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Auto merge of #115276 - fmease:rustdoc-obj-lt-defs-handle-self-ty-par…
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…ams, r=GuillaumeGomez

rustdoc: correctly deal with self ty params when eliding default object lifetimes

Fixes #115179.
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bors committed Sep 1, 2023
2 parents 270eb58 + f5a68f6 commit 35e4163
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Showing 4 changed files with 57 additions and 8 deletions.
27 changes: 20 additions & 7 deletions src/librustdoc/clean/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1959,31 +1959,44 @@ fn can_elide_trait_object_lifetime_bound<'tcx>(
#[derive(Debug)]
pub(crate) enum ContainerTy<'tcx> {
Ref(ty::Region<'tcx>),
Regular { ty: DefId, args: ty::Binder<'tcx, &'tcx [ty::GenericArg<'tcx>]>, arg: usize },
Regular {
ty: DefId,
args: ty::Binder<'tcx, &'tcx [ty::GenericArg<'tcx>]>,
has_self: bool,
arg: usize,
},
}

impl<'tcx> ContainerTy<'tcx> {
fn object_lifetime_default(self, tcx: TyCtxt<'tcx>) -> ObjectLifetimeDefault<'tcx> {
match self {
Self::Ref(region) => ObjectLifetimeDefault::Arg(region),
Self::Regular { ty: container, args, arg: index } => {
Self::Regular { ty: container, args, has_self, arg: index } => {
let (DefKind::Struct
| DefKind::Union
| DefKind::Enum
| DefKind::TyAlias { .. }
| DefKind::Trait
| DefKind::AssocTy
| DefKind::Variant) = tcx.def_kind(container)
| DefKind::Trait) = tcx.def_kind(container)
else {
return ObjectLifetimeDefault::Empty;
};

let generics = tcx.generics_of(container);
let param = generics.params[index].def_id;
let default = tcx.object_lifetime_default(param);
debug_assert_eq!(generics.parent_count, 0);

// If the container is a trait object type, the arguments won't contain the self type but the
// generics of the corresponding trait will. In such a case, offset the index by one.
// For comparison, if the container is a trait inside a bound, the arguments do contain the
// self type.
let offset =
if !has_self && generics.parent.is_none() && generics.has_self { 1 } else { 0 };
let param = generics.params[index + offset].def_id;

let default = tcx.object_lifetime_default(param);
match default {
rbv::ObjectLifetimeDefault::Param(lifetime) => {
// The index is relative to the parent generics but since we don't have any,
// we don't need to translate it.
let index = generics.param_def_id_to_index[&lifetime];
let arg = args.skip_binder()[index as usize].expect_region();
ObjectLifetimeDefault::Arg(arg)
Expand Down
4 changes: 3 additions & 1 deletion src/librustdoc/clean/utils.rs
Original file line number Diff line number Diff line change
Expand Up @@ -77,9 +77,10 @@ pub(crate) fn krate(cx: &mut DocContext<'_>) -> Crate {
pub(crate) fn ty_args_to_args<'tcx>(
cx: &mut DocContext<'tcx>,
args: ty::Binder<'tcx, &'tcx [ty::GenericArg<'tcx>]>,
mut skip_first: bool,
has_self: bool,
container: Option<DefId>,
) -> Vec<GenericArg> {
let mut skip_first = has_self;
let mut ret_val =
Vec::with_capacity(args.skip_binder().len().saturating_sub(if skip_first { 1 } else { 0 }));

Expand All @@ -99,6 +100,7 @@ pub(crate) fn ty_args_to_args<'tcx>(
container.map(|container| crate::clean::ContainerTy::Regular {
ty: container,
args,
has_self,
arg: index,
}),
))),
Expand Down
19 changes: 19 additions & 0 deletions tests/rustdoc/inline_cross/auxiliary/dyn_trait.rs
Original file line number Diff line number Diff line change
Expand Up @@ -65,3 +65,22 @@ pub trait HigherRankedBoundTrait1<'e> where for<'l> Self: 'e + 'l {}
pub trait AmbiguousBoundTrait<'a, 'b>: 'a + 'b {}

pub struct AmbiguousBoundWrapper<'a, 'b, T: ?Sized + 'a + 'b>(&'a T, &'b T);

// Trait objects inside of another trait object, a trait bound or an associated type.

pub trait Inner {}
pub trait Outer<T: ?Sized> {}
pub trait Base {
type Type<T: ?Sized>;
}
impl Base for () {
type Type<T: ?Sized> = ();
}

pub type NestedTraitObjects = dyn Outer<dyn Inner>;

pub fn apit_rpit(o: impl Outer<dyn Inner>) -> impl Outer<dyn Inner> {
o
}

pub type AssocTy = <() as Base>::Type<dyn Inner>;
15 changes: 15 additions & 0 deletions tests/rustdoc/inline_cross/dyn_trait.rs
Original file line number Diff line number Diff line change
Expand Up @@ -128,3 +128,18 @@ pub use dyn_trait::BareAmbiguousBoundEarly1;
// @has user/type.BareAmbiguousBoundStatic.html
// @has - '//*[@class="rust item-decl"]//code' "dyn AmbiguousBoundTrait<'o, 'o> + 'static;"
pub use dyn_trait::BareAmbiguousBoundStatic;

// Regression test for issue #115179:

// @has user/type.NestedTraitObjects.html
// @has - '//*[@class="rust item-decl"]//code' "dyn Outer<dyn Inner>;"
pub use dyn_trait::NestedTraitObjects;

// @has user/fn.apit_rpit.html
// @has - '//pre[@class="rust item-decl"]' \
// "apit_rpit(o: impl Outer<dyn Inner>) -> impl Outer<dyn Inner>"
pub use dyn_trait::apit_rpit;

// @has user/type.AssocTy.html
// @has - '//*[@class="rust item-decl"]//code' "<() as Base>::Type<dyn Inner>"
pub use dyn_trait::AssocTy;

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