Auto merge of #86502 - JohnTitor:rollup-wge0f3x, r=JohnTitor

Rollup of 8 pull requests

Successful merges:

 - #83739 (Account for bad placeholder errors on consts/statics with trait objects)
 - #85637 (document PartialEq, PartialOrd, Ord requirements more explicitly)
 - #86152 (Lazify is_really_default condition in the RustdocGUI bootstrap step)
 - #86156 (Fix a bug in the linkchecker)
 - #86427 (Updated release note)
 - #86452 (fix panic-safety in specialized Zip::next_back)
 - #86484 (Do not set depth to 0 in fully_expand_fragment)
 - #86491 (expand: Move some more derive logic to rustc_builtin_macros)

Failed merges:

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

Cargo.lock

@@ -179,6 +179,7 @@ dependencies = [
  "libc",
  "merge",
  "num_cpus",
+ "once_cell",
  "opener",
  "pretty_assertions",
  "serde",

RELEASES.md

@@ -1749,6 +1749,7 @@ Language
 - [You can now use `#[repr(transparent)]` on univariant `enum`s.][68122] Meaning
   that you can create an enum that has the exact layout and ABI of the type
   it contains.
+- [You can now use outer attribute procedural macros on inline modules.][64273]  
 - [There are some *syntax-only* changes:][67131]
    - `default` is syntactically allowed before items in `trait` definitions.
    - Items in `impl`s (i.e. `const`s, `type`s, and `fn`s) may syntactically
@@ -1810,6 +1811,7 @@ Compatibility Notes
 [67935]: https://github.com/rust-lang/rust/pull/67935/
 [68339]: https://github.com/rust-lang/rust/pull/68339/
 [68122]: https://github.com/rust-lang/rust/pull/68122/
+[64273]: https://github.com/rust-lang/rust/pull/64273/
 [67712]: https://github.com/rust-lang/rust/pull/67712/
 [67887]: https://github.com/rust-lang/rust/pull/67887/
 [67131]: https://github.com/rust-lang/rust/pull/67131/

compiler/rustc_builtin_macros/src/cfg_eval.rs

@@ -24,61 +24,60 @@ crate fn expand(
     annotatable: Annotatable,
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(ecx, meta_item, sym::cfg_eval);
-    cfg_eval(ecx, annotatable)
+    vec![cfg_eval(ecx, annotatable)]
 }
 
-crate fn cfg_eval(ecx: &ExtCtxt<'_>, annotatable: Annotatable) -> Vec<Annotatable> {
-    let mut visitor = CfgEval {
+crate fn cfg_eval(ecx: &ExtCtxt<'_>, annotatable: Annotatable) -> Annotatable {
+    CfgEval {
         cfg: &mut StripUnconfigured {
             sess: ecx.sess,
             features: ecx.ecfg.features,
             config_tokens: true,
         },
-    };
-    let annotatable = visitor.configure_annotatable(annotatable);
-    vec![annotatable]
+    }
+    .configure_annotatable(annotatable)
+    // Since the item itself has already been configured by the `InvocationCollector`,
+    // we know that fold result vector will contain exactly one element.
+    .unwrap()
 }
 
 struct CfgEval<'a, 'b> {
     cfg: &'a mut StripUnconfigured<'b>,
 }
 
-fn flat_map_annotatable(vis: &mut impl MutVisitor, annotatable: Annotatable) -> Annotatable {
-    // Since the item itself has already been configured by the InvocationCollector,
-    // we know that fold result vector will contain exactly one element
+fn flat_map_annotatable(
+    vis: &mut impl MutVisitor,
+    annotatable: Annotatable,
+) -> Option<Annotatable> {
     match annotatable {
-        Annotatable::Item(item) => Annotatable::Item(vis.flat_map_item(item).pop().unwrap()),
+        Annotatable::Item(item) => vis.flat_map_item(item).pop().map(Annotatable::Item),
         Annotatable::TraitItem(item) => {
-            Annotatable::TraitItem(vis.flat_map_trait_item(item).pop().unwrap())
+            vis.flat_map_trait_item(item).pop().map(Annotatable::TraitItem)
         }
         Annotatable::ImplItem(item) => {
-            Annotatable::ImplItem(vis.flat_map_impl_item(item).pop().unwrap())
+            vis.flat_map_impl_item(item).pop().map(Annotatable::ImplItem)
         }
         Annotatable::ForeignItem(item) => {
-            Annotatable::ForeignItem(vis.flat_map_foreign_item(item).pop().unwrap())
+            vis.flat_map_foreign_item(item).pop().map(Annotatable::ForeignItem)
         }
         Annotatable::Stmt(stmt) => {
-            Annotatable::Stmt(stmt.map(|stmt| vis.flat_map_stmt(stmt).pop().unwrap()))
+            vis.flat_map_stmt(stmt.into_inner()).pop().map(P).map(Annotatable::Stmt)
         }
-        Annotatable::Expr(mut expr) => Annotatable::Expr({
+        Annotatable::Expr(mut expr) => {
             vis.visit_expr(&mut expr);
-            expr
-        }),
-        Annotatable::Arm(arm) => Annotatable::Arm(vis.flat_map_arm(arm).pop().unwrap()),
-        Annotatable::ExprField(field) => {
-            Annotatable::ExprField(vis.flat_map_expr_field(field).pop().unwrap())
+            Some(Annotatable::Expr(expr))
         }
-        Annotatable::PatField(fp) => {
-            Annotatable::PatField(vis.flat_map_pat_field(fp).pop().unwrap())
+        Annotatable::Arm(arm) => vis.flat_map_arm(arm).pop().map(Annotatable::Arm),
+        Annotatable::ExprField(field) => {
+            vis.flat_map_expr_field(field).pop().map(Annotatable::ExprField)
         }
+        Annotatable::PatField(fp) => vis.flat_map_pat_field(fp).pop().map(Annotatable::PatField),
         Annotatable::GenericParam(param) => {
-            Annotatable::GenericParam(vis.flat_map_generic_param(param).pop().unwrap())
-        }
-        Annotatable::Param(param) => Annotatable::Param(vis.flat_map_param(param).pop().unwrap()),
-        Annotatable::FieldDef(sf) => {
-            Annotatable::FieldDef(vis.flat_map_field_def(sf).pop().unwrap())
+            vis.flat_map_generic_param(param).pop().map(Annotatable::GenericParam)
         }
-        Annotatable::Variant(v) => Annotatable::Variant(vis.flat_map_variant(v).pop().unwrap()),
+        Annotatable::Param(param) => vis.flat_map_param(param).pop().map(Annotatable::Param),
+        Annotatable::FieldDef(sf) => vis.flat_map_field_def(sf).pop().map(Annotatable::FieldDef),
+        Annotatable::Variant(v) => vis.flat_map_variant(v).pop().map(Annotatable::Variant),
     }
 }
 
@@ -123,11 +122,11 @@ impl CfgEval<'_, '_> {
         self.cfg.configure(node)
     }
 
-    pub fn configure_annotatable(&mut self, mut annotatable: Annotatable) -> Annotatable {
+    fn configure_annotatable(&mut self, mut annotatable: Annotatable) -> Option<Annotatable> {
         // Tokenizing and re-parsing the `Annotatable` can have a significant
         // performance impact, so try to avoid it if possible
         if !CfgFinder::has_cfg_or_cfg_attr(&annotatable) {
-            return annotatable;
+            return Some(annotatable);
         }
 
         // The majority of parsed attribute targets will never need to have early cfg-expansion

compiler/rustc_builtin_macros/src/derive.rs

@@ -26,6 +26,8 @@ impl MultiItemModifier for Expander {
             return ExpandResult::Ready(vec![item]);
         }
 
+        let item = cfg_eval(ecx, item);
+
         let result =
             ecx.resolver.resolve_derives(ecx.current_expansion.id, ecx.force_mode, &|| {
                 let template =
@@ -54,12 +56,12 @@ impl MultiItemModifier for Expander {
                         report_path_args(sess, &meta);
                         meta.path
                     })
-                    .map(|path| (path, None))
+                    .map(|path| (path, item.clone(), None))
                     .collect()
             });
 
         match result {
-            Ok(()) => ExpandResult::Ready(cfg_eval(ecx, item)),
+            Ok(()) => ExpandResult::Ready(vec![item]),
             Err(Indeterminate) => ExpandResult::Retry(item),
         }
     }

compiler/rustc_expand/src/base.rs

@@ -835,7 +835,7 @@ impl SyntaxExtension {
 /// Error type that denotes indeterminacy.
 pub struct Indeterminate;
 
-pub type DeriveResolutions = Vec<(ast::Path, Option<Lrc<SyntaxExtension>>)>;
+pub type DeriveResolutions = Vec<(ast::Path, Annotatable, Option<Lrc<SyntaxExtension>>)>;
 
 pub trait ResolverExpand {
     fn next_node_id(&mut self) -> NodeId;

compiler/rustc_expand/src/expand.rs

@@ -427,7 +427,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
     pub fn fully_expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
         let orig_expansion_data = self.cx.current_expansion.clone();
         let orig_force_mode = self.cx.force_mode;
-        self.cx.current_expansion.depth = 0;
 
         // Collect all macro invocations and replace them with placeholders.
         let (mut fragment_with_placeholders, mut invocations) =
@@ -488,6 +487,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             };
 
             let ExpansionData { depth, id: expn_id, .. } = invoc.expansion_data;
+            let depth = depth - orig_expansion_data.depth;
             self.cx.current_expansion = invoc.expansion_data.clone();
             self.cx.force_mode = force;
 
@@ -500,42 +500,16 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         .resolver
                         .take_derive_resolutions(expn_id)
                         .map(|derives| {
-                            enum AnnotatableRef<'a> {
-                                Item(&'a P<ast::Item>),
-                                Stmt(&'a ast::Stmt),
-                            }
-                            let item = match &fragment {
-                                AstFragment::Items(items) => match &items[..] {
-                                    [item] => AnnotatableRef::Item(item),
-                                    _ => unreachable!(),
-                                },
-                                AstFragment::Stmts(stmts) => match &stmts[..] {
-                                    [stmt] => AnnotatableRef::Stmt(stmt),
-                                    _ => unreachable!(),
-                                },
-                                _ => unreachable!(),
-                            };
-
                             derive_invocations.reserve(derives.len());
                             derives
                                 .into_iter()
-                                .map(|(path, _exts)| {
+                                .map(|(path, item, _exts)| {
                                     // FIXME: Consider using the derive resolutions (`_exts`)
                                     // instead of enqueuing the derives to be resolved again later.
                                     let expn_id = ExpnId::fresh(None);
                                     derive_invocations.push((
                                         Invocation {
-                                            kind: InvocationKind::Derive {
-                                                path,
-                                                item: match item {
-                                                    AnnotatableRef::Item(item) => {
-                                                        Annotatable::Item(item.clone())
-                                                    }
-                                                    AnnotatableRef::Stmt(stmt) => {
-                                                        Annotatable::Stmt(P(stmt.clone()))
-                                                    }
-                                                },
-                                            },
+                                            kind: InvocationKind::Derive { path, item },
                                             fragment_kind,
                                             expansion_data: ExpansionData {
                                                 id: expn_id,

compiler/rustc_resolve/src/macros.rs

@@ -380,7 +380,7 @@ impl<'a> ResolverExpand for Resolver<'a> {
             has_derive_copy: false,
         });
         let parent_scope = self.invocation_parent_scopes[&expn_id];
-        for (i, (path, opt_ext)) in entry.resolutions.iter_mut().enumerate() {
+        for (i, (path, _, opt_ext)) in entry.resolutions.iter_mut().enumerate() {
             if opt_ext.is_none() {
                 *opt_ext = Some(
                     match self.resolve_macro_path(

compiler/rustc_typeck/src/collect.rs

@@ -813,6 +813,14 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
             match it.kind {
                 hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
                 hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
+                hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
+                    // (#75889): Account for `const C: dyn Fn() -> _ = "";`
+                    if let hir::TyKind::TraitObject(..) = ty.kind {
+                        let mut visitor = PlaceholderHirTyCollector::default();
+                        visitor.visit_item(it);
+                        placeholder_type_error(tcx, None, &[], visitor.0, false, None);
+                    }
+                }
                 _ => (),
             }
         }

library/core/src/cmp.rs

@@ -27,12 +27,25 @@ use self::Ordering::*;
 /// Trait for equality comparisons which are [partial equivalence
 /// relations](https://en.wikipedia.org/wiki/Partial_equivalence_relation).
 ///
+/// `x.eq(y)` can also be written `x == y`, and `x.ne(y)` can be written `x != y`.
+/// We use the easier-to-read infix notation in the remainder of this documentation.
+///
 /// This trait allows for partial equality, for types that do not have a full
 /// equivalence relation. For example, in floating point numbers `NaN != NaN`,
 /// so floating point types implement `PartialEq` but not [`trait@Eq`].
 ///
-/// Formally, the equality must be (for all `a`, `b`, `c` of type `A`, `B`,
-/// `C`):
+/// Implementations must ensure that `eq` and `ne` are consistent with each other:
+///
+/// - `a != b` if and only if `!(a == b)`
+///   (ensured by the default implementation).
+///
+/// If [`PartialOrd`] or [`Ord`] are also implemented for `Self` and `Rhs`, their methods must also
+/// be consistent with `PartialEq` (see the documentation of those traits for the exact
+/// requirememts). It's easy to accidentally make them disagree by deriving some of the traits and
+/// manually implementing others.
+///
+/// The equality relation `==` must satisfy the following conditions
+/// (for all `a`, `b`, `c` of type `A`, `B`, `C`):
 ///
 /// - **Symmetric**: if `A: PartialEq<B>` and `B: PartialEq<A>`, then **`a == b`
 ///   implies `b == a`**; and
@@ -53,15 +66,6 @@ use self::Ordering::*;
 ///
 /// ## How can I implement `PartialEq`?
 ///
-/// `PartialEq` only requires the [`eq`] method to be implemented; [`ne`] is defined
-/// in terms of it by default. Any manual implementation of [`ne`] *must* respect
-/// the rule that [`eq`] is a strict inverse of [`ne`]; that is, `!(a == b)` if and
-/// only if `a != b`.
-///
-/// Implementations of `PartialEq`, [`PartialOrd`], and [`Ord`] *must* agree with
-/// each other. It's easy to accidentally make them disagree by deriving some
-/// of the traits and manually implementing others.
-///
 /// An example implementation for a domain in which two books are considered
 /// the same book if their ISBN matches, even if the formats differ:
 ///
@@ -631,10 +635,25 @@ impl<T: Clone> Clone for Reverse<T> {
 
 /// Trait for types that form a [total order](https://en.wikipedia.org/wiki/Total_order).
 ///
-/// An order is a total order if it is (for all `a`, `b` and `c`):
+/// Implementations must be consistent with the [`PartialOrd`] implementation, and ensure
+/// `max`, `min`, and `clamp` are consistent with `cmp`:
+///
+/// - `partial_cmp(a, b) == Some(cmp(a, b))`.
+/// - `max(a, b) == max_by(a, b, cmp)` (ensured by the default implementation).
+/// - `min(a, b) == min_by(a, b, cmp)` (ensured by the default implementation).
+/// - For `a.clamp(min, max)`, see the [method docs](#method.clamp)
+///   (ensured by the default implementation).
+///
+/// It's easy to accidentally make `cmp` and `partial_cmp` disagree by
+/// deriving some of the traits and manually implementing others.
+///
+/// ## Corollaries
+///
+/// From the above and the requirements of `PartialOrd`, it follows that `<` defines a strict total order.
+/// This means that for all `a`, `b` and `c`:
 ///
-/// - total and asymmetric: exactly one of `a < b`, `a == b` or `a > b` is true; and
-/// - transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.
+/// - exactly one of `a < b`, `a == b` or `a > b` is true; and
+/// - `<` is transitive: `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.
 ///
 /// ## Derivable
 ///
@@ -659,12 +678,6 @@ impl<T: Clone> Clone for Reverse<T> {
 /// Then you must define an implementation for [`cmp`]. You may find it useful to use
 /// [`cmp`] on your type's fields.
 ///
-/// Implementations of [`PartialEq`], [`PartialOrd`], and `Ord` *must*
-/// agree with each other. That is, `a.cmp(b) == Ordering::Equal` if
-/// and only if `a == b` and `Some(a.cmp(b)) == a.partial_cmp(b)` for
-/// all `a` and `b`. It's easy to accidentally make them disagree by
-/// deriving some of the traits and manually implementing others.
-///
 /// Here's an example where you want to sort people by height only, disregarding `id`
 /// and `name`:
 ///
@@ -824,15 +837,45 @@ impl PartialOrd for Ordering {
 
 /// Trait for values that can be compared for a sort-order.
 ///
+/// The `lt`, `le`, `gt`, and `ge` methods of this trait can be called using
+/// the `<`, `<=`, `>`, and `>=` operators, respectively.
+///
+/// The methods of this trait must be consistent with each other and with those of `PartialEq` in
+/// the following sense:
+///
+/// - `a == b` if and only if `partial_cmp(a, b) == Some(Equal)`.
+/// - `a < b` if and only if `partial_cmp(a, b) == Some(Less)`
+///   (ensured by the default implementation).
+/// - `a > b` if and only if `partial_cmp(a, b) == Some(Greater)`
+///   (ensured by the default implementation).
+/// - `a <= b` if and only if `a < b || a == b`
+///   (ensured by the default implementation).
+/// - `a >= b` if and only if `a > b || a == b`
+///   (ensured by the default implementation).
+/// - `a != b` if and only if `!(a == b)` (already part of `PartialEq`).
+///
+/// If [`Ord`] is also implemented for `Self` and `Rhs`, it must also be consistent with
+/// `partial_cmp` (see the documentation of that trait for the exact requirements). It's
+/// easy to accidentally make them disagree by deriving some of the traits and manually
+/// implementing others.
+///
 /// The comparison must satisfy, for all `a`, `b` and `c`:
 ///
-/// - asymmetry: if `a < b` then `!(a > b)`, as well as `a > b` implying `!(a < b)`; and
 /// - transitivity: `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.
+/// - duality: `a < b` if and only if `b > a`.
 ///
 /// Note that these requirements mean that the trait itself must be implemented symmetrically and
 /// transitively: if `T: PartialOrd<U>` and `U: PartialOrd<V>` then `U: PartialOrd<T>` and `T:
 /// PartialOrd<V>`.
 ///
+/// ## Corollaries
+///
+/// The following corollaries follow from the above requirements:
+///
+/// - irreflexivity of `<` and `>`: `!(a < a)`, `!(a > a)`
+/// - transitivity of `>`: if `a > b` and `b > c` then `a > c`
+/// - duality of `partial_cmp`: `partial_cmp(a, b) == partial_cmp(b, a).map(Ordering::reverse)`
+///
 /// ## Derivable
 ///
 /// This trait can be used with `#[derive]`. When `derive`d on structs, it will produce a
@@ -850,10 +893,6 @@ impl PartialOrd for Ordering {
 ///
 /// `PartialOrd` requires your type to be [`PartialEq`].
 ///
-/// Implementations of [`PartialEq`], `PartialOrd`, and [`Ord`] *must* agree with each other. It's
-/// easy to accidentally make them disagree by deriving some of the traits and manually
-/// implementing others.
-///
 /// If your type is [`Ord`], you can implement [`partial_cmp`] by using [`cmp`]:
 ///
 /// ```