Auto merge of rust-lang#97622 - JohnTitor:rollup-4qoxrjn, r=JohnTitor

Rollup of 9 pull requests

Successful merges:

 - rust-lang#94647 (Expose `get_many_mut` and `get_many_unchecked_mut` to HashMap)
 - rust-lang#97216 (Ensure we never consider the null pointer dereferencable)
 - rust-lang#97399 (simplify code of finding arg index in `opt_const_param_of`)
 - rust-lang#97470 (rustdoc: add more test coverage)
 - rust-lang#97498 (Corrected EBNF grammar for from_str)
 - rust-lang#97562 (Fix comment in `poly_project_and_unify_type`)
 - rust-lang#97580 (Add regression test for rust-lang#71546)
 - rust-lang#97611 (Tweak insert docs)
 - rust-lang#97616 (Remove an unnecessary `Option`)

Failed merges:

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

Author: bors

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -441,6 +441,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         msg,
                     })
                 }
+                // Ensure we never consider the null pointer dereferencable.
+                if M::PointerTag::OFFSET_IS_ADDR {
+                    assert_ne!(ptr.addr(), Size::ZERO);
+                }
                 // Test align. Check this last; if both bounds and alignment are violated
                 // we want the error to be about the bounds.
                 if let Some(align) = align {

compiler/rustc_data_structures/src/sso/set.rs

@@ -126,9 +126,10 @@ impl<T: Eq + Hash> SsoHashSet<T> {
 
     /// Adds a value to the set.
     ///
-    /// If the set did not have this value present, `true` is returned.
+    /// Returns whether the value was newly inserted. That is:
     ///
-    /// If the set did have this value present, `false` is returned.
+    /// - If the set did not previously contain this value, `true` is returned.
+    /// - If the set already contained this value, `false` is returned.
     #[inline]
     pub fn insert(&mut self, elem: T) -> bool {
         self.map.insert(elem, ()).is_none()

compiler/rustc_trait_selection/src/traits/project.rs

@@ -145,15 +145,28 @@ impl<'tcx> ProjectionCandidateSet<'tcx> {
     }
 }
 
-/// Takes the place of a
+/// States returned from `poly_project_and_unify_type`. Takes the place
+/// of the old return type, which was:
+/// ```ignore (not-rust)
 /// Result<
 ///     Result<Option<Vec<PredicateObligation<'tcx>>>, InProgress>,
 ///     MismatchedProjectionTypes<'tcx>,
 /// >
+/// ```
 pub(super) enum ProjectAndUnifyResult<'tcx> {
+    /// The projection bound holds subject to the given obligations. If the
+    /// projection cannot be normalized because the required trait bound does
+    /// not hold, this is returned, with `obligations` being a predicate that
+    /// cannot be proven.
     Holds(Vec<PredicateObligation<'tcx>>),
+    /// The projection cannot be normalized due to ambiguity. Resolving some
+    /// inference variables in the projection may fix this.
     FailedNormalization,
+    /// The project cannot be normalized because `poly_project_and_unify_type`
+    /// is called recursively while normalizing the same projection.
     Recursive,
+    // the projection can be normalized, but is not equal to the expected type.
+    // Returns the type error that arose from the mismatch.
     MismatchedProjectionTypes(MismatchedProjectionTypes<'tcx>),
 }
 
@@ -163,19 +176,6 @@ pub(super) enum ProjectAndUnifyResult<'tcx> {
 /// ```
 /// If successful, this may result in additional obligations. Also returns
 /// the projection cache key used to track these additional obligations.
-///
-/// ## Returns
-///
-/// - `Err(_)`: the projection can be normalized, but is not equal to the
-///   expected type.
-/// - `Ok(Err(InProgress))`: this is called recursively while normalizing
-///   the same projection.
-/// - `Ok(Ok(None))`: The projection cannot be normalized due to ambiguity
-///   (resolving some inference variables in the projection may fix this).
-/// - `Ok(Ok(Some(obligations)))`: The projection bound holds subject to
-///    the given obligations. If the projection cannot be normalized because
-///    the required trait bound doesn't hold this returned with `obligations`
-///    being a predicate that cannot be proven.
 #[instrument(level = "debug", skip(selcx))]
 pub(super) fn poly_project_and_unify_type<'cx, 'tcx>(
     selcx: &mut SelectionContext<'cx, 'tcx>,

compiler/rustc_trait_selection/src/traits/wf.rs

@@ -81,10 +81,17 @@ pub fn trait_obligations<'a, 'tcx>(
     body_id: hir::HirId,
     trait_ref: &ty::TraitRef<'tcx>,
     span: Span,
-    item: Option<&'tcx hir::Item<'tcx>>,
+    item: &'tcx hir::Item<'tcx>,
 ) -> Vec<traits::PredicateObligation<'tcx>> {
-    let mut wf =
-        WfPredicates { infcx, param_env, body_id, span, out: vec![], recursion_depth: 0, item };
+    let mut wf = WfPredicates {
+        infcx,
+        param_env,
+        body_id,
+        span,
+        out: vec![],
+        recursion_depth: 0,
+        item: Some(item),
+    };
     wf.compute_trait_ref(trait_ref, Elaborate::All);
     debug!(obligations = ?wf.out);
     wf.normalize()

compiler/rustc_typeck/src/check/wfcheck.rs

@@ -1228,7 +1228,7 @@ fn check_impl<'tcx>(
                     fcx.body_id,
                     &trait_ref,
                     ast_trait_ref.path.span,
-                    Some(item),
+                    item,
                 );
                 debug!(?obligations);
                 for obligation in obligations {

compiler/rustc_typeck/src/collect/type_of.rs

@@ -161,38 +161,23 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
             // We've encountered an `AnonConst` in some path, so we need to
             // figure out which generic parameter it corresponds to and return
             // the relevant type.
-            let filtered = path.segments.iter().find_map(|seg| {
-                seg.args?
-                    .args
+            let Some((arg_index, segment)) = path.segments.iter().find_map(|seg| {
+                let args = seg.args?;
+                args.args
+                .iter()
+                .filter(|arg| arg.is_ty_or_const())
+                .position(|arg| arg.id() == hir_id)
+                .map(|index| (index, seg)).or_else(|| args.bindings
                     .iter()
-                    .filter(|arg| arg.is_ty_or_const())
-                    .position(|arg| arg.id() == hir_id)
-                    .map(|index| (index, seg))
-            });
-
-            // FIXME(associated_const_generics): can we blend this with iteration above?
-            let (arg_index, segment) = match filtered {
-                None => {
-                    let binding_filtered = path.segments.iter().find_map(|seg| {
-                        seg.args?
-                            .bindings
-                            .iter()
-                            .filter_map(TypeBinding::opt_const)
-                            .position(|ct| ct.hir_id == hir_id)
-                            .map(|idx| (idx, seg))
-                    });
-                    match binding_filtered {
-                        Some(inner) => inner,
-                        None => {
-                            tcx.sess.delay_span_bug(
-                                tcx.def_span(def_id),
-                                "no arg matching AnonConst in path",
-                            );
-                            return None;
-                        }
-                    }
-                }
-                Some(inner) => inner,
+                    .filter_map(TypeBinding::opt_const)
+                    .position(|ct| ct.hir_id == hir_id)
+                    .map(|idx| (idx, seg)))
+            }) else {
+                tcx.sess.delay_span_bug(
+                    tcx.def_span(def_id),
+                    "no arg matching AnonConst in path",
+                );
+                return None;
             };
 
             // Try to use the segment resolution if it is valid, otherwise we

library/alloc/src/collections/btree/set.rs

@@ -770,10 +770,14 @@ impl<T> BTreeSet<T> {
 
     /// Adds a value to the set.
     ///
-    /// If the set did not have an equal element present, `true` is returned.
+    /// Returns whether the value was newly inserted. That is:
     ///
-    /// If the set did have an equal element present, `false` is returned, and
-    /// the entry is not updated. See the [module-level documentation] for more.
+    /// - If the set did not previously contain an equal value, `true` is
+    ///   returned.
+    /// - If the set already contained an equal value, `false` is returned, and
+    ///   the entry is not updated.
+    ///
+    /// See the [module-level documentation] for more.
     ///
     /// [module-level documentation]: index.html#insert-and-complex-keys
     ///

library/core/src/num/dec2flt/mod.rs

@@ -126,7 +126,6 @@ macro_rules! from_str_float_impl {
             /// ```txt
             /// Float  ::= Sign? ( 'inf' | 'infinity' | 'nan' | Number )
             /// Number ::= ( Digit+ |
-            ///              '.' Digit* |
             ///              Digit+ '.' Digit* |
             ///              Digit* '.' Digit+ ) Exp?
             /// Exp    ::= 'e' Sign? Digit+

library/std/src/collections/hash/map.rs

@@ -896,6 +896,119 @@ where
         self.base.get_key_value(k)
     }
 
+    /// Attempts to get mutable references to `N` values in the map at once.
+    ///
+    /// Returns an array of length `N` with the results of each query. For soundness, at most one
+    /// mutable reference will be returned to any value. `None` will be returned if any of the
+    /// keys are duplicates or missing.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(map_many_mut)]
+    /// use std::collections::HashMap;
+    ///
+    /// let mut libraries = HashMap::new();
+    /// libraries.insert("Bodleian Library".to_string(), 1602);
+    /// libraries.insert("Athenæum".to_string(), 1807);
+    /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
+    /// libraries.insert("Library of Congress".to_string(), 1800);
+    ///
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "Library of Congress",
+    /// ]);
+    /// assert_eq!(
+    ///     got,
+    ///     Some([
+    ///         &mut 1807,
+    ///         &mut 1800,
+    ///     ]),
+    /// );
+    ///
+    /// // Missing keys result in None
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "New York Public Library",
+    /// ]);
+    /// assert_eq!(got, None);
+    ///
+    /// // Duplicate keys result in None
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "Athenæum",
+    /// ]);
+    /// assert_eq!(got, None);
+    /// ```
+    #[inline]
+    #[unstable(feature = "map_many_mut", issue = "97601")]
+    pub fn get_many_mut<Q: ?Sized, const N: usize>(&mut self, ks: [&Q; N]) -> Option<[&'_ mut V; N]>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.get_many_mut(ks)
+    }
+
+    /// Attempts to get mutable references to `N` values in the map at once, without validating that
+    /// the values are unique.
+    ///
+    /// Returns an array of length `N` with the results of each query. `None` will be returned if
+    /// any of the keys are missing.
+    ///
+    /// For a safe alternative see [`get_many_mut`](Self::get_many_mut).
+    ///
+    /// # Safety
+    ///
+    /// Calling this method with overlapping keys is *[undefined behavior]* even if the resulting
+    /// references are not used.
+    ///
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(map_many_mut)]
+    /// use std::collections::HashMap;
+    ///
+    /// let mut libraries = HashMap::new();
+    /// libraries.insert("Bodleian Library".to_string(), 1602);
+    /// libraries.insert("Athenæum".to_string(), 1807);
+    /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
+    /// libraries.insert("Library of Congress".to_string(), 1800);
+    ///
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "Library of Congress",
+    /// ]);
+    /// assert_eq!(
+    ///     got,
+    ///     Some([
+    ///         &mut 1807,
+    ///         &mut 1800,
+    ///     ]),
+    /// );
+    ///
+    /// // Missing keys result in None
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "New York Public Library",
+    /// ]);
+    /// assert_eq!(got, None);
+    /// ```
+    #[inline]
+    #[unstable(feature = "map_many_mut", issue = "97601")]
+    pub unsafe fn get_many_unchecked_mut<Q: ?Sized, const N: usize>(
+        &mut self,
+        ks: [&Q; N],
+    ) -> Option<[&'_ mut V; N]>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq,
+    {
+        self.base.get_many_unchecked_mut(ks)
+    }
+
     /// Returns `true` if the map contains a value for the specified key.
     ///
     /// The key may be any borrowed form of the map's key type, but

library/std/src/collections/hash/set.rs

@@ -858,9 +858,10 @@ where
 
     /// Adds a value to the set.
     ///
-    /// If the set did not have this value present, `true` is returned.
+    /// Returns whether the value was newly inserted. That is:
     ///
-    /// If the set did have this value present, `false` is returned.
+    /// - If the set did not previously contain this value, `true` is returned.
+    /// - If the set already contained this value, `false` is returned.
     ///
     /// # Examples
     ///