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Normalize <X as Y>::T for rustdoc #77467

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Nov 26, 2020
Merged

Normalize <X as Y>::T for rustdoc #77467

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7f60ee0
Refactor clean_qpath into a separate function
jyn514 Oct 2, 2020
a192e5d
Normalize `<X as Y>::T` for rustdoc
jyn514 Oct 2, 2020
6278daa
Track `ParamEnv`s properly
jyn514 Oct 18, 2020
277bdbc
Remove redundant `lift_to_tcx`
jyn514 Nov 26, 2020
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325 changes: 185 additions & 140 deletions src/librustdoc/clean/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1283,6 +1283,157 @@ impl Clean<Item> for ty::AssocItem {
}
}

fn clean_qpath(hir_ty: &hir::Ty<'_>, cx: &DocContext<'_>) -> Type {
use rustc_hir::GenericParamCount;
let hir::Ty { hir_id, span, ref kind } = *hir_ty;
let qpath = match kind {
hir::TyKind::Path(qpath) => qpath,
_ => unreachable!(),
};

match qpath {
hir::QPath::Resolved(None, ref path) => {
if let Res::Def(DefKind::TyParam, did) = path.res {
if let Some(new_ty) = cx.ty_substs.borrow().get(&did).cloned() {
return new_ty;
}
if let Some(bounds) = cx.impl_trait_bounds.borrow_mut().remove(&did.into()) {
return ImplTrait(bounds);
}
}

let mut alias = None;
if let Res::Def(DefKind::TyAlias, def_id) = path.res {
// Substitute private type aliases
if let Some(def_id) = def_id.as_local() {
let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
if !cx.renderinfo.borrow().access_levels.is_exported(def_id.to_def_id()) {
alias = Some(&cx.tcx.hir().expect_item(hir_id).kind);
}
}
};

if let Some(&hir::ItemKind::TyAlias(ref ty, ref generics)) = alias {
let provided_params = &path.segments.last().expect("segments were empty");
let mut ty_substs = FxHashMap::default();
let mut lt_substs = FxHashMap::default();
let mut ct_substs = FxHashMap::default();
let generic_args = provided_params.generic_args();
{
let mut indices: GenericParamCount = Default::default();
for param in generics.params.iter() {
match param.kind {
hir::GenericParamKind::Lifetime { .. } => {
let mut j = 0;
let lifetime = generic_args.args.iter().find_map(|arg| match arg {
hir::GenericArg::Lifetime(lt) => {
if indices.lifetimes == j {
return Some(lt);
}
j += 1;
None
}
_ => None,
});
if let Some(lt) = lifetime.cloned() {
let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
let cleaned = if !lt.is_elided() {
lt.clean(cx)
} else {
self::types::Lifetime::elided()
};
lt_substs.insert(lt_def_id.to_def_id(), cleaned);
}
indices.lifetimes += 1;
}
hir::GenericParamKind::Type { ref default, .. } => {
let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
let mut j = 0;
let type_ = generic_args.args.iter().find_map(|arg| match arg {
hir::GenericArg::Type(ty) => {
if indices.types == j {
return Some(ty);
}
j += 1;
None
}
_ => None,
});
if let Some(ty) = type_ {
ty_substs.insert(ty_param_def_id.to_def_id(), ty.clean(cx));
} else if let Some(default) = *default {
ty_substs
.insert(ty_param_def_id.to_def_id(), default.clean(cx));
}
indices.types += 1;
}
hir::GenericParamKind::Const { .. } => {
let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
let mut j = 0;
let const_ = generic_args.args.iter().find_map(|arg| match arg {
hir::GenericArg::Const(ct) => {
if indices.consts == j {
return Some(ct);
}
j += 1;
None
}
_ => None,
});
if let Some(ct) = const_ {
ct_substs.insert(const_param_def_id.to_def_id(), ct.clean(cx));
}
// FIXME(const_generics:defaults)
indices.consts += 1;
}
}
}
}
return cx.enter_alias(ty_substs, lt_substs, ct_substs, || ty.clean(cx));
}
resolve_type(cx, path.clean(cx), hir_id)
}
hir::QPath::Resolved(Some(ref qself), ref p) => {
// Try to normalize `<X as Y>::T` to a type
let ty = hir_ty_to_ty(cx.tcx, hir_ty);
if let Some(normalized_value) = normalize(cx.tcx, ty) {
return normalized_value.clean(cx);
}

let segments = if p.is_global() { &p.segments[1..] } else { &p.segments };
let trait_segments = &segments[..segments.len() - 1];
let trait_path = self::Path {
global: p.is_global(),
res: Res::Def(
DefKind::Trait,
cx.tcx.associated_item(p.res.def_id()).container.id(),
),
segments: trait_segments.clean(cx),
};
Type::QPath {
name: p.segments.last().expect("segments were empty").ident.name.clean(cx),
self_type: box qself.clean(cx),
trait_: box resolve_type(cx, trait_path, hir_id),
}
}
hir::QPath::TypeRelative(ref qself, ref segment) => {
let ty = hir_ty_to_ty(cx.tcx, hir_ty);
let res = if let ty::Projection(proj) = ty.kind() {
Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id)
} else {
Res::Err
};
let trait_path = hir::Path { span, res, segments: &[] };
Type::QPath {
name: segment.ident.name.clean(cx),
self_type: box qself.clean(cx),
trait_: box resolve_type(cx, trait_path.clean(cx), hir_id),
}
}
hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
}
}

impl Clean<Type> for hir::Ty<'_> {
fn clean(&self, cx: &DocContext<'_>) -> Type {
use rustc_hir::*;
Expand Down Expand Up @@ -1318,145 +1469,7 @@ impl Clean<Type> for hir::Ty<'_> {
unreachable!()
}
}
TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
if let Res::Def(DefKind::TyParam, did) = path.res {
if let Some(new_ty) = cx.ty_substs.borrow().get(&did).cloned() {
return new_ty;
}
if let Some(bounds) = cx.impl_trait_bounds.borrow_mut().remove(&did.into()) {
return ImplTrait(bounds);
}
}

let mut alias = None;
if let Res::Def(DefKind::TyAlias, def_id) = path.res {
// Substitute private type aliases
if let Some(def_id) = def_id.as_local() {
let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
if !cx.renderinfo.borrow().access_levels.is_exported(def_id.to_def_id()) {
alias = Some(&cx.tcx.hir().expect_item(hir_id).kind);
}
}
};

if let Some(&hir::ItemKind::TyAlias(ref ty, ref generics)) = alias {
let provided_params = &path.segments.last().expect("segments were empty");
let mut ty_substs = FxHashMap::default();
let mut lt_substs = FxHashMap::default();
let mut ct_substs = FxHashMap::default();
let generic_args = provided_params.generic_args();
{
let mut indices: GenericParamCount = Default::default();
for param in generics.params.iter() {
match param.kind {
hir::GenericParamKind::Lifetime { .. } => {
let mut j = 0;
let lifetime =
generic_args.args.iter().find_map(|arg| match arg {
hir::GenericArg::Lifetime(lt) => {
if indices.lifetimes == j {
return Some(lt);
}
j += 1;
None
}
_ => None,
});
if let Some(lt) = lifetime.cloned() {
let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
let cleaned = if !lt.is_elided() {
lt.clean(cx)
} else {
self::types::Lifetime::elided()
};
lt_substs.insert(lt_def_id.to_def_id(), cleaned);
}
indices.lifetimes += 1;
}
hir::GenericParamKind::Type { ref default, .. } => {
let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
let mut j = 0;
let type_ =
generic_args.args.iter().find_map(|arg| match arg {
hir::GenericArg::Type(ty) => {
if indices.types == j {
return Some(ty);
}
j += 1;
None
}
_ => None,
});
if let Some(ty) = type_ {
ty_substs.insert(ty_param_def_id.to_def_id(), ty.clean(cx));
} else if let Some(default) = *default {
ty_substs
.insert(ty_param_def_id.to_def_id(), default.clean(cx));
}
indices.types += 1;
}
hir::GenericParamKind::Const { .. } => {
let const_param_def_id =
cx.tcx.hir().local_def_id(param.hir_id);
let mut j = 0;
let const_ =
generic_args.args.iter().find_map(|arg| match arg {
hir::GenericArg::Const(ct) => {
if indices.consts == j {
return Some(ct);
}
j += 1;
None
}
_ => None,
});
if let Some(ct) = const_ {
ct_substs
.insert(const_param_def_id.to_def_id(), ct.clean(cx));
}
// FIXME(const_generics:defaults)
indices.consts += 1;
}
}
}
}
return cx.enter_alias(ty_substs, lt_substs, ct_substs, || ty.clean(cx));
}
resolve_type(cx, path.clean(cx), self.hir_id)
}
TyKind::Path(hir::QPath::Resolved(Some(ref qself), ref p)) => {
let segments = if p.is_global() { &p.segments[1..] } else { &p.segments };
let trait_segments = &segments[..segments.len() - 1];
let trait_path = self::Path {
global: p.is_global(),
res: Res::Def(
DefKind::Trait,
cx.tcx.associated_item(p.res.def_id()).container.id(),
),
segments: trait_segments.clean(cx),
};
Type::QPath {
name: p.segments.last().expect("segments were empty").ident.name.clean(cx),
self_type: box qself.clean(cx),
trait_: box resolve_type(cx, trait_path, self.hir_id),
}
}
TyKind::Path(hir::QPath::TypeRelative(ref qself, ref segment)) => {
let mut res = Res::Err;
let ty = hir_ty_to_ty(cx.tcx, self);
if let ty::Projection(proj) = ty.kind() {
res = Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id);
}
let trait_path = hir::Path { span: self.span, res, segments: &[] };
Type::QPath {
name: segment.ident.name.clean(cx),
self_type: box qself.clean(cx),
trait_: box resolve_type(cx, trait_path.clean(cx), self.hir_id),
}
}
TyKind::Path(hir::QPath::LangItem(..)) => {
bug!("clean: requiring documentation of lang item")
}
TyKind::Path(_) => clean_qpath(&self, cx),
TyKind::TraitObject(ref bounds, ref lifetime) => {
match bounds[0].clean(cx).trait_ {
ResolvedPath { path, param_names: None, did, is_generic } => {
Expand Down Expand Up @@ -1484,10 +1497,42 @@ impl Clean<Type> for hir::Ty<'_> {
}
}

/// Returns `None` if the type could not be normalized
fn normalize(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
use crate::rustc_trait_selection::infer::TyCtxtInferExt;
use crate::rustc_trait_selection::traits::query::normalize::AtExt;
use rustc_middle::traits::ObligationCause;
use rustc_middle::ty::ParamEnv;

// Try to normalize `<X as Y>::T` to a type
// FIXME: rustdoc won't be able to perform 'partial' normalization
// until this param env is actually correct
// 'partial': `<Vec<T> as IntoIterator>::IntoIter>` -> `vec::IntoIter<T>`
let param_env = ParamEnv::empty();
let lifted = ty.lift_to_tcx(tcx).unwrap();
let normalized = tcx.infer_ctxt().enter(|infcx| {
infcx
.at(&ObligationCause::dummy(), param_env)
.normalize(lifted)
.map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
});
match normalized {
Ok(normalized_value) => {
debug!("resolved {:?} to {:?}", ty, normalized_value);
Some(normalized_value)
}
Err(err) => {
debug!("failed to resolve {:?}: {:?}", ty, err);
None
}
}
}

impl<'tcx> Clean<Type> for Ty<'tcx> {
fn clean(&self, cx: &DocContext<'_>) -> Type {
debug!("cleaning type: {:?}", self);
match *self.kind() {
let ty = normalize(cx.tcx, self.lift_to_tcx(cx.tcx).unwrap()).unwrap_or(self);
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match *ty.kind() {
ty::Never => Never,
ty::Bool => Primitive(PrimitiveType::Bool),
ty::Char => Primitive(PrimitiveType::Char),
Expand Down
12 changes: 12 additions & 0 deletions src/test/rustdoc/auxiliary/normalize-assoc-item.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
#![crate_name = "inner"]
pub trait MyTrait {
type Y;
}

impl MyTrait for u32 {
type Y = i32;
}

pub fn foo() -> <u32 as MyTrait>::Y {
0
}
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