-    for i in 0..ORD_VIOLATION_MAX_LEN {
-        v[i] = i as i32;
-    }
-
-    // Sort using a completely random comparison function. This will reorder the elements *somehow*,
-    // it may panic but the original elements must still be present.
-    let _ = panic::catch_unwind(move || {
-        v.sort_by(|_, _| *[Less, Equal, Greater].choose(&mut rng).unwrap());
-    });
-
-    v.sort();
-    for i in 0..ORD_VIOLATION_MAX_LEN {
-        assert_eq!(v[i], i as i32);
-    }
-
-    // Should not panic.
-    [0i32; 0].sort();
-    [(); 10].sort();
-    [(); 100].sort();
-
-    let mut v = [0xDEADBEEFu64];
-    v.sort();
-    assert!(v == [0xDEADBEEF]);
-}
-
-#[test]
-fn test_sort_stability() {
-    // Miri is too slow
-    let large_range = if cfg!(miri) { 0..0 } else { 500..510 };
-    let rounds = if cfg!(miri) { 1 } else { 10 };
-
-    let mut rng = test_rng();
-    for len in (2..25).chain(large_range) {
-        for _ in 0..rounds {
-            let mut counts = [0; 10];
-
-            // create a vector like [(6, 1), (5, 1), (6, 2), ...],
-            // where the first item of each tuple is random, but
-            // the second item represents which occurrence of that
-            // number this element is, i.e., the second elements
-            // will occur in sorted order.
-            let orig: Vec<_> = (0..len)
-                .map(|_| {
-                    let n = rng.gen::<usize>() % 10;
-                    counts[n] += 1;
-                    (n, counts[n])
-                })
-                .collect();
-
-            let mut v = orig.clone();
-            // Only sort on the first element, so an unstable sort
-            // may mix up the counts.
-            v.sort_by(|&(a, _), &(b, _)| a.cmp(&b));
-
-            // This comparison includes the count (the second item
-            // of the tuple), so elements with equal first items
-            // will need to be ordered with increasing
-            // counts... i.e., exactly asserting that this sort is
-            // stable.
-            assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-            let mut v = orig.clone();
-            v.sort_by_cached_key(|&(x, _)| x);
-            assert!(v.windows(2).all(|w| w[0] <= w[1]));
-        }
-    }
-}
diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
index 1d07a7690da43..23efd605ff9ee 100644
--- a/library/alloc/tests/lib.rs
+++ b/library/alloc/tests/lib.rs
@@ -41,6 +41,7 @@
 #![feature(local_waker)]
 #![feature(vec_pop_if)]
 #![feature(unique_rc_arc)]
+#![feature(macro_metavar_expr_concat)]
 #![allow(internal_features)]
 #![deny(fuzzy_provenance_casts)]
 #![deny(unsafe_op_in_unsafe_fn)]
@@ -60,6 +61,7 @@ mod heap;
 mod linked_list;
 mod rc;
 mod slice;
+mod sort;
 mod str;
 mod string;
 mod task;
diff --git a/library/alloc/tests/sort/ffi_types.rs b/library/alloc/tests/sort/ffi_types.rs
new file mode 100644
index 0000000000000..11515ea476971
--- /dev/null
+++ b/library/alloc/tests/sort/ffi_types.rs
@@ -0,0 +1,82 @@
+use std::cmp::Ordering;
+
+// Very large stack value.
+#[repr(C)]
+#[derive(PartialEq, Eq, Debug, Clone)]
+pub struct FFIOneKibiByte {
+    values: [i64; 128],
+}
+
+impl FFIOneKibiByte {
+    pub fn new(val: i32) -> Self {
+        let mut values = [0i64; 128];
+        let mut val_i64 = val as i64;
+
+        for elem in &mut values {
+            *elem = val_i64;
+            val_i64 = std::hint::black_box(val_i64 + 1);
+        }
+        Self { values }
+    }
+
+    fn as_i64(&self) -> i64 {
+        self.values[11] + self.values[55] + self.values[77]
+    }
+}
+
+impl PartialOrd for FFIOneKibiByte {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for FFIOneKibiByte {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.as_i64().cmp(&other.as_i64())
+    }
+}
+
+// 16 byte stack value, with more expensive comparison.
+#[repr(C)]
+#[derive(PartialEq, Debug, Clone, Copy)]
+pub struct F128 {
+    x: f64,
+    y: f64,
+}
+
+impl F128 {
+    pub fn new(val: i32) -> Self {
+        let val_f = (val as f64) + (i32::MAX as f64) + 10.0;
+
+        let x = val_f + 0.1;
+        let y = val_f.log(4.1);
+
+        assert!(y < x);
+        assert!(x.is_normal() && y.is_normal());
+
+        Self { x, y }
+    }
+}
+
+// This is kind of hacky, but we know we only have normal comparable floats in there.
+impl Eq for F128 {}
+
+impl PartialOrd for F128 {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+// Goal is similar code-gen between Rust and C++
+// - Rust https://godbolt.org/z/3YM3xenPP
+// - C++ https://godbolt.org/z/178M6j1zz
+impl Ord for F128 {
+    fn cmp(&self, other: &Self) -> Ordering {
+        // Simulate expensive comparison function.
+        let this_div = self.x / self.y;
+        let other_div = other.x / other.y;
+
+        // SAFETY: We checked in the ctor that both are normal.
+        unsafe { this_div.partial_cmp(&other_div).unwrap_unchecked() }
+    }
+}
diff --git a/library/alloc/tests/sort/known_good_stable_sort.rs b/library/alloc/tests/sort/known_good_stable_sort.rs
new file mode 100644
index 0000000000000..f8615435fc2a7
--- /dev/null
+++ b/library/alloc/tests/sort/known_good_stable_sort.rs
@@ -0,0 +1,192 @@
+// This module implements a known good stable sort implementation that helps provide better error
+// messages when the correctness tests fail, we can't use the stdlib sort functions because we are
+// testing them for correctness.
+//
+// Based on https://github.com/voultapher/tiny-sort-rs.
+
+use alloc::alloc::{Layout, alloc, dealloc};
+use std::{mem, ptr};
+
+/// Sort `v` preserving initial order of equal elements.
+///
+/// - Guaranteed O(N * log(N)) worst case perf
+/// - No adaptiveness
+/// - Branch miss-prediction not affected by outcome of comparison function
+/// - Uses `v.len()` auxiliary memory.
+///
+/// If `T: Ord` does not implement a total order the resulting order is
+/// unspecified. All original elements will remain in `v` and any possible modifications via
+/// interior mutability will be observable. Same is true if `T: Ord` panics.
+///
+/// Panics if allocating the auxiliary memory fails.
+#[inline(always)]
+pub fn sort<T: Ord>(v: &mut [T]) {
+    stable_sort(v, |a, b| a.lt(b))
+}
+
+#[inline(always)]
+fn stable_sort<T, F: FnMut(&T, &T) -> bool>(v: &mut [T], mut is_less: F) {
+    if mem::size_of::<T>() == 0 {
+        return;
+    }
+
+    let len = v.len();
+
+    // Inline the check for len < 2. This happens a lot, instrumenting the Rust compiler suggests
+    // len < 2 accounts for 94% of its calls to `slice::sort`.
+    if len < 2 {
+        return;
+    }
+
+    // SAFETY: We checked that len is > 0 and that T is not a ZST.
+    unsafe {
+        mergesort_main(v, &mut is_less);
+    }
+}
+
+/// The core logic should not be inlined.
+///
+/// SAFETY: The caller has to ensure that len is > 0 and that T is not a ZST.
+#[inline(never)]
+unsafe fn mergesort_main<T, F: FnMut(&T, &T) -> bool>(v: &mut [T], is_less: &mut F) {
+    // While it would be nice to have a merge implementation that only requires N / 2 auxiliary
+    // memory. Doing so would make the merge implementation significantly more complex and
+
+    // SAFETY: See function safety description.
+    let buf = unsafe { BufGuard::new(v.len()) };
+
+    // SAFETY: `scratch` has space for `v.len()` writes. And does not alias `v`.
+    unsafe {
+        mergesort_core(v, buf.buf_ptr.as_ptr(), is_less);
+    }
+}
+
+/// Tiny recursive top-down merge sort optimized for binary size. It has no adaptiveness whatsoever,
+/// no run detection, etc.
+///
+/// Buffer as pointed to by `scratch` must have space for `v.len()` writes. And must not alias `v`.
+#[inline(always)]
+unsafe fn mergesort_core<T, F: FnMut(&T, &T) -> bool>(
+    v: &mut [T],
+    scratch_ptr: *mut T,
+    is_less: &mut F,
+) {
+    let len = v.len();
+
+    if len > 2 {
+        // SAFETY: `mid` is guaranteed in-bounds. And caller has to ensure that `scratch_ptr` can
+        // hold `v.len()` values.
+        unsafe {
+            let mid = len / 2;
+            // Sort the left half recursively.
+            mergesort_core(v.get_unchecked_mut(..mid), scratch_ptr, is_less);
+            // Sort the right half recursively.
+            mergesort_core(v.get_unchecked_mut(mid..), scratch_ptr, is_less);
+            // Combine the two halves.
+            merge(v, scratch_ptr, is_less, mid);
+        }
+    } else if len == 2 {
+        if is_less(&v[1], &v[0]) {
+            v.swap(0, 1);
+        }
+    }
+}
+
+/// Branchless merge function.
+///
+/// SAFETY: The caller must ensure that `scratch_ptr` is valid for `v.len()` writes. And that mid is
+/// in-bounds.
+#[inline(always)]
+unsafe fn merge<T, F>(v: &mut [T], scratch_ptr: *mut T, is_less: &mut F, mid: usize)
+where
+    F: FnMut(&T, &T) -> bool,
+{
+    let len = v.len();
+    debug_assert!(mid > 0 && mid < len);
+
+    let len = v.len();
+
+    // Indexes to track the positions while merging.
+    let mut l = 0;
+    let mut r = mid;
+
+    // SAFETY: No matter what the result of is_less is we check that l and r remain in-bounds and if
+    // is_less panics the original elements remain in `v`.
+    unsafe {
+        let arr_ptr = v.as_ptr();
+
+        for i in 0..len {
+            let left_ptr = arr_ptr.add(l);
+            let right_ptr = arr_ptr.add(r);
+
+            let is_lt = !is_less(&*right_ptr, &*left_ptr);
+            let copy_ptr = if is_lt { left_ptr } else { right_ptr };
+            ptr::copy_nonoverlapping(copy_ptr, scratch_ptr.add(i), 1);
+
+            l += is_lt as usize;
+            r += !is_lt as usize;
+
+            // As long as neither side is exhausted merge left and right elements.
+            if ((l == mid) as u8 + (r == len) as u8) != 0 {
+                break;
+            }
+        }
+
+        // The left or right side is exhausted, drain the right side in one go.
+        let copy_ptr = if l == mid { arr_ptr.add(r) } else { arr_ptr.add(l) };
+        let i = l + (r - mid);
+        ptr::copy_nonoverlapping(copy_ptr, scratch_ptr.add(i), len - i);
+
+        // Now that scratch_ptr holds the full merged content, write it back on-top of v.
+        ptr::copy_nonoverlapping(scratch_ptr, v.as_mut_ptr(), len);
+    }
+}
+
+// SAFETY: The caller has to ensure that Option is Some, UB otherwise.
+unsafe fn unwrap_unchecked<T>(opt_val: Option<T>) -> T {
+    match opt_val {
+        Some(val) => val,
+        None => {
+            // SAFETY: See function safety description.
+            unsafe {
+                core::hint::unreachable_unchecked();
+            }
+        }
+    }
+}
+
+// Extremely basic versions of Vec.
+// Their use is super limited and by having the code here, it allows reuse between the sort
+// implementations.
+struct BufGuard<T> {
+    buf_ptr: ptr::NonNull<T>,
+    capacity: usize,
+}
+
+impl<T> BufGuard<T> {
+    // SAFETY: The caller has to ensure that len is not 0 and that T is not a ZST.
+    unsafe fn new(len: usize) -> Self {
+        debug_assert!(len > 0 && mem::size_of::<T>() > 0);
+
+        // SAFETY: See function safety description.
+        let layout = unsafe { unwrap_unchecked(Layout::array::<T>(len).ok()) };
+
+        // SAFETY: We checked that T is not a ZST.
+        let buf_ptr = unsafe { alloc(layout) as *mut T };
+
+        if buf_ptr.is_null() {
+            panic!("allocation failure");
+        }
+
+        Self { buf_ptr: ptr::NonNull::new(buf_ptr).unwrap(), capacity: len }
+    }
+}
+
+impl<T> Drop for BufGuard<T> {
+    fn drop(&mut self) {
+        // SAFETY: We checked that T is not a ZST.
+        unsafe {
+            dealloc(self.buf_ptr.as_ptr() as *mut u8, Layout::array::<T>(self.capacity).unwrap());
+        }
+    }
+}
diff --git a/library/alloc/tests/sort/mod.rs b/library/alloc/tests/sort/mod.rs
new file mode 100644
index 0000000000000..0e2494ca9d34e
--- /dev/null
+++ b/library/alloc/tests/sort/mod.rs
@@ -0,0 +1,17 @@
+pub trait Sort {
+    fn name() -> String;
+
+    fn sort<T>(v: &mut [T])
+    where
+        T: Ord;
+
+    fn sort_by<T, F>(v: &mut [T], compare: F)
+    where
+        F: FnMut(&T, &T) -> std::cmp::Ordering;
+}
+
+mod ffi_types;
+mod known_good_stable_sort;
+mod patterns;
+mod tests;
+mod zipf;
diff --git a/library/alloc/tests/sort/patterns.rs b/library/alloc/tests/sort/patterns.rs
new file mode 100644
index 0000000000000..e5d31d868b251
--- /dev/null
+++ b/library/alloc/tests/sort/patterns.rs
@@ -0,0 +1,211 @@
+use std::env;
+use std::hash::Hash;
+use std::str::FromStr;
+use std::sync::OnceLock;
+
+use rand::prelude::*;
+use rand_xorshift::XorShiftRng;
+
+use crate::sort::zipf::ZipfDistribution;
+
+/// Provides a set of patterns useful for testing and benchmarking sorting algorithms.
+/// Currently limited to i32 values.
+
+// --- Public ---
+
+pub fn random(len: usize) -> Vec<i32> {
+    //     .
+    // : . : :
+    // :.:::.::
+
+    random_vec(len)
+}
+
+pub fn random_uniform<R>(len: usize, range: R) -> Vec<i32>
+where
+    R: Into<rand::distributions::Uniform<i32>> + Hash,
+{
+    // :.:.:.::
+
+    let mut rng: XorShiftRng = rand::SeedableRng::seed_from_u64(get_or_init_rand_seed());
+
+    // Abstracting over ranges in Rust :(
+    let dist: rand::distributions::Uniform<i32> = range.into();
+    (0..len).map(|_| dist.sample(&mut rng)).collect()
+}
+
+pub fn random_zipf(len: usize, exponent: f64) -> Vec<i32> {
+    // https://en.wikipedia.org/wiki/Zipf's_law
+
+    let mut rng: XorShiftRng = rand::SeedableRng::seed_from_u64(get_or_init_rand_seed());
+
+    // Abstracting over ranges in Rust :(
+    let dist = ZipfDistribution::new(len, exponent).unwrap();
+    (0..len).map(|_| dist.sample(&mut rng) as i32).collect()
+}
+
+pub fn random_sorted(len: usize, sorted_percent: f64) -> Vec<i32> {
+    //     .:
+    //   .:::. :
+    // .::::::.::
+    // [----][--]
+    //  ^      ^
+    //  |      |
+    // sorted  |
+    //     unsorted
+
+    // Simulate pre-existing sorted slice, where len - sorted_percent are the new unsorted values
+    // and part of the overall distribution.
+    let mut v = random_vec(len);
+    let sorted_len = ((len as f64) * (sorted_percent / 100.0)).round() as usize;
+
+    v[0..sorted_len].sort_unstable();
+
+    v
+}
+
+pub fn all_equal(len: usize) -> Vec<i32> {
+    // ......
+    // ::::::
+
+    (0..len).map(|_| 66).collect::<Vec<_>>()
+}
+
+pub fn ascending(len: usize) -> Vec<i32> {
+    //     .:
+    //   .:::
+    // .:::::
+
+    (0..len as i32).collect::<Vec<_>>()
+}
+
+pub fn descending(len: usize) -> Vec<i32> {
+    // :.
+    // :::.
+    // :::::.
+
+    (0..len as i32).rev().collect::<Vec<_>>()
+}
+
+pub fn saw_mixed(len: usize, saw_count: usize) -> Vec<i32> {
+    // :.  :.    .::.    .:
+    // :::.:::..::::::..:::
+
+    if len == 0 {
+        return Vec::new();
+    }
+
+    let mut vals = random_vec(len);
+    let chunks_size = len / saw_count.max(1);
+    let saw_directions = random_uniform((len / chunks_size) + 1, 0..=1);
+
+    for (i, chunk) in vals.chunks_mut(chunks_size).enumerate() {
+        if saw_directions[i] == 0 {
+            chunk.sort_unstable();
+        } else if saw_directions[i] == 1 {
+            chunk.sort_unstable_by_key(|&e| std::cmp::Reverse(e));
+        } else {
+            unreachable!();
+        }
+    }
+
+    vals
+}
+
+pub fn saw_mixed_range(len: usize, range: std::ops::Range<usize>) -> Vec<i32> {
+    //     :.
+    // :.  :::.    .::.      .:
+    // :::.:::::..::::::..:.:::
+
+    // ascending and descending randomly picked, with length in `range`.
+
+    if len == 0 {
+        return Vec::new();
+    }
+
+    let mut vals = random_vec(len);
+
+    let max_chunks = len / range.start;
+    let saw_directions = random_uniform(max_chunks + 1, 0..=1);
+    let chunk_sizes = random_uniform(max_chunks + 1, (range.start as i32)..(range.end as i32));
+
+    let mut i = 0;
+    let mut l = 0;
+    while l < len {
+        let chunk_size = chunk_sizes[i] as usize;
+        let chunk_end = std::cmp::min(l + chunk_size, len);
+        let chunk = &mut vals[l..chunk_end];
+
+        if saw_directions[i] == 0 {
+            chunk.sort_unstable();
+        } else if saw_directions[i] == 1 {
+            chunk.sort_unstable_by_key(|&e| std::cmp::Reverse(e));
+        } else {
+            unreachable!();
+        }
+
+        i += 1;
+        l += chunk_size;
+    }
+
+    vals
+}
+
+pub fn pipe_organ(len: usize) -> Vec<i32> {
+    //   .:.
+    // .:::::.
+
+    let mut vals = random_vec(len);
+
+    let first_half = &mut vals[0..(len / 2)];
+    first_half.sort_unstable();
+
+    let second_half = &mut vals[(len / 2)..len];
+    second_half.sort_unstable_by_key(|&e| std::cmp::Reverse(e));
+
+    vals
+}
+
+pub fn get_or_init_rand_seed() -> u64 {
+    *SEED_VALUE.get_or_init(|| {
+        env::var("OVERRIDE_SEED")
+            .ok()
+            .map(|seed| u64::from_str(&seed).unwrap())
+            .unwrap_or_else(rand_root_seed)
+    })
+}
+
+// --- Private ---
+
+static SEED_VALUE: OnceLock<u64> = OnceLock::new();
+
+#[cfg(not(miri))]
+fn rand_root_seed() -> u64 {
+    // Other test code hashes `panic::Location::caller()` and constructs a seed from that, in these
+    // tests we want to have a fuzzer like exploration of the test space, if we used the same caller
+    // based construction we would always test the same.
+    //
+    // Instead we use the seconds since UNIX epoch / 10, given CI log output this value should be
+    // reasonably easy to re-construct.
+
+    use std::time::{SystemTime, UNIX_EPOCH};
+
+    let epoch_seconds = SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_secs();
+
+    epoch_seconds / 10
+}
+
+#[cfg(miri)]
+fn rand_root_seed() -> u64 {
+    // Miri is usually run with isolation with gives us repeatability but also permutations based on
+    // other code that runs before.
+    use core::hash::{BuildHasher, Hash, Hasher};
+    let mut hasher = std::hash::RandomState::new().build_hasher();
+    core::panic::Location::caller().hash(&mut hasher);
+    hasher.finish()
+}
+
+fn random_vec(len: usize) -> Vec<i32> {
+    let mut rng: XorShiftRng = rand::SeedableRng::seed_from_u64(get_or_init_rand_seed());
+    (0..len).map(|_| rng.gen::<i32>()).collect()
+}
diff --git a/library/alloc/tests/sort/tests.rs b/library/alloc/tests/sort/tests.rs
new file mode 100644
index 0000000000000..14e6013f965d8
--- /dev/null
+++ b/library/alloc/tests/sort/tests.rs
@@ -0,0 +1,1233 @@
+use std::cell::Cell;
+use std::cmp::Ordering;
+use std::fmt::Debug;
+use std::panic::{self, AssertUnwindSafe};
+use std::rc::Rc;
+use std::{env, fs};
+
+use crate::sort::ffi_types::{F128, FFIOneKibiByte};
+use crate::sort::{Sort, known_good_stable_sort, patterns};
+
+#[cfg(miri)]
+const TEST_LENGTHS: &[usize] = &[2, 3, 4, 7, 10, 15, 20, 24, 33, 50, 100, 171, 300];
+
+#[cfg(not(miri))]
+const TEST_LENGTHS: &[usize] = &[
+    2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 20, 24, 30, 32, 33, 35, 50, 100, 200, 500, 1_000,
+    2_048, 5_000, 10_000, 100_000, 1_100_000,
+];
+
+fn check_is_sorted<T: Ord + Clone + Debug, S: Sort>(v: &mut [T]) {
+    let seed = patterns::get_or_init_rand_seed();
+
+    let is_small_test = v.len() <= 100;
+    let v_orig = v.to_vec();
+
+    <S as Sort>::sort(v);
+
+    assert_eq!(v.len(), v_orig.len());
+
+    for window in v.windows(2) {
+        if window[0] > window[1] {
+            let mut known_good_sorted_vec = v_orig.clone();
+            known_good_stable_sort::sort(known_good_sorted_vec.as_mut_slice());
+
+            if is_small_test {
+                eprintln!("Orginal:  {:?}", v_orig);
+                eprintln!("Expected: {:?}", known_good_sorted_vec);
+                eprintln!("Got:      {:?}", v);
+            } else {
+                if env::var("WRITE_LARGE_FAILURE").is_ok() {
+                    // Large arrays output them as files.
+                    let original_name = format!("original_{}.txt", seed);
+                    let std_name = format!("known_good_sorted_{}.txt", seed);
+                    let testsort_name = format!("{}_sorted_{}.txt", S::name(), seed);
+
+                    fs::write(&original_name, format!("{:?}", v_orig)).unwrap();
+                    fs::write(&std_name, format!("{:?}", known_good_sorted_vec)).unwrap();
+                    fs::write(&testsort_name, format!("{:?}", v)).unwrap();
+
+                    eprintln!(
+                        "Failed comparison, see files {original_name}, {std_name}, and {testsort_name}"
+                    );
+                } else {
+                    eprintln!(
+                        "Failed comparison, re-run with WRITE_LARGE_FAILURE env var set, to get output."
+                    );
+                }
+            }
+
+            panic!("Test assertion failed!")
+        }
+    }
+}
+
+fn test_is_sorted<T: Ord + Clone + Debug, S: Sort>(
+    test_len: usize,
+    map_fn: impl Fn(i32) -> T,
+    pattern_fn: impl Fn(usize) -> Vec<i32>,
+) {
+    let mut test_data: Vec<T> = pattern_fn(test_len).into_iter().map(map_fn).collect();
+    check_is_sorted::<T, S>(test_data.as_mut_slice());
+}
+
+trait DynTrait: Debug {
+    fn get_val(&self) -> i32;
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+struct DynValA {
+    value: i32,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+struct DynValB {
+    value: u64,
+}
+
+impl DynTrait for DynValA {
+    fn get_val(&self) -> i32 {
+        self.value
+    }
+}
+impl DynTrait for DynValB {
+    fn get_val(&self) -> i32 {
+        let bytes = self.value.to_ne_bytes();
+        i32::from_ne_bytes([bytes[0], bytes[1], bytes[6], bytes[7]])
+    }
+}
+
+impl PartialOrd for dyn DynTrait {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for dyn DynTrait {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.get_val().cmp(&other.get_val())
+    }
+}
+
+impl PartialEq for dyn DynTrait {
+    fn eq(&self, other: &Self) -> bool {
+        self.get_val() == other.get_val()
+    }
+}
+
+impl Eq for dyn DynTrait {}
+
+fn shift_i32_to_u32(val: i32) -> u32 {
+    (val as i64 + (i32::MAX as i64 + 1)) as u32
+}
+
+fn reverse_shift_i32_to_u32(val: u32) -> i32 {
+    (val as i64 - (i32::MAX as i64 + 1)) as i32
+}
+
+fn extend_i32_to_u64(val: i32) -> u64 {
+    // Extends the value into the 64 bit range,
+    // while preserving input order.
+    (shift_i32_to_u32(val) as u64) * i32::MAX as u64
+}
+
+fn extend_i32_to_u128(val: i32) -> u128 {
+    // Extends the value into the 64 bit range,
+    // while preserving input order.
+    (shift_i32_to_u32(val) as u128) * i64::MAX as u128
+}
+
+fn dyn_trait_from_i32(val: i32) -> Rc<dyn DynTrait> {
+    if val % 2 == 0 {
+        Rc::new(DynValA { value: val })
+    } else {
+        Rc::new(DynValB { value: extend_i32_to_u64(val) })
+    }
+}
+
+fn i32_from_i32(val: i32) -> i32 {
+    val
+}
+
+fn i32_from_i32_ref(val: &i32) -> i32 {
+    *val
+}
+
+fn string_from_i32(val: i32) -> String {
+    format!("{:010}", shift_i32_to_u32(val))
+}
+
+fn i32_from_string(val: &String) -> i32 {
+    reverse_shift_i32_to_u32(val.parse::<u32>().unwrap())
+}
+
+fn cell_i32_from_i32(val: i32) -> Cell<i32> {
+    Cell::new(val)
+}
+
+fn i32_from_cell_i32(val: &Cell<i32>) -> i32 {
+    val.get()
+}
+
+fn calc_comps_required<T, S: Sort>(v: &mut [T], mut cmp_fn: impl FnMut(&T, &T) -> Ordering) -> u32 {
+    let mut comp_counter = 0u32;
+
+    <S as Sort>::sort_by(v, |a, b| {
+        comp_counter += 1;
+
+        cmp_fn(a, b)
+    });
+
+    comp_counter
+}
+
+#[derive(PartialEq, Eq, Debug, Clone)]
+#[repr(C)]
+struct CompCount {
+    val: i32,
+    comp_count: Cell<u32>,
+}
+
+impl CompCount {
+    fn new(val: i32) -> Self {
+        Self { val, comp_count: Cell::new(0) }
+    }
+}
+
+/// Generates $base_name_pattern_name_impl functions calling the test_fns for all test_len.
+macro_rules! gen_sort_test_fns {
+    (
+        $base_name:ident,
+        $test_fn:expr,
+        $test_lengths:expr,
+        [$(($pattern_name:ident, $pattern_fn:expr)),* $(,)?] $(,)?
+    ) => {
+        $(fn ${concat($base_name, _, $pattern_name, _impl)}<S: Sort>() {
+            for test_len in $test_lengths {
+                $test_fn(*test_len, $pattern_fn);
+            }
+        })*
+    };
+}
+
+/// Generates $base_name_pattern_name_impl functions calling the test_fns for all test_len,
+/// with a default set of patterns that can be extended by the caller.
+macro_rules! gen_sort_test_fns_with_default_patterns {
+    (
+        $base_name:ident,
+        $test_fn:expr,
+        $test_lengths:expr,
+        [$(($pattern_name:ident, $pattern_fn:expr)),* $(,)?] $(,)?
+    ) => {
+        gen_sort_test_fns!(
+            $base_name,
+            $test_fn,
+            $test_lengths,
+            [
+                (random, patterns::random),
+                (random_z1, |len| patterns::random_zipf(len, 1.0)),
+                (random_d2, |len| patterns::random_uniform(len, 0..2)),
+                (random_d20, |len| patterns::random_uniform(len, 0..16)),
+                (random_s95, |len| patterns::random_sorted(len, 95.0)),
+                (ascending, patterns::ascending),
+                (descending, patterns::descending),
+                (saw_mixed, |len| patterns::saw_mixed(
+                    len,
+                    ((len as f64).log2().round()) as usize
+                )),
+                $(($pattern_name, $pattern_fn),)*
+            ]
+        );
+    };
+}
+
+/// Generates $base_name_type_pattern_name_impl functions calling the test_fns for all test_len for
+/// three types that cover the core specialization differences in the sort implementations, with a
+/// default set of patterns that can be extended by the caller.
+macro_rules! gen_sort_test_fns_with_default_patterns_3_ty {
+    (
+        $base_name:ident,
+        $test_fn:ident,
+        [$(($pattern_name:ident, $pattern_fn:expr)),* $(,)?] $(,)?
+    ) => {
+        gen_sort_test_fns_with_default_patterns!(
+            ${concat($base_name, _i32)},
+            |len, pattern_fn| $test_fn::<i32, S>(len, i32_from_i32, i32_from_i32_ref, pattern_fn),
+            &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+            [$(($pattern_name, $pattern_fn),)*],
+        );
+
+        gen_sort_test_fns_with_default_patterns!(
+            ${concat($base_name, _cell_i32)},
+            |len, pattern_fn| $test_fn::<Cell<i32>, S>(len, cell_i32_from_i32, i32_from_cell_i32, pattern_fn),
+            &TEST_LENGTHS[..TEST_LENGTHS.len() - 3],
+            [$(($pattern_name, $pattern_fn),)*],
+        );
+
+        gen_sort_test_fns_with_default_patterns!(
+            ${concat($base_name, _string)},
+            |len, pattern_fn| $test_fn::<String, S>(len, string_from_i32, i32_from_string, pattern_fn),
+            &TEST_LENGTHS[..TEST_LENGTHS.len() - 3],
+            [$(($pattern_name, $pattern_fn),)*],
+        );
+    };
+}
+
+// --- TESTS ---
+
+pub fn basic_impl<S: Sort>() {
+    check_is_sorted::<i32, S>(&mut []);
+    check_is_sorted::<(), S>(&mut []);
+    check_is_sorted::<(), S>(&mut [()]);
+    check_is_sorted::<(), S>(&mut [(), ()]);
+    check_is_sorted::<(), S>(&mut [(), (), ()]);
+    check_is_sorted::<i32, S>(&mut []);
+    check_is_sorted::<i32, S>(&mut [77]);
+    check_is_sorted::<i32, S>(&mut [2, 3]);
+    check_is_sorted::<i32, S>(&mut [2, 3, 6]);
+    check_is_sorted::<i32, S>(&mut [2, 3, 99, 6]);
+    check_is_sorted::<i32, S>(&mut [2, 7709, 400, 90932]);
+    check_is_sorted::<i32, S>(&mut [15, -1, 3, -1, -3, -1, 7]);
+}
+
+fn fixed_seed_impl<S: Sort>() {
+    let fixed_seed_a = patterns::get_or_init_rand_seed();
+    let fixed_seed_b = patterns::get_or_init_rand_seed();
+
+    assert_eq!(fixed_seed_a, fixed_seed_b);
+}
+
+fn fixed_seed_rand_vec_prefix_impl<S: Sort>() {
+    let vec_rand_len_5 = patterns::random(5);
+    let vec_rand_len_7 = patterns::random(7);
+
+    assert_eq!(vec_rand_len_5, vec_rand_len_7[..5]);
+}
+
+fn int_edge_impl<S: Sort>() {
+    // Ensure that the sort can handle integer edge cases.
+    check_is_sorted::<i32, S>(&mut [i32::MIN, i32::MAX]);
+    check_is_sorted::<i32, S>(&mut [i32::MAX, i32::MIN]);
+    check_is_sorted::<i32, S>(&mut [i32::MIN, 3]);
+    check_is_sorted::<i32, S>(&mut [i32::MIN, -3]);
+    check_is_sorted::<i32, S>(&mut [i32::MIN, -3, i32::MAX]);
+    check_is_sorted::<i32, S>(&mut [i32::MIN, -3, i32::MAX, i32::MIN, 5]);
+    check_is_sorted::<i32, S>(&mut [i32::MAX, 3, i32::MIN, 5, i32::MIN, -3, 60, 200, 50, 7, 10]);
+
+    check_is_sorted::<u64, S>(&mut [u64::MIN, u64::MAX]);
+    check_is_sorted::<u64, S>(&mut [u64::MAX, u64::MIN]);
+    check_is_sorted::<u64, S>(&mut [u64::MIN, 3]);
+    check_is_sorted::<u64, S>(&mut [u64::MIN, u64::MAX - 3]);
+    check_is_sorted::<u64, S>(&mut [u64::MIN, u64::MAX - 3, u64::MAX]);
+    check_is_sorted::<u64, S>(&mut [u64::MIN, u64::MAX - 3, u64::MAX, u64::MIN, 5]);
+    check_is_sorted::<u64, S>(&mut [
+        u64::MAX,
+        3,
+        u64::MIN,
+        5,
+        u64::MIN,
+        u64::MAX - 3,
+        60,
+        200,
+        50,
+        7,
+        10,
+    ]);
+
+    let mut large = patterns::random(TEST_LENGTHS[TEST_LENGTHS.len() - 2]);
+    large.push(i32::MAX);
+    large.push(i32::MIN);
+    large.push(i32::MAX);
+    check_is_sorted::<i32, S>(&mut large);
+}
+
+fn sort_vs_sort_by_impl<S: Sort>() {
+    // Ensure that sort and sort_by produce the same result.
+    let mut input_normal = [800, 3, -801, 5, -801, -3, 60, 200, 50, 7, 10];
+    let expected = [-801, -801, -3, 3, 5, 7, 10, 50, 60, 200, 800];
+
+    let mut input_sort_by = input_normal.to_vec();
+
+    <S as Sort>::sort(&mut input_normal);
+    <S as Sort>::sort_by(&mut input_sort_by, |a, b| a.cmp(b));
+
+    assert_eq!(input_normal, expected);
+    assert_eq!(input_sort_by, expected);
+}
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_i32,
+    |len, pattern_fn| test_is_sorted::<i32, S>(len, |val| val, pattern_fn),
+    TEST_LENGTHS,
+    [
+        (random_d4, |len| patterns::random_uniform(len, 0..4)),
+        (random_d8, |len| patterns::random_uniform(len, 0..8)),
+        (random_d311, |len| patterns::random_uniform(len, 0..311)),
+        (random_d1024, |len| patterns::random_uniform(len, 0..1024)),
+        (random_z1_03, |len| patterns::random_zipf(len, 1.03)),
+        (random_z2, |len| patterns::random_zipf(len, 2.0)),
+        (random_s50, |len| patterns::random_sorted(len, 50.0)),
+        (narrow, |len| patterns::random_uniform(
+            len,
+            0..=(((len as f64).log2().round()) as i32) * 100
+        )),
+        (all_equal, patterns::all_equal),
+        (saw_mixed_range, |len| patterns::saw_mixed_range(len, 20..50)),
+        (pipe_organ, patterns::pipe_organ),
+    ]
+);
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_u64,
+    |len, pattern_fn| test_is_sorted::<u64, S>(len, extend_i32_to_u64, pattern_fn),
+    TEST_LENGTHS,
+    []
+);
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_u128,
+    |len, pattern_fn| test_is_sorted::<u128, S>(len, extend_i32_to_u128, pattern_fn),
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_cell_i32,
+    |len, pattern_fn| test_is_sorted::<Cell<i32>, S>(len, Cell::new, pattern_fn),
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_string,
+    |len, pattern_fn| test_is_sorted::<String, S>(
+        len,
+        |val| format!("{:010}", shift_i32_to_u32(val)),
+        pattern_fn
+    ),
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_f128,
+    |len, pattern_fn| test_is_sorted::<F128, S>(len, F128::new, pattern_fn),
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+gen_sort_test_fns_with_default_patterns!(
+    correct_1k,
+    |len, pattern_fn| test_is_sorted::<FFIOneKibiByte, S>(len, FFIOneKibiByte::new, pattern_fn),
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+// Dyn values are fat pointers, something the implementation might have overlooked.
+gen_sort_test_fns_with_default_patterns!(
+    correct_dyn_val,
+    |len, pattern_fn| test_is_sorted::<Rc<dyn DynTrait>, S>(len, dyn_trait_from_i32, pattern_fn),
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+fn stability_legacy_impl<S: Sort>() {
+    // This non pattern variant has proven to catch some bugs the pattern version of this function
+    // doesn't catch, so it remains in conjunction with the other one.
+
+    if <S as Sort>::name().contains("unstable") {
+        // It would be great to mark the test as skipped, but that isn't possible as of now.
+        return;
+    }
+
+    let large_range = if cfg!(miri) { 100..110 } else { 3000..3010 };
+    let rounds = if cfg!(miri) { 1 } else { 10 };
+
+    let rand_vals = patterns::random_uniform(5_000, 0..=9);
+    let mut rand_idx = 0;
+
+    for len in (2..55).chain(large_range) {
+        for _ in 0..rounds {
+            let mut counts = [0; 10];
+
+            // create a vector like [(6, 1), (5, 1), (6, 2), ...],
+            // where the first item of each tuple is random, but
+            // the second item represents which occurrence of that
+            // number this element is, i.e., the second elements
+            // will occur in sorted order.
+            let orig: Vec<_> = (0..len)
+                .map(|_| {
+                    let n = rand_vals[rand_idx];
+                    rand_idx += 1;
+                    if rand_idx >= rand_vals.len() {
+                        rand_idx = 0;
+                    }
+
+                    counts[n as usize] += 1;
+                    i32_tup_as_u64((n, counts[n as usize]))
+                })
+                .collect();
+
+            let mut v = orig.clone();
+            // Only sort on the first element, so an unstable sort
+            // may mix up the counts.
+            <S as Sort>::sort_by(&mut v, |a_packed, b_packed| {
+                let a = i32_tup_from_u64(*a_packed).0;
+                let b = i32_tup_from_u64(*b_packed).0;
+
+                a.cmp(&b)
+            });
+
+            // This comparison includes the count (the second item
+            // of the tuple), so elements with equal first items
+            // will need to be ordered with increasing
+            // counts... i.e., exactly asserting that this sort is
+            // stable.
+            assert!(v.windows(2).all(|w| i32_tup_from_u64(w[0]) <= i32_tup_from_u64(w[1])));
+        }
+    }
+
+    // For cpp_sorts that only support u64 we can pack the two i32 inside a u64.
+    fn i32_tup_as_u64(val: (i32, i32)) -> u64 {
+        let a_bytes = val.0.to_le_bytes();
+        let b_bytes = val.1.to_le_bytes();
+
+        u64::from_le_bytes([a_bytes, b_bytes].concat().try_into().unwrap())
+    }
+
+    fn i32_tup_from_u64(val: u64) -> (i32, i32) {
+        let bytes = val.to_le_bytes();
+
+        let a = i32::from_le_bytes(bytes[0..4].try_into().unwrap());
+        let b = i32::from_le_bytes(bytes[4..8].try_into().unwrap());
+
+        (a, b)
+    }
+}
+
+fn stability_with_patterns<T: Ord + Clone, S: Sort>(
+    len: usize,
+    type_into_fn: impl Fn(i32) -> T,
+    _type_from_fn: impl Fn(&T) -> i32,
+    pattern_fn: fn(usize) -> Vec<i32>,
+) {
+    if <S as Sort>::name().contains("unstable") {
+        // It would be great to mark the test as skipped, but that isn't possible as of now.
+        return;
+    }
+
+    let pattern = pattern_fn(len);
+
+    let mut counts = [0i32; 128];
+
+    // create a vector like [(6, 1), (5, 1), (6, 2), ...],
+    // where the first item of each tuple is random, but
+    // the second item represents which occurrence of that
+    // number this element is, i.e., the second elements
+    // will occur in sorted order.
+    let orig: Vec<_> = pattern
+        .iter()
+        .map(|val| {
+            let n = val.saturating_abs() % counts.len() as i32;
+            counts[n as usize] += 1;
+            (type_into_fn(n), counts[n as usize])
+        })
+        .collect();
+
+    let mut v = orig.clone();
+    // Only sort on the first element, so an unstable sort
+    // may mix up the counts.
+    <S as Sort>::sort(&mut v);
+
+    // This comparison includes the count (the second item
+    // of the tuple), so elements with equal first items
+    // will need to be ordered with increasing
+    // counts... i.e., exactly asserting that this sort is
+    // stable.
+    assert!(v.windows(2).all(|w| w[0] <= w[1]));
+}
+
+gen_sort_test_fns_with_default_patterns_3_ty!(stability, stability_with_patterns, []);
+
+fn observable_is_less<S: Sort>(len: usize, pattern_fn: fn(usize) -> Vec<i32>) {
+    // This test, tests that every is_less is actually observable. Ie. this can go wrong if a hole
+    // is created using temporary memory and, the whole is used as comparison but not copied back.
+    //
+    // If this is not upheld a custom type + comparison function could yield UB in otherwise safe
+    // code. Eg T == Mutex<Option<Box<str>>> which replaces the pointer with none in the comparison
+    // function, which would not be observed in the original slice and would lead to a double free.
+
+    let pattern = pattern_fn(len);
+    let mut test_input = pattern.into_iter().map(|val| CompCount::new(val)).collect::<Vec<_>>();
+
+    let mut comp_count_global = 0;
+
+    <S as Sort>::sort_by(&mut test_input, |a, b| {
+        a.comp_count.replace(a.comp_count.get() + 1);
+        b.comp_count.replace(b.comp_count.get() + 1);
+        comp_count_global += 1;
+
+        a.val.cmp(&b.val)
+    });
+
+    let total_inner: u64 = test_input.iter().map(|c| c.comp_count.get() as u64).sum();
+
+    assert_eq!(total_inner, comp_count_global * 2);
+}
+
+gen_sort_test_fns_with_default_patterns!(
+    observable_is_less,
+    observable_is_less::<S>,
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+fn panic_retain_orig_set<T: Ord + Clone, S: Sort>(
+    len: usize,
+    type_into_fn: impl Fn(i32) -> T + Copy,
+    type_from_fn: impl Fn(&T) -> i32,
+    pattern_fn: fn(usize) -> Vec<i32>,
+) {
+    let mut test_data: Vec<T> = pattern_fn(len).into_iter().map(type_into_fn).collect();
+
+    let sum_before: i64 = test_data.iter().map(|x| type_from_fn(x) as i64).sum();
+
+    // Calculate a specific comparison that should panic.
+    // Ensure that it can be any of the possible comparisons and that it always panics.
+    let required_comps = calc_comps_required::<T, S>(&mut test_data.clone(), |a, b| a.cmp(b));
+    let panic_threshold = patterns::random_uniform(1, 1..=required_comps as i32)[0] as usize - 1;
+
+    let mut comp_counter = 0;
+
+    let res = panic::catch_unwind(AssertUnwindSafe(|| {
+        <S as Sort>::sort_by(&mut test_data, |a, b| {
+            if comp_counter == panic_threshold {
+                // Make the panic dependent on the test len and some random factor. We want to
+                // make sure that panicking may also happen when comparing elements a second
+                // time.
+                panic!();
+            }
+            comp_counter += 1;
+
+            a.cmp(b)
+        });
+    }));
+
+    assert!(res.is_err());
+
+    // If the sum before and after don't match, it means the set of elements hasn't remained the
+    // same.
+    let sum_after: i64 = test_data.iter().map(|x| type_from_fn(x) as i64).sum();
+    assert_eq!(sum_before, sum_after);
+}
+
+gen_sort_test_fns_with_default_patterns_3_ty!(panic_retain_orig_set, panic_retain_orig_set, []);
+
+fn panic_observable_is_less<S: Sort>(len: usize, pattern_fn: fn(usize) -> Vec<i32>) {
+    // This test, tests that every is_less is actually observable. Ie. this can go wrong if a hole
+    // is created using temporary memory and, the whole is used as comparison but not copied back.
+    // This property must also hold if the user provided comparison panics.
+    //
+    // If this is not upheld a custom type + comparison function could yield UB in otherwise safe
+    // code. Eg T == Mutex<Option<Box<str>>> which replaces the pointer with none in the comparison
+    // function, which would not be observed in the original slice and would lead to a double free.
+
+    let mut test_input =
+        pattern_fn(len).into_iter().map(|val| CompCount::new(val)).collect::<Vec<_>>();
+
+    let sum_before: i64 = test_input.iter().map(|x| x.val as i64).sum();
+
+    // Calculate a specific comparison that should panic.
+    // Ensure that it can be any of the possible comparisons and that it always panics.
+    let required_comps =
+        calc_comps_required::<CompCount, S>(&mut test_input.clone(), |a, b| a.val.cmp(&b.val));
+
+    let panic_threshold = patterns::random_uniform(1, 1..=required_comps as i32)[0] as u64 - 1;
+
+    let mut comp_count_global = 0;
+
+    let res = panic::catch_unwind(AssertUnwindSafe(|| {
+        <S as Sort>::sort_by(&mut test_input, |a, b| {
+            if comp_count_global == panic_threshold {
+                // Make the panic dependent on the test len and some random factor. We want to
+                // make sure that panicking may also happen when comparing elements a second
+                // time.
+                panic!();
+            }
+
+            a.comp_count.replace(a.comp_count.get() + 1);
+            b.comp_count.replace(b.comp_count.get() + 1);
+            comp_count_global += 1;
+
+            a.val.cmp(&b.val)
+        });
+    }));
+
+    assert!(res.is_err());
+
+    let total_inner: u64 = test_input.iter().map(|c| c.comp_count.get() as u64).sum();
+
+    assert_eq!(total_inner, comp_count_global * 2);
+
+    // If the sum before and after don't match, it means the set of elements hasn't remained the
+    // same.
+    let sum_after: i64 = test_input.iter().map(|x| x.val as i64).sum();
+    assert_eq!(sum_before, sum_after);
+}
+
+gen_sort_test_fns_with_default_patterns!(
+    panic_observable_is_less,
+    panic_observable_is_less::<S>,
+    &TEST_LENGTHS[..TEST_LENGTHS.len() - 2],
+    []
+);
+
+fn deterministic<T: Ord + Clone + Debug, S: Sort>(
+    len: usize,
+    type_into_fn: impl Fn(i32) -> T + Copy,
+    type_from_fn: impl Fn(&T) -> i32,
+    pattern_fn: fn(usize) -> Vec<i32>,
+) {
+    // A property similar to stability is deterministic output order. If the entire value is used as
+    // the comparison key a lack of determinism has no effect. But if only a part of the value is
+    // used as comparison key, a lack of determinism can manifest itself in the order of values
+    // considered equal by the comparison predicate.
+    //
+    // This test only tests that results are deterministic across runs, it does not test determinism
+    // on different platforms and with different toolchains.
+
+    let mut test_input =
+        pattern_fn(len).into_iter().map(|val| type_into_fn(val)).collect::<Vec<_>>();
+
+    let mut test_input_clone = test_input.clone();
+
+    let comparison_fn = |a: &T, b: &T| {
+        let a_i32 = type_from_fn(a);
+        let b_i32 = type_from_fn(b);
+
+        let a_i32_key_space_reduced = a_i32 % 10_000;
+        let b_i32_key_space_reduced = b_i32 % 10_000;
+
+        a_i32_key_space_reduced.cmp(&b_i32_key_space_reduced)
+    };
+
+    <S as Sort>::sort_by(&mut test_input, comparison_fn);
+    <S as Sort>::sort_by(&mut test_input_clone, comparison_fn);
+
+    assert_eq!(test_input, test_input_clone);
+}
+
+gen_sort_test_fns_with_default_patterns_3_ty!(deterministic, deterministic, []);
+
+fn self_cmp<T: Ord + Clone + Debug, S: Sort>(
+    len: usize,
+    type_into_fn: impl Fn(i32) -> T + Copy,
+    _type_from_fn: impl Fn(&T) -> i32,
+    pattern_fn: fn(usize) -> Vec<i32>,
+) {
+    // It's possible for comparisons to run into problems if the values of `a` and `b` passed into
+    // the comparison function are the same reference. So this tests that they never are.
+
+    let mut test_input =
+        pattern_fn(len).into_iter().map(|val| type_into_fn(val)).collect::<Vec<_>>();
+
+    let comparison_fn = |a: &T, b: &T| {
+        assert_ne!(a as *const T as usize, b as *const T as usize);
+        a.cmp(b)
+    };
+
+    <S as Sort>::sort_by(&mut test_input, comparison_fn);
+
+    // Check that the output is actually sorted and wasn't stopped by the assert.
+    for window in test_input.windows(2) {
+        assert!(window[0] <= window[1]);
+    }
+}
+
+gen_sort_test_fns_with_default_patterns_3_ty!(self_cmp, self_cmp, []);
+
+fn violate_ord_retain_orig_set<T: Ord, S: Sort>(
+    len: usize,
+    type_into_fn: impl Fn(i32) -> T + Copy,
+    type_from_fn: impl Fn(&T) -> i32,
+    pattern_fn: fn(usize) -> Vec<i32>,
+) {
+    // A user may implement Ord incorrectly for a type or violate it by calling sort_by with a
+    // comparison function that violates Ord with the orderings it returns. Even under such
+    // circumstances the input must retain its original set of elements.
+
+    // Ord implies a strict total order see https://en.wikipedia.org/wiki/Total_order.
+
+    // Generating random numbers with miri is quite expensive.
+    let random_orderings_len = if cfg!(miri) { 200 } else { 10_000 };
+
+    // Make sure we get a good distribution of random orderings, that are repeatable with the seed.
+    // Just using random_uniform with the same len and range will always yield the same value.
+    let random_orderings = patterns::random_uniform(random_orderings_len, 0..2);
+
+    let get_random_0_1_or_2 = |random_idx: &mut usize| {
+        let ridx = *random_idx;
+        *random_idx += 1;
+        if ridx + 1 == random_orderings.len() {
+            *random_idx = 0;
+        }
+
+        random_orderings[ridx] as usize
+    };
+
+    let mut random_idx_a = 0;
+    let mut random_idx_b = 0;
+    let mut random_idx_c = 0;
+
+    let mut last_element_a = -1;
+    let mut last_element_b = -1;
+
+    let mut rand_counter_b = 0;
+    let mut rand_counter_c = 0;
+
+    let mut streak_counter_a = 0;
+    let mut streak_counter_b = 0;
+
+    // Examples, a = 3, b = 5, c = 9.
+    // Correct Ord -> 10010 | is_less(a, b) is_less(a, a) is_less(b, a) is_less(a, c) is_less(c, a)
+    let mut invalid_ord_comp_functions: Vec<Box<dyn FnMut(&T, &T) -> Ordering>> = vec![
+        Box::new(|_a, _b| -> Ordering {
+            // random
+            // Eg. is_less(3, 5) == true, is_less(3, 5) == false
+
+            let idx = get_random_0_1_or_2(&mut random_idx_a);
+            [Ordering::Less, Ordering::Equal, Ordering::Greater][idx]
+        }),
+        Box::new(|_a, _b| -> Ordering {
+            // everything is less -> 11111
+            Ordering::Less
+        }),
+        Box::new(|_a, _b| -> Ordering {
+            // everything is equal -> 00000
+            Ordering::Equal
+        }),
+        Box::new(|_a, _b| -> Ordering {
+            // everything is greater -> 00000
+            // Eg. is_less(3, 5) == false, is_less(5, 3) == false, is_less(3, 3) == false
+            Ordering::Greater
+        }),
+        Box::new(|a, b| -> Ordering {
+            // equal means less else greater -> 01000
+            if a == b { Ordering::Less } else { Ordering::Greater }
+        }),
+        Box::new(|a, b| -> Ordering {
+            // Transitive breaker. remember last element -> 10001
+            let lea = last_element_a;
+            let leb = last_element_b;
+
+            let a_as_i32 = type_from_fn(a);
+            let b_as_i32 = type_from_fn(b);
+
+            last_element_a = a_as_i32;
+            last_element_b = b_as_i32;
+
+            if a_as_i32 == lea && b_as_i32 != leb { b.cmp(a) } else { a.cmp(b) }
+        }),
+        Box::new(|a, b| -> Ordering {
+            // Sampled random 1% of comparisons are reversed.
+            rand_counter_b += get_random_0_1_or_2(&mut random_idx_b);
+            if rand_counter_b >= 100 {
+                rand_counter_b = 0;
+                b.cmp(a)
+            } else {
+                a.cmp(b)
+            }
+        }),
+        Box::new(|a, b| -> Ordering {
+            // Sampled random 33% of comparisons are reversed.
+            rand_counter_c += get_random_0_1_or_2(&mut random_idx_c);
+            if rand_counter_c >= 3 {
+                rand_counter_c = 0;
+                b.cmp(a)
+            } else {
+                a.cmp(b)
+            }
+        }),
+        Box::new(|a, b| -> Ordering {
+            // STREAK_LEN comparisons yield a.cmp(b) then STREAK_LEN comparisons less. This can
+            // discover bugs that neither, random Ord, or just Less or Greater can find. Because it
+            // can push a pointer further than expected. Random Ord will average out how far a
+            // comparison based pointer travels. Just Less or Greater will be caught by pattern
+            // analysis and never enter interesting code.
+            const STREAK_LEN: usize = 50;
+
+            streak_counter_a += 1;
+            if streak_counter_a <= STREAK_LEN {
+                a.cmp(b)
+            } else {
+                if streak_counter_a == STREAK_LEN * 2 {
+                    streak_counter_a = 0;
+                }
+                Ordering::Less
+            }
+        }),
+        Box::new(|a, b| -> Ordering {
+            // See above.
+            const STREAK_LEN: usize = 50;
+
+            streak_counter_b += 1;
+            if streak_counter_b <= STREAK_LEN {
+                a.cmp(b)
+            } else {
+                if streak_counter_b == STREAK_LEN * 2 {
+                    streak_counter_b = 0;
+                }
+                Ordering::Greater
+            }
+        }),
+    ];
+
+    for comp_func in &mut invalid_ord_comp_functions {
+        let mut test_data: Vec<T> = pattern_fn(len).into_iter().map(type_into_fn).collect();
+        let sum_before: i64 = test_data.iter().map(|x| type_from_fn(x) as i64).sum();
+
+        // It's ok to panic on Ord violation or to complete.
+        // In both cases the original elements must still be present.
+        let _ = panic::catch_unwind(AssertUnwindSafe(|| {
+            <S as Sort>::sort_by(&mut test_data, &mut *comp_func);
+        }));
+
+        // If the sum before and after don't match, it means the set of elements hasn't remained the
+        // same.
+        let sum_after: i64 = test_data.iter().map(|x| type_from_fn(x) as i64).sum();
+        assert_eq!(sum_before, sum_after);
+
+        if cfg!(miri) {
+            // This test is prohibitively expensive in miri, so only run one of the comparison
+            // functions. This test is not expected to yield direct UB, but rather surface potential
+            // UB by showing that the sum is different now.
+            break;
+        }
+    }
+}
+
+gen_sort_test_fns_with_default_patterns_3_ty!(
+    violate_ord_retain_orig_set,
+    violate_ord_retain_orig_set,
+    []
+);
+
+macro_rules! instantiate_sort_test_inner {
+    ($sort_impl:ty, miri_yes, $test_fn_name:ident) => {
+        #[test]
+        fn $test_fn_name() {
+            $crate::sort::tests::$test_fn_name::<$sort_impl>();
+        }
+    };
+    ($sort_impl:ty, miri_no, $test_fn_name:ident) => {
+        #[test]
+        #[cfg_attr(miri, ignore)]
+        fn $test_fn_name() {
+            $crate::sort::tests::$test_fn_name::<$sort_impl>();
+        }
+    };
+}
+
+// Using this construct allows us to get warnings for unused test functions.
+macro_rules! define_instantiate_sort_tests {
+    ($([$miri_use:ident, $test_fn_name:ident]),*,) => {
+        $(pub fn $test_fn_name<S: Sort>() {
+            ${concat($test_fn_name, _impl)}::<S>();
+        })*
+
+
+        macro_rules! instantiate_sort_tests_gen {
+            ($sort_impl:ty) => {
+                $(
+                    instantiate_sort_test_inner!(
+                        $sort_impl,
+                        $miri_use,
+                        $test_fn_name
+                    );
+                )*
+            }
+        }
+    };
+}
+
+// Some tests are not tested with miri to avoid prohibitively long test times. This leaves coverage
+// holes, but the way they are selected should make for relatively small holes. Many properties that
+// can lead to UB are tested directly, for example that the original set of elements is retained
+// even when a panic occurs or Ord is implemented incorrectly.
+define_instantiate_sort_tests!(
+    [miri_yes, basic],
+    [miri_yes, fixed_seed],
+    [miri_yes, fixed_seed_rand_vec_prefix],
+    [miri_yes, int_edge],
+    [miri_yes, sort_vs_sort_by],
+    [miri_yes, correct_i32_random],
+    [miri_yes, correct_i32_random_z1],
+    [miri_yes, correct_i32_random_d2],
+    [miri_yes, correct_i32_random_d20],
+    [miri_yes, correct_i32_random_s95],
+    [miri_yes, correct_i32_ascending],
+    [miri_yes, correct_i32_descending],
+    [miri_yes, correct_i32_saw_mixed],
+    [miri_no, correct_i32_random_d4],
+    [miri_no, correct_i32_random_d8],
+    [miri_no, correct_i32_random_d311],
+    [miri_no, correct_i32_random_d1024],
+    [miri_no, correct_i32_random_z1_03],
+    [miri_no, correct_i32_random_z2],
+    [miri_no, correct_i32_random_s50],
+    [miri_no, correct_i32_narrow],
+    [miri_no, correct_i32_all_equal],
+    [miri_no, correct_i32_saw_mixed_range],
+    [miri_yes, correct_i32_pipe_organ],
+    [miri_no, correct_u64_random],
+    [miri_yes, correct_u64_random_z1],
+    [miri_no, correct_u64_random_d2],
+    [miri_no, correct_u64_random_d20],
+    [miri_no, correct_u64_random_s95],
+    [miri_no, correct_u64_ascending],
+    [miri_no, correct_u64_descending],
+    [miri_no, correct_u64_saw_mixed],
+    [miri_no, correct_u128_random],
+    [miri_yes, correct_u128_random_z1],
+    [miri_no, correct_u128_random_d2],
+    [miri_no, correct_u128_random_d20],
+    [miri_no, correct_u128_random_s95],
+    [miri_no, correct_u128_ascending],
+    [miri_no, correct_u128_descending],
+    [miri_no, correct_u128_saw_mixed],
+    [miri_no, correct_cell_i32_random],
+    [miri_yes, correct_cell_i32_random_z1],
+    [miri_no, correct_cell_i32_random_d2],
+    [miri_no, correct_cell_i32_random_d20],
+    [miri_no, correct_cell_i32_random_s95],
+    [miri_no, correct_cell_i32_ascending],
+    [miri_no, correct_cell_i32_descending],
+    [miri_no, correct_cell_i32_saw_mixed],
+    [miri_no, correct_string_random],
+    [miri_yes, correct_string_random_z1],
+    [miri_no, correct_string_random_d2],
+    [miri_no, correct_string_random_d20],
+    [miri_no, correct_string_random_s95],
+    [miri_no, correct_string_ascending],
+    [miri_no, correct_string_descending],
+    [miri_no, correct_string_saw_mixed],
+    [miri_no, correct_f128_random],
+    [miri_yes, correct_f128_random_z1],
+    [miri_no, correct_f128_random_d2],
+    [miri_no, correct_f128_random_d20],
+    [miri_no, correct_f128_random_s95],
+    [miri_no, correct_f128_ascending],
+    [miri_no, correct_f128_descending],
+    [miri_no, correct_f128_saw_mixed],
+    [miri_no, correct_1k_random],
+    [miri_yes, correct_1k_random_z1],
+    [miri_no, correct_1k_random_d2],
+    [miri_no, correct_1k_random_d20],
+    [miri_no, correct_1k_random_s95],
+    [miri_no, correct_1k_ascending],
+    [miri_no, correct_1k_descending],
+    [miri_no, correct_1k_saw_mixed],
+    [miri_no, correct_dyn_val_random],
+    [miri_yes, correct_dyn_val_random_z1],
+    [miri_no, correct_dyn_val_random_d2],
+    [miri_no, correct_dyn_val_random_d20],
+    [miri_no, correct_dyn_val_random_s95],
+    [miri_no, correct_dyn_val_ascending],
+    [miri_no, correct_dyn_val_descending],
+    [miri_no, correct_dyn_val_saw_mixed],
+    [miri_no, stability_legacy],
+    [miri_no, stability_i32_random],
+    [miri_yes, stability_i32_random_z1],
+    [miri_no, stability_i32_random_d2],
+    [miri_no, stability_i32_random_d20],
+    [miri_no, stability_i32_random_s95],
+    [miri_no, stability_i32_ascending],
+    [miri_no, stability_i32_descending],
+    [miri_no, stability_i32_saw_mixed],
+    [miri_no, stability_cell_i32_random],
+    [miri_yes, stability_cell_i32_random_z1],
+    [miri_no, stability_cell_i32_random_d2],
+    [miri_no, stability_cell_i32_random_d20],
+    [miri_no, stability_cell_i32_random_s95],
+    [miri_no, stability_cell_i32_ascending],
+    [miri_no, stability_cell_i32_descending],
+    [miri_no, stability_cell_i32_saw_mixed],
+    [miri_no, stability_string_random],
+    [miri_yes, stability_string_random_z1],
+    [miri_no, stability_string_random_d2],
+    [miri_no, stability_string_random_d20],
+    [miri_no, stability_string_random_s95],
+    [miri_no, stability_string_ascending],
+    [miri_no, stability_string_descending],
+    [miri_no, stability_string_saw_mixed],
+    [miri_no, observable_is_less_random],
+    [miri_yes, observable_is_less_random_z1],
+    [miri_no, observable_is_less_random_d2],
+    [miri_no, observable_is_less_random_d20],
+    [miri_no, observable_is_less_random_s95],
+    [miri_no, observable_is_less_ascending],
+    [miri_no, observable_is_less_descending],
+    [miri_no, observable_is_less_saw_mixed],
+    [miri_no, panic_retain_orig_set_i32_random],
+    [miri_yes, panic_retain_orig_set_i32_random_z1],
+    [miri_no, panic_retain_orig_set_i32_random_d2],
+    [miri_no, panic_retain_orig_set_i32_random_d20],
+    [miri_no, panic_retain_orig_set_i32_random_s95],
+    [miri_no, panic_retain_orig_set_i32_ascending],
+    [miri_no, panic_retain_orig_set_i32_descending],
+    [miri_no, panic_retain_orig_set_i32_saw_mixed],
+    [miri_no, panic_retain_orig_set_cell_i32_random],
+    [miri_yes, panic_retain_orig_set_cell_i32_random_z1],
+    [miri_no, panic_retain_orig_set_cell_i32_random_d2],
+    [miri_no, panic_retain_orig_set_cell_i32_random_d20],
+    [miri_no, panic_retain_orig_set_cell_i32_random_s95],
+    [miri_no, panic_retain_orig_set_cell_i32_ascending],
+    [miri_no, panic_retain_orig_set_cell_i32_descending],
+    [miri_no, panic_retain_orig_set_cell_i32_saw_mixed],
+    [miri_no, panic_retain_orig_set_string_random],
+    [miri_yes, panic_retain_orig_set_string_random_z1],
+    [miri_no, panic_retain_orig_set_string_random_d2],
+    [miri_no, panic_retain_orig_set_string_random_d20],
+    [miri_no, panic_retain_orig_set_string_random_s95],
+    [miri_no, panic_retain_orig_set_string_ascending],
+    [miri_no, panic_retain_orig_set_string_descending],
+    [miri_no, panic_retain_orig_set_string_saw_mixed],
+    [miri_no, panic_observable_is_less_random],
+    [miri_yes, panic_observable_is_less_random_z1],
+    [miri_no, panic_observable_is_less_random_d2],
+    [miri_no, panic_observable_is_less_random_d20],
+    [miri_no, panic_observable_is_less_random_s95],
+    [miri_no, panic_observable_is_less_ascending],
+    [miri_no, panic_observable_is_less_descending],
+    [miri_no, panic_observable_is_less_saw_mixed],
+    [miri_no, deterministic_i32_random],
+    [miri_yes, deterministic_i32_random_z1],
+    [miri_no, deterministic_i32_random_d2],
+    [miri_no, deterministic_i32_random_d20],
+    [miri_no, deterministic_i32_random_s95],
+    [miri_no, deterministic_i32_ascending],
+    [miri_no, deterministic_i32_descending],
+    [miri_no, deterministic_i32_saw_mixed],
+    [miri_no, deterministic_cell_i32_random],
+    [miri_yes, deterministic_cell_i32_random_z1],
+    [miri_no, deterministic_cell_i32_random_d2],
+    [miri_no, deterministic_cell_i32_random_d20],
+    [miri_no, deterministic_cell_i32_random_s95],
+    [miri_no, deterministic_cell_i32_ascending],
+    [miri_no, deterministic_cell_i32_descending],
+    [miri_no, deterministic_cell_i32_saw_mixed],
+    [miri_no, deterministic_string_random],
+    [miri_yes, deterministic_string_random_z1],
+    [miri_no, deterministic_string_random_d2],
+    [miri_no, deterministic_string_random_d20],
+    [miri_no, deterministic_string_random_s95],
+    [miri_no, deterministic_string_ascending],
+    [miri_no, deterministic_string_descending],
+    [miri_no, deterministic_string_saw_mixed],
+    [miri_no, self_cmp_i32_random],
+    [miri_yes, self_cmp_i32_random_z1],
+    [miri_no, self_cmp_i32_random_d2],
+    [miri_no, self_cmp_i32_random_d20],
+    [miri_no, self_cmp_i32_random_s95],
+    [miri_no, self_cmp_i32_ascending],
+    [miri_no, self_cmp_i32_descending],
+    [miri_no, self_cmp_i32_saw_mixed],
+    [miri_no, self_cmp_cell_i32_random],
+    [miri_yes, self_cmp_cell_i32_random_z1],
+    [miri_no, self_cmp_cell_i32_random_d2],
+    [miri_no, self_cmp_cell_i32_random_d20],
+    [miri_no, self_cmp_cell_i32_random_s95],
+    [miri_no, self_cmp_cell_i32_ascending],
+    [miri_no, self_cmp_cell_i32_descending],
+    [miri_no, self_cmp_cell_i32_saw_mixed],
+    [miri_no, self_cmp_string_random],
+    [miri_yes, self_cmp_string_random_z1],
+    [miri_no, self_cmp_string_random_d2],
+    [miri_no, self_cmp_string_random_d20],
+    [miri_no, self_cmp_string_random_s95],
+    [miri_no, self_cmp_string_ascending],
+    [miri_no, self_cmp_string_descending],
+    [miri_no, self_cmp_string_saw_mixed],
+    [miri_no, violate_ord_retain_orig_set_i32_random],
+    [miri_yes, violate_ord_retain_orig_set_i32_random_z1],
+    [miri_no, violate_ord_retain_orig_set_i32_random_d2],
+    [miri_no, violate_ord_retain_orig_set_i32_random_d20],
+    [miri_no, violate_ord_retain_orig_set_i32_random_s95],
+    [miri_no, violate_ord_retain_orig_set_i32_ascending],
+    [miri_no, violate_ord_retain_orig_set_i32_descending],
+    [miri_no, violate_ord_retain_orig_set_i32_saw_mixed],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_random],
+    [miri_yes, violate_ord_retain_orig_set_cell_i32_random_z1],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_random_d2],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_random_d20],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_random_s95],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_ascending],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_descending],
+    [miri_no, violate_ord_retain_orig_set_cell_i32_saw_mixed],
+    [miri_no, violate_ord_retain_orig_set_string_random],
+    [miri_yes, violate_ord_retain_orig_set_string_random_z1],
+    [miri_no, violate_ord_retain_orig_set_string_random_d2],
+    [miri_no, violate_ord_retain_orig_set_string_random_d20],
+    [miri_no, violate_ord_retain_orig_set_string_random_s95],
+    [miri_no, violate_ord_retain_orig_set_string_ascending],
+    [miri_no, violate_ord_retain_orig_set_string_descending],
+    [miri_no, violate_ord_retain_orig_set_string_saw_mixed],
+);
+
+macro_rules! instantiate_sort_tests {
+    ($sort_impl:ty) => {
+        instantiate_sort_tests_gen!($sort_impl);
+    };
+}
+
+mod unstable {
+    struct SortImpl {}
+
+    impl crate::sort::Sort for SortImpl {
+        fn name() -> String {
+            "rust_std_unstable".into()
+        }
+
+        fn sort<T>(v: &mut [T])
+        where
+            T: Ord,
+        {
+            v.sort_unstable();
+        }
+
+        fn sort_by<T, F>(v: &mut [T], mut compare: F)
+        where
+            F: FnMut(&T, &T) -> std::cmp::Ordering,
+        {
+            v.sort_unstable_by(|a, b| compare(a, b));
+        }
+    }
+
+    instantiate_sort_tests!(SortImpl);
+}
+
+mod stable {
+    struct SortImpl {}
+
+    impl crate::sort::Sort for SortImpl {
+        fn name() -> String {
+            "rust_std_stable".into()
+        }
+
+        fn sort<T>(v: &mut [T])
+        where
+            T: Ord,
+        {
+            v.sort();
+        }
+
+        fn sort_by<T, F>(v: &mut [T], mut compare: F)
+        where
+            F: FnMut(&T, &T) -> std::cmp::Ordering,
+        {
+            v.sort_by(|a, b| compare(a, b));
+        }
+    }
+
+    instantiate_sort_tests!(SortImpl);
+}
diff --git a/library/alloc/tests/sort/zipf.rs b/library/alloc/tests/sort/zipf.rs
new file mode 100644
index 0000000000000..cc774ee5c43bf
--- /dev/null
+++ b/library/alloc/tests/sort/zipf.rs
@@ -0,0 +1,208 @@
+// This module implements a Zipfian distribution generator.
+//
+// Based on https://github.com/jonhoo/rust-zipf.
+
+use rand::Rng;
+
+/// Random number generator that generates Zipf-distributed random numbers using rejection
+/// inversion.
+#[derive(Clone, Copy)]
+pub struct ZipfDistribution {
+    /// Number of elements
+    num_elements: f64,
+    /// Exponent parameter of the distribution
+    exponent: f64,
+    /// `hIntegral(1.5) - 1}`
+    h_integral_x1: f64,
+    /// `hIntegral(num_elements + 0.5)}`
+    h_integral_num_elements: f64,
+    /// `2 - hIntegralInverse(hIntegral(2.5) - h(2)}`
+    s: f64,
+}
+
+impl ZipfDistribution {
+    /// Creates a new [Zipf-distributed](https://en.wikipedia.org/wiki/Zipf's_law)
+    /// random number generator.
+    ///
+    /// Note that both the number of elements and the exponent must be greater than 0.
+    pub fn new(num_elements: usize, exponent: f64) -> Result<Self, ()> {
+        if num_elements == 0 {
+            return Err(());
+        }
+        if exponent <= 0f64 {
+            return Err(());
+        }
+
+        let z = ZipfDistribution {
+            num_elements: num_elements as f64,
+            exponent,
+            h_integral_x1: ZipfDistribution::h_integral(1.5, exponent) - 1f64,
+            h_integral_num_elements: ZipfDistribution::h_integral(
+                num_elements as f64 + 0.5,
+                exponent,
+            ),
+            s: 2f64
+                - ZipfDistribution::h_integral_inv(
+                    ZipfDistribution::h_integral(2.5, exponent)
+                        - ZipfDistribution::h(2f64, exponent),
+                    exponent,
+                ),
+        };
+
+        // populate cache
+
+        Ok(z)
+    }
+}
+
+impl ZipfDistribution {
+    fn next<R: Rng + ?Sized>(&self, rng: &mut R) -> usize {
+        // The paper describes an algorithm for exponents larger than 1 (Algorithm ZRI).
+        //
+        // The original method uses
+        //   H(x) = (v + x)^(1 - q) / (1 - q)
+        // as the integral of the hat function.
+        //
+        // This function is undefined for q = 1, which is the reason for the limitation of the
+        // exponent.
+        //
+        // If instead the integral function
+        //   H(x) = ((v + x)^(1 - q) - 1) / (1 - q)
+        // is used, for which a meaningful limit exists for q = 1, the method works for all
+        // positive exponents.
+        //
+        // The following implementation uses v = 0 and generates integral number in the range [1,
+        // num_elements]. This is different to the original method where v is defined to
+        // be positive and numbers are taken from [0, i_max]. This explains why the implementation
+        // looks slightly different.
+
+        let hnum = self.h_integral_num_elements;
+
+        loop {
+            use std::cmp;
+            let u: f64 = hnum + rng.gen::<f64>() * (self.h_integral_x1 - hnum);
+            // u is uniformly distributed in (h_integral_x1, h_integral_num_elements]
+
+            let x: f64 = ZipfDistribution::h_integral_inv(u, self.exponent);
+
+            // Limit k to the range [1, num_elements] if it would be outside
+            // due to numerical inaccuracies.
+            let k64 = x.max(1.0).min(self.num_elements);
+            // float -> integer rounds towards zero, so we add 0.5
+            // to prevent bias towards k == 1
+            let k = cmp::max(1, (k64 + 0.5) as usize);
+
+            // Here, the distribution of k is given by:
+            //
+            //   P(k = 1) = C * (hIntegral(1.5) - h_integral_x1) = C
+            //   P(k = m) = C * (hIntegral(m + 1/2) - hIntegral(m - 1/2)) for m >= 2
+            //
+            // where C = 1 / (h_integral_num_elements - h_integral_x1)
+            if k64 - x <= self.s
+                || u >= ZipfDistribution::h_integral(k64 + 0.5, self.exponent)
+                    - ZipfDistribution::h(k64, self.exponent)
+            {
+                // Case k = 1:
+                //
+                //   The right inequality is always true, because replacing k by 1 gives
+                //   u >= hIntegral(1.5) - h(1) = h_integral_x1 and u is taken from
+                //   (h_integral_x1, h_integral_num_elements].
+                //
+                //   Therefore, the acceptance rate for k = 1 is P(accepted | k = 1) = 1
+                //   and the probability that 1 is returned as random value is
+                //   P(k = 1 and accepted) = P(accepted | k = 1) * P(k = 1) = C = C / 1^exponent
+                //
+                // Case k >= 2:
+                //
+                //   The left inequality (k - x <= s) is just a short cut
+                //   to avoid the more expensive evaluation of the right inequality
+                //   (u >= hIntegral(k + 0.5) - h(k)) in many cases.
+                //
+                //   If the left inequality is true, the right inequality is also true:
+                //     Theorem 2 in the paper is valid for all positive exponents, because
+                //     the requirements h'(x) = -exponent/x^(exponent + 1) < 0 and
+                //     (-1/hInverse'(x))'' = (1+1/exponent) * x^(1/exponent-1) >= 0
+                //     are both fulfilled.
+                //     Therefore, f(x) = x - hIntegralInverse(hIntegral(x + 0.5) - h(x))
+                //     is a non-decreasing function. If k - x <= s holds,
+                //     k - x <= s + f(k) - f(2) is obviously also true which is equivalent to
+                //     -x <= -hIntegralInverse(hIntegral(k + 0.5) - h(k)),
+                //     -hIntegralInverse(u) <= -hIntegralInverse(hIntegral(k + 0.5) - h(k)),
+                //     and finally u >= hIntegral(k + 0.5) - h(k).
+                //
+                //   Hence, the right inequality determines the acceptance rate:
+                //   P(accepted | k = m) = h(m) / (hIntegrated(m+1/2) - hIntegrated(m-1/2))
+                //   The probability that m is returned is given by
+                //   P(k = m and accepted) = P(accepted | k = m) * P(k = m)
+                //                         = C * h(m) = C / m^exponent.
+                //
+                // In both cases the probabilities are proportional to the probability mass
+                // function of the Zipf distribution.
+
+                return k;
+            }
+        }
+    }
+}
+
+impl rand::distributions::Distribution<usize> for ZipfDistribution {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> usize {
+        self.next(rng)
+    }
+}
+
+use std::fmt;
+impl fmt::Debug for ZipfDistribution {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        f.debug_struct("ZipfDistribution")
+            .field("e", &self.exponent)
+            .field("n", &self.num_elements)
+            .finish()
+    }
+}
+
+impl ZipfDistribution {
+    /// Computes `H(x)`, defined as
+    ///
+    ///  - `(x^(1 - exponent) - 1) / (1 - exponent)`, if `exponent != 1`
+    ///  - `log(x)`, if `exponent == 1`
+    ///
+    /// `H(x)` is an integral function of `h(x)`, the derivative of `H(x)` is `h(x)`.
+    fn h_integral(x: f64, exponent: f64) -> f64 {
+        let log_x = x.ln();
+        helper2((1f64 - exponent) * log_x) * log_x
+    }
+
+    /// Computes `h(x) = 1 / x^exponent`
+    fn h(x: f64, exponent: f64) -> f64 {
+        (-exponent * x.ln()).exp()
+    }
+
+    /// The inverse function of `H(x)`.
+    /// Returns the `y` for which `H(y) = x`.
+    fn h_integral_inv(x: f64, exponent: f64) -> f64 {
+        let mut t: f64 = x * (1f64 - exponent);
+        if t < -1f64 {
+            // Limit value to the range [-1, +inf).
+            // t could be smaller than -1 in some rare cases due to numerical errors.
+            t = -1f64;
+        }
+        (helper1(t) * x).exp()
+    }
+}
+
+/// Helper function that calculates `log(1 + x) / x`.
+/// A Taylor series expansion is used, if x is close to 0.
+fn helper1(x: f64) -> f64 {
+    if x.abs() > 1e-8 { x.ln_1p() / x } else { 1f64 - x * (0.5 - x * (1.0 / 3.0 - 0.25 * x)) }
+}
+
+/// Helper function to calculate `(exp(x) - 1) / x`.
+/// A Taylor series expansion is used, if x is close to 0.
+fn helper2(x: f64) -> f64 {
+    if x.abs() > 1e-8 {
+        x.exp_m1() / x
+    } else {
+        1f64 + x * 0.5 * (1f64 + x * 1.0 / 3.0 * (1f64 + 0.25 * x))
+    }
+}
diff --git a/library/core/tests/slice.rs b/library/core/tests/slice.rs
index 7197f3812e542..9ae2bcc852649 100644
--- a/library/core/tests/slice.rs
+++ b/library/core/tests/slice.rs
@@ -1800,57 +1800,6 @@ fn brute_force_rotate_test_1() {
     }
 }
 
-#[test]
-#[cfg(not(target_arch = "wasm32"))]
-fn sort_unstable() {
-    use rand::Rng;
-
-    // Miri is too slow (but still need to `chain` to make the types match)
-    let lens = if cfg!(miri) { (2..20).chain(0..0) } else { (2..25).chain(500..510) };
-    let rounds = if cfg!(miri) { 1 } else { 100 };
-
-    let mut v = [0; 600];
-    let mut tmp = [0; 600];
-    let mut rng = crate::test_rng();
-
-    for len in lens {
-        let v = &mut v[0..len];
-        let tmp = &mut tmp[0..len];
-
-        for &modulus in &[5, 10, 100, 1000] {
-            for _ in 0..rounds {
-                for i in 0..len {
-                    v[i] = rng.gen::<i32>() % modulus;
-                }
-
-                // Sort in default order.
-                tmp.copy_from_slice(v);
-                tmp.sort_unstable();
-                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in ascending order.
-                tmp.copy_from_slice(v);
-                tmp.sort_unstable_by(|a, b| a.cmp(b));
-                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in descending order.
-                tmp.copy_from_slice(v);
-                tmp.sort_unstable_by(|a, b| b.cmp(a));
-                assert!(tmp.windows(2).all(|w| w[0] >= w[1]));
-            }
-        }
-    }
-
-    // Should not panic.
-    [0i32; 0].sort_unstable();
-    [(); 10].sort_unstable();
-    [(); 100].sort_unstable();
-
-    let mut v = [0xDEADBEEFu64];
-    v.sort_unstable();
-    assert!(v == [0xDEADBEEF]);
-}
-
 #[test]
 #[cfg(not(target_arch = "wasm32"))]
 #[cfg_attr(miri, ignore)] // Miri is too slow

From 2bc2304e30f9b35cd41e15a483f1dfcb727050e7 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Tue, 1 Oct 2024 14:40:45 -0400
Subject: [PATCH 3/7] Stabilize `debug_more_non_exhaustive`

Fixes: https://github.com/rust-lang/rust/issues/127942
---
 library/core/src/fmt/builders.rs | 16 ++++------------
 library/core/tests/lib.rs        |  1 -
 2 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/library/core/src/fmt/builders.rs b/library/core/src/fmt/builders.rs
index c7c462a4df1f5..3d0c9f7c96414 100644
--- a/library/core/src/fmt/builders.rs
+++ b/library/core/src/fmt/builders.rs
@@ -366,8 +366,6 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(i32, String);
@@ -385,7 +383,7 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     ///     "Foo(10, ..)",
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "CURRENT_RUSTC_VERSION")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.result = self.result.and_then(|_| {
             if self.fields > 0 {
@@ -606,8 +604,6 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(Vec<i32>);
@@ -630,7 +626,7 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     ///     "{1, 2, ..}",
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "CURRENT_RUSTC_VERSION")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.inner.result = self.inner.result.and_then(|_| {
             if self.inner.has_fields {
@@ -800,8 +796,6 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(Vec<i32>);
@@ -824,7 +818,7 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
     ///     "[1, 2, ..]",
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "CURRENT_RUSTC_VERSION")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.inner.result.and_then(|_| {
             if self.inner.has_fields {
@@ -1126,8 +1120,6 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(Vec<(String, i32)>);
@@ -1154,7 +1146,7 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     ///     r#"{"A": 10, "B": 11, ..}"#,
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "CURRENT_RUSTC_VERSION")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.result = self.result.and_then(|_| {
             assert!(!self.has_key, "attempted to finish a map with a partial entry");
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 4f2190f78bf59..91632c28e00b7 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -39,7 +39,6 @@
 #![feature(core_io_borrowed_buf)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
-#![feature(debug_more_non_exhaustive)]
 #![feature(dec2flt)]
 #![feature(duration_constants)]
 #![feature(duration_constructors)]

From 00f98275990f4673641d5ae787bb4c1d2d4d3f78 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gabriel=20Bj=C3=B8rnager=20Jensen?= <gabriel@achernar.io>
Date: Wed, 9 Oct 2024 22:15:38 +0200
Subject: [PATCH 4/7] Stabilise 'const_char_encode_utf8';

---
 library/core/src/char/methods.rs | 7 +++++--
 library/core/src/lib.rs          | 1 -
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 7f3c998aaa5bc..6bedb0d0dc4e5 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -674,8 +674,9 @@ impl char {
     /// 'ß'.encode_utf8(&mut b);
     /// ```
     #[stable(feature = "unicode_encode_char", since = "1.15.0")]
-    #[rustc_const_unstable(feature = "const_char_encode_utf8", issue = "130512")]
+    #[rustc_const_stable(feature = "const_char_encode_utf8", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
+    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
     pub const fn encode_utf8(self, dst: &mut [u8]) -> &mut str {
         // SAFETY: `char` is not a surrogate, so this is valid UTF-8.
         unsafe { from_utf8_unchecked_mut(encode_utf8_raw(self as u32, dst)) }
@@ -1770,9 +1771,11 @@ const fn len_utf16(code: u32) -> usize {
 /// Panics if the buffer is not large enough.
 /// A buffer of length four is large enough to encode any `char`.
 #[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
-#[rustc_const_unstable(feature = "const_char_encode_utf8", issue = "130512")]
+#[rustc_const_stable(feature = "const_char_encode_utf8", since = "CURRENT_RUSTC_VERSION")]
 #[doc(hidden)]
 #[inline]
+#[rustc_allow_const_fn_unstable(const_eval_select)]
+#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
 pub const fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
     const fn panic_at_const(_code: u32, _len: usize, _dst_len: usize) {
         // Note that we cannot format in constant expressions.
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 817d9e3b962e3..ce5a1791f5ed4 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -119,7 +119,6 @@
 #![feature(const_bigint_helper_methods)]
 #![feature(const_black_box)]
 #![feature(const_char_encode_utf16)]
-#![feature(const_char_encode_utf8)]
 #![feature(const_eval_select)]
 #![feature(const_exact_div)]
 #![feature(const_float_classify)]

From 9357277de7d452fb542abd0264e9d71bb2403c20 Mon Sep 17 00:00:00 2001
From: Zalathar <Zalathar@users.noreply.github.com>
Date: Fri, 11 Oct 2024 21:44:36 +1100
Subject: [PATCH 5/7] coverage: Remove code related to LLVM 17

---
 .../src/coverageinfo/mapgen.rs                | 21 ++++++-------------
 .../llvm-wrapper/CoverageMappingWrapper.cpp   |  2 +-
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
index 267a22449167d..c2c261da79b68 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
@@ -14,29 +14,20 @@ use crate::coverageinfo::ffi::CounterMappingRegion;
 use crate::coverageinfo::map_data::{FunctionCoverage, FunctionCoverageCollector};
 use crate::{coverageinfo, llvm};
 
-/// Generates and exports the Coverage Map.
+/// Generates and exports the coverage map, which is embedded in special
+/// linker sections in the final binary.
 ///
-/// Rust Coverage Map generation supports LLVM Coverage Mapping Format versions
-/// 6 and 7 (encoded as 5 and 6 respectively), as described at
-/// [LLVM Code Coverage Mapping Format](https://github.com/rust-lang/llvm-project/blob/rustc/18.0-2024-02-13/llvm/docs/CoverageMappingFormat.rst).
-/// These versions are supported by the LLVM coverage tools (`llvm-profdata` and `llvm-cov`)
-/// distributed in the `llvm-tools-preview` rustup component.
-///
-/// Consequently, Rust's bundled version of Clang also generates Coverage Maps compliant with
-/// the same version. Clang's implementation of Coverage Map generation was referenced when
-/// implementing this Rust version, and though the format documentation is very explicit and
-/// detailed, some undocumented details in Clang's implementation (that may or may not be important)
-/// were also replicated for Rust's Coverage Map.
+/// Those sections are then read and understood by LLVM's `llvm-cov` tool,
+/// which is distributed in the `llvm-tools` rustup component.
 pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
     let tcx = cx.tcx;
 
     // Ensure that LLVM is using a version of the coverage mapping format that
     // agrees with our Rust-side code. Expected versions (encoded as n-1) are:
-    // - `CovMapVersion::Version6` (5) used by LLVM 13-17
-    // - `CovMapVersion::Version7` (6) used by LLVM 18
+    // - `CovMapVersion::Version7` (6) used by LLVM 18-19
     let covmap_version = {
         let llvm_covmap_version = coverageinfo::mapping_version();
-        let expected_versions = 5..=6;
+        let expected_versions = 6..=6;
         assert!(
             expected_versions.contains(&llvm_covmap_version),
             "Coverage mapping version exposed by `llvm-wrapper` is out of sync; \
diff --git a/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp
index 8ee0597732083..cda81d4a9b5b2 100644
--- a/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/CoverageMappingWrapper.cpp
@@ -183,7 +183,7 @@ extern "C" void LLVMRustCoverageWriteMappingToBuffer(
            RustMappingRegions, NumMappingRegions)) {
     MappingRegions.emplace_back(
         fromRust(Region.Count), fromRust(Region.FalseCount),
-#if LLVM_VERSION_GE(18, 0) && LLVM_VERSION_LT(19, 0)
+#if LLVM_VERSION_LT(19, 0)
         coverage::CounterMappingRegion::MCDCParameters{},
 #endif
         Region.FileID, Region.ExpandedFileID, // File IDs, then region info.

From 19345d5c6ec522e6037c76c52fccd83860515313 Mon Sep 17 00:00:00 2001
From: Augie Fackler <augie@google.com>
Date: Fri, 11 Oct 2024 11:29:37 -0400
Subject: [PATCH 6/7] RustWrapper: adapt for rename of
 Intrinsic::getDeclaration

llvm/llvm-project@fa789dffb1e12c2aece0187aeacc48dfb1768340 renamed
getDeclaration to getOrInsertDeclaration.

@rustbot label: +llvm-main
---
 .../rustc_llvm/llvm-wrapper/RustWrapper.cpp   | 25 ++++++++++++++-----
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 8faa521240830..72b03fa0560e6 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -1533,27 +1533,40 @@ extern "C" LLVMValueRef LLVMRustBuildCall(LLVMBuilderRef B, LLVMTypeRef Ty,
 
 extern "C" LLVMValueRef
 LLVMRustGetInstrProfIncrementIntrinsic(LLVMModuleRef M) {
+#if LLVM_VERSION_GE(20, 0)
+  return wrap(llvm::Intrinsic::getOrInsertDeclaration(
+      unwrap(M), llvm::Intrinsic::instrprof_increment));
+#else
   return wrap(llvm::Intrinsic::getDeclaration(
       unwrap(M), llvm::Intrinsic::instrprof_increment));
+#endif
 }
 
 extern "C" LLVMValueRef
 LLVMRustGetInstrProfMCDCParametersIntrinsic(LLVMModuleRef M) {
-#if LLVM_VERSION_GE(19, 0)
-  return wrap(llvm::Intrinsic::getDeclaration(
+#if LLVM_VERSION_LT(19, 0)
+  report_fatal_error("LLVM 19.0 is required for mcdc intrinsic functions");
+#endif
+#if LLVM_VERSION_GE(20, 0)
+  return wrap(llvm::Intrinsic::getOrInsertDeclaration(
       unwrap(M), llvm::Intrinsic::instrprof_mcdc_parameters));
 #else
-  report_fatal_error("LLVM 19.0 is required for mcdc intrinsic functions");
+  return wrap(llvm::Intrinsic::getDeclaration(
+      unwrap(M), llvm::Intrinsic::instrprof_mcdc_parameters));
 #endif
 }
 
 extern "C" LLVMValueRef
 LLVMRustGetInstrProfMCDCTVBitmapUpdateIntrinsic(LLVMModuleRef M) {
-#if LLVM_VERSION_GE(19, 0)
-  return wrap(llvm::Intrinsic::getDeclaration(
+#if LLVM_VERSION_LT(19, 0)
+  report_fatal_error("LLVM 19.0 is required for mcdc intrinsic functions");
+#endif
+#if LLVM_VERSION_GE(20, 0)
+  return wrap(llvm::Intrinsic::getOrInsertDeclaration(
       unwrap(M), llvm::Intrinsic::instrprof_mcdc_tvbitmap_update));
 #else
-  report_fatal_error("LLVM 19.0 is required for mcdc intrinsic functions");
+  return wrap(llvm::Intrinsic::getDeclaration(
+      unwrap(M), llvm::Intrinsic::instrprof_mcdc_tvbitmap_update));
 #endif
 }
 

From 92f65684a8433ade29d8fea8c258dd7eed22ea3f Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 5 Oct 2024 13:04:18 +0200
Subject: [PATCH 7/7] stabilize const_result

---
 library/core/src/result.rs | 13 +++++++++----
 library/core/tests/lib.rs  |  1 -
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 610edae48d36b..95faacbf96db7 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -734,7 +734,8 @@ impl<T, E> Result<T, E> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "CURRENT_RUSTC_VERSION")]
+    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
     pub const fn as_mut(&mut self) -> Result<&mut T, &mut E> {
         match *self {
             Ok(ref mut x) => Ok(x),
@@ -1536,7 +1537,8 @@ impl<T, E> Result<&T, E> {
     /// ```
     #[inline]
     #[stable(feature = "result_copied", since = "1.59.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn copied(self) -> Result<T, E>
     where
         T: Copy,
@@ -1586,7 +1588,9 @@ impl<T, E> Result<&mut T, E> {
     /// ```
     #[inline]
     #[stable(feature = "result_copied", since = "1.59.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "CURRENT_RUSTC_VERSION")]
+    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn copied(self) -> Result<T, E>
     where
         T: Copy,
@@ -1639,7 +1643,8 @@ impl<T, E> Result<Option<T>, E> {
     /// ```
     #[inline]
     #[stable(feature = "transpose_result", since = "1.33.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn transpose(self) -> Option<Result<T, E>> {
         match self {
             Ok(Some(x)) => Some(Ok(x)),
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 0d4ec96f8426f..d5f7010343e8f 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -29,7 +29,6 @@
 #![feature(const_pin)]
 #![feature(const_pointer_is_aligned)]
 #![feature(const_ptr_write)]
-#![feature(const_result)]
 #![feature(const_three_way_compare)]
 #![feature(const_trait_impl)]
 #![feature(core_intrinsics)]