Auto merge of #81578 - jonas-schievink:rollup-yhiyowl, r=jonas-schievink

Rollup of 18 pull requests

Successful merges:

 - #78044 (Implement io::Seek for io::Empty)
 - #79285 (Stabilize Arc::{increment,decrement}_strong_count)
 - #80053 (stabilise `cargo test -- --include-ignored`)
 - #80279 (Implement missing `AsMut<str>` for `str`)
 - #80470 (Stabilize by-value `[T; N]` iterator `core::array::IntoIter`)
 - #80945 (Add Box::downcast() for dyn Any + Send + Sync)
 - #81048 (Stabilize `core::slice::fill_with`)
 - #81198 (Remove requirement that forces symmetric and transitive PartialEq impls to exist)
 - #81422 (Account for existing `_` field pattern when suggesting `..`)
 - #81472 (Clone entire `TokenCursor` when collecting tokens)
 - #81484 (Optimize decimal formatting of 128-bit integers)
 - #81491 (Balance sidebar `Deref` cycle check with main content)
 - #81509 (Add a regression test for ICE of bad_placeholder_type)
 - #81547 (Edit rustc_typeck top-level docs)
 - #81550 (Replace predecessor with range in collections documentation)
 - #81558 (Fix ascii art text wrapping in mobile)
 - #81562 (Clarify that InPlaceIterable guarantees extend to all advancing iterator methods.)
 - #81563 (Improve docblock readability on small screen)

Failed merges:

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

Author: bors

compiler/rustc_arena/src/lib.rs

@@ -11,11 +11,9 @@
     html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(no_crate_inject, attr(deny(warnings)))
 )]
-#![feature(array_value_iter_slice)]
 #![feature(dropck_eyepatch)]
 #![feature(new_uninit)]
 #![feature(maybe_uninit_slice)]
-#![feature(array_value_iter)]
 #![cfg_attr(bootstrap, feature(min_const_generics))]
 #![feature(min_specialization)]
 #![cfg_attr(test, feature(test))]

compiler/rustc_ast_lowering/src/lib.rs

@@ -30,7 +30,6 @@
 //! get confused if the spans from leaf AST nodes occur in multiple places
 //! in the HIR, especially for multiple identifiers.
 
-#![feature(array_value_iter)]
 #![feature(crate_visibility_modifier)]
 #![feature(or_patterns)]
 #![recursion_limit = "256"]

compiler/rustc_hir/src/lib.rs

@@ -2,7 +2,6 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 
-#![feature(array_value_iter)]
 #![feature(crate_visibility_modifier)]
 #![feature(const_fn)] // For the unsizing cast on `&[]`
 #![feature(const_panic)]

compiler/rustc_parse/src/parser/mod.rs

@@ -1254,15 +1254,7 @@ impl<'a> Parser<'a> {
         f: impl FnOnce(&mut Self) -> PResult<'a, (R, TrailingToken)>,
     ) -> PResult<'a, R> {
         let start_token = (self.token.clone(), self.token_spacing);
-        let cursor_snapshot = TokenCursor {
-            frame: self.token_cursor.frame.clone(),
-            // We only ever capture tokens within our current frame,
-            // so we can just use an empty frame stack
-            stack: vec![],
-            desugar_doc_comments: self.token_cursor.desugar_doc_comments,
-            num_next_calls: self.token_cursor.num_next_calls,
-            append_unglued_token: self.token_cursor.append_unglued_token.clone(),
-        };
+        let cursor_snapshot = self.token_cursor.clone();
 
         let (mut ret, trailing_token) = f(self)?;
 

compiler/rustc_trait_selection/src/lib.rs

@@ -11,7 +11,6 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![feature(array_value_iter)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(drain_filter)]

compiler/rustc_typeck/src/check/mod.rs

@@ -52,13 +52,13 @@ The types of top-level items, which never contain unbound type
 variables, are stored directly into the `tcx` typeck_results.
 
 N.B., a type variable is not the same thing as a type parameter.  A
-type variable is rather an "instance" of a type parameter: that is,
-given a generic function `fn foo<T>(t: T)`: while checking the
+type variable is an instance of a type parameter. That is,
+given a generic function `fn foo<T>(t: T)`, while checking the
 function `foo`, the type `ty_param(0)` refers to the type `T`, which
-is treated in abstract.  When `foo()` is called, however, `T` will be
+is treated in abstract. However, when `foo()` is called, `T` will be
 substituted for a fresh type variable `N`.  This variable will
 eventually be resolved to some concrete type (which might itself be
-type parameter).
+a type parameter).
 
 */
 

compiler/rustc_typeck/src/check/pat.rs

@@ -1041,12 +1041,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 vec![(left, "(".to_string()), (right.shrink_to_hi(), ")".to_string())],
                 Applicability::MachineApplicable,
             );
-        } else if fields.len() > subpats.len() {
-            let after_fields_span = if pat_span == DUMMY_SP {
-                pat_span
-            } else {
-                pat_span.with_hi(pat_span.hi() - BytePos(1)).shrink_to_hi()
-            };
+        } else if fields.len() > subpats.len() && pat_span != DUMMY_SP {
+            let after_fields_span = pat_span.with_hi(pat_span.hi() - BytePos(1)).shrink_to_hi();
             let all_fields_span = match subpats {
                 [] => after_fields_span,
                 [field] => field.span,
@@ -1055,7 +1051,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
             // Check if all the fields in the pattern are wildcards.
             let all_wildcards = subpats.iter().all(|pat| matches!(pat.kind, PatKind::Wild));
+            let first_tail_wildcard =
+                subpats.iter().enumerate().fold(None, |acc, (pos, pat)| match (acc, &pat.kind) {
+                    (None, PatKind::Wild) => Some(pos),
+                    (Some(_), PatKind::Wild) => acc,
+                    _ => None,
+                });
+            let tail_span = match first_tail_wildcard {
+                None => after_fields_span,
+                Some(0) => subpats[0].span.to(after_fields_span),
+                Some(pos) => subpats[pos - 1].span.shrink_to_hi().to(after_fields_span),
+            };
 
+            // FIXME: heuristic-based suggestion to check current types for where to add `_`.
             let mut wildcard_sugg = vec!["_"; fields.len() - subpats.len()].join(", ");
             if !subpats.is_empty() {
                 wildcard_sugg = String::from(", ") + &wildcard_sugg;
@@ -1080,7 +1088,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     );
                 } else {
                     err.span_suggestion_verbose(
-                        after_fields_span,
+                        tail_span,
                         "use `..` to ignore the rest of the fields",
                         String::from(", .."),
                         Applicability::MaybeIncorrect,

compiler/rustc_typeck/src/lib.rs

@@ -7,9 +7,9 @@ The type checker is responsible for:
 1. Determining the type of each expression.
 2. Resolving methods and traits.
 3. Guaranteeing that most type rules are met. ("Most?", you say, "why most?"
-   Well, dear reader, read on)
+   Well, dear reader, read on.)
 
-The main entry point is `check_crate()`. Type checking operates in
+The main entry point is [`check_crate()`]. Type checking operates in
 several major phases:
 
 1. The collect phase first passes over all items and determines their
@@ -25,7 +25,7 @@ several major phases:
    containing function).  Inference is used to supply types wherever
    they are unknown. The actual checking of a function itself has
    several phases (check, regionck, writeback), as discussed in the
-   documentation for the `check` module.
+   documentation for the [`check`] module.
 
 The type checker is defined into various submodules which are documented
 independently:
@@ -56,7 +56,6 @@ This API is completely unstable and subject to change.
 */
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![feature(array_value_iter)]
 #![feature(bool_to_option)]
 #![feature(box_syntax)]
 #![feature(crate_visibility_modifier)]

library/alloc/src/boxed.rs

@@ -1372,6 +1372,39 @@ impl<A: Allocator> Box<dyn Any + Send, A> {
     }
 }
 
+impl<A: Allocator> Box<dyn Any + Send + Sync, A> {
+    #[inline]
+    #[stable(feature = "box_send_sync_any_downcast", since = "1.51.0")]
+    /// Attempt to downcast the box to a concrete type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::any::Any;
+    ///
+    /// fn print_if_string(value: Box<dyn Any + Send + Sync>) {
+    ///     if let Ok(string) = value.downcast::<String>() {
+    ///         println!("String ({}): {}", string.len(), string);
+    ///     }
+    /// }
+    ///
+    /// let my_string = "Hello World".to_string();
+    /// print_if_string(Box::new(my_string));
+    /// print_if_string(Box::new(0i8));
+    /// ```
+    pub fn downcast<T: Any>(self) -> Result<Box<T, A>, Self> {
+        if self.is::<T>() {
+            unsafe {
+                let (raw, alloc): (*mut (dyn Any + Send + Sync), _) =
+                    Box::into_raw_with_allocator(self);
+                Ok(Box::from_raw_in(raw as *mut T, alloc))
+            }
+        } else {
+            Err(self)
+        }
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: fmt::Display + ?Sized, A: Allocator> fmt::Display for Box<T, A> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

library/alloc/src/lib.rs

@@ -78,7 +78,6 @@
 #![feature(allocator_api)]
 #![feature(array_chunks)]
 #![feature(array_methods)]
-#![feature(array_value_iter)]
 #![feature(array_windows)]
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]