Auto merge of rust-lang#107071 - Mark-Simulacrum:beta-next, r=Mark-Simulacrum

[beta] backport rollup

* Revert "Make nested RPITIT inherit the parent opaque's generics." rust-lang#106759
*  Fix mpsc::SyncSender spinning behavior rust-lang#106701
*  rustdoc: fix outdated lint section of the book rust-lang#106605
*  Do not filter substs in remap_generic_params_to_declaration_params. rust-lang#106503
*  Correct detection of elided lifetimes in impl-trait. rust-lang#106501
*  Bump rust-installer rust-lang#106196
*  Don't panic on stable since miri is not available there rust-lang#105901

Author: bors

Diff for: compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -250,7 +250,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         }
 
         let definition_ty = instantiated_ty
-            .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false, origin)
+            .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false)
             .ty;
 
         if !check_opaque_type_parameter_valid(

Diff for: compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -4,6 +4,7 @@ use hir::{
     GenericParamKind, HirId, Node,
 };
 use rustc_hir as hir;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint;
@@ -142,7 +143,20 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
             Some(tcx.typeck_root_def_id(def_id))
         }
         Node::Item(item) => match item.kind {
-            ItemKind::OpaqueTy(hir::OpaqueTy { .. }) => {
+            ItemKind::OpaqueTy(hir::OpaqueTy {
+                origin:
+                    hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
+                in_trait,
+                ..
+            }) => {
+                if in_trait {
+                    assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn))
+                } else {
+                    assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn | DefKind::Fn))
+                }
+                Some(fn_def_id.to_def_id())
+            }
+            ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
                 let parent_id = tcx.hir().get_parent_item(hir_id);
                 assert_ne!(parent_id, hir::CRATE_OWNER_ID);
                 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);

Diff for: compiler/rustc_hir_analysis/src/collect/lifetimes.rs

@@ -1195,8 +1195,10 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                     // Fresh lifetimes in APIT used to be allowed in async fns and forbidden in
                     // regular fns.
                     if let Some(hir::PredicateOrigin::ImplTrait) = where_bound_origin
-                        && let hir::LifetimeName::Param(_) = lifetime_ref.res
-                        && lifetime_ref.is_anonymous()
+                        && let hir::LifetimeName::Param(param_id) = lifetime_ref.res
+                        && let Some(generics) = self.tcx.hir().get_generics(self.tcx.local_parent(param_id))
+                        && let Some(param) = generics.params.iter().find(|p| p.def_id == param_id)
+                        && param.is_elided_lifetime()
                         && let hir::IsAsync::NotAsync = self.tcx.asyncness(lifetime_ref.hir_id.owner.def_id)
                         && !self.tcx.features().anonymous_lifetime_in_impl_trait
                     {

Diff for: compiler/rustc_hir_typeck/src/writeback.rs

@@ -565,7 +565,6 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
                 opaque_type_key,
                 self.fcx.infcx.tcx,
                 true,
-                decl.origin,
             );
 
             self.typeck_results.concrete_opaque_types.insert(opaque_type_key.def_id, hidden_type);

Diff for: compiler/rustc_middle/src/ty/mod.rs

@@ -28,7 +28,6 @@ use crate::ty::util::Discr;
 pub use adt::*;
 pub use assoc::*;
 pub use generics::*;
-use hir::OpaqueTyOrigin;
 use rustc_ast as ast;
 use rustc_ast::node_id::NodeMap;
 use rustc_attr as attr;
@@ -1287,7 +1286,6 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
         tcx: TyCtxt<'tcx>,
         // typeck errors have subpar spans for opaque types, so delay error reporting until borrowck.
         ignore_errors: bool,
-        origin: OpaqueTyOrigin,
     ) -> Self {
         let OpaqueTypeKey { def_id, substs } = opaque_type_key;
 
@@ -1303,30 +1301,7 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
         // This zip may have several times the same lifetime in `substs` paired with a different
         // lifetime from `id_substs`.  Simply `collect`ing the iterator is the correct behaviour:
         // it will pick the last one, which is the one we introduced in the impl-trait desugaring.
-        let map = substs.iter().zip(id_substs);
-
-        let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> = match origin {
-            // HACK: The HIR lowering for async fn does not generate
-            // any `+ Captures<'x>` bounds for the `impl Future<...>`, so all async fns with lifetimes
-            // would now fail to compile. We should probably just make hir lowering fill this in properly.
-            OpaqueTyOrigin::AsyncFn(_) => map.collect(),
-            OpaqueTyOrigin::FnReturn(_) | OpaqueTyOrigin::TyAlias => {
-                // Opaque types may only use regions that are bound. So for
-                // ```rust
-                // type Foo<'a, 'b, 'c> = impl Trait<'a> + 'b;
-                // ```
-                // we may not use `'c` in the hidden type.
-                let variances = tcx.variances_of(def_id);
-                debug!(?variances);
-
-                map.filter(|(_, v)| {
-                    let ty::GenericArgKind::Lifetime(lt) = v.unpack() else { return true };
-                    let ty::ReEarlyBound(ebr) = lt.kind() else { bug!() };
-                    variances[ebr.index as usize] == ty::Variance::Invariant
-                })
-                .collect()
-            }
-        };
+        let map = substs.iter().zip(id_substs).collect();
         debug!("map = {:#?}", map);
 
         // Convert the type from the function into a type valid outside

Diff for: library/std/src/sync/mpmc/array.rs

@@ -168,7 +168,7 @@ impl<T> Channel<T> {
                         return true;
                     }
                     Err(_) => {
-                        backoff.spin();
+                        backoff.spin_light();
                         tail = self.tail.load(Ordering::Relaxed);
                     }
                 }
@@ -182,11 +182,11 @@ impl<T> Channel<T> {
                     return false;
                 }
 
-                backoff.spin();
+                backoff.spin_light();
                 tail = self.tail.load(Ordering::Relaxed);
             } else {
                 // Snooze because we need to wait for the stamp to get updated.
-                backoff.snooze();
+                backoff.spin_heavy();
                 tail = self.tail.load(Ordering::Relaxed);
             }
         }
@@ -251,7 +251,7 @@ impl<T> Channel<T> {
                         return true;
                     }
                     Err(_) => {
-                        backoff.spin();
+                        backoff.spin_light();
                         head = self.head.load(Ordering::Relaxed);
                     }
                 }
@@ -273,11 +273,11 @@ impl<T> Channel<T> {
                     }
                 }
 
-                backoff.spin();
+                backoff.spin_light();
                 head = self.head.load(Ordering::Relaxed);
             } else {
                 // Snooze because we need to wait for the stamp to get updated.
-                backoff.snooze();
+                backoff.spin_heavy();
                 head = self.head.load(Ordering::Relaxed);
             }
         }
@@ -330,7 +330,7 @@ impl<T> Channel<T> {
                 if backoff.is_completed() {
                     break;
                 } else {
-                    backoff.spin();
+                    backoff.spin_light();
                 }
             }
 

Diff for: library/std/src/sync/mpmc/list.rs

@@ -46,7 +46,7 @@ impl<T> Slot<T> {
     fn wait_write(&self) {
         let backoff = Backoff::new();
         while self.state.load(Ordering::Acquire) & WRITE == 0 {
-            backoff.snooze();
+            backoff.spin_heavy();
         }
     }
 }
@@ -82,7 +82,7 @@ impl<T> Block<T> {
             if !next.is_null() {
                 return next;
             }
-            backoff.snooze();
+            backoff.spin_heavy();
         }
     }
 
@@ -191,7 +191,7 @@ impl<T> Channel<T> {
 
             // If we reached the end of the block, wait until the next one is installed.
             if offset == BLOCK_CAP {
-                backoff.snooze();
+                backoff.spin_heavy();
                 tail = self.tail.index.load(Ordering::Acquire);
                 block = self.tail.block.load(Ordering::Acquire);
                 continue;
@@ -247,7 +247,7 @@ impl<T> Channel<T> {
                     return true;
                 },
                 Err(_) => {
-                    backoff.spin();
+                    backoff.spin_light();
                     tail = self.tail.index.load(Ordering::Acquire);
                     block = self.tail.block.load(Ordering::Acquire);
                 }
@@ -286,7 +286,7 @@ impl<T> Channel<T> {
 
             // If we reached the end of the block, wait until the next one is installed.
             if offset == BLOCK_CAP {
-                backoff.snooze();
+                backoff.spin_heavy();
                 head = self.head.index.load(Ordering::Acquire);
                 block = self.head.block.load(Ordering::Acquire);
                 continue;
@@ -320,7 +320,7 @@ impl<T> Channel<T> {
             // The block can be null here only if the first message is being sent into the channel.
             // In that case, just wait until it gets initialized.
             if block.is_null() {
-                backoff.snooze();
+                backoff.spin_heavy();
                 head = self.head.index.load(Ordering::Acquire);
                 block = self.head.block.load(Ordering::Acquire);
                 continue;
@@ -351,7 +351,7 @@ impl<T> Channel<T> {
                     return true;
                 },
                 Err(_) => {
-                    backoff.spin();
+                    backoff.spin_light();
                     head = self.head.index.load(Ordering::Acquire);
                     block = self.head.block.load(Ordering::Acquire);
                 }
@@ -542,7 +542,7 @@ impl<T> Channel<T> {
             // New updates to tail will be rejected by MARK_BIT and aborted unless it's
             // at boundary. We need to wait for the updates take affect otherwise there
             // can be memory leaks.
-            backoff.snooze();
+            backoff.spin_heavy();
             tail = self.tail.index.load(Ordering::Acquire);
         }
 

Diff for: library/std/src/sync/mpmc/mod.rs

@@ -43,7 +43,7 @@ mod zero;
 use crate::fmt;
 use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::time::{Duration, Instant};
-use error::*;
+pub use error::*;
 
 /// Creates a channel of unbounded capacity.
 ///

Diff for: library/std/src/sync/mpmc/utils.rs

@@ -91,9 +91,8 @@ impl<T> DerefMut for CachePadded<T> {
 }
 
 const SPIN_LIMIT: u32 = 6;
-const YIELD_LIMIT: u32 = 10;
 
-/// Performs exponential backoff in spin loops.
+/// Performs quadratic backoff in spin loops.
 pub struct Backoff {
     step: Cell<u32>,
 }
@@ -104,25 +103,27 @@ impl Backoff {
         Backoff { step: Cell::new(0) }
     }
 
-    /// Backs off in a lock-free loop.
+    /// Backs off using lightweight spinning.
     ///
-    /// This method should be used when we need to retry an operation because another thread made
-    /// progress.
+    /// This method should be used for:
+    ///     - Retrying an operation because another thread made progress. i.e. on CAS failure.
+    ///     - Waiting for an operation to complete by spinning optimistically for a few iterations
+    ///     before falling back to parking the thread (see `Backoff::is_completed`).
     #[inline]
-    pub fn spin(&self) {
+    pub fn spin_light(&self) {
         let step = self.step.get().min(SPIN_LIMIT);
         for _ in 0..step.pow(2) {
             crate::hint::spin_loop();
         }
 
-        if self.step.get() <= SPIN_LIMIT {
-            self.step.set(self.step.get() + 1);
-        }
+        self.step.set(self.step.get() + 1);
     }
 
-    /// Backs off in a blocking loop.
+    /// Backs off using heavyweight spinning.
+    ///
+    /// This method should be used in blocking loops where parking the thread is not an option.
     #[inline]
-    pub fn snooze(&self) {
+    pub fn spin_heavy(&self) {
         if self.step.get() <= SPIN_LIMIT {
             for _ in 0..self.step.get().pow(2) {
                 crate::hint::spin_loop()
@@ -131,14 +132,12 @@ impl Backoff {
             crate::thread::yield_now();
         }
 
-        if self.step.get() <= YIELD_LIMIT {
-            self.step.set(self.step.get() + 1);
-        }
+        self.step.set(self.step.get() + 1);
     }
 
-    /// Returns `true` if exponential backoff has completed and blocking the thread is advised.
+    /// Returns `true` if quadratic backoff has completed and parking the thread is advised.
     #[inline]
     pub fn is_completed(&self) -> bool {
-        self.step.get() > YIELD_LIMIT
+        self.step.get() > SPIN_LIMIT
     }
 }

Diff for: library/std/src/sync/mpmc/zero.rs

@@ -57,7 +57,7 @@ impl<T> Packet<T> {
     fn wait_ready(&self) {
         let backoff = Backoff::new();
         while !self.ready.load(Ordering::Acquire) {
-            backoff.snooze();
+            backoff.spin_heavy();
         }
     }
 }

Diff for: library/std/src/sync/mpsc/mod.rs

@@ -738,6 +738,15 @@ impl<T> SyncSender<T> {
     pub fn try_send(&self, t: T) -> Result<(), TrySendError<T>> {
         self.inner.try_send(t)
     }
+
+    // Attempts to send for a value on this receiver, returning an error if the
+    // corresponding channel has hung up, or if it waits more than `timeout`.
+    //
+    // This method is currently private and only used for tests.
+    #[allow(unused)]
+    fn send_timeout(&self, t: T, timeout: Duration) -> Result<(), mpmc::SendTimeoutError<T>> {
+        self.inner.send_timeout(t, timeout)
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

Diff for: library/std/src/sync/mpsc/sync_tests.rs

@@ -1,5 +1,6 @@
 use super::*;
 use crate::env;
+use crate::sync::mpmc::SendTimeoutError;
 use crate::thread;
 use crate::time::Duration;
 
@@ -41,6 +42,13 @@ fn recv_timeout() {
     assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(1));
 }
 
+#[test]
+fn send_timeout() {
+    let (tx, _rx) = sync_channel::<i32>(1);
+    assert_eq!(tx.send_timeout(1, Duration::from_millis(1)), Ok(()));
+    assert_eq!(tx.send_timeout(1, Duration::from_millis(1)), Err(SendTimeoutError::Timeout(1)));
+}
+
 #[test]
 fn smoke_threads() {
     let (tx, rx) = sync_channel::<i32>(0);

Diff for: src/bootstrap/install.rs

@@ -200,10 +200,14 @@ install!((self, builder, _config),
         install_sh(builder, "clippy", self.compiler.stage, Some(self.target), &tarball);
     };
     Miri, alias = "miri", Self::should_build(_config), only_hosts: true, {
-        let tarball = builder
-            .ensure(dist::Miri { compiler: self.compiler, target: self.target })
-            .expect("missing miri");
-        install_sh(builder, "miri", self.compiler.stage, Some(self.target), &tarball);
+        if let Some(tarball) = builder.ensure(dist::Miri { compiler: self.compiler, target: self.target }) {
+            install_sh(builder, "miri", self.compiler.stage, Some(self.target), &tarball);
+        } else {
+            // Miri is only available on nightly
+            builder.info(
+                &format!("skipping Install miri stage{} ({})", self.compiler.stage, self.target),
+            );
+        }
     };
     Rustfmt, alias = "rustfmt", Self::should_build(_config), only_hosts: true, {
         if let Some(tarball) = builder.ensure(dist::Rustfmt {

Diff for: src/doc/rustdoc/src/lints.md

@@ -261,7 +261,7 @@ typo mistakes for some common attributes.
 
 ## `invalid_html_tags`
 
-This lint is **allowed by default** and is **nightly-only**. It detects unclosed
+This lint **warns by default**. It detects unclosed
 or invalid HTML tags. For example:
 
 ```rust

Diff for: src/test/ui/async-await/in-trait/nested-rpit.rs

@@ -1,5 +1,7 @@
-// check-pass
 // edition: 2021
+// known-bug: #105197
+// failure-status:101
+// dont-check-compiler-stderr
 
 #![feature(async_fn_in_trait)]
 #![feature(return_position_impl_trait_in_trait)]