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Jun 6, 2025
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rustdoc: Support middle::ty associated const equality predicates again #142092

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911d4a0
Rename `should_show_cast` to `should_fully_qualify`
fmease Jun 5, 2025
95bf127
Support middle::ty assoc const eq predicates again
fmease Jun 5, 2025
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150 changes: 61 additions & 89 deletions src/librustdoc/clean/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -371,10 +371,9 @@ fn clean_where_predicate<'tcx>(
bounds: wrp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
},

hir::WherePredicateKind::EqPredicate(wrp) => WherePredicate::EqPredicate {
lhs: clean_ty(wrp.lhs_ty, cx),
rhs: clean_ty(wrp.rhs_ty, cx).into(),
},
// We should never actually reach this case because these predicates should've already been
// rejected in an earlier compiler pass. This feature isn't fully implemented (#20041).
hir::WherePredicateKind::EqPredicate(_) => bug!("EqPredicate"),
})
}

Expand Down Expand Up @@ -470,68 +469,55 @@ fn clean_projection_predicate<'tcx>(
cx: &mut DocContext<'tcx>,
) -> WherePredicate {
WherePredicate::EqPredicate {
lhs: clean_projection(
pred.map_bound(|p| {
// FIXME: This needs to be made resilient for `AliasTerm`s that
// are associated consts.
p.projection_term.expect_ty(cx.tcx)
}),
cx,
None,
),
lhs: clean_projection(pred.map_bound(|p| p.projection_term), cx, None),
rhs: clean_middle_term(pred.map_bound(|p| p.term), cx),
}
}

fn clean_projection<'tcx>(
ty: ty::Binder<'tcx, ty::AliasTy<'tcx>>,
proj: ty::Binder<'tcx, ty::AliasTerm<'tcx>>,
cx: &mut DocContext<'tcx>,
def_id: Option<DefId>,
) -> Type {
if cx.tcx.is_impl_trait_in_trait(ty.skip_binder().def_id) {
return clean_middle_opaque_bounds(cx, ty.skip_binder().def_id, ty.skip_binder().args);
}

parent_def_id: Option<DefId>,
) -> QPathData {
let trait_ = clean_trait_ref_with_constraints(
cx,
ty.map_bound(|ty| ty.trait_ref(cx.tcx)),
proj.map_bound(|proj| proj.trait_ref(cx.tcx)),
ThinVec::new(),
);
let self_type = clean_middle_ty(ty.map_bound(|ty| ty.self_ty()), cx, None, None);
let self_def_id = if let Some(def_id) = def_id {
cx.tcx.opt_parent(def_id).or(Some(def_id))
} else {
self_type.def_id(&cx.cache)
let self_type = clean_middle_ty(proj.map_bound(|proj| proj.self_ty()), cx, None, None);
let self_def_id = match parent_def_id {
Some(parent_def_id) => cx.tcx.opt_parent(parent_def_id).or(Some(parent_def_id)),
None => self_type.def_id(&cx.cache),
};
let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
Type::QPath(Box::new(QPathData {
assoc: projection_to_path_segment(ty, cx),
should_show_cast,
let should_fully_qualify = should_fully_qualify_path(self_def_id, &trait_, &self_type);

QPathData {
assoc: projection_to_path_segment(proj, cx),
self_type,
should_fully_qualify,
trait_: Some(trait_),
}))
}
}

fn compute_should_show_cast(self_def_id: Option<DefId>, trait_: &Path, self_type: &Type) -> bool {
fn should_fully_qualify_path(self_def_id: Option<DefId>, trait_: &Path, self_type: &Type) -> bool {
!trait_.segments.is_empty()
&& self_def_id
.zip(Some(trait_.def_id()))
.map_or(!self_type.is_self_type(), |(id, trait_)| id != trait_)
}

fn projection_to_path_segment<'tcx>(
ty: ty::Binder<'tcx, ty::AliasTy<'tcx>>,
proj: ty::Binder<'tcx, ty::AliasTerm<'tcx>>,
cx: &mut DocContext<'tcx>,
) -> PathSegment {
let def_id = ty.skip_binder().def_id;
let item = cx.tcx.associated_item(def_id);
let def_id = proj.skip_binder().def_id;
let generics = cx.tcx.generics_of(def_id);
PathSegment {
name: item.name(),
name: cx.tcx.item_name(def_id),
args: GenericArgs::AngleBracketed {
args: clean_middle_generic_args(
cx,
ty.map_bound(|ty| &ty.args[generics.parent_count..]),
proj.map_bound(|ty| &ty.args[generics.parent_count..]),
false,
def_id,
),
Expand Down Expand Up @@ -845,7 +831,7 @@ fn clean_ty_generics<'tcx>(
.predicates
.iter()
.flat_map(|(pred, _)| {
let mut projection = None;
let mut proj_pred = None;
let param_idx = {
let bound_p = pred.kind();
match bound_p.skip_binder() {
Expand All @@ -860,7 +846,7 @@ fn clean_ty_generics<'tcx>(
ty::ClauseKind::Projection(p)
if let ty::Param(param) = p.projection_term.self_ty().kind() =>
{
projection = Some(bound_p.rebind(p));
proj_pred = Some(bound_p.rebind(p));
Some(param.index)
}
_ => None,
Expand All @@ -874,22 +860,12 @@ fn clean_ty_generics<'tcx>(

bounds.extend(pred.get_bounds().into_iter().flatten().cloned());

if let Some(proj) = projection
&& let lhs = clean_projection(
proj.map_bound(|p| {
// FIXME: This needs to be made resilient for `AliasTerm`s that
// are associated consts.
p.projection_term.expect_ty(cx.tcx)
}),
cx,
None,
)
&& let Some((_, trait_did, name)) = lhs.projection()
{
if let Some(pred) = proj_pred {
let lhs = clean_projection(pred.map_bound(|p| p.projection_term), cx, None);
impl_trait_proj.entry(param_idx).or_default().push((
trait_did,
name,
proj.map_bound(|p| p.term),
lhs.trait_.unwrap().def_id(),
lhs.assoc,
pred.map_bound(|p| p.term),
));
}

Expand Down Expand Up @@ -1695,10 +1671,11 @@ fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type
register_res(cx, trait_.res);
let self_def_id = DefId::local(qself.hir_id.owner.def_id.local_def_index);
let self_type = clean_ty(qself, cx);
let should_show_cast = compute_should_show_cast(Some(self_def_id), &trait_, &self_type);
let should_fully_qualify =
should_fully_qualify_path(Some(self_def_id), &trait_, &self_type);
Type::QPath(Box::new(QPathData {
assoc: clean_path_segment(p.segments.last().expect("segments were empty"), cx),
should_show_cast,
should_fully_qualify,
self_type,
trait_: Some(trait_),
}))
Expand All @@ -1707,16 +1684,16 @@ fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type
let ty = lower_ty(cx.tcx, hir_ty);
let self_type = clean_ty(qself, cx);

let (trait_, should_show_cast) = match ty.kind() {
let (trait_, should_fully_qualify) = match ty.kind() {
ty::Alias(ty::Projection, proj) => {
let res = Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id);
let trait_ = clean_path(&hir::Path { span, res, segments: &[] }, cx);
register_res(cx, trait_.res);
let self_def_id = res.opt_def_id();
let should_show_cast =
compute_should_show_cast(self_def_id, &trait_, &self_type);
let should_fully_qualify =
should_fully_qualify_path(self_def_id, &trait_, &self_type);

(Some(trait_), should_show_cast)
(Some(trait_), should_fully_qualify)
}
ty::Alias(ty::Inherent, _) => (None, false),
// Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
Expand All @@ -1726,7 +1703,7 @@ fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type

Type::QPath(Box::new(QPathData {
assoc: clean_path_segment(segment, cx),
should_show_cast,
should_fully_qualify,
self_type,
trait_,
}))
Expand Down Expand Up @@ -2145,14 +2122,8 @@ pub(crate) fn clean_middle_ty<'tcx>(
.map(|pb| AssocItemConstraint {
assoc: projection_to_path_segment(
pb.map_bound(|pb| {
pb
// HACK(compiler-errors): Doesn't actually matter what self
// type we put here, because we're only using the GAT's args.
.with_self_ty(cx.tcx, cx.tcx.types.self_param)
pb.with_self_ty(cx.tcx, cx.tcx.types.trait_object_dummy_self)
.projection_term
// FIXME: This needs to be made resilient for `AliasTerm`s
// that are associated consts.
.expect_ty(cx.tcx)
}),
cx,
),
Expand Down Expand Up @@ -2185,18 +2156,25 @@ pub(crate) fn clean_middle_ty<'tcx>(
Tuple(t.iter().map(|t| clean_middle_ty(bound_ty.rebind(t), cx, None, None)).collect())
}

ty::Alias(ty::Projection, data) => {
clean_projection(bound_ty.rebind(data), cx, parent_def_id)
ty::Alias(ty::Projection, alias_ty @ ty::AliasTy { def_id, args, .. }) => {
if cx.tcx.is_impl_trait_in_trait(def_id) {
clean_middle_opaque_bounds(cx, def_id, args)
} else {
Type::QPath(Box::new(clean_projection(
bound_ty.rebind(alias_ty.into()),
cx,
parent_def_id,
)))
}
}

ty::Alias(ty::Inherent, alias_ty) => {
let def_id = alias_ty.def_id;
ty::Alias(ty::Inherent, alias_ty @ ty::AliasTy { def_id, .. }) => {
let alias_ty = bound_ty.rebind(alias_ty);
let self_type = clean_middle_ty(alias_ty.map_bound(|ty| ty.self_ty()), cx, None, None);

Type::QPath(Box::new(QPathData {
assoc: PathSegment {
name: cx.tcx.associated_item(def_id).name(),
name: cx.tcx.item_name(def_id),
args: GenericArgs::AngleBracketed {
args: clean_middle_generic_args(
cx,
Expand All @@ -2207,26 +2185,21 @@ pub(crate) fn clean_middle_ty<'tcx>(
constraints: Default::default(),
},
},
should_show_cast: false,
should_fully_qualify: false,
self_type,
trait_: None,
}))
}

ty::Alias(ty::Free, data) => {
ty::Alias(ty::Free, ty::AliasTy { def_id, args, .. }) => {
if cx.tcx.features().lazy_type_alias() {
// Free type alias `data` represents the `type X` in `type X = Y`. If we need `Y`,
// we need to use `type_of`.
let path = clean_middle_path(
cx,
data.def_id,
false,
ThinVec::new(),
bound_ty.rebind(data.args),
);
let path =
clean_middle_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
Type::Path { path }
} else {
let ty = cx.tcx.type_of(data.def_id).instantiate(cx.tcx, data.args);
let ty = cx.tcx.type_of(def_id).instantiate(cx.tcx, args);
clean_middle_ty(bound_ty.rebind(ty), cx, None, None)
}
}
Expand Down Expand Up @@ -2313,18 +2286,17 @@ fn clean_middle_opaque_bounds<'tcx>(
let bindings: ThinVec<_> = bounds
.iter()
.filter_map(|(bound, _)| {
if let ty::ClauseKind::Projection(proj) = bound.kind().skip_binder()
&& proj.projection_term.trait_ref(cx.tcx) == trait_ref.skip_binder()
let bound = bound.kind();
if let ty::ClauseKind::Projection(proj_pred) = bound.skip_binder()
&& proj_pred.projection_term.trait_ref(cx.tcx) == trait_ref.skip_binder()
{
return Some(AssocItemConstraint {
assoc: projection_to_path_segment(
// FIXME: This needs to be made resilient for `AliasTerm`s that
// are associated consts.
bound.kind().rebind(proj.projection_term.expect_ty(cx.tcx)),
bound.rebind(proj_pred.projection_term),
cx,
),
kind: AssocItemConstraintKind::Equality {
term: clean_middle_term(bound.kind().rebind(proj.term), cx),
term: clean_middle_term(bound.rebind(proj_pred.term), cx),
},
});
}
Expand Down
7 changes: 2 additions & 5 deletions src/librustdoc/clean/simplify.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -46,11 +46,8 @@ pub(crate) fn where_clauses(cx: &DocContext<'_>, clauses: ThinVec<WP>) -> ThinVe
// Look for equality predicates on associated types that can be merged into
// general bound predicates.
equalities.retain(|(lhs, rhs)| {
let Some((ty, trait_did, name)) = lhs.projection() else {
return true;
};
let Some((bounds, _)) = tybounds.get_mut(ty) else { return true };
merge_bounds(cx, bounds, trait_did, name, rhs)
let Some((bounds, _)) = tybounds.get_mut(&lhs.self_type) else { return true };
merge_bounds(cx, bounds, lhs.trait_.as_ref().unwrap().def_id(), lhs.assoc.clone(), rhs)
});

// And finally, let's reassemble everything
Expand Down
12 changes: 2 additions & 10 deletions src/librustdoc/clean/types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1341,7 +1341,7 @@ impl PreciseCapturingArg {
pub(crate) enum WherePredicate {
BoundPredicate { ty: Type, bounds: Vec<GenericBound>, bound_params: Vec<GenericParamDef> },
RegionPredicate { lifetime: Lifetime, bounds: Vec<GenericBound> },
EqPredicate { lhs: Type, rhs: Term },
EqPredicate { lhs: QPathData, rhs: Term },
}

impl WherePredicate {
Expand Down Expand Up @@ -1704,14 +1704,6 @@ impl Type {
matches!(self, Type::Tuple(v) if v.is_empty())
}

pub(crate) fn projection(&self) -> Option<(&Type, DefId, PathSegment)> {
if let QPath(box QPathData { self_type, trait_, assoc, .. }) = self {
Some((self_type, trait_.as_ref()?.def_id(), assoc.clone()))
} else {
None
}
}

/// Use this method to get the [DefId] of a [clean] AST node, including [PrimitiveType]s.
///
/// [clean]: crate::clean
Expand Down Expand Up @@ -1746,7 +1738,7 @@ pub(crate) struct QPathData {
pub assoc: PathSegment,
pub self_type: Type,
/// FIXME: compute this field on demand.
pub should_show_cast: bool,
pub should_fully_qualify: bool,
pub trait_: Option<Path>,
}

Expand Down
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