Auto merge of rust-lang#103629 - matthiaskrgr:rollup-r94tqfa, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#103110 (remove redundant Send impl for references)
 - rust-lang#103255 (Clean up hidden type registration)
 - rust-lang#103394 (Clarify documentation about the memory layout of `UnsafeCell`)
 - rust-lang#103408 (Clean return-position `impl Trait` in traits correctly in rustdoc)
 - rust-lang#103505 (rustdoc: parse self-closing tags and attributes in `invalid_html_tags`)
 - rust-lang#103524 (rustc_metadata: Add struct and variant constructors to module children at encoding time)
 - rust-lang#103544 (Add flag to forbid recovery in the parser)
 - rust-lang#103616 (rustdoc: remove CSS workaround for Firefox 29)

Failed merges:

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

Author: bors

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -263,13 +263,11 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
 
         // Require that the hidden type actually fulfills all the bounds of the opaque type, even without
         // the bounds that the function supplies.
-        match infcx.register_hidden_type(
-            OpaqueTypeKey { def_id, substs: id_substs },
-            ObligationCause::misc(instantiated_ty.span, body_id),
-            param_env,
-            definition_ty,
-            origin,
-        ) {
+        let opaque_ty = self.tcx.mk_opaque(def_id.to_def_id(), id_substs);
+        match infcx
+            .at(&ObligationCause::misc(instantiated_ty.span, body_id), param_env)
+            .eq(opaque_ty, definition_ty)
+        {
             Ok(infer_ok) => {
                 for obligation in infer_ok.obligations {
                     fulfillment_cx.register_predicate_obligation(&infcx, obligation);
@@ -280,7 +278,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                     .err_ctxt()
                     .report_mismatched_types(
                         &ObligationCause::misc(instantiated_ty.span, body_id),
-                        self.tcx.mk_opaque(def_id.to_def_id(), id_substs),
+                        opaque_ty,
                         definition_ty,
                         err,
                     )

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -1,6 +1,6 @@
 use rustc_infer::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRelatingDelegate};
 use rustc_infer::infer::NllRegionVariableOrigin;
-use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::PredicateObligations;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::TypeRelation;
@@ -155,27 +155,16 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
         true
     }
 
-    fn register_opaque_type(
+    fn register_opaque_type_obligations(
         &mut self,
-        a: Ty<'tcx>,
-        b: Ty<'tcx>,
-        a_is_expected: bool,
+        obligations: PredicateObligations<'tcx>,
     ) -> Result<(), TypeError<'tcx>> {
-        let param_env = self.param_env();
-        let span = self.span();
-        let def_id = self.type_checker.body.source.def_id().expect_local();
-        let body_id = self.type_checker.tcx().hir().local_def_id_to_hir_id(def_id);
-        let cause = ObligationCause::misc(span, body_id);
         self.type_checker
             .fully_perform_op(
                 self.locations,
                 self.category,
                 InstantiateOpaqueType {
-                    obligations: self
-                        .type_checker
-                        .infcx
-                        .handle_opaque_type(a, b, a_is_expected, &cause, param_env)?
-                        .obligations,
+                    obligations,
                     // These fields are filled in during execution of the operation
                     base_universe: None,
                     region_constraints: None,

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -250,6 +250,7 @@ fn expand_macro<'cx>(
     // hacky, but speeds up the `html5ever` benchmark significantly. (Issue
     // 68836 suggests a more comprehensive but more complex change to deal with
     // this situation.)
+    // FIXME(Nilstrieb): Stop recovery from happening on this parser and retry later with recovery if the macro failed to match.
     let parser = parser_from_cx(sess, arg.clone());
 
     // Try each arm's matchers.

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -16,8 +16,8 @@ use crate::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRelating
 use crate::infer::region_constraints::{Constraint, RegionConstraintData};
 use crate::infer::{InferCtxt, InferOk, InferResult, NllRegionVariableOrigin};
 use crate::traits::query::{Fallible, NoSolution};
-use crate::traits::TraitEngine;
 use crate::traits::{Obligation, ObligationCause, PredicateObligation};
+use crate::traits::{PredicateObligations, TraitEngine};
 use rustc_data_structures::captures::Captures;
 use rustc_index::vec::Idx;
 use rustc_index::vec::IndexVec;
@@ -509,7 +509,7 @@ impl<'tcx> InferCtxt<'tcx> {
         for &(a, b) in &query_response.value.opaque_types {
             let a = substitute_value(self.tcx, &result_subst, a);
             let b = substitute_value(self.tcx, &result_subst, b);
-            obligations.extend(self.handle_opaque_type(a, b, true, cause, param_env)?.obligations);
+            obligations.extend(self.at(cause, param_env).eq(a, b)?.obligations);
         }
 
         Ok(InferOk { value: result_subst, obligations })
@@ -741,17 +741,11 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
         true
     }
 
-    fn register_opaque_type(
+    fn register_opaque_type_obligations(
         &mut self,
-        a: Ty<'tcx>,
-        b: Ty<'tcx>,
-        a_is_expected: bool,
+        obligations: PredicateObligations<'tcx>,
     ) -> Result<(), TypeError<'tcx>> {
-        self.obligations.extend(
-            self.infcx
-                .handle_opaque_type(a, b, a_is_expected, &self.cause, self.param_env)?
-                .obligations,
-        );
+        self.obligations.extend(obligations);
         Ok(())
     }
 }

compiler/rustc_infer/src/infer/nll_relate/mod.rs

@@ -25,7 +25,9 @@ use crate::infer::combine::ConstEquateRelation;
 use crate::infer::InferCtxt;
 use crate::infer::{ConstVarValue, ConstVariableValue};
 use crate::infer::{TypeVariableOrigin, TypeVariableOriginKind};
+use crate::traits::PredicateObligation;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
@@ -91,11 +93,9 @@ pub trait TypeRelatingDelegate<'tcx> {
     );
 
     fn const_equate(&mut self, a: ty::Const<'tcx>, b: ty::Const<'tcx>);
-    fn register_opaque_type(
+    fn register_opaque_type_obligations(
         &mut self,
-        a: Ty<'tcx>,
-        b: Ty<'tcx>,
-        a_is_expected: bool,
+        obligations: Vec<PredicateObligation<'tcx>>,
     ) -> Result<(), TypeError<'tcx>>;
 
     /// Creates a new universe index. Used when instantiating placeholders.
@@ -414,7 +414,12 @@ where
             (_, &ty::Opaque(..)) => (generalize(a, true)?, b),
             _ => unreachable!(),
         };
-        self.delegate.register_opaque_type(a, b, true)?;
+        let cause = ObligationCause::dummy_with_span(self.delegate.span());
+        let obligations = self
+            .infcx
+            .handle_opaque_type(a, b, true, &cause, self.delegate.param_env())?
+            .obligations;
+        self.delegate.register_opaque_type_obligations(obligations)?;
         trace!(a = ?a.kind(), b = ?b.kind(), "opaque type instantiated");
         Ok(a)
     }

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -103,7 +103,7 @@ impl<'tcx> InferCtxt<'tcx> {
             return Ok(InferOk { value: (), obligations: vec![] });
         }
         let (a, b) = if a_is_expected { (a, b) } else { (b, a) };
-        let process = |a: Ty<'tcx>, b: Ty<'tcx>| match *a.kind() {
+        let process = |a: Ty<'tcx>, b: Ty<'tcx>, a_is_expected| match *a.kind() {
             ty::Opaque(def_id, substs) if def_id.is_local() => {
                 let def_id = def_id.expect_local();
                 let origin = match self.defining_use_anchor {
@@ -169,13 +169,14 @@ impl<'tcx> InferCtxt<'tcx> {
                     param_env,
                     b,
                     origin,
+                    a_is_expected,
                 ))
             }
             _ => None,
         };
-        if let Some(res) = process(a, b) {
+        if let Some(res) = process(a, b, true) {
             res
-        } else if let Some(res) = process(b, a) {
+        } else if let Some(res) = process(b, a, false) {
             res
         } else {
             let (a, b) = self.resolve_vars_if_possible((a, b));
@@ -514,13 +515,14 @@ impl UseKind {
 
 impl<'tcx> InferCtxt<'tcx> {
     #[instrument(skip(self), level = "debug")]
-    pub fn register_hidden_type(
+    fn register_hidden_type(
         &self,
         opaque_type_key: OpaqueTypeKey<'tcx>,
         cause: ObligationCause<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         hidden_ty: Ty<'tcx>,
         origin: hir::OpaqueTyOrigin,
+        a_is_expected: bool,
     ) -> InferResult<'tcx, ()> {
         let tcx = self.tcx;
         let OpaqueTypeKey { def_id, substs } = opaque_type_key;
@@ -539,7 +541,8 @@ impl<'tcx> InferCtxt<'tcx> {
             origin,
         );
         if let Some(prev) = prev {
-            obligations = self.at(&cause, param_env).eq(prev, hidden_ty)?.obligations;
+            obligations =
+                self.at(&cause, param_env).eq_exp(a_is_expected, prev, hidden_ty)?.obligations;
         }
 
         let item_bounds = tcx.bound_explicit_item_bounds(def_id.to_def_id());

compiler/rustc_infer/src/infer/sub.rs

@@ -2,9 +2,7 @@ use super::combine::{CombineFields, RelationDir};
 use super::SubregionOrigin;
 
 use crate::infer::combine::ConstEquateRelation;
-use crate::infer::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::traits::Obligation;
-use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::relate::{Cause, Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::TyVar;
@@ -130,39 +128,18 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> {
             (&ty::Opaque(did, ..), _) | (_, &ty::Opaque(did, ..))
                 if self.fields.define_opaque_types && did.is_local() =>
             {
-                let mut generalize = |ty, ty_is_expected| {
-                    let var = infcx.next_ty_var_id_in_universe(
-                        TypeVariableOrigin {
-                            kind: TypeVariableOriginKind::MiscVariable,
-                            span: self.fields.trace.cause.span,
-                        },
-                        ty::UniverseIndex::ROOT,
-                    );
-                    self.fields.instantiate(ty, RelationDir::SubtypeOf, var, ty_is_expected)?;
-                    Ok(infcx.tcx.mk_ty_var(var))
-                };
-                let (a, b) = if self.a_is_expected { (a, b) } else { (b, a) };
-                let (ga, gb) = match (a.kind(), b.kind()) {
-                    (&ty::Opaque(..), _) => (a, generalize(b, true)?),
-                    (_, &ty::Opaque(..)) => (generalize(a, false)?, b),
-                    _ => unreachable!(),
-                };
                 self.fields.obligations.extend(
                     infcx
-                        .handle_opaque_type(ga, gb, true, &self.fields.trace.cause, self.param_env())
-                        // Don't leak any generalized type variables out of this
-                        // subtyping relation in the case of a type error.
-                        .map_err(|err| {
-                            let (ga, gb) = self.fields.infcx.resolve_vars_if_possible((ga, gb));
-                            if let TypeError::Sorts(sorts) = err && sorts.expected == ga && sorts.found == gb {
-                                TypeError::Sorts(ExpectedFound { expected: a, found: b })
-                            } else {
-                                err
-                            }
-                        })?
+                        .handle_opaque_type(
+                            a,
+                            b,
+                            self.a_is_expected,
+                            &self.fields.trace.cause,
+                            self.param_env(),
+                        )?
                         .obligations,
                 );
-                Ok(ga)
+                Ok(a)
             }
             // Optimization of GeneratorWitness relation since we know that all
             // free regions are replaced with bound regions during construction.

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -773,7 +773,15 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     fn opt_item_name(self, item_index: DefIndex) -> Option<Symbol> {
-        self.def_key(item_index).disambiguated_data.data.get_opt_name()
+        let def_key = self.def_key(item_index);
+        def_key.disambiguated_data.data.get_opt_name().or_else(|| {
+            if def_key.disambiguated_data.data == DefPathData::Ctor {
+                let parent_index = def_key.parent.expect("no parent for a constructor");
+                self.def_key(parent_index).disambiguated_data.data.get_opt_name()
+            } else {
+                None
+            }
+        })
     }
 
     fn item_name(self, item_index: DefIndex) -> Symbol {
@@ -905,7 +913,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                 .get(self, item_id)
                 .unwrap_or_else(LazyArray::empty)
                 .decode(self)
-                .map(|index| self.get_variant(&self.def_kind(index), index, did))
+                .filter_map(|index| {
+                    let kind = self.def_kind(index);
+                    match kind {
+                        DefKind::Ctor(..) => None,
+                        _ => Some(self.get_variant(&kind, index, did)),
+                    }
+                })
                 .collect()
         } else {
             std::iter::once(self.get_variant(&kind, item_id, did)).collect()
@@ -1029,50 +1043,27 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
 
                 callback(ModChild { ident, res, vis, span, macro_rules });
 
-                // For non-re-export structs and variants add their constructors to children.
-                // Re-export lists automatically contain constructors when necessary.
-                match kind {
-                    DefKind::Struct => {
-                        if let Some((ctor_def_id, ctor_kind)) =
-                            self.get_ctor_def_id_and_kind(child_index)
-                        {
-                            let ctor_res =
-                                Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
-                            let vis = self.get_visibility(ctor_def_id.index);
-                            callback(ModChild {
-                                ident,
-                                res: ctor_res,
-                                vis,
-                                span,
-                                macro_rules: false,
-                            });
-                        }
-                    }
-                    DefKind::Variant => {
-                        // Braced variants, unlike structs, generate unusable names in
-                        // value namespace, they are reserved for possible future use.
-                        // It's ok to use the variant's id as a ctor id since an
-                        // error will be reported on any use of such resolution anyway.
-                        let (ctor_def_id, ctor_kind) = self
-                            .get_ctor_def_id_and_kind(child_index)
-                            .unwrap_or((def_id, CtorKind::Fictive));
-                        let ctor_res =
-                            Res::Def(DefKind::Ctor(CtorOf::Variant, ctor_kind), ctor_def_id);
-                        let mut vis = self.get_visibility(ctor_def_id.index);
-                        if ctor_def_id == def_id && vis.is_public() {
-                            // For non-exhaustive variants lower the constructor visibility to
-                            // within the crate. We only need this for fictive constructors,
-                            // for other constructors correct visibilities
-                            // were already encoded in metadata.
-                            let mut attrs = self.get_item_attrs(def_id.index, sess);
-                            if attrs.any(|item| item.has_name(sym::non_exhaustive)) {
-                                let crate_def_id = self.local_def_id(CRATE_DEF_INDEX);
-                                vis = ty::Visibility::Restricted(crate_def_id);
-                            }
+                // For non-reexport variants add their fictive constructors to children.
+                // Braced variants, unlike structs, generate unusable names in value namespace,
+                // they are reserved for possible future use. It's ok to use the variant's id as
+                // a ctor id since an error will be reported on any use of such resolution anyway.
+                // Reexport lists automatically contain such constructors when necessary.
+                if kind == DefKind::Variant && self.get_ctor_def_id_and_kind(child_index).is_none()
+                {
+                    let ctor_res =
+                        Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fictive), def_id);
+                    let mut vis = vis;
+                    if vis.is_public() {
+                        // For non-exhaustive variants lower the constructor visibility to
+                        // within the crate. We only need this for fictive constructors,
+                        // for other constructors correct visibilities
+                        // were already encoded in metadata.
+                        let mut attrs = self.get_item_attrs(def_id.index, sess);
+                        if attrs.any(|item| item.has_name(sym::non_exhaustive)) {
+                            vis = ty::Visibility::Restricted(self.local_def_id(CRATE_DEF_INDEX));
                         }
-                        callback(ModChild { ident, res: ctor_res, vis, span, macro_rules: false });
                     }
-                    _ => {}
+                    callback(ModChild { ident, res: ctor_res, vis, span, macro_rules: false });
                 }
             }
         }