Merge from rustc

10 files changed, 55 insertions, 99 deletions

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 922846775f6..d3ce3617dd6 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -23,7 +23,7 @@ use crate::{
 use rustc_lint_defs::pluralize;
 
 use derive_setters::Setters;
-use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_data_structures::sync::{DynSend, IntoDynSyncSend, Lrc};
 use rustc_error_messages::{FluentArgs, SpanLabel};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -370,7 +370,7 @@ pub trait Emitter: Translate {
     }
 
     fn render_multispan_macro_backtrace(&self, span: &mut MultiSpan, always_backtrace: bool) {
-        let mut new_labels: Vec<(Span, String)> = vec![];
+        let mut new_labels = FxIndexSet::default();
 
         for &sp in span.primary_spans() {
             if sp.is_dummy() {
@@ -387,7 +387,7 @@ pub trait Emitter: Translate {
                 }
 
                 if always_backtrace {
-                    new_labels.push((
+                    new_labels.insert((
                         trace.def_site,
                         format!(
                             "in this expansion of `{}`{}",
@@ -431,7 +431,7 @@ pub trait Emitter: Translate {
                             format!("this {} desugaring", kind.descr()).into()
                         }
                     };
-                    new_labels.push((
+                    new_labels.insert((
                         trace.call_site,
                         format!(
                             "in {}{}",
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index 6b0dc73d49c..3ed22e095e8 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -26,7 +26,6 @@ use rustc_infer::infer::{
     RegionVariableOrigin,
 };
 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
-use rustc_middle::traits::util::supertraits;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
 use rustc_middle::ty::print::{with_crate_prefix, with_forced_trimmed_paths};
@@ -40,7 +39,7 @@ use rustc_trait_selection::traits::error_reporting::on_unimplemented::OnUnimplem
 use rustc_trait_selection::traits::error_reporting::on_unimplemented::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_trait_selection::traits::{
-    FulfillmentError, Obligation, ObligationCause, ObligationCauseCode,
+    supertraits, FulfillmentError, Obligation, ObligationCause, ObligationCauseCode,
 };
 use std::borrow::Cow;
 
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index 93dfbe63bcd..3c566e0dd6d 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -2,7 +2,7 @@ use smallvec::smallvec;
 
 use crate::infer::outlives::components::{push_outlives_components, Component};
 use crate::traits::{self, Obligation, PredicateObligation};
-use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt};
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
@@ -76,7 +76,13 @@ impl<'tcx> Extend<ty::Predicate<'tcx>> for PredicateSet<'tcx> {
 pub struct Elaborator<'tcx, O> {
     stack: Vec<O>,
     visited: PredicateSet<'tcx>,
-    only_self: bool,
+    mode: Filter,
+}
+
+enum Filter {
+    All,
+    OnlySelf,
+    OnlySelfThatDefines(Ident),
 }
 
 /// Describes how to elaborate an obligation into a sub-obligation.
@@ -224,7 +230,7 @@ pub fn elaborate<'tcx, O: Elaboratable<'tcx>>(
     obligations: impl IntoIterator<Item = O>,
 ) -> Elaborator<'tcx, O> {
     let mut elaborator =
-        Elaborator { stack: Vec::new(), visited: PredicateSet::new(tcx), only_self: false };
+        Elaborator { stack: Vec::new(), visited: PredicateSet::new(tcx), mode: Filter::All };
     elaborator.extend_deduped(obligations);
     elaborator
 }
@@ -242,7 +248,13 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
     /// Filter to only the supertraits of trait predicates, i.e. only the predicates
     /// that have `Self` as their self type, instead of all implied predicates.
     pub fn filter_only_self(mut self) -> Self {
-        self.only_self = true;
+        self.mode = Filter::OnlySelf;
+        self
+    }
+
+    /// Filter to only the supertraits of trait predicates that define the assoc_ty.
+    pub fn filter_only_self_that_defines(mut self, assoc_ty: Ident) -> Self {
+        self.mode = Filter::OnlySelfThatDefines(assoc_ty);
         self
     }
 
@@ -257,10 +269,12 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
                     return;
                 }
                 // Get predicates implied by the trait, or only super predicates if we only care about self predicates.
-                let predicates = if self.only_self {
-                    tcx.super_predicates_of(data.def_id())
-                } else {
-                    tcx.implied_predicates_of(data.def_id())
+                let predicates = match self.mode {
+                    Filter::All => tcx.implied_predicates_of(data.def_id()),
+                    Filter::OnlySelf => tcx.super_predicates_of(data.def_id()),
+                    Filter::OnlySelfThatDefines(ident) => {
+                        tcx.super_predicates_that_define_assoc_item((data.def_id(), ident))
+                    }
                 };
 
                 let obligations =
@@ -409,14 +423,14 @@ impl<'tcx, O: Elaboratable<'tcx>> Iterator for Elaborator<'tcx, O> {
 pub fn supertraits<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_ref: ty::PolyTraitRef<'tcx>,
-) -> impl Iterator<Item = ty::PolyTraitRef<'tcx>> {
+) -> FilterToTraits<Elaborator<'tcx, ty::Predicate<'tcx>>> {
     elaborate(tcx, [trait_ref.to_predicate(tcx)]).filter_only_self().filter_to_traits()
 }
 
 pub fn transitive_bounds<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
-) -> impl Iterator<Item = ty::PolyTraitRef<'tcx>> {
+) -> FilterToTraits<Elaborator<'tcx, ty::Predicate<'tcx>>> {
     elaborate(tcx, trait_refs.map(|trait_ref| trait_ref.to_predicate(tcx)))
         .filter_only_self()
         .filter_to_traits()
@@ -429,31 +443,12 @@ pub fn transitive_bounds<'tcx>(
 /// `T::Item` and helps to avoid cycle errors (see e.g. #35237).
 pub fn transitive_bounds_that_define_assoc_item<'tcx>(
     tcx: TyCtxt<'tcx>,
-    bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
+    trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
     assoc_name: Ident,
-) -> impl Iterator<Item = ty::PolyTraitRef<'tcx>> {
-    let mut stack: Vec<_> = bounds.collect();
-    let mut visited = FxIndexSet::default();
-
-    std::iter::from_fn(move || {
-        while let Some(trait_ref) = stack.pop() {
-            let anon_trait_ref = tcx.anonymize_bound_vars(trait_ref);
-            if visited.insert(anon_trait_ref) {
-                let super_predicates =
-                    tcx.super_predicates_that_define_assoc_item((trait_ref.def_id(), assoc_name));
-                for (super_predicate, _) in super_predicates.predicates {
-                    let subst_predicate = super_predicate.subst_supertrait(tcx, &trait_ref);
-                    if let Some(binder) = subst_predicate.as_trait_clause() {
-                        stack.push(binder.map_bound(|t| t.trait_ref));
-                    }
-                }
-
-                return Some(trait_ref);
-            }
-        }
-
-        return None;
-    })
+) -> FilterToTraits<Elaborator<'tcx, ty::Predicate<'tcx>>> {
+    elaborate(tcx, trait_refs.map(|trait_ref| trait_ref.to_predicate(tcx)))
+        .filter_only_self_that_defines(assoc_name)
+        .filter_to_traits()
 }
 
 ///////////////////////////////////////////////////////////////////////////
diff --git a/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs b/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs
index bc11082d278..d2d99bc0da8 100644
--- a/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs
+++ b/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs
@@ -4,9 +4,10 @@ use crate::{
 };
 
 use rustc_hir as hir;
-use rustc_middle::{traits::util::supertraits, ty};
+use rustc_middle::ty;
 use rustc_session::lint::FutureIncompatibilityReason;
 use rustc_span::sym;
+use rustc_trait_selection::traits::supertraits;
 
 declare_lint! {
     /// The `deref_into_dyn_supertrait` lint is output whenever there is a use of the
diff --git a/compiler/rustc_middle/src/traits/util.rs b/compiler/rustc_middle/src/traits/util.rs
index 05c06efaf16..b4054f8ff5e 100644
--- a/compiler/rustc_middle/src/traits/util.rs
+++ b/compiler/rustc_middle/src/traits/util.rs
@@ -3,9 +3,10 @@ use rustc_data_structures::fx::FxHashSet;
 use crate::ty::{PolyTraitRef, TyCtxt};
 
 /// Given a PolyTraitRef, get the PolyTraitRefs of the trait's (transitive) supertraits.
-///
-/// A simplified version of the same function at `rustc_infer::traits::util::supertraits`.
-pub fn supertraits<'tcx>(
+/// This only exists in `rustc_middle` because the more powerful elaborator depends on
+/// `rustc_infer` for elaborating outlives bounds -- this should only be used for pretty
+/// printing.
+pub fn supertraits_for_pretty_printing<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_ref: PolyTraitRef<'tcx>,
 ) -> impl Iterator<Item = PolyTraitRef<'tcx>> {
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index d8010c71497..117aa69596c 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1,6 +1,7 @@
 use crate::mir::interpret::{AllocRange, GlobalAlloc, Pointer, Provenance, Scalar};
 use crate::query::IntoQueryParam;
 use crate::query::Providers;
+use crate::traits::util::supertraits_for_pretty_printing;
 use crate::ty::{
     self, ConstInt, ParamConst, ScalarInt, Term, TermKind, Ty, TyCtxt, TypeFoldable,
     TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
@@ -1150,14 +1151,14 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                 entry.has_fn_once = true;
                 return;
             } else if Some(trait_def_id) == self.tcx().lang_items().fn_mut_trait() {
-                let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
+                let super_trait_ref = supertraits_for_pretty_printing(self.tcx(), trait_ref)
                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
                     .unwrap();
 
                 fn_traits.entry(super_trait_ref).or_default().fn_mut_trait_ref = Some(trait_ref);
                 return;
             } else if Some(trait_def_id) == self.tcx().lang_items().fn_trait() {
-                let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref)
+                let super_trait_ref = supertraits_for_pretty_printing(self.tcx(), trait_ref)
                     .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait)
                     .unwrap();
 
diff --git a/compiler/rustc_monomorphize/Cargo.toml b/compiler/rustc_monomorphize/Cargo.toml
index 6d3a3bf906e..fe097424e8a 100644
--- a/compiler/rustc_monomorphize/Cargo.toml
+++ b/compiler/rustc_monomorphize/Cargo.toml
@@ -13,7 +13,6 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
-rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }
diff --git a/compiler/rustc_monomorphize/messages.ftl b/compiler/rustc_monomorphize/messages.ftl
index cf23d79afaf..e27875853df 100644
--- a/compiler/rustc_monomorphize/messages.ftl
+++ b/compiler/rustc_monomorphize/messages.ftl
@@ -27,8 +27,6 @@ monomorphize_type_length_limit = reached the type-length limit while instantiati
 monomorphize_unknown_cgu_collection_mode =
     unknown codegen-item collection mode '{$mode}', falling back to 'lazy' mode
 
-monomorphize_unknown_partition_strategy = unknown partitioning strategy
-
 monomorphize_unused_generic_params = item has unused generic parameters
 
 monomorphize_written_to_path = the full type name has been written to '{$path}'
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 6ea177bb6ea..eb1c7db026e 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -173,7 +173,7 @@ use rustc_hir::lang_items::LangItem;
 use rustc_middle::mir::interpret::{AllocId, ErrorHandled, GlobalAlloc, Scalar};
 use rustc_middle::mir::mono::{InstantiationMode, MonoItem};
 use rustc_middle::mir::visit::Visitor as MirVisitor;
-use rustc_middle::mir::{self, Local, Location};
+use rustc_middle::mir::{self, Location};
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::adjustment::{CustomCoerceUnsized, PointerCoercion};
 use rustc_middle::ty::print::with_no_trimmed_paths;
@@ -874,14 +874,6 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
         self.super_operand(operand, location);
         self.check_operand_move_size(operand, location);
     }
-
-    fn visit_local(
-        &mut self,
-        _place_local: Local,
-        _context: mir::visit::PlaceContext,
-        _location: Location,
-    ) {
-    }
 }
 
 fn visit_drop_use<'tcx>(
@@ -1220,7 +1212,7 @@ impl<'v> RootCollector<'_, 'v> {
     }
 
     fn is_root(&self, def_id: LocalDefId) -> bool {
-        !item_requires_monomorphization(self.tcx, def_id)
+        !self.tcx.generics_of(def_id).requires_monomorphization(self.tcx)
             && match self.mode {
                 MonoItemCollectionMode::Eager => true,
                 MonoItemCollectionMode::Lazy => {
@@ -1283,11 +1275,6 @@ impl<'v> RootCollector<'_, 'v> {
     }
 }
 
-fn item_requires_monomorphization(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
-    let generics = tcx.generics_of(def_id);
-    generics.requires_monomorphization(tcx)
-}
-
 #[instrument(level = "debug", skip(tcx, output))]
 fn create_mono_items_for_default_impls<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -1394,17 +1381,6 @@ fn collect_alloc<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoIt
     }
 }
 
-fn add_assoc_fn<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    def_id: Option<DefId>,
-    fn_ident: Ident,
-    skip_move_check_fns: &mut Vec<DefId>,
-) {
-    if let Some(def_id) = def_id.and_then(|def_id| assoc_fn_of_type(tcx, def_id, fn_ident)) {
-        skip_move_check_fns.push(def_id);
-    }
-}
-
 fn assoc_fn_of_type<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, fn_ident: Ident) -> Option<DefId> {
     for impl_def_id in tcx.inherent_impls(def_id) {
         if let Some(new) = tcx.associated_items(impl_def_id).find_by_name_and_kind(
@@ -1420,26 +1396,16 @@ fn assoc_fn_of_type<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, fn_ident: Ident) ->
 }
 
 fn build_skip_move_check_fns(tcx: TyCtxt<'_>) -> Vec<DefId> {
-    let mut skip_move_check_fns = vec![];
-    add_assoc_fn(
-        tcx,
-        tcx.lang_items().owned_box(),
-        Ident::from_str("new"),
-        &mut skip_move_check_fns,
-    );
-    add_assoc_fn(
-        tcx,
-        tcx.get_diagnostic_item(sym::Arc),
-        Ident::from_str("new"),
-        &mut skip_move_check_fns,
-    );
-    add_assoc_fn(
-        tcx,
-        tcx.get_diagnostic_item(sym::Rc),
-        Ident::from_str("new"),
-        &mut skip_move_check_fns,
-    );
-    skip_move_check_fns
+    let fns = [
+        (tcx.lang_items().owned_box(), "new"),
+        (tcx.get_diagnostic_item(sym::Rc), "new"),
+        (tcx.get_diagnostic_item(sym::Arc), "new"),
+    ];
+    fns.into_iter()
+        .filter_map(|(def_id, fn_name)| {
+            def_id.and_then(|def_id| assoc_fn_of_type(tcx, def_id, Ident::from_str(fn_name)))
+        })
+        .collect::<Vec<_>>()
 }
 
 /// Scans the MIR in order to find function calls, closures, and drop-glue.
diff --git a/compiler/rustc_monomorphize/src/errors.rs b/compiler/rustc_monomorphize/src/errors.rs
index fdcc95f137f..d242a7baec1 100644
--- a/compiler/rustc_monomorphize/src/errors.rs
+++ b/compiler/rustc_monomorphize/src/errors.rs
@@ -76,10 +76,6 @@ pub struct LargeAssignmentsLint {
 }
 
 #[derive(Diagnostic)]
-#[diag(monomorphize_unknown_partition_strategy)]
-pub struct UnknownPartitionStrategy;
-
-#[derive(Diagnostic)]
 #[diag(monomorphize_symbol_already_defined)]
 pub struct SymbolAlreadyDefined {
     #[primary_span]