rustdoc: render bounds of cross-crate GAT params

src/librustdoc/clean/mod.rs

@@ -1201,21 +1201,19 @@ pub(crate) fn clean_middle_assoc_item<'tcx>(
  }
 
  if let ty::TraitContainer = assoc_item.container {
- // FIXME(fmease): `tcx.explicit_item_bounds` does not contain the bounds of GATs,
- // e.g. the bounds `Copy`, `Display` & (implicitly) `Sized` in
- // `type Assoc<T: Copy> where T: Display`. This also means that we
- // later incorrectly render `where T: ?Sized`.
- //
- // The result of `tcx.explicit_predicates_of` *does* contain them but
- // it does not contain the other bounds / predicates we need.
- // Either merge those two interned lists somehow or refactor
- // `clean_ty_generics` to call `explicit_item_bounds` by itself.
  let bounds = tcx.explicit_item_bounds(assoc_item.def_id);
- let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
- let mut generics =
- clean_ty_generics(cx, tcx.generics_of(assoc_item.def_id), predicates);
- // Filter out the bounds that are (likely?) directly attached to the associated type,
- // as opposed to being located in the where clause.
+ let predicates = tcx.explicit_predicates_of(assoc_item.def_id).predicates;
+ let predicates =
+ tcx.arena.alloc_from_iter(bounds.into_iter().chain(predicates).copied());
+ let mut generics = clean_ty_generics(
+ cx,
+ tcx.generics_of(assoc_item.def_id),
+ ty::GenericPredicates { parent: None, predicates },
+ );
+ // Move bounds that are (likely) directly attached to the associated type
+ // from the where clause to the associated type.
+ // There is no guarantee that this is what the user actually wrote but we have
+ // no way of knowing.
  let mut bounds = generics
  .where_predicates
  .drain_filter(|pred| match *pred {
@@ -1273,6 +1271,24 @@ pub(crate) fn clean_middle_assoc_item<'tcx>(
  }
  None => bounds.push(GenericBound::maybe_sized(cx)),
  }
+ // Move bounds that are (likely) directly attached to the parameters of the
+ // (generic) associated type from the where clause to the respective parameter.
+ // There is no guarantee that this is what the user actually wrote but we have
+ // no way of knowing.
+ let mut where_predicates = Vec::new();
+ for mut pred in generics.where_predicates {
+ if let WherePredicate::BoundPredicate { ty: Generic(arg), bounds, .. } = &mut pred
+ && let Some(GenericParamDef {
+ kind: GenericParamDefKind::Type { bounds: param_bounds, .. },
+ ..
+ }) = generics.params.iter_mut().find(|param| &param.name == arg)
+ {
+ param_bounds.extend(mem::take(bounds));
+ } else {
+ where_predicates.push(pred);
+ }
+ }
+ generics.where_predicates = where_predicates;
 
  if tcx.impl_defaultness(assoc_item.def_id).has_value() {
  AssocTypeItem(

src/test/rustdoc/inline_cross/assoc_item_trait_bounds.out0.html

@@ -0,0 +1 @@
+<h4 class="code-header">type <a href="#associatedtype.Out0" class="associatedtype">Out0</a>: <a class="trait" href="../assoc_item_trait_bounds/trait.Support.html" title="trait assoc_item_trait_bounds::Support">Support</a>&lt;Item = <a class="primitive" href="{{channel}}/std/primitive.unit.html">()</a>&gt;</h4>

src/test/rustdoc/inline_cross/assoc_item_trait_bounds.out2.html

@@ -0,0 +1 @@
+<h4 class="code-header">type <a href="#associatedtype.Out2" class="associatedtype">Out2</a>&lt;T&gt;: <a class="trait" href="../assoc_item_trait_bounds/trait.Support.html" title="trait assoc_item_trait_bounds::Support">Support</a>&lt;Item = T&gt;</h4>

src/test/rustdoc/inline_cross/assoc_item_trait_bounds_with_bindings.rs → src/test/rustdoc/inline_cross/assoc_item_trait_bounds.rs

@@ -1,13 +1,10 @@
 // Regression test for issues #77763, #84579 and #102142.
 #![crate_name = "main"]
 
-// aux-build:assoc_item_trait_bounds_with_bindings.rs
+// aux-build:assoc_item_trait_bounds.rs
 // build-aux-docs
 // ignore-cross-compile
-extern crate assoc_item_trait_bounds_with_bindings as aux;
-
-// FIXME(fmease): Don't render an incorrect `T: ?Sized` where-clause for parameters
-// of GATs like `Main::Out{2,4}`. Add a snapshot test once it's fixed.
+extern crate assoc_item_trait_bounds as aux;
 
 // @has main/trait.Main.html
 // @has - '//*[@id="associatedtype.Out0"]' 'type Out0: Support<Item = ()>'
@@ -24,11 +21,15 @@ extern crate assoc_item_trait_bounds_with_bindings as aux;
 // @has - '//*[@id="associatedtype.Out11"]' "type Out11: for<'r, 's> Helper<A<'s> = &'s (), B<'r> = ()>"
 // @has - '//*[@id="associatedtype.Out12"]' "type Out12: for<'w> Helper<B<'w> = Cow<'w, str>, A<'w> = bool>"
 // @has - '//*[@id="associatedtype.Out13"]' "type Out13: for<'fst, 'snd> Aid<'snd, Result<'fst> = &'fst mut str>"
+// @has - '//*[@id="associatedtype.Out14"]' "type Out14<P: Copy + Eq, Q: ?Sized>"
 //
-// Snapshots: Check that we do not render any where-clauses for those associated types since all of
-// the trait bounds contained within were moved to the bounds of the respective item.
+// Snapshots:
+// Check that we don't render any where-clauses for the following associated types since
+// all corresponding projection equality predicates should have already been re-sugared
+// to associated type bindings:
 //
 // @snapshot out0 - '//*[@id="associatedtype.Out0"]/*[@class="code-header"]'
+// @snapshot out2 - '//*[@id="associatedtype.Out2"]/*[@class="code-header"]'
 // @snapshot out9 - '//*[@id="associatedtype.Out9"]/*[@class="code-header"]'
 //
 // @has - '//*[@id="tymethod.make"]' \

src/test/rustdoc/inline_cross/auxiliary/assoc_item_trait_bounds_with_bindings.rs → src/test/rustdoc/inline_cross/auxiliary/assoc_item_trait_bounds.rs

@@ -15,6 +15,7 @@ pub trait Main {
  type Out11: for<'r, 's> Helper<A<'s> = &'s (), B<'r> = ()>;
  type Out12: for<'w> Helper<B<'w> = std::borrow::Cow<'w, str>, A<'w> = bool>;
  type Out13: for<'fst, 'snd> Aid<'snd, Result<'fst> = &'fst mut str>;
+ type Out14<P: Copy + Eq, Q: ?Sized>;
 
  fn make<F>(_: F, _: impl FnMut(&str) -> bool)
  where