Auto merge of rust-lang#107215 - Dylan-DPC:rollup-zqtiufk, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - rust-lang#104926 (Move relationships from FulfillmentContext to Inherited)
 - rust-lang#106854 (Add `Arc::into_inner` for safely discarding `Arc`s without calling the destructor on the inner type.)
 - rust-lang#107108 (Consider doc(alias) when providing typo suggestions)
 - rust-lang#107186 (rustdoc: Use correct pseudo-element selector)
 - rust-lang#107192 (Add myself to the mailmap)
 - rust-lang#107195 (Fix typo in universal_regions.rs comment)
 - rust-lang#107203 (Suggest remove deref for type mismatch)

Failed merges:

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

.mailmap

@@ -325,6 +325,7 @@ Lennart Kudling <github@kudling.de>
 Léo Lanteri Thauvin <leseulartichaut@gmail.com>
 Léo Lanteri Thauvin <leseulartichaut@gmail.com> <38361244+LeSeulArtichaut@users.noreply.github.com>
 Léo Testard <leo.testard@gmail.com>
+León Orell Valerian Liehr <me@fmease.dev> <liehr.exchange@gmx.net>
 Leonardo Yvens <leoyvens@gmail.com>
 Liigo Zhuang <liigo@qq.com>
 Lily Ballard <lily@ballards.net> <kevin@sb.org>

compiler/rustc_borrowck/src/universal_regions.rs

@@ -162,7 +162,7 @@ struct UniversalRegionIndices<'tcx> {
     /// `ty::Region` to the internal `RegionVid` we are using. This is
     /// used because trait matching and type-checking will feed us
     /// region constraints that reference those regions and we need to
-    /// be able to map them our internal `RegionVid`. This is
+    /// be able to map them to our internal `RegionVid`. This is
     /// basically equivalent to an `InternalSubsts`, except that it also
     /// contains an entry for `ReStatic` -- it might be nice to just
     /// use a substs, and then handle `ReStatic` another way.

compiler/rustc_hir_typeck/src/demand.rs

@@ -1233,6 +1233,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             sugg_sp = receiver.span;
                         }
                     }
+
+                    if let hir::ExprKind::Unary(hir::UnOp::Deref, ref inner) = expr.kind
+                        && let Some(1) = self.deref_steps(expected, checked_ty) {
+                        // We have `*&T`, check if what was expected was `&T`.
+                        // If so, we may want to suggest removing a `*`.
+                        sugg_sp = sugg_sp.with_hi(inner.span.lo());
+                        return Some((
+                            sugg_sp,
+                            "consider removing deref here".to_string(),
+                            "".to_string(),
+                            Applicability::MachineApplicable,
+                            true,
+                            false,
+                        ));
+                    }
+
                     if let Ok(src) = sm.span_to_snippet(sugg_sp) {
                         let needs_parens = match expr.kind {
                             // parenthesize if needed (Issue #46756)

compiler/rustc_hir_typeck/src/fallback.rs

@@ -196,8 +196,6 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
     ) -> FxHashMap<Ty<'tcx>, Ty<'tcx>> {
         debug!("calculate_diverging_fallback({:?})", unsolved_variables);
 
-        let relationships = self.fulfillment_cx.borrow_mut().relationships().clone();
-
         // Construct a coercion graph where an edge `A -> B` indicates
         // a type variable is that is coerced
         let coercion_graph = self.create_coercion_graph();
@@ -281,9 +279,7 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
             roots_reachable_from_non_diverging,
         );
 
-        debug!("inherited: {:#?}", self.inh.fulfillment_cx.borrow_mut().pending_obligations());
         debug!("obligations: {:#?}", self.fulfillment_cx.borrow_mut().pending_obligations());
-        debug!("relationships: {:#?}", relationships);
 
         // For each diverging variable, figure out whether it can
         // reach a member of N. If so, it falls back to `()`. Else
@@ -297,16 +293,16 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
                 .depth_first_search(root_vid)
                 .any(|n| roots_reachable_from_non_diverging.visited(n));
 
-            let mut relationship = ty::FoundRelationships { self_in_trait: false, output: false };
+            let mut found_infer_var_info = ty::InferVarInfo { self_in_trait: false, output: false };
 
-            for (vid, rel) in relationships.iter() {
-                if self.root_var(*vid) == root_vid {
-                    relationship.self_in_trait |= rel.self_in_trait;
-                    relationship.output |= rel.output;
+            for (vid, info) in self.inh.infer_var_info.borrow().iter() {
+                if self.infcx.root_var(*vid) == root_vid {
+                    found_infer_var_info.self_in_trait |= info.self_in_trait;
+                    found_infer_var_info.output |= info.output;
                 }
             }
 
-            if relationship.self_in_trait && relationship.output {
+            if found_infer_var_info.self_in_trait && found_infer_var_info.output {
                 // This case falls back to () to ensure that the code pattern in
                 // tests/ui/never_type/fallback-closure-ret.rs continues to
                 // compile when never_type_fallback is enabled.

compiler/rustc_hir_typeck/src/inherited.rs

@@ -1,6 +1,6 @@
 use super::callee::DeferredCallResolution;
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::HirIdMap;
@@ -10,7 +10,8 @@ use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::def_id::LocalDefIdMap;
 use rustc_span::{self, Span};
-use rustc_trait_selection::traits::{self, TraitEngine, TraitEngineExt as _};
+use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
+use rustc_trait_selection::traits::{self, PredicateObligation, TraitEngine, TraitEngineExt as _};
 
 use std::cell::RefCell;
 use std::ops::Deref;
@@ -63,6 +64,8 @@ pub struct Inherited<'tcx> {
     /// we record that type variable here. This is later used to inform
     /// fallback. See the `fallback` module for details.
     pub(super) diverging_type_vars: RefCell<FxHashSet<Ty<'tcx>>>,
+
+    pub(super) infer_var_info: RefCell<FxHashMap<ty::TyVid, ty::InferVarInfo>>,
 }
 
 impl<'tcx> Deref for Inherited<'tcx> {
@@ -128,6 +131,7 @@ impl<'tcx> Inherited<'tcx> {
             deferred_generator_interiors: RefCell::new(Vec::new()),
             diverging_type_vars: RefCell::new(Default::default()),
             body_id,
+            infer_var_info: RefCell::new(Default::default()),
         }
     }
 
@@ -136,6 +140,9 @@ impl<'tcx> Inherited<'tcx> {
         if obligation.has_escaping_bound_vars() {
             span_bug!(obligation.cause.span, "escaping bound vars in predicate {:?}", obligation);
         }
+
+        self.update_infer_var_info(&obligation);
+
         self.fulfillment_cx.borrow_mut().register_predicate_obligation(self, obligation);
     }
 
@@ -152,4 +159,43 @@ impl<'tcx> Inherited<'tcx> {
         self.register_predicates(infer_ok.obligations);
         infer_ok.value
     }
+
+    pub fn update_infer_var_info(&self, obligation: &PredicateObligation<'tcx>) {
+        let infer_var_info = &mut self.infer_var_info.borrow_mut();
+
+        // (*) binder skipped
+        if let ty::PredicateKind::Clause(ty::Clause::Trait(tpred)) = obligation.predicate.kind().skip_binder()
+            && let Some(ty) = self.shallow_resolve(tpred.self_ty()).ty_vid().map(|t| self.root_var(t))
+            && self.tcx.lang_items().sized_trait().map_or(false, |st| st != tpred.trait_ref.def_id)
+        {
+            let new_self_ty = self.tcx.types.unit;
+
+            // Then construct a new obligation with Self = () added
+            // to the ParamEnv, and see if it holds.
+            let o = obligation.with(self.tcx,
+                obligation
+                    .predicate
+                    .kind()
+                    .rebind(
+                        // (*) binder moved here
+                        ty::PredicateKind::Clause(ty::Clause::Trait(tpred.with_self_ty(self.tcx, new_self_ty)))
+                    ),
+            );
+            // Don't report overflow errors. Otherwise equivalent to may_hold.
+            if let Ok(result) = self.probe(|_| self.evaluate_obligation(&o)) && result.may_apply() {
+                infer_var_info.entry(ty).or_default().self_in_trait = true;
+            }
+        }
+
+        if let ty::PredicateKind::Clause(ty::Clause::Projection(predicate)) =
+            obligation.predicate.kind().skip_binder()
+        {
+            // If the projection predicate (Foo::Bar == X) has X as a non-TyVid,
+            // we need to make it into one.
+            if let Some(vid) = predicate.term.ty().and_then(|ty| ty.ty_vid()) {
+                debug!("infer_var_info: {:?}.output = true", vid);
+                infer_var_info.entry(vid).or_default().output = true;
+            }
+        }
+    }
 }

compiler/rustc_hir_typeck/src/method/mod.rs

@@ -76,7 +76,7 @@ pub struct NoMatchData<'tcx> {
     pub unsatisfied_predicates:
         Vec<(ty::Predicate<'tcx>, Option<ty::Predicate<'tcx>>, Option<ObligationCause<'tcx>>)>,
     pub out_of_scope_traits: Vec<DefId>,
-    pub lev_candidate: Option<ty::AssocItem>,
+    pub similar_candidate: Option<ty::AssocItem>,
     pub mode: probe::Mode,
 }
 

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -461,7 +461,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     static_candidates: Vec::new(),
                     unsatisfied_predicates: Vec::new(),
                     out_of_scope_traits: Vec::new(),
-                    lev_candidate: None,
+                    similar_candidate: None,
                     mode,
                 }));
             }
@@ -1076,13 +1076,13 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         if let Some((kind, def_id)) = private_candidate {
             return Err(MethodError::PrivateMatch(kind, def_id, out_of_scope_traits));
         }
-        let lev_candidate = self.probe_for_lev_candidate()?;
+        let similar_candidate = self.probe_for_similar_candidate()?;
 
         Err(MethodError::NoMatch(NoMatchData {
             static_candidates,
             unsatisfied_predicates,
             out_of_scope_traits,
-            lev_candidate,
+            similar_candidate,
             mode: self.mode,
         }))
     }
@@ -1787,7 +1787,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     /// Similarly to `probe_for_return_type`, this method attempts to find the best matching
     /// candidate method where the method name may have been misspelled. Similarly to other
     /// Levenshtein based suggestions, we provide at most one such suggestion.
-    fn probe_for_lev_candidate(&mut self) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {
+    fn probe_for_similar_candidate(&mut self) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {
         debug!("probing for method names similar to {:?}", self.method_name);
 
         let steps = self.steps.clone();
@@ -1831,6 +1831,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         None,
                     )
                 }
+                .or_else(|| {
+                    applicable_close_candidates
+                        .iter()
+                        .find(|cand| self.matches_by_doc_alias(cand.def_id))
+                        .map(|cand| cand.name)
+                })
                 .unwrap();
                 Ok(applicable_close_candidates.into_iter().find(|method| method.name == best_name))
             }
@@ -1981,6 +1987,38 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    /// Determine if the associated item withe the given DefId matches
+    /// the desired name via a doc alias.
+    fn matches_by_doc_alias(&self, def_id: DefId) -> bool {
+        let Some(name) = self.method_name else { return false; };
+        let Some(local_def_id) = def_id.as_local() else { return false; };
+        let hir_id = self.fcx.tcx.hir().local_def_id_to_hir_id(local_def_id);
+        let attrs = self.fcx.tcx.hir().attrs(hir_id);
+        for attr in attrs {
+            let sym::doc = attr.name_or_empty() else { continue; };
+            let Some(values) = attr.meta_item_list() else { continue; };
+            for v in values {
+                if v.name_or_empty() != sym::alias {
+                    continue;
+                }
+                if let Some(nested) = v.meta_item_list() {
+                    // #[doc(alias("foo", "bar"))]
+                    for n in nested {
+                        if let Some(lit) = n.lit() && name.as_str() == lit.symbol.as_str() {
+                            return true;
+                        }
+                    }
+                } else if let Some(meta) = v.meta_item()
+                    && let Some(lit) = meta.name_value_literal()
+                    && name.as_str() == lit.symbol.as_str() {
+                        // #[doc(alias = "foo")]
+                        return true;
+                }
+            }
+        }
+        false
+    }
+
     /// Finds the method with the appropriate name (or return type, as the case may be). If
     /// `allow_similar_names` is set, find methods with close-matching names.
     // The length of the returned iterator is nearly always 0 or 1 and this
@@ -1996,6 +2034,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         if !self.is_relevant_kind_for_mode(x.kind) {
                             return false;
                         }
+                        if self.matches_by_doc_alias(x.def_id) {
+                            return true;
+                        }
                         match lev_distance_with_substrings(name.as_str(), x.name.as_str(), max_dist)
                         {
                             Some(d) => d > 0,

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -262,7 +262,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let ty_str = with_forced_trimmed_paths!(self.ty_to_string(rcvr_ty));
         let is_method = mode == Mode::MethodCall;
         let unsatisfied_predicates = &no_match_data.unsatisfied_predicates;
-        let lev_candidate = no_match_data.lev_candidate;
+        let similar_candidate = no_match_data.similar_candidate;
         let item_kind = if is_method {
             "method"
         } else if rcvr_ty.is_enum() {
@@ -937,7 +937,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // give a helping note that it has to be called as `(x.f)(...)`.
         if let SelfSource::MethodCall(expr) = source {
             if !self.suggest_calling_field_as_fn(span, rcvr_ty, expr, item_name, &mut err)
-                && lev_candidate.is_none()
+                && similar_candidate.is_none()
                 && !custom_span_label
             {
                 label_span_not_found(&mut err);
@@ -1015,20 +1015,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if fallback_span {
                 err.span_label(span, msg);
             }
-        } else if let Some(lev_candidate) = lev_candidate {
+        } else if let Some(similar_candidate) = similar_candidate {
             // Don't emit a suggestion if we found an actual method
             // that had unsatisfied trait bounds
             if unsatisfied_predicates.is_empty() {
-                let def_kind = lev_candidate.kind.as_def_kind();
+                let def_kind = similar_candidate.kind.as_def_kind();
                 // Methods are defined within the context of a struct and their first parameter is always self,
                 // which represents the instance of the struct the method is being called on
                 // Associated functions don’t take self as a parameter and
                 // they are not methods because they don’t have an instance of the struct to work with.
-                if def_kind == DefKind::AssocFn && lev_candidate.fn_has_self_parameter {
+                if def_kind == DefKind::AssocFn && similar_candidate.fn_has_self_parameter {
                     err.span_suggestion(
                         span,
                         "there is a method with a similar name",
-                        lev_candidate.name,
+                        similar_candidate.name,
                         Applicability::MaybeIncorrect,
                     );
                 } else {
@@ -1037,9 +1037,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         &format!(
                             "there is {} {} with a similar name",
                             def_kind.article(),
-                            def_kind.descr(lev_candidate.def_id),
+                            def_kind.descr(similar_candidate.def_id),
                         ),
-                        lev_candidate.name,
+                        similar_candidate.name,
                         Applicability::MaybeIncorrect,
                     );
                 }

compiler/rustc_infer/src/traits/engine.rs

@@ -1,6 +1,5 @@
 use crate::infer::InferCtxt;
 use crate::traits::Obligation;
-use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::{self, ToPredicate, Ty};
 
@@ -42,8 +41,6 @@ pub trait TraitEngine<'tcx>: 'tcx {
     fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
 
     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;
-
-    fn relationships(&mut self) -> &mut FxHashMap<ty::TyVid, ty::FoundRelationships>;
 }
 
 pub trait TraitEngineExt<'tcx> {

compiler/rustc_middle/src/ty/mod.rs

@@ -2619,7 +2619,7 @@ impl<'tcx> fmt::Debug for SymbolName<'tcx> {
 }
 
 #[derive(Debug, Default, Copy, Clone)]
-pub struct FoundRelationships {
+pub struct InferVarInfo {
     /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
     /// obligation, where:
     ///

compiler/rustc_trait_selection/src/solve/fulfill.rs

@@ -1,14 +1,12 @@
 use std::mem;
 
-use rustc_data_structures::fx::FxHashMap;
 use rustc_infer::{
     infer::InferCtxt,
     traits::{
         query::NoSolution, FulfillmentError, FulfillmentErrorCode, PredicateObligation,
         SelectionError, TraitEngine,
     },
 };
-use rustc_middle::ty;
 
 use super::{search_graph, Certainty, EvalCtxt};
 
@@ -102,8 +100,4 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>> {
         self.obligations.clone()
     }
-
-    fn relationships(&mut self) -> &mut FxHashMap<ty::TyVid, ty::FoundRelationships> {
-        unimplemented!("Should be moved out of `TraitEngine`")
-    }
 }