Auto merge of #92003 - matthiaskrgr:rollup-obgv0rt, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #91172 (Warn when a `#[test]`-like built-in attribute macro is present multiple times.)
 - #91796 (Fix since attribute for const_manually_drop feature)
 - #91879 (Remove `in_band_lifetimes` from `rustc_borrowck`)
 - #91947 (Add `io::Error::other`)
 - #91967 (Pull in libdevstat on FreeBSD)
 - #91987 (Add module documentation for rustdoc passes)
 - #92001 (Fix default_method_body_is_const when used across crates)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Cargo.lock

@@ -3688,6 +3688,7 @@ dependencies = [
  "rustc_expand",
  "rustc_feature",
  "rustc_lexer",
+ "rustc_lint_defs",
  "rustc_parse",
  "rustc_parse_format",
  "rustc_session",

compiler/rustc_borrowck/src/borrow_set.rs

@@ -84,7 +84,7 @@ pub enum LocalsStateAtExit {
 }
 
 impl LocalsStateAtExit {
-    fn build(
+    fn build<'tcx>(
         locals_are_invalidated_at_exit: bool,
         body: &Body<'tcx>,
         move_data: &MoveData<'tcx>,

compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs

@@ -31,7 +31,7 @@ enum UniverseInfoInner<'tcx> {
     Other,
 }
 
-impl UniverseInfo<'tcx> {
+impl<'tcx> UniverseInfo<'tcx> {
     crate fn other() -> UniverseInfo<'tcx> {
         UniverseInfo(UniverseInfoInner::Other)
     }
@@ -191,7 +191,7 @@ struct PredicateQuery<'tcx> {
     base_universe: ty::UniverseIndex,
 }
 
-impl TypeOpInfo<'tcx> for PredicateQuery<'tcx> {
+impl<'tcx> TypeOpInfo<'tcx> for PredicateQuery<'tcx> {
     fn fallback_error(&self, tcx: TyCtxt<'tcx>, span: Span) -> DiagnosticBuilder<'tcx> {
         let mut err = tcx.sess.struct_span_err(span, "higher-ranked lifetime error");
         err.note(&format!("could not prove {}", self.canonical_query.value.value.predicate));
@@ -231,7 +231,7 @@ struct NormalizeQuery<'tcx, T> {
     base_universe: ty::UniverseIndex,
 }
 
-impl<T> TypeOpInfo<'tcx> for NormalizeQuery<'tcx, T>
+impl<'tcx, T> TypeOpInfo<'tcx> for NormalizeQuery<'tcx, T>
 where
     T: Copy + fmt::Display + TypeFoldable<'tcx> + 'tcx,
 {
@@ -291,7 +291,7 @@ struct AscribeUserTypeQuery<'tcx> {
     base_universe: ty::UniverseIndex,
 }
 
-impl TypeOpInfo<'tcx> for AscribeUserTypeQuery<'tcx> {
+impl<'tcx> TypeOpInfo<'tcx> for AscribeUserTypeQuery<'tcx> {
     fn fallback_error(&self, tcx: TyCtxt<'tcx>, span: Span) -> DiagnosticBuilder<'tcx> {
         // FIXME: This error message isn't great, but it doesn't show up in the existing UI tests,
         // and is only the fallback when the nice error fails. Consider improving this some more.

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1598,8 +1598,8 @@ fn get_moved_indexes(
         location: Location,
         mpi: MovePathIndex,
     ) -> (Vec<MoveSite>, Vec<Location>) {
-        fn predecessor_locations(
-            body: &'a mir::Body<'tcx>,
+        fn predecessor_locations<'a>(
+            body: &'a mir::Body<'_>,
             location: Location,
         ) -> impl Iterator<Item = Location> + 'a {
             if location.statement_index == 0 {

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -409,7 +409,7 @@ fn describe_field_from_ty(
     /// Add a note that a type does not implement `Copy`
     pub(super) fn note_type_does_not_implement_copy(
         &self,
-        err: &mut DiagnosticBuilder<'a>,
+        err: &mut DiagnosticBuilder<'_>,
         place_desc: &str,
         ty: Ty<'tcx>,
         span: Option<Span>,
@@ -733,7 +733,7 @@ pub(super) enum BorrowedContentSource<'tcx> {
     OverloadedIndex(Ty<'tcx>),
 }
 
-impl BorrowedContentSource<'tcx> {
+impl<'tcx> BorrowedContentSource<'tcx> {
     pub(super) fn describe_for_unnamed_place(&self, tcx: TyCtxt<'_>) -> String {
         match *self {
             BorrowedContentSource::DerefRawPointer => "a raw pointer".to_string(),

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -747,7 +747,7 @@ fn suggest_similar_mut_method_for_for_loop(&self, err: &mut DiagnosticBuilder<'_
             HirId, ImplItem, ImplItemKind, Item, ItemKind,
         };
 
-        fn maybe_body_id_of_fn(hir_map: &Map<'tcx>, id: HirId) -> Option<BodyId> {
+        fn maybe_body_id_of_fn(hir_map: &Map<'_>, id: HirId) -> Option<BodyId> {
             match hir_map.find(id) {
                 Some(Node::Item(Item { kind: ItemKind::Fn(_, _, body_id), .. }))
                 | Some(Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(_, body_id), .. })) => {
@@ -1066,7 +1066,7 @@ fn is_closure_or_generator(ty: Ty<'_>) -> bool {
 /// LL |     s: &'a String
 ///    |        ---------- use `&'a mut String` here to make mutable
 /// ```
-fn annotate_struct_field(
+fn annotate_struct_field<'tcx>(
     tcx: TyCtxt<'tcx>,
     ty: Ty<'tcx>,
     field: &mir::Field,

compiler/rustc_borrowck/src/lib.rs

@@ -3,7 +3,6 @@
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(crate_visibility_modifier)]
-#![feature(in_band_lifetimes)]
 #![feature(let_else)]
 #![feature(min_specialization)]
 #![feature(stmt_expr_attributes)]

compiler/rustc_borrowck/src/member_constraints.rs

@@ -53,7 +53,7 @@
     }
 }
 
-impl Default for MemberConstraintSet<'tcx, ty::RegionVid> {
+impl Default for MemberConstraintSet<'_, ty::RegionVid> {
     fn default() -> Self {
         Self {
             first_constraints: Default::default(),
@@ -97,7 +97,7 @@ impl<'tcx> MemberConstraintSet<'tcx, ty::RegionVid> {
     }
 }
 
-impl<R1> MemberConstraintSet<'tcx, R1>
+impl<'tcx, R1> MemberConstraintSet<'tcx, R1>
 where
     R1: Copy + Hash + Eq,
 {
@@ -140,7 +140,7 @@ impl<R1> MemberConstraintSet<'tcx, R1>
     }
 }
 
-impl<R> MemberConstraintSet<'tcx, R>
+impl<R> MemberConstraintSet<'_, R>
 where
     R: Copy + Hash + Eq,
 {

compiler/rustc_borrowck/src/path_utils.rs

@@ -141,7 +141,7 @@ pub(super) fn borrow_of_local_data(place: Place<'_>) -> bool {
 /// then returns the index of the field being projected. Note that this closure will always
 /// be `self` in the current MIR, because that is the only time we directly access the fields
 /// of a closure type.
-pub(crate) fn is_upvar_field_projection(
+pub(crate) fn is_upvar_field_projection<'tcx>(
     tcx: TyCtxt<'tcx>,
     upvars: &[Upvar<'tcx>],
     place_ref: PlaceRef<'tcx>,

compiler/rustc_borrowck/src/type_check/free_region_relations.rs

@@ -58,7 +58,7 @@
     crate normalized_inputs_and_output: NormalizedInputsAndOutput<'tcx>,
 }
 
-crate fn create(
+crate fn create<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     implicit_region_bound: Option<ty::Region<'tcx>>,
@@ -81,7 +81,7 @@
     .create()
 }
 
-impl UniversalRegionRelations<'tcx> {
+impl UniversalRegionRelations<'_> {
     /// Records in the `outlives_relation` (and
     /// `inverse_outlives_relation`) that `fr_a: fr_b`. Invoked by the
     /// builder below.
@@ -110,7 +110,7 @@ fn relate_universal_regions(&mut self, fr_a: RegionVid, fr_b: RegionVid) {
     /// outlives `fr` and (b) is not local.
     ///
     /// (*) If there are multiple competing choices, we return all of them.
-    crate fn non_local_upper_bounds(&'a self, fr: &'a RegionVid) -> Vec<&'a RegionVid> {
+    crate fn non_local_upper_bounds<'a>(&'a self, fr: &'a RegionVid) -> Vec<&'a RegionVid> {
         debug!("non_local_upper_bound(fr={:?})", fr);
         let res = self.non_local_bounds(&self.inverse_outlives, fr);
         assert!(!res.is_empty(), "can't find an upper bound!?");
@@ -232,7 +232,7 @@ struct UniversalRegionRelationsBuilder<'this, 'tcx> {
     region_bound_pairs: RegionBoundPairs<'tcx>,
 }
 
-impl UniversalRegionRelationsBuilder<'cx, 'tcx> {
+impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
     crate fn create(mut self) -> CreateResult<'tcx> {
         let unnormalized_input_output_tys = self
             .universal_regions

compiler/rustc_borrowck/src/type_check/liveness/local_use_map.rs

@@ -152,7 +152,7 @@ fn insert(
     }
 }
 
-impl Visitor<'tcx> for LocalUseMapBuild<'_> {
+impl Visitor<'_> for LocalUseMapBuild<'_> {
     fn visit_local(&mut self, &local: &Local, context: PlaceContext, location: Location) {
         if self.locals_with_use_data[local] {
             match def_use::categorize(context) {

compiler/rustc_borrowck/src/type_check/liveness/mod.rs

@@ -74,7 +74,7 @@ pub(super) fn generate<'mir, 'tcx>(
 // to compute whether a variable `X` is live if that variable contains
 // some region `R` in its type where `R` is not known to outlive a free
 // region (i.e., where `R` may be valid for just a subset of the fn body).
-fn compute_live_locals(
+fn compute_live_locals<'tcx>(
     tcx: TyCtxt<'tcx>,
     free_regions: &FxHashSet<RegionVid>,
     body: &Body<'tcx>,
@@ -104,7 +104,7 @@ fn compute_live_locals(
 /// regions. For these regions, we do not need to compute
 /// liveness, since the outlives constraints will ensure that they
 /// are live over the whole fn body anyhow.
-fn regions_that_outlive_free_regions(
+fn regions_that_outlive_free_regions<'tcx>(
     num_region_vars: usize,
     universal_regions: &UniversalRegions<'tcx>,
     constraint_set: &OutlivesConstraintSet<'tcx>,

compiler/rustc_borrowck/src/type_check/liveness/polonius.rs

@@ -53,7 +53,7 @@ fn place_to_mpi(&self, place: &Place<'_>) -> Option<MovePathIndex> {
     }
 }
 
-impl Visitor<'tcx> for UseFactsExtractor<'_> {
+impl Visitor<'_> for UseFactsExtractor<'_> {
     fn visit_local(&mut self, &local: &Local, context: PlaceContext, location: Location) {
         match def_use::categorize(context) {
             Some(DefUse::Def) => self.insert_def(local, location),
@@ -63,7 +63,7 @@ fn visit_local(&mut self, &local: &Local, context: PlaceContext, location: Locat
         }
     }
 
-    fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
+    fn visit_place(&mut self, place: &Place<'_>, context: PlaceContext, location: Location) {
         self.super_place(place, context, location);
         match context {
             PlaceContext::NonMutatingUse(_) => {
@@ -82,7 +82,7 @@ fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location:
     }
 }
 
-pub(super) fn populate_access_facts(
+pub(super) fn populate_access_facts<'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     body: &Body<'tcx>,
     location_table: &LocationTable,
@@ -123,7 +123,7 @@ pub(super) fn populate_access_facts(
 
 // For every potentially drop()-touched region `region` in `local`'s type
 // (`kind`), emit a Polonius `use_of_var_derefs_origin(local, origin)` fact.
-pub(super) fn add_drop_of_var_derefs_origin(
+pub(super) fn add_drop_of_var_derefs_origin<'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     local: Local,
     kind: &GenericArg<'tcx>,

compiler/rustc_borrowck/src/type_check/liveness/trace.rs

@@ -34,7 +34,7 @@
 /// DROP-LIVE set are to the liveness sets for regions found in the
 /// `dropck_outlives` result of the variable's type (in particular,
 /// this respects `#[may_dangle]` annotations).
-pub(super) fn trace(
+pub(super) fn trace<'mir, 'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     body: &Body<'tcx>,
     elements: &Rc<RegionValueElements>,
@@ -119,7 +119,7 @@ struct LivenessResults<'me, 'typeck, 'flow, 'tcx> {
     stack: Vec<PointIndex>,
 }
 
-impl LivenessResults<'me, 'typeck, 'flow, 'tcx> {
+impl<'me, 'typeck, 'flow, 'tcx> LivenessResults<'me, 'typeck, 'flow, 'tcx> {
     fn new(cx: LivenessContext<'me, 'typeck, 'flow, 'tcx>) -> Self {
         let num_points = cx.elements.num_points();
         LivenessResults {
@@ -418,7 +418,7 @@ fn compute_drop_live_points_for_block(&mut self, mpi: MovePathIndex, term_point:
     }
 }
 
-impl LivenessContext<'_, '_, '_, 'tcx> {
+impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
     /// Returns `true` if the local variable (or some part of it) is initialized at the current
     /// cursor position. Callers should call one of the `seek` methods immediately before to point
     /// the cursor to the desired location.

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -945,7 +945,7 @@ struct BorrowCheckContext<'a, 'tcx> {
     crate type_tests: Vec<TypeTest<'tcx>>,
 }
 
-impl MirTypeckRegionConstraints<'tcx> {
+impl<'tcx> MirTypeckRegionConstraints<'tcx> {
     fn placeholder_region(
         &mut self,
         infcx: &InferCtxt<'_, 'tcx>,

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -51,7 +51,7 @@ struct NllTypeRelatingDelegate<'me, 'bccx, 'tcx> {
     universe_info: UniverseInfo<'tcx>,
 }
 
-impl NllTypeRelatingDelegate<'me, 'bccx, 'tcx> {
+impl<'me, 'bccx, 'tcx> NllTypeRelatingDelegate<'me, 'bccx, 'tcx> {
     fn new(
         type_checker: &'me mut TypeChecker<'bccx, 'tcx>,
         locations: Locations,
@@ -62,7 +62,7 @@ fn new(
     }
 }
 
-impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> {
+impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> {
     fn param_env(&self) -> ty::ParamEnv<'tcx> {
         self.type_checker.param_env
     }

compiler/rustc_builtin_macros/Cargo.toml

@@ -15,6 +15,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
 rustc_lexer = { path = "../rustc_lexer" }
+rustc_lint_defs = { path = "../rustc_lint_defs" }
 rustc_parse = { path = "../rustc_parse" }
 rustc_target = { path = "../rustc_target" }
 rustc_session = { path = "../rustc_session" }

compiler/rustc_builtin_macros/src/cfg_eval.rs

@@ -1,4 +1,4 @@
-use crate::util::check_builtin_macro_attribute;
+use crate::util::{check_builtin_macro_attribute, warn_on_duplicate_attribute};
 
 use rustc_ast as ast;
 use rustc_ast::mut_visit::MutVisitor;
@@ -25,6 +25,7 @@
     annotatable: Annotatable,
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(ecx, meta_item, sym::cfg_eval);
+    warn_on_duplicate_attribute(&ecx, &annotatable, sym::cfg_eval);
     vec![cfg_eval(ecx.sess, ecx.ecfg.features, annotatable)]
 }
 

compiler/rustc_builtin_macros/src/test.rs

@@ -1,6 +1,6 @@
 /// The expansion from a test function to the appropriate test struct for libtest
 /// Ideally, this code would be in libtest but for efficiency and error messages it lives here.
-use crate::util::check_builtin_macro_attribute;
+use crate::util::{check_builtin_macro_attribute, warn_on_duplicate_attribute};
 
 use rustc_ast as ast;
 use rustc_ast::attr;
@@ -27,6 +27,7 @@ pub fn expand_test_case(
     anno_item: Annotatable,
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(ecx, meta_item, sym::test_case);
+    warn_on_duplicate_attribute(&ecx, &anno_item, sym::test_case);
 
     if !ecx.ecfg.should_test {
         return vec![];
@@ -55,6 +56,7 @@ pub fn expand_test(
     item: Annotatable,
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(cx, meta_item, sym::test);
+    warn_on_duplicate_attribute(&cx, &item, sym::test);
     expand_test_or_bench(cx, attr_sp, item, false)
 }
 
@@ -65,6 +67,7 @@ pub fn expand_bench(
     item: Annotatable,
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(cx, meta_item, sym::bench);
+    warn_on_duplicate_attribute(&cx, &item, sym::bench);
     expand_test_or_bench(cx, attr_sp, item, true)
 }
 

compiler/rustc_builtin_macros/src/util.rs

@@ -1,6 +1,7 @@
-use rustc_ast::MetaItem;
-use rustc_expand::base::ExtCtxt;
+use rustc_ast::{Attribute, MetaItem};
+use rustc_expand::base::{Annotatable, ExtCtxt};
 use rustc_feature::AttributeTemplate;
+use rustc_lint_defs::builtin::DUPLICATE_MACRO_ATTRIBUTES;
 use rustc_parse::validate_attr;
 use rustc_span::Symbol;
 
@@ -10,3 +11,33 @@ pub fn check_builtin_macro_attribute(ecx: &ExtCtxt<'_>, meta_item: &MetaItem, na
     let attr = ecx.attribute(meta_item.clone());
     validate_attr::check_builtin_attribute(&ecx.sess.parse_sess, &attr, name, template);
 }
+
+/// Emit a warning if the item is annotated with the given attribute. This is used to diagnose when
+/// an attribute may have been mistakenly duplicated.
+pub fn warn_on_duplicate_attribute(ecx: &ExtCtxt<'_>, item: &Annotatable, name: Symbol) {
+    let attrs: Option<&[Attribute]> = match item {
+        Annotatable::Item(item) => Some(&item.attrs),
+        Annotatable::TraitItem(item) => Some(&item.attrs),
+        Annotatable::ImplItem(item) => Some(&item.attrs),
+        Annotatable::ForeignItem(item) => Some(&item.attrs),
+        Annotatable::Expr(expr) => Some(&expr.attrs),
+        Annotatable::Arm(arm) => Some(&arm.attrs),
+        Annotatable::ExprField(field) => Some(&field.attrs),
+        Annotatable::PatField(field) => Some(&field.attrs),
+        Annotatable::GenericParam(param) => Some(&param.attrs),
+        Annotatable::Param(param) => Some(&param.attrs),
+        Annotatable::FieldDef(def) => Some(&def.attrs),
+        Annotatable::Variant(variant) => Some(&variant.attrs),
+        _ => None,
+    };
+    if let Some(attrs) = attrs {
+        if let Some(attr) = ecx.sess.find_by_name(attrs, name) {
+            ecx.parse_sess().buffer_lint(
+                DUPLICATE_MACRO_ATTRIBUTES,
+                attr.span,
+                ecx.current_expansion.lint_node_id,
+                "duplicated attribute",
+            );
+        }
+    }
+}

compiler/rustc_lint_defs/src/builtin.rs

@@ -3066,6 +3066,7 @@
         TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
         DEREF_INTO_DYN_SUPERTRAIT,
         DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
+        DUPLICATE_MACRO_ATTRIBUTES,
     ]
 }
 
@@ -3603,3 +3604,32 @@
         reference: "issue #89460 <https://github.com/rust-lang/rust/issues/89460>",
     };
 }
+
+declare_lint! {
+    /// The `duplicate_macro_attributes` lint detects when a `#[test]`-like built-in macro
+    /// attribute is duplicated on an item. This lint may trigger on `bench`, `cfg_eval`, `test`
+    /// and `test_case`.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,ignore (needs --test)
+    /// #[test]
+    /// #[test]
+    /// fn foo() {}
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// A duplicated attribute may erroneously originate from a copy-paste and the effect of it
+    /// being duplicated may not be obvious or desireable.
+    ///
+    /// For instance, doubling the `#[test]` attributes registers the test to be run twice with no
+    /// change to its environment.
+    ///
+    /// [issue #90979]: https://github.com/rust-lang/rust/issues/90979
+    pub DUPLICATE_MACRO_ATTRIBUTES,
+    Warn,
+    "duplicated attribute"
+}

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -870,8 +870,9 @@ fn should_encode_mir(tcx: TyCtxt<'_>, def_id: LocalDefId) -> (bool, bool) {
             let needs_inline = (generics.requires_monomorphization(tcx)
                 || tcx.codegen_fn_attrs(def_id).requests_inline())
                 && tcx.sess.opts.output_types.should_codegen();
-            // Only check the presence of the `const` modifier.
-            let is_const_fn = tcx.is_const_fn_raw(def_id.to_def_id());
+            // The function has a `const` modifier or is annotated with `default_method_body_is_const`.
+            let is_const_fn = tcx.is_const_fn_raw(def_id.to_def_id())
+                || tcx.has_attr(def_id.to_def_id(), sym::default_method_body_is_const);
             let always_encode_mir = tcx.sess.opts.debugging_opts.always_encode_mir;
             (is_const_fn, needs_inline || always_encode_mir)
         }

library/core/src/mem/manually_drop.rs

@@ -64,7 +64,7 @@ impl<T> ManuallyDrop<T> {
     /// ```
     #[must_use = "if you don't need the wrapper, you can use `mem::forget` instead"]
     #[stable(feature = "manually_drop", since = "1.20.0")]
-    #[rustc_const_stable(feature = "const_manually_drop", since = "1.36.0")]
+    #[rustc_const_stable(feature = "const_manually_drop", since = "1.32.0")]
     #[inline(always)]
     pub const fn new(value: T) -> ManuallyDrop<T> {
         ManuallyDrop { value }
@@ -82,7 +82,7 @@ pub const fn new(value: T) -> ManuallyDrop<T> {
     /// let _: Box<()> = ManuallyDrop::into_inner(x); // This drops the `Box`.
     /// ```
     #[stable(feature = "manually_drop", since = "1.20.0")]
-    #[rustc_const_stable(feature = "const_manually_drop", since = "1.36.0")]
+    #[rustc_const_stable(feature = "const_manually_drop", since = "1.32.0")]
     #[inline(always)]
     pub const fn into_inner(slot: ManuallyDrop<T>) -> T {
         slot.value

library/std/src/io/error.rs

@@ -417,6 +417,33 @@ pub fn new<E>(kind: ErrorKind, error: E) -> Error
         Self::_new(kind, error.into())
     }
 
+    /// Creates a new I/O error from an arbitrary error payload.
+    ///
+    /// This function is used to generically create I/O errors which do not
+    /// originate from the OS itself. It is a shortcut for [`Error::new`]
+    /// with [`ErrorKind::Other`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(io_error_other)]
+    ///
+    /// use std::io::Error;
+    ///
+    /// // errors can be created from strings
+    /// let custom_error = Error::other("oh no!");
+    ///
+    /// // errors can also be created from other errors
+    /// let custom_error2 = Error::other(custom_error);
+    /// ```
+    #[unstable(feature = "io_error_other", issue = "91946")]
+    pub fn other<E>(error: E) -> Error
+    where
+        E: Into<Box<dyn error::Error + Send + Sync>>,
+    {
+        Self::_new(ErrorKind::Other, error.into())
+    }
+
     fn _new(kind: ErrorKind, error: Box<dyn error::Error + Send + Sync>) -> Error {
         Error { repr: Repr::Custom(Box::new(Custom { kind, error })) }
     }

src/ci/docker/scripts/freebsd-toolchain.sh

@@ -53,7 +53,7 @@ files_to_extract=(
 for lib in c cxxrt gcc_s m thr util; do
   files_to_extract=("${files_to_extract[@]}" "./lib/lib${lib}.*" "./usr/lib/lib${lib}.*")
 done
-for lib in c++ c_nonshared compiler_rt execinfo gcc pthread rt ssp_nonshared procstat kvm; do
+for lib in c++ c_nonshared compiler_rt execinfo gcc pthread rt ssp_nonshared procstat devstat kvm; do
   files_to_extract=("${files_to_extract[@]}" "./usr/lib/lib${lib}.*")
 done
 

src/librustdoc/passes/bare_urls.rs

@@ -1,3 +1,5 @@
+//! Detects links that are not linkified, e.g., in Markdown such as `Go to https://example.com/.`
+//! Suggests wrapping the link with angle brackets: `Go to <https://example.com/>.` to linkify it.
 use super::Pass;
 use crate::clean::*;
 use crate::core::DocContext;

src/librustdoc/passes/calculate_doc_coverage.rs

@@ -1,3 +1,4 @@
+//! Calculates information used for the --show-coverage flag.
 use crate::clean;
 use crate::core::DocContext;
 use crate::html::markdown::{find_testable_code, ErrorCodes};

src/librustdoc/passes/check_code_block_syntax.rs

@@ -1,3 +1,4 @@
+//! Validates syntax inside Rust code blocks (\`\`\`rust).
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_errors::{emitter::Emitter, Applicability, Diagnostic, Handler};
 use rustc_middle::lint::LintDiagnosticBuilder;

src/librustdoc/passes/check_doc_test_visibility.rs

@@ -1,3 +1,5 @@
+//! Looks for items missing (or incorrectly having) doctests.
+//!
 //! This pass is overloaded and runs two different lints.
 //!
 //! - MISSING_DOC_CODE_EXAMPLES: this lint is **UNSTABLE** and looks for public items missing doctests.

src/librustdoc/passes/collect_trait_impls.rs

@@ -1,3 +1,6 @@
+//! Collects trait impls for each item in the crate. For example, if a crate
+//! defines a struct that implements a trait, this pass will note that the
+//! struct implements that trait.
 use super::Pass;
 use crate::clean::*;
 use crate::core::DocContext;

src/librustdoc/passes/html_tags.rs

@@ -1,3 +1,4 @@
+//! Detects invalid HTML (like an unclosed `<span>`) in doc comments.
 use super::Pass;
 use crate::clean::*;
 use crate::core::DocContext;

src/librustdoc/passes/propagate_doc_cfg.rs

@@ -1,3 +1,4 @@
+//! Propagates [`#[doc(cfg(...))]`](https://github.com/rust-lang/rust/issues/43781) to child items.
 use std::sync::Arc;
 
 use crate::clean::cfg::Cfg;

src/librustdoc/passes/strip_hidden.rs

@@ -1,3 +1,4 @@
+//! Strip all doc(hidden) items from the output.
 use rustc_span::symbol::sym;
 use std::mem;
 

src/librustdoc/passes/strip_priv_imports.rs

@@ -1,3 +1,5 @@
+//! Strips all private import statements (use, extern crate) from a
+//! crate.
 use crate::clean;
 use crate::core::DocContext;
 use crate::fold::DocFolder;

src/librustdoc/passes/strip_private.rs

@@ -1,3 +1,5 @@
+//! Strip all private items from the output. Additionally implies strip_priv_imports.
+//! Basically, the goal is to remove items that are not relevant for public documentation.
 use crate::clean::{self, ItemIdSet};
 use crate::core::DocContext;
 use crate::fold::DocFolder;

src/librustdoc/passes/stripper.rs

@@ -1,3 +1,4 @@
+//! A collection of utility functions for the `strip_*` passes.
 use rustc_hir::def_id::DefId;
 use rustc_middle::middle::privacy::AccessLevels;
 use std::mem;

src/librustdoc/passes/unindent_comments.rs

@@ -1,3 +1,16 @@
+//! Removes excess indentation on comments in order for the Markdown
+//! to be parsed correctly. This is necessary because the convention for
+//! writing documentation is to provide a space between the /// or //! marker
+//! and the doc text, but Markdown is whitespace-sensitive. For example,
+//! a block of text with four-space indentation is parsed as a code block,
+//! so if we didn't unindent comments, these list items
+//!
+//! /// A list:
+//! ///
+//! ///    - Foo
+//! ///    - Bar
+//!
+//! would be parsed as if they were in a code block, which is likely not what the user intended.
 use std::cmp;
 
 use rustc_span::symbol::kw;

src/test/ui/attributes/duplicated-attributes.rs

@@ -0,0 +1,41 @@
+// Test that, if an item is annotated with a builtin attribute more than once, a warning is
+// emitted.
+// Tests https://github.com/rust-lang/rust/issues/90979
+
+// check-pass
+// compile-flags: --test
+
+#![feature(test)]
+#![feature(cfg_eval)]
+
+#[test]
+#[test]
+//~^ WARNING duplicated attribute
+fn f() {}
+
+// The following shouldn't trigger an error. The attribute is not duplicated.
+#[test]
+fn f2() {}
+
+// The following shouldn't trigger an error either. The second attribute is not #[test].
+#[test]
+#[inline]
+fn f3() {}
+
+extern crate test;
+use test::Bencher;
+
+#[bench]
+#[bench]
+//~^ WARNING duplicated attribute
+fn f4(_: &mut Bencher) {}
+
+#[cfg_eval]
+#[cfg_eval]
+//~^ WARNING duplicated attribute
+struct S;
+
+#[cfg_eval]
+struct S2;
+
+fn main() {}

src/test/ui/attributes/duplicated-attributes.stderr

@@ -0,0 +1,22 @@
+warning: duplicated attribute
+  --> $DIR/duplicated-attributes.rs:12:1
+   |
+LL | #[test]
+   | ^^^^^^^
+   |
+   = note: `#[warn(duplicate_macro_attributes)]` on by default
+
+warning: duplicated attribute
+  --> $DIR/duplicated-attributes.rs:29:1
+   |
+LL | #[bench]
+   | ^^^^^^^^
+
+warning: duplicated attribute
+  --> $DIR/duplicated-attributes.rs:34:1
+   |
+LL | #[cfg_eval]
+   | ^^^^^^^^^^^
+
+warning: 3 warnings emitted
+

src/test/ui/rfc-2632-const-trait-impl/auxiliary/cross-crate.rs

@@ -1,6 +1,9 @@
+#![feature(const_fn_trait_bound)]
 #![feature(const_trait_impl)]
 
 pub trait MyTrait {
+    #[default_method_body_is_const]
+    fn defaulted_func(&self) {}
     fn func(self);
 }
 

src/test/ui/rfc-2632-const-trait-impl/cross-crate-default-method-body-is-const.rs

@@ -0,0 +1,18 @@
+// This tests that `default_method_body_is_const` methods can
+// be called from a const context when used across crates.
+//
+// check-pass
+
+#![feature(const_trait_impl)]
+
+// aux-build: cross-crate.rs
+extern crate cross_crate;
+
+use cross_crate::*;
+
+const _: () = {
+    Const.func();
+    Const.defaulted_func();
+};
+
+fn main() {}