rustdoc: use JS to inline target type impl docs into alias

Cargo.lock

@@ -4688,6 +4688,7 @@ dependencies = [
  "arrayvec",
  "askama",
  "expect-test",
+ "indexmap 2.0.0",
  "itertools",
  "minifier",
  "once_cell",

src/librustdoc/Cargo.toml

@@ -10,6 +10,7 @@ path = "lib.rs"
 arrayvec = { version = "0.7", default-features = false }
 askama = { version = "0.12", default-features = false, features = ["config"] }
 itertools = "0.10.1"
+indexmap = "2"
 minifier = "0.2.3"
 once_cell = "1.10.0"
 regex = "1"

src/librustdoc/clean/inline.rs

@@ -26,6 +26,8 @@ use crate::clean::{
 use crate::core::DocContext;
 use crate::formats::item_type::ItemType;
 
+use super::Item;
+
 /// Attempt to inline a definition into this AST.
 ///
 /// This function will fetch the definition specified, and if it is
@@ -83,7 +85,7 @@ pub(crate) fn try_inline(
         Res::Def(DefKind::TyAlias, did) => {
             record_extern_fqn(cx, did, ItemType::TypeAlias);
             build_impls(cx, did, attrs_without_docs, &mut ret);
-            clean::TypeAliasItem(build_type_alias(cx, did))
+            clean::TypeAliasItem(build_type_alias(cx, did, &mut ret))
         }
         Res::Def(DefKind::Enum, did) => {
             record_extern_fqn(cx, did, ItemType::Enum);
@@ -281,11 +283,15 @@ fn build_union(cx: &mut DocContext<'_>, did: DefId) -> clean::Union {
     clean::Union { generics, fields }
 }
 
-fn build_type_alias(cx: &mut DocContext<'_>, did: DefId) -> Box<clean::TypeAlias> {
+fn build_type_alias(
+    cx: &mut DocContext<'_>,
+    did: DefId,
+    ret: &mut Vec<Item>,
+) -> Box<clean::TypeAlias> {
     let predicates = cx.tcx.explicit_predicates_of(did);
     let ty = cx.tcx.type_of(did).instantiate_identity();
     let type_ = clean_middle_ty(ty::Binder::dummy(ty), cx, Some(did), None);
-    let inner_type = clean_ty_alias_inner_type(ty, cx);
+    let inner_type = clean_ty_alias_inner_type(ty, cx, ret);
 
     Box::new(clean::TypeAlias {
         type_,

src/librustdoc/clean/mod.rs

@@ -934,18 +934,27 @@ fn clean_ty_generics<'tcx>(
 fn clean_ty_alias_inner_type<'tcx>(
     ty: Ty<'tcx>,
     cx: &mut DocContext<'tcx>,
+    ret: &mut Vec<Item>,
 ) -> Option<TypeAliasInnerType> {
     let ty::Adt(adt_def, args) = ty.kind() else {
         return None;
     };
 
+    if !adt_def.did().is_local() {
+        inline::build_impls(cx, adt_def.did(), None, ret);
+    }
+
     Some(if adt_def.is_enum() {
         let variants: rustc_index::IndexVec<_, _> = adt_def
             .variants()
             .iter()
             .map(|variant| clean_variant_def_with_args(variant, args, cx))
             .collect();
 
+        if !adt_def.did().is_local() {
+            inline::record_extern_fqn(cx, adt_def.did(), ItemType::Enum);
+        }
+
         TypeAliasInnerType::Enum {
             variants,
             is_non_exhaustive: adt_def.is_variant_list_non_exhaustive(),
@@ -961,8 +970,14 @@ fn clean_ty_alias_inner_type<'tcx>(
             clean_variant_def_with_args(variant, args, cx).kind.inner_items().cloned().collect();
 
         if adt_def.is_struct() {
+            if !adt_def.did().is_local() {
+                inline::record_extern_fqn(cx, adt_def.did(), ItemType::Struct);
+            }
             TypeAliasInnerType::Struct { ctor_kind: variant.ctor_kind(), fields }
         } else {
+            if !adt_def.did().is_local() {
+                inline::record_extern_fqn(cx, adt_def.did(), ItemType::Union);
+            }
             TypeAliasInnerType::Union { fields }
         }
     })
@@ -2744,14 +2759,24 @@ fn clean_maybe_renamed_item<'tcx>(
                 }
 
                 let ty = cx.tcx.type_of(def_id).instantiate_identity();
-                let inner_type = clean_ty_alias_inner_type(ty, cx);
 
-                TypeAliasItem(Box::new(TypeAlias {
-                    generics,
-                    inner_type,
-                    type_: rustdoc_ty,
-                    item_type: Some(type_),
-                }))
+                let mut ret = Vec::new();
+                let inner_type = clean_ty_alias_inner_type(ty, cx, &mut ret);
+
+                ret.push(generate_item_with_correct_attrs(
+                    cx,
+                    TypeAliasItem(Box::new(TypeAlias {
+                        generics,
+                        inner_type,
+                        type_: rustdoc_ty,
+                        item_type: Some(type_),
+                    })),
+                    item.owner_id.def_id.to_def_id(),
+                    name,
+                    import_id,
+                    renamed,
+                ));
+                return ret;
             }
             ItemKind::Enum(ref def, generics) => EnumItem(Enum {
                 variants: def.variants.iter().map(|v| clean_variant(v, cx)).collect(),

src/librustdoc/formats/cache.rs

@@ -50,8 +50,8 @@ pub(crate) struct Cache {
     /// Unlike 'paths', this mapping ignores any renames that occur
     /// due to 'use' statements.
     ///
-    /// This map is used when writing out the special 'implementors'
-    /// javascript file. By using the exact path that the type
+    /// This map is used when writing out the `impl.trait` and `impl.type`
+    /// javascript files. By using the exact path that the type
     /// is declared with, we ensure that each path will be identical
     /// to the path used if the corresponding type is inlined. By
     /// doing this, we can detect duplicate impls on a trait page, and only display

src/librustdoc/formats/item_type.rs

@@ -180,6 +180,9 @@ impl ItemType {
     pub(crate) fn is_method(&self) -> bool {
         matches!(*self, ItemType::Method | ItemType::TyMethod)
     }
+    pub(crate) fn is_adt(&self) -> bool {
+        matches!(*self, ItemType::Struct | ItemType::Union | ItemType::Enum)
+    }
 }
 
 impl fmt::Display for ItemType {

src/librustdoc/html/render/context.rs

@@ -7,10 +7,8 @@ use std::sync::mpsc::{channel, Receiver};
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir::def_id::{DefIdMap, LOCAL_CRATE};
-use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
-use rustc_span::def_id::DefId;
 use rustc_span::edition::Edition;
 use rustc_span::source_map::FileName;
 use rustc_span::{sym, Symbol};
@@ -25,13 +23,13 @@ use super::{
     AllTypes, LinkFromSrc, StylePath,
 };
 use crate::clean::utils::has_doc_flag;
-use crate::clean::{self, types::ExternalLocation, ExternalCrate, TypeAliasItem};
+use crate::clean::{self, types::ExternalLocation, ExternalCrate};
 use crate::config::{ModuleSorting, RenderOptions};
 use crate::docfs::{DocFS, PathError};
 use crate::error::Error;
 use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
-use crate::formats::{self, FormatRenderer};
+use crate::formats::FormatRenderer;
 use crate::html::escape::Escape;
 use crate::html::format::{join_with_double_colon, Buffer};
 use crate::html::markdown::{self, plain_text_summary, ErrorCodes, IdMap};
@@ -150,53 +148,6 @@ impl SharedContext<'_> {
     pub(crate) fn edition(&self) -> Edition {
         self.tcx.sess.edition()
     }
-
-    /// Returns a list of impls on the given type, and, if it's a type alias,
-    /// other types that it aliases.
-    pub(crate) fn all_impls_for_item<'a>(
-        &'a self,
-        it: &clean::Item,
-        did: DefId,
-    ) -> Vec<&'a formats::Impl> {
-        let tcx = self.tcx;
-        let cache = &self.cache;
-        let mut saw_impls = FxHashSet::default();
-        let mut v: Vec<&formats::Impl> = cache
-            .impls
-            .get(&did)
-            .map(Vec::as_slice)
-            .unwrap_or(&[])
-            .iter()
-            .filter(|i| saw_impls.insert(i.def_id()))
-            .collect();
-        if let TypeAliasItem(ait) = &*it.kind &&
-            let aliased_clean_type = ait.item_type.as_ref().unwrap_or(&ait.type_) &&
-            let Some(aliased_type_defid) = aliased_clean_type.def_id(cache) &&
-            let Some(av) = cache.impls.get(&aliased_type_defid) &&
-            let Some(alias_def_id) = it.item_id.as_def_id()
-        {
-            // This branch of the compiler compares types structually, but does
-            // not check trait bounds. That's probably fine, since type aliases
-            // don't normally constrain on them anyway.
-            // https://github.com/rust-lang/rust/issues/21903
-            //
-            // FIXME(lazy_type_alias): Once the feature is complete or stable, rewrite this to use type unification.
-            // Be aware of `tests/rustdoc/issue-112515-impl-ty-alias.rs` which might regress.
-            let aliased_ty = tcx.type_of(alias_def_id).skip_binder();
-            let reject_cx = DeepRejectCtxt {
-                treat_obligation_params: TreatParams::AsCandidateKey,
-            };
-            v.extend(av.iter().filter(|impl_| {
-                if let Some(impl_def_id) = impl_.impl_item.item_id.as_def_id() {
-                    reject_cx.types_may_unify(aliased_ty, tcx.type_of(impl_def_id).skip_binder())
-                        && saw_impls.insert(impl_def_id)
-                } else {
-                    false
-                }
-            }));
-        }
-        v
-    }
 }
 
 impl<'tcx> Context<'tcx> {

src/librustdoc/html/render/mod.rs

@@ -1132,13 +1132,13 @@ pub(crate) fn render_all_impls(
 fn render_assoc_items<'a, 'cx: 'a>(
     cx: &'a mut Context<'cx>,
     containing_item: &'a clean::Item,
-    did: DefId,
+    it: DefId,
     what: AssocItemRender<'a>,
 ) -> impl fmt::Display + 'a + Captures<'cx> {
     let mut derefs = DefIdSet::default();
-    derefs.insert(did);
+    derefs.insert(it);
     display_fn(move |f| {
-        render_assoc_items_inner(f, cx, containing_item, did, what, &mut derefs);
+        render_assoc_items_inner(f, cx, containing_item, it, what, &mut derefs);
         Ok(())
     })
 }
@@ -1147,17 +1147,15 @@ fn render_assoc_items_inner(
     mut w: &mut dyn fmt::Write,
     cx: &mut Context<'_>,
     containing_item: &clean::Item,
-    did: DefId,
+    it: DefId,
     what: AssocItemRender<'_>,
     derefs: &mut DefIdSet,
 ) {
     info!("Documenting associated items of {:?}", containing_item.name);
     let shared = Rc::clone(&cx.shared);
-    let v = shared.all_impls_for_item(containing_item, did);
-    let v = v.as_slice();
-    let (non_trait, traits): (Vec<&Impl>, _) =
-        v.iter().partition(|i| i.inner_impl().trait_.is_none());
-    let mut saw_impls = FxHashSet::default();
+    let cache = &shared.cache;
+    let Some(v) = cache.impls.get(&it) else { return };
+    let (non_trait, traits): (Vec<_>, _) = v.iter().partition(|i| i.inner_impl().trait_.is_none());
     if !non_trait.is_empty() {
         let mut tmp_buf = Buffer::html();
         let (render_mode, id, class_html) = match what {
@@ -1186,9 +1184,6 @@ fn render_assoc_items_inner(
         };
         let mut impls_buf = Buffer::html();
         for i in &non_trait {
-            if !saw_impls.insert(i.def_id()) {
-                continue;
-            }
             render_impl(
                 &mut impls_buf,
                 cx,
@@ -1234,10 +1229,8 @@ fn render_assoc_items_inner(
 
         let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) =
             traits.into_iter().partition(|t| t.inner_impl().kind.is_auto());
-        let (blanket_impl, concrete): (Vec<&Impl>, _) = concrete
-            .into_iter()
-            .filter(|t| saw_impls.insert(t.def_id()))
-            .partition(|t| t.inner_impl().kind.is_blanket());
+        let (blanket_impl, concrete): (Vec<&Impl>, _) =
+            concrete.into_iter().partition(|t| t.inner_impl().kind.is_blanket());
 
         render_all_impls(w, cx, containing_item, &concrete, &synthetic, &blanket_impl);
     }