@@ -53,12 +53,15 @@ use rustc_data_structures::captures::Captures;
5353use rustc_data_structures::fx::{FxHashMap, FxHashSet};
5454use rustc_hir::def_id::{DefId, DefIdSet};
5555use rustc_hir::Mutability;
56+ use rustc_infer::infer::TyCtxtInferExt;
57+ use rustc_infer::traits::{Obligation, ObligationCause};
5658use rustc_middle::middle::stability;
57- use rustc_middle:: ty:: TyCtxt ;
59+ use rustc_middle::ty::{ParamEnv, TyCtxt} ;
5860use rustc_span::{
5961 symbol::{sym, Symbol},
6062 BytePos, FileName, RealFileName,
6163};
64+ use rustc_trait_selection::traits::ObligationCtxt;
6265use serde::ser::{SerializeMap, SerializeSeq};
6366use serde::{Serialize, Serializer};
6467
@@ -1112,28 +1115,76 @@ fn render_assoc_items<'a, 'cx: 'a>(
11121115 containing_item: &'a clean::Item,
11131116 it: DefId,
11141117 what: AssocItemRender<'a>,
1118+ aliased_type: Option<DefId>,
11151119) -> impl fmt::Display + 'a + Captures<'cx> {
11161120 let mut derefs = DefIdSet::default();
11171121 derefs.insert(it);
11181122 display_fn(move |f| {
1119- render_assoc_items_inner ( f, cx, containing_item, it, what, & mut derefs) ;
1123+ render_assoc_items_inner(f, cx, containing_item, it, what, &mut derefs, aliased_type );
11201124 Ok(())
11211125 })
11221126}
11231127
1128+ /// Check whether `impl_def_id` may apply to *some instantiation* of `item_def_id`.
1129+ fn is_valid_impl_for(tcx: TyCtxt<'_>, item_def_id: DefId, impl_def_id: DefId) -> bool {
1130+ let infcx = tcx.infer_ctxt().intercrate(true).build();
1131+ let ocx = ObligationCtxt::new(&infcx);
1132+ let param_env = ParamEnv::empty();
1133+
1134+ let alias_substs = infcx.fresh_substs_for_item(rustc_span::DUMMY_SP, item_def_id);
1135+ let alias_ty = tcx.type_of(item_def_id).subst(tcx, alias_substs);
1136+ let alias_bounds = tcx.predicates_of(item_def_id).instantiate(tcx, alias_substs);
1137+
1138+ let impl_substs = infcx.fresh_substs_for_item(rustc_span::DUMMY_SP, impl_def_id);
1139+ let impl_self_ty = tcx.type_of(impl_def_id).subst(tcx, impl_substs);
1140+ let impl_bounds = tcx.predicates_of(impl_def_id).instantiate(tcx, impl_substs);
1141+
1142+ if ocx.eq(&ObligationCause::dummy(), param_env, impl_self_ty, alias_ty).is_err() {
1143+ return false;
1144+ }
1145+ ocx.register_obligations(
1146+ alias_bounds
1147+ .iter()
1148+ .chain(impl_bounds)
1149+ .map(|(p, _)| Obligation::new(tcx, ObligationCause::dummy(), param_env, p)),
1150+ );
1151+
1152+ let errors = ocx.select_where_possible();
1153+ errors.is_empty()
1154+ }
1155+
1156+ // If `aliased_type` is `Some`, it means `it` is a type alias and `aliased_type` is the "actual"
1157+ // type aliased behind `it`. It is used to check whether or not the implementation of the aliased
1158+ // type can be displayed on the alias doc page.
11241159fn render_assoc_items_inner(
11251160 mut w: &mut dyn fmt::Write,
11261161 cx: &mut Context<'_>,
11271162 containing_item: &clean::Item,
11281163 it: DefId,
11291164 what: AssocItemRender<'_>,
11301165 derefs: &mut DefIdSet,
1166+ aliased_type: Option<DefId>,
11311167) {
11321168 info!("Documenting associated items of {:?}", containing_item.name);
11331169 let shared = Rc::clone(&cx.shared);
11341170 let cache = &shared.cache;
1135- let Some ( v) = cache. impls . get ( & it) else { return } ;
1136- let ( non_trait, traits) : ( Vec < _ > , _ ) = v. iter ( ) . partition ( |i| i. inner_impl ( ) . trait_ . is_none ( ) ) ;
1171+ let empty = Vec::new();
1172+ let v = match cache.impls.get(&it) {
1173+ Some(v) => v,
1174+ None => &empty,
1175+ };
1176+ let v2 = match aliased_type {
1177+ Some(aliased_type) => cache.impls.get(&aliased_type).unwrap_or(&empty),
1178+ None => &empty,
1179+ };
1180+ if v.is_empty() && v2.is_empty() {
1181+ return;
1182+ }
1183+ let mut saw_impls = FxHashSet::default();
1184+ let (non_trait, traits): (Vec<_>, _) =
1185+ v.iter().chain(v2).partition(|i| i.inner_impl().trait_.is_none());
1186+ let tcx = cx.tcx();
1187+ let is_alias = aliased_type.is_some();
11371188 if !non_trait.is_empty() {
11381189 let mut tmp_buf = Buffer::html();
11391190 let (render_mode, id, class_html) = match what {
@@ -1165,6 +1216,12 @@ fn render_assoc_items_inner(
11651216 };
11661217 let mut impls_buf = Buffer::html();
11671218 for i in &non_trait {
1219+ if !saw_impls.insert(i.def_id()) {
1220+ continue;
1221+ }
1222+ if is_alias && !is_valid_impl_for(tcx, it, i.def_id()) {
1223+ continue;
1224+ }
11681225 render_impl(
11691226 &mut impls_buf,
11701227 cx,
@@ -1193,9 +1250,14 @@ fn render_assoc_items_inner(
11931250 if !traits.is_empty() {
11941251 let deref_impl =
11951252 traits.iter().find(|t| t.trait_did() == cx.tcx().lang_items().deref_trait());
1196- if let Some ( impl_) = deref_impl {
1253+ if let Some(impl_) = deref_impl &&
1254+ (!is_alias || is_valid_impl_for(tcx, it, impl_.def_id()))
1255+ {
11971256 let has_deref_mut =
1198- traits. iter ( ) . any ( |t| t. trait_did ( ) == cx. tcx ( ) . lang_items ( ) . deref_mut_trait ( ) ) ;
1257+ traits.iter().any(|t| {
1258+ t.trait_did() == cx.tcx().lang_items().deref_mut_trait() &&
1259+ (!is_alias || is_valid_impl_for(tcx, it, t.def_id()))
1260+ });
11991261 render_deref_methods(&mut w, cx, impl_, containing_item, has_deref_mut, derefs);
12001262 }
12011263
@@ -1205,10 +1267,14 @@ fn render_assoc_items_inner(
12051267 return;
12061268 }
12071269
1208- let ( synthetic, concrete) : ( Vec < & Impl > , Vec < & Impl > ) =
1209- traits. into_iter ( ) . partition ( |t| t. inner_impl ( ) . kind . is_auto ( ) ) ;
1210- let ( blanket_impl, concrete) : ( Vec < & Impl > , _ ) =
1211- concrete. into_iter ( ) . partition ( |t| t. inner_impl ( ) . kind . is_blanket ( ) ) ;
1270+ let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) = traits
1271+ .into_iter()
1272+ .filter(|t| saw_impls.insert(t.def_id()))
1273+ .partition(|t| t.inner_impl().kind.is_auto());
1274+ let (blanket_impl, concrete): (Vec<&Impl>, _) = concrete
1275+ .into_iter()
1276+ .filter(|t| !is_alias || is_valid_impl_for(tcx, it, t.def_id()))
1277+ .partition(|t| t.inner_impl().kind.is_blanket());
12121278
12131279 render_all_impls(w, cx, containing_item, &concrete, &synthetic, &blanket_impl);
12141280 }
@@ -1247,10 +1313,10 @@ fn render_deref_methods(
12471313 return;
12481314 }
12491315 }
1250- render_assoc_items_inner ( & mut w, cx, container_item, did, what, derefs) ;
1316+ render_assoc_items_inner(&mut w, cx, container_item, did, what, derefs, None );
12511317 } else if let Some(prim) = target.primitive_type() {
12521318 if let Some(&did) = cache.primitive_locations.get(&prim) {
1253- render_assoc_items_inner ( & mut w, cx, container_item, did, what, derefs) ;
1319+ render_assoc_items_inner(&mut w, cx, container_item, did, what, derefs, None );
12541320 }
12551321 }
12561322}
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