Auto merge of #101652 - Dylan-DPC:rollup-f4atky0, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #101578 (remove bound var hack in `resolve`)
 - #101606 (doc: fix minor typo)
 - #101614 (Equate fn outputs when inferring RPITIT hidden types)
 - #101631 (rustdoc: avoid cleaning modules with duplicate names)
 - #101635 (Move `Queries::new` out of the macro)
 - #101641 (Update browser-ui-test version to 0.9.8)

Failed merges:

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

Author: bors

compiler/rustc_data_structures/src/sync.rs

@@ -48,7 +48,7 @@ cfg_if! {
         /// the native atomic types.
         /// You should use this type through the `AtomicU64`, `AtomicUsize`, etc, type aliases
         /// as it's not intended to be used separately.
-        #[derive(Debug)]
+        #[derive(Debug, Default)]
         pub struct Atomic<T: Copy>(Cell<T>);
 
         impl<T: Copy> Atomic<T> {

compiler/rustc_middle/src/query/mod.rs

@@ -1202,14 +1202,11 @@ rustc_queries! {
         }
     }
 
-    query codegen_fulfill_obligation(
+    query codegen_select_candidate(
         key: (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>)
     ) -> Result<&'tcx ImplSource<'tcx, ()>, traits::CodegenObligationError> {
         cache_on_disk_if { true }
-        desc { |tcx|
-            "checking if `{}` fulfills its obligations",
-            tcx.def_path_str(key.1.def_id())
-        }
+        desc { |tcx| "computing candidate for `{}`", key.1 }
     }
 
     /// Return all `impl` blocks in the current crate.

compiler/rustc_middle/src/traits/mod.rs

@@ -1024,7 +1024,7 @@ pub enum MethodViolationCode {
     UndispatchableReceiver(Option<Span>),
 }
 
-/// These are the error cases for `codegen_fulfill_obligation`.
+/// These are the error cases for `codegen_select_candidate`.
 #[derive(Copy, Clone, Debug, Hash, HashStable, Encodable, Decodable)]
 pub enum CodegenObligationError {
     /// Ambiguity can happen when monomorphizing during trans

compiler/rustc_monomorphize/src/lib.rs

@@ -35,7 +35,7 @@ fn custom_coerce_unsize_info<'tcx>(
         substs: tcx.mk_substs_trait(source_ty, &[target_ty.into()]),
     });
 
-    match tcx.codegen_fulfill_obligation((ty::ParamEnv::reveal_all(), trait_ref)) {
+    match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), trait_ref)) {
         Ok(traits::ImplSource::UserDefined(traits::ImplSourceUserDefinedData {
             impl_def_id,
             ..

compiler/rustc_query_impl/src/plumbing.rs

@@ -5,7 +5,7 @@
 use crate::keys::Key;
 use crate::{on_disk_cache, Queries};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_data_structures::sync::Lock;
+use rustc_data_structures::sync::{AtomicU64, Lock};
 use rustc_errors::{Diagnostic, Handler};
 use rustc_middle::dep_graph::{
     self, DepKind, DepKindStruct, DepNode, DepNodeIndex, SerializedDepNodeIndex,
@@ -499,9 +499,28 @@ macro_rules! define_queries {
     }
 }
 
+use crate::{ExternProviders, OnDiskCache, Providers};
+
+impl<'tcx> Queries<'tcx> {
+    pub fn new(
+        local_providers: Providers,
+        extern_providers: ExternProviders,
+        on_disk_cache: Option<OnDiskCache<'tcx>>,
+    ) -> Self {
+        Queries {
+            local_providers: Box::new(local_providers),
+            extern_providers: Box::new(extern_providers),
+            on_disk_cache,
+            jobs: AtomicU64::new(1),
+            ..Queries::default()
+        }
+    }
+}
+
 macro_rules! define_queries_struct {
     (
      input: ($(([$($modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => {
+        #[derive(Default)]
         pub struct Queries<'tcx> {
             local_providers: Box<Providers>,
             extern_providers: Box<ExternProviders>,
@@ -514,20 +533,6 @@ macro_rules! define_queries_struct {
         }
 
         impl<'tcx> Queries<'tcx> {
-            pub fn new(
-                local_providers: Providers,
-                extern_providers: ExternProviders,
-                on_disk_cache: Option<OnDiskCache<'tcx>>,
-            ) -> Self {
-                Queries {
-                    local_providers: Box::new(local_providers),
-                    extern_providers: Box::new(extern_providers),
-                    on_disk_cache,
-                    jobs: AtomicU64::new(1),
-                    $($name: Default::default()),*
-                }
-            }
-
             pub(crate) fn try_collect_active_jobs(
                 &'tcx self,
                 tcx: TyCtxt<'tcx>,

compiler/rustc_trait_selection/src/traits/codegen.rs

@@ -18,7 +18,7 @@ use rustc_middle::ty::{self, TyCtxt};
 /// obligations *could be* resolved if we wanted to.
 ///
 /// This also expects that `trait_ref` is fully normalized.
-pub fn codegen_fulfill_obligation<'tcx>(
+pub fn codegen_select_candidate<'tcx>(
     tcx: TyCtxt<'tcx>,
     (param_env, trait_ref): (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>),
 ) -> Result<&'tcx ImplSource<'tcx, ()>, CodegenObligationError> {

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -971,7 +971,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         specialization_graph_of: specialize::specialization_graph_provider,
         specializes: specialize::specializes,
-        codegen_fulfill_obligation: codegen::codegen_fulfill_obligation,
+        codegen_select_candidate: codegen::codegen_select_candidate,
         own_existential_vtable_entries,
         vtable_entries,
         vtable_trait_upcasting_coercion_new_vptr_slot,

compiler/rustc_ty_utils/src/instance.rs

@@ -3,113 +3,11 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::traits::CodegenObligationError;
 use rustc_middle::ty::subst::SubstsRef;
-use rustc_middle::ty::{
-    self, Binder, Instance, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor,
-};
+use rustc_middle::ty::{self, Instance, TyCtxt, TypeVisitable};
 use rustc_span::{sym, DUMMY_SP};
 use rustc_trait_selection::traits;
 use traits::{translate_substs, Reveal};
 
-use rustc_data_structures::sso::SsoHashSet;
-use std::collections::btree_map::Entry;
-use std::collections::BTreeMap;
-use std::ops::ControlFlow;
-
-// FIXME(#86795): `BoundVarsCollector` here should **NOT** be used
-// outside of `resolve_associated_item`. It's just to address #64494,
-// #83765, and #85848 which are creating bound types/regions that lose
-// their `Binder` *unintentionally*.
-// It's ideal to remove `BoundVarsCollector` and just use
-// `ty::Binder::*` methods but we use this stopgap until we figure out
-// the "real" fix.
-struct BoundVarsCollector<'tcx> {
-    binder_index: ty::DebruijnIndex,
-    vars: BTreeMap<u32, ty::BoundVariableKind>,
-    // We may encounter the same variable at different levels of binding, so
-    // this can't just be `Ty`
-    visited: SsoHashSet<(ty::DebruijnIndex, Ty<'tcx>)>,
-}
-
-impl<'tcx> BoundVarsCollector<'tcx> {
-    fn new() -> Self {
-        BoundVarsCollector {
-            binder_index: ty::INNERMOST,
-            vars: BTreeMap::new(),
-            visited: SsoHashSet::default(),
-        }
-    }
-
-    fn into_vars(self, tcx: TyCtxt<'tcx>) -> &'tcx ty::List<ty::BoundVariableKind> {
-        let max = self.vars.iter().map(|(k, _)| *k).max().unwrap_or(0);
-        for i in 0..max {
-            if let None = self.vars.get(&i) {
-                panic!("Unknown variable: {:?}", i);
-            }
-        }
-
-        tcx.mk_bound_variable_kinds(self.vars.into_iter().map(|(_, v)| v))
-    }
-}
-
-impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> {
-    type BreakTy = ();
-
-    fn visit_binder<T: TypeVisitable<'tcx>>(
-        &mut self,
-        t: &Binder<'tcx, T>,
-    ) -> ControlFlow<Self::BreakTy> {
-        self.binder_index.shift_in(1);
-        let result = t.super_visit_with(self);
-        self.binder_index.shift_out(1);
-        result
-    }
-
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
-        if t.outer_exclusive_binder() < self.binder_index
-            || !self.visited.insert((self.binder_index, t))
-        {
-            return ControlFlow::CONTINUE;
-        }
-        match *t.kind() {
-            ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => {
-                match self.vars.entry(bound_ty.var.as_u32()) {
-                    Entry::Vacant(entry) => {
-                        entry.insert(ty::BoundVariableKind::Ty(bound_ty.kind));
-                    }
-                    Entry::Occupied(entry) => match entry.get() {
-                        ty::BoundVariableKind::Ty(_) => {}
-                        _ => bug!("Conflicting bound vars"),
-                    },
-                }
-            }
-
-            _ => (),
-        };
-
-        t.super_visit_with(self)
-    }
-
-    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
-        match *r {
-            ty::ReLateBound(index, br) if index == self.binder_index => {
-                match self.vars.entry(br.var.as_u32()) {
-                    Entry::Vacant(entry) => {
-                        entry.insert(ty::BoundVariableKind::Region(br.kind));
-                    }
-                    Entry::Occupied(entry) => match entry.get() {
-                        ty::BoundVariableKind::Region(_) => {}
-                        _ => bug!("Conflicting bound vars"),
-                    },
-                }
-            }
-
-            _ => (),
-        };
-
-        r.super_visit_with(self)
-    }
-}
-
 fn resolve_instance<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::ParamEnvAnd<'tcx, (DefId, SubstsRef<'tcx>)>,
@@ -201,19 +99,14 @@ fn resolve_associated_item<'tcx>(
 
     let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
 
-    // See FIXME on `BoundVarsCollector`.
-    let mut bound_vars_collector = BoundVarsCollector::new();
-    trait_ref.visit_with(&mut bound_vars_collector);
-    let trait_binder = ty::Binder::bind_with_vars(trait_ref, bound_vars_collector.into_vars(tcx));
-    let vtbl = match tcx.codegen_fulfill_obligation((param_env, trait_binder)) {
+    let vtbl = match tcx.codegen_select_candidate((param_env, ty::Binder::dummy(trait_ref))) {
         Ok(vtbl) => vtbl,
         Err(CodegenObligationError::Ambiguity) => {
             let reported = tcx.sess.delay_span_bug(
                 tcx.def_span(trait_item_id),
                 &format!(
-                    "encountered ambiguity selecting `{:?}` during codegen, presuming due to \
+                    "encountered ambiguity selecting `{trait_ref:?}` during codegen, presuming due to \
                      overflow or prior type error",
-                    trait_binder
                 ),
             );
             return Err(reported);

compiler/rustc_typeck/src/check/compare_method.rs

@@ -295,12 +295,26 @@ pub(super) fn compare_predicates_and_trait_impl_trait_tys<'tcx>(
         // type would be more appropriate. In other places we have a `Vec<Span>`
         // corresponding to their `Vec<Predicate>`, but we don't have that here.
         // Fixing this would improve the output of test `issue-83765.rs`.
-        let sub_result = infcx
+        let mut result = infcx
             .at(&cause, param_env)
             .sup(trait_fty, impl_fty)
             .map(|infer_ok| ocx.register_infer_ok_obligations(infer_ok));
 
-        if let Err(terr) = sub_result {
+        // HACK(RPITIT): #101614. When we are trying to infer the hidden types for
+        // RPITITs, we need to equate the output tys instead of just subtyping. If
+        // we just use `sup` above, we'll end up `&'static str <: _#1t`, which causes
+        // us to infer `_#1t = #'_#2r str`, where `'_#2r` is unconstrained, which gets
+        // fixed up to `ReEmpty`, and which is certainly not what we want.
+        if trait_fty.has_infer_types() {
+            result = result.and_then(|()| {
+                infcx
+                    .at(&cause, param_env)
+                    .eq(trait_sig.output(), impl_sig.output())
+                    .map(|infer_ok| ocx.register_infer_ok_obligations(infer_ok))
+            });
+        }
+
+        if let Err(terr) = result {
             debug!("sub_types failed: impl ty {:?}, trait ty {:?}", impl_fty, trait_fty);
 
             let (impl_err_span, trait_err_span) =
@@ -445,6 +459,7 @@ pub(super) fn compare_predicates_and_trait_impl_trait_tys<'tcx>(
                             region
                         }
                     });
+                    debug!(%ty);
                     collected_tys.insert(def_id, ty);
                 }
                 Err(err) => {

library/std/src/thread/mod.rs

@@ -116,7 +116,7 @@
 //! Threads are able to have associated names for identification purposes. By default, spawned
 //! threads are unnamed. To specify a name for a thread, build the thread with [`Builder`] and pass
 //! the desired thread name to [`Builder::name`]. To retrieve the thread name from within the
-//! thread, use [`Thread::name`]. A couple examples of where the name of a thread gets used:
+//! thread, use [`Thread::name`]. A couple of examples where the name of a thread gets used:
 //!
 //! * If a panic occurs in a named thread, the thread name will be printed in the panic message.
 //! * The thread name is provided to the OS where applicable (e.g., `pthread_setname_np` in