Auto merge of #95435 - cjgillot:one-name, r=oli-obk

Make def names and HIR names consistent.

The name in the `DefKey` is interned to create the `DefId`, so it does not
require any query to access.  This can be leveraged to avoid a few useless
HIR accesses for names.

~In order to achieve that, generic parameters created from universal
impl-trait are given the pretty-printed ast as a name, instead of
`{{opaque}}`.~

~Drive-by: the `TyCtxt::opt_item_name` used a dummy span for non-local
definitions.  We have access to `def_ident_span`, so we use it.~

compiler/rustc_hir/src/definitions.rs

@@ -147,6 +147,11 @@ impl DefKey {
  // DefPathHashes in this DefPathTable.
  DefPathHash::new(parent.stable_crate_id(), local_hash)
  }
+
+ #[inline]
+ pub fn get_opt_name(&self) -> Option<Symbol> {
+ self.disambiguated_data.data.get_opt_name()
+ }
 }
 
 /// A pair of `DefPathData` and an integer disambiguator. The integer is

compiler/rustc_middle/src/hir/map/mod.rs

@@ -1,5 +1,5 @@
 use crate::hir::{ModuleItems, Owner};
-use crate::ty::TyCtxt;
+use crate::ty::{DefIdTree, TyCtxt};
 use rustc_ast as ast;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -545,23 +545,21 @@ impl<'hir> Map<'hir> {
  });
  }
 
- pub fn ty_param_owner(self, id: HirId) -> LocalDefId {
- match self.get(id) {
- Node::Item(&Item { kind: ItemKind::Trait(..) | ItemKind::TraitAlias(..), .. }) => {
- id.expect_owner()
- }
- Node::GenericParam(_) => self.get_parent_item(id),
- _ => bug!("ty_param_owner: {} not a type parameter", self.node_to_string(id)),
+ pub fn ty_param_owner(self, def_id: LocalDefId) -> LocalDefId {
+ let def_kind = self.tcx.def_kind(def_id);
+ match def_kind {
+ DefKind::Trait | DefKind::TraitAlias => def_id,
+ DefKind::TyParam | DefKind::ConstParam => self.tcx.local_parent(def_id).unwrap(),
+ _ => bug!("ty_param_owner: {:?} is a {:?} not a type parameter", def_id, def_kind),
  }
  }
 
- pub fn ty_param_name(self, id: HirId) -> Symbol {
- match self.get(id) {
- Node::Item(&Item { kind: ItemKind::Trait(..) | ItemKind::TraitAlias(..), .. }) => {
- kw::SelfUpper
- }
- Node::GenericParam(param) => param.name.ident().name,
- _ => bug!("ty_param_name: {} not a type parameter", self.node_to_string(id)),
+ pub fn ty_param_name(self, def_id: LocalDefId) -> Symbol {
+ let def_kind = self.tcx.def_kind(def_id);
+ match def_kind {
+ DefKind::Trait | DefKind::TraitAlias => kw::SelfUpper,
+ DefKind::TyParam | DefKind::ConstParam => self.tcx.item_name(def_id.to_def_id()),
+ _ => bug!("ty_param_name: {:?} is a {:?} not a type parameter", def_id, def_kind),
  }
  }
 

compiler/rustc_middle/src/query/mod.rs

@@ -517,10 +517,7 @@ rustc_queries! {
  /// To avoid cycles within the predicates of a single item we compute
  /// per-type-parameter predicates for resolving `T::AssocTy`.
  query type_param_predicates(key: (DefId, LocalDefId, rustc_span::symbol::Ident)) -> ty::GenericPredicates<'tcx> {
- desc { |tcx| "computing the bounds for type parameter `{}`", {
- let id = tcx.hir().local_def_id_to_hir_id(key.1);
- tcx.hir().ty_param_name(id)
- }}
+ desc { |tcx| "computing the bounds for type parameter `{}`", tcx.hir().ty_param_name(key.1) }
  }
 
  query trait_def(key: DefId) -> ty::TraitDef {

compiler/rustc_middle/src/ty/mod.rs

@@ -1991,27 +1991,25 @@ impl<'tcx> TyCtxt<'tcx> {
  .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
  }
 
- fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
- self.hir().get_if_local(def_id).and_then(|node| node.ident())
- }
-
- fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
+ fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
  if def_id.index == CRATE_DEF_INDEX {
  Some(self.crate_name(def_id.krate))
  } else {
  let def_key = self.def_key(def_id);
  match def_key.disambiguated_data.data {
  // The name of a constructor is that of its parent.
- rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
- krate: def_id.krate,
- index: def_key.parent.unwrap(),
- }),
- _ => def_key.disambiguated_data.data.get_opt_name(),
+ rustc_hir::definitions::DefPathData::Ctor => self
+ .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
+ // The name of opaque types only exists in HIR.
+ rustc_hir::definitions::DefPathData::ImplTrait
+ if let Some(def_id) = def_id.as_local() =>
+ self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)),
+ _ => def_key.get_opt_name(),
  }
  }
  }
 
- /// Look up the name of an item across crates. This does not look at HIR.
+ /// Look up the name of a definition across crates. This does not look at HIR.
  ///
  /// When possible, this function should be used for cross-crate lookups over
  /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
@@ -2023,18 +2021,21 @@ impl<'tcx> TyCtxt<'tcx> {
  pub fn item_name(self, id: DefId) -> Symbol {
  // Look at cross-crate items first to avoid invalidating the incremental cache
  // unless we have to.
- self.item_name_from_def_id(id).unwrap_or_else(|| {
+ self.opt_item_name(id).unwrap_or_else(|| {
  bug!("item_name: no name for {:?}", self.def_path(id));
  })
  }
 
- /// Look up the name and span of an item or [`Node`].
+ /// Look up the name and span of a definition.
  ///
  /// See [`item_name`][Self::item_name] for more information.
- pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
- // Look at the HIR first so the span will be correct if this is a local item.
- self.item_name_from_hir(def_id)
- .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
+ pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
+ let def = self.opt_item_name(def_id)?;
+ let span = def_id
+ .as_local()
+ .and_then(|id| self.def_ident_span(id))
+ .unwrap_or(rustc_span::DUMMY_SP);
+ Some(Ident::new(def, span))
  }
 
  pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {

compiler/rustc_monomorphize/src/polymorphize.rs

@@ -201,7 +201,7 @@ fn emit_unused_generic_params_error<'tcx>(
  return;
  }
 
- let fn_span = match tcx.opt_item_name(def_id) {
+ let fn_span = match tcx.opt_item_ident(def_id) {
  Some(ident) => ident.span,
  _ => tcx.def_span(def_id),
  };

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2064,7 +2064,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  ObligationCauseCode::BindingObligation(item_def_id, span) => {
  let item_name = tcx.def_path_str(item_def_id);
  let mut multispan = MultiSpan::from(span);
- if let Some(ident) = tcx.opt_item_name(item_def_id) {
+ if let Some(ident) = tcx.opt_item_ident(item_def_id) {
  let sm = tcx.sess.source_map();
  let same_line =
  match (sm.lookup_line(ident.span.hi()), sm.lookup_line(span.lo())) {
@@ -2267,7 +2267,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  if !is_upvar_tys_infer_tuple {
  let msg = format!("required because it appears within the type `{}`", ty);
  match ty.kind() {
- ty::Adt(def, _) => match self.tcx.opt_item_name(def.did()) {
+ ty::Adt(def, _) => match self.tcx.opt_item_ident(def.did()) {
  Some(ident) => err.span_note(ident.span, &msg),
  None => err.note(&msg),
  },
@@ -2475,7 +2475,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  );
  let sp = self
  .tcx
- .opt_item_name(trait_item_def_id)
+ .opt_item_ident(trait_item_def_id)
  .map(|i| i.span)
  .unwrap_or_else(|| self.tcx.def_span(trait_item_def_id));
  let mut assoc_span: MultiSpan = sp.into();
@@ -2486,7 +2486,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  if let Some(ident) = self
  .tcx
  .opt_associated_item(trait_item_def_id)
- .and_then(|i| self.tcx.opt_item_name(i.container.id()))
+ .and_then(|i| self.tcx.opt_item_ident(i.container.id()))
  {
  assoc_span.push_span_label(ident.span, "in this trait");
  }
@@ -2511,7 +2511,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  if let Some(ident) = self
  .tcx
  .opt_associated_item(trait_item_def_id)
- .and_then(|i| self.tcx.opt_item_name(i.container.id()))
+ .and_then(|i| self.tcx.opt_item_ident(i.container.id()))
  {
  assoc_span.push_span_label(ident.span, "in this trait");
  }

compiler/rustc_typeck/src/astconv/generics.rs

@@ -82,8 +82,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
  }
  Res::Def(DefKind::TyParam, src_def_id) => {
  if let Some(param_local_id) = param.def_id.as_local() {
- let param_hir_id = tcx.hir().local_def_id_to_hir_id(param_local_id);
- let param_name = tcx.hir().ty_param_name(param_hir_id);
+ let param_name = tcx.hir().ty_param_name(param_local_id);
  let param_type = tcx.infer_ctxt().enter(|infcx| {
  infcx.resolve_numeric_literals_with_default(tcx.type_of(param.def_id))
  });

compiler/rustc_typeck/src/astconv/mod.rs

@@ -1620,8 +1620,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
  debug!("find_bound_for_assoc_item: predicates={:#?}", predicates);
 
- let param_hir_id = tcx.hir().local_def_id_to_hir_id(ty_param_def_id);
- let param_name = tcx.hir().ty_param_name(param_hir_id);
+ let param_name = tcx.hir().ty_param_name(ty_param_def_id);
  self.one_bound_for_assoc_type(
  || {
  traits::transitive_bounds_that_define_assoc_type(
@@ -2265,12 +2264,11 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
  assert_eq!(opt_self_ty, None);
  self.prohibit_generics(path.segments);
 
- let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
- let item_id = tcx.hir().get_parent_node(hir_id);
- let item_def_id = tcx.hir().local_def_id(item_id);
+ let def_id = def_id.expect_local();
+ let item_def_id = tcx.hir().ty_param_owner(def_id);
  let generics = tcx.generics_of(item_def_id);
- let index = generics.param_def_id_to_index[&def_id];
- tcx.mk_ty_param(index, tcx.hir().name(hir_id))
+ let index = generics.param_def_id_to_index[&def_id.to_def_id()];
+ tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id))
  }
  Res::SelfTy { trait_: Some(_), alias_to: None } => {
  // `Self` in trait or type alias.

compiler/rustc_typeck/src/check/expr.rs

@@ -2195,7 +2195,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  None => return,
  };
  let param_span = self.tcx.hir().span(param_hir_id);
- let param_name = self.tcx.hir().ty_param_name(param_hir_id);
+ let param_name = self.tcx.hir().ty_param_name(param_def_id.expect_local());
 
  err.span_label(param_span, &format!("type parameter '{}' declared here", param_name));
  }

compiler/rustc_typeck/src/check/fn_ctxt/mod.rs

@@ -184,8 +184,7 @@ impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
  _: Ident,
  ) -> ty::GenericPredicates<'tcx> {
  let tcx = self.tcx;
- let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
- let item_def_id = tcx.hir().ty_param_owner(hir_id);
+ let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local());
  let generics = tcx.generics_of(item_def_id);
  let index = generics.param_def_id_to_index[&def_id];
  ty::GenericPredicates {

compiler/rustc_typeck/src/collect.rs

@@ -558,10 +558,10 @@ fn type_param_predicates(
  // `where T: Foo`.
 
  let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
- let param_owner = tcx.hir().ty_param_owner(param_id);
+ let param_owner = tcx.hir().ty_param_owner(def_id);
  let generics = tcx.generics_of(param_owner);
  let index = generics.param_def_id_to_index[&def_id.to_def_id()];
- let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));
+ let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
 
  // Don't look for bounds where the type parameter isn't in scope.
  let parent = if item_def_id == param_owner.to_def_id() {

src/test/ui/const-generics/occurs-check/unused-substs-1.stderr

@@ -8,6 +8,9 @@ LL | let _ = A;
 note: required by a bound in `A`
  --> $DIR/unused-substs-1.rs:9:11
  |
+LL | struct A<const N: usize>
+ | - required by a bound in this
+LL | where
 LL | A<N>: Bar<N>;
  | ^^^^^^ required by this bound in `A`