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rustdoc: slightly clean up the synthesis of blanket impls #123647

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Apr 9, 2024
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rustdoc: slightly clean up the synthesis of blanket impls #123647

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229 changes: 109 additions & 120 deletions src/librustdoc/clean/blanket_impl.rs
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Original file line number Diff line number Diff line change
@@ -1,141 +1,130 @@
use crate::rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_hir as hir;
use rustc_infer::infer::{DefineOpaqueTypes, InferOk, TyCtxtInferExt};
use rustc_infer::traits;
use rustc_middle::ty::ToPredicate;
use rustc_middle::ty::{self, ToPredicate};
use rustc_span::def_id::DefId;
use rustc_span::DUMMY_SP;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;

use super::*;
use thin_vec::ThinVec;

pub(crate) struct BlanketImplFinder<'a, 'tcx> {
pub(crate) cx: &'a mut core::DocContext<'tcx>,
}
use crate::clean;
use crate::clean::{
clean_middle_assoc_item, clean_middle_ty, clean_trait_ref_with_bindings, clean_ty_generics,
};
use crate::core::DocContext;

#[instrument(level = "debug", skip(cx))]
pub(crate) fn synthesize_blanket_impls(
cx: &mut DocContext<'_>,
item_def_id: DefId,
) -> Vec<clean::Item> {
let tcx = cx.tcx;
let ty = tcx.type_of(item_def_id);

impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
pub(crate) fn get_blanket_impls(&mut self, item_def_id: DefId) -> Vec<Item> {
let cx = &mut self.cx;
let ty = cx.tcx.type_of(item_def_id);
let mut blanket_impls = Vec::new();
for trait_def_id in tcx.all_traits() {
if !cx.cache.effective_visibilities.is_reachable(tcx, trait_def_id)
|| cx.generated_synthetics.get(&(ty.skip_binder(), trait_def_id)).is_some()
{
continue;
}
// NOTE: doesn't use `for_each_relevant_impl` to avoid looking at anything besides blanket impls
let trait_impls = tcx.trait_impls_of(trait_def_id);
'blanket_impls: for &impl_def_id in trait_impls.blanket_impls() {
trace!("considering impl `{impl_def_id:?}` for trait `{trait_def_id:?}`");

trace!("get_blanket_impls({ty:?})");
let mut impls = Vec::new();
for trait_def_id in cx.tcx.all_traits() {
if !cx.cache.effective_visibilities.is_reachable(cx.tcx, trait_def_id)
|| cx.generated_synthetics.get(&(ty.skip_binder(), trait_def_id)).is_some()
{
let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
if !matches!(trait_ref.skip_binder().self_ty().kind(), ty::Param(_)) {
continue;
}
// NOTE: doesn't use `for_each_relevant_impl` to avoid looking at anything besides blanket impls
let trait_impls = cx.tcx.trait_impls_of(trait_def_id);
'blanket_impls: for &impl_def_id in trait_impls.blanket_impls() {
trace!(
"get_blanket_impls: Considering impl for trait '{:?}' {:?}",
trait_def_id,
impl_def_id
);
let trait_ref = cx.tcx.impl_trait_ref(impl_def_id).unwrap();
if !matches!(trait_ref.skip_binder().self_ty().kind(), ty::Param(_)) {
continue;
}
let infcx = cx.tcx.infer_ctxt().build();
let args = infcx.fresh_args_for_item(DUMMY_SP, item_def_id);
let impl_ty = ty.instantiate(infcx.tcx, args);
let param_env = ty::ParamEnv::empty();
let infcx = tcx.infer_ctxt().build();
let args = infcx.fresh_args_for_item(DUMMY_SP, item_def_id);
let impl_ty = ty.instantiate(tcx, args);
let param_env = ty::ParamEnv::empty();

let impl_args = infcx.fresh_args_for_item(DUMMY_SP, impl_def_id);
let impl_trait_ref = trait_ref.instantiate(infcx.tcx, impl_args);
let impl_args = infcx.fresh_args_for_item(DUMMY_SP, impl_def_id);
let impl_trait_ref = trait_ref.instantiate(tcx, impl_args);

// Require the type the impl is implemented on to match
// our type, and ignore the impl if there was a mismatch.
let Ok(eq_result) = infcx.at(&traits::ObligationCause::dummy(), param_env).eq(
DefineOpaqueTypes::Yes,
impl_trait_ref.self_ty(),
impl_ty,
) else {
continue;
};
let InferOk { value: (), obligations } = eq_result;
// FIXME(eddyb) ignoring `obligations` might cause false positives.
drop(obligations);
// Require the type the impl is implemented on to match
// our type, and ignore the impl if there was a mismatch.
let Ok(eq_result) = infcx.at(&traits::ObligationCause::dummy(), param_env).eq(
DefineOpaqueTypes::Yes,
impl_trait_ref.self_ty(),
impl_ty,
) else {
continue;
};
let InferOk { value: (), obligations } = eq_result;
// FIXME(eddyb) ignoring `obligations` might cause false positives.
drop(obligations);

trace!(
"invoking predicate_may_hold: param_env={:?}, impl_trait_ref={:?}, impl_ty={:?}",
let predicates = tcx
.predicates_of(impl_def_id)
.instantiate(tcx, impl_args)
.predicates
.into_iter()
.chain(Some(ty::Binder::dummy(impl_trait_ref).to_predicate(tcx)));
for predicate in predicates {
let obligation = traits::Obligation::new(
tcx,
traits::ObligationCause::dummy(),
param_env,
impl_trait_ref,
impl_ty
predicate,
);
let predicates = cx
.tcx
.predicates_of(impl_def_id)
.instantiate(cx.tcx, impl_args)
.predicates
.into_iter()
.chain(Some(ty::Binder::dummy(impl_trait_ref).to_predicate(infcx.tcx)));
for predicate in predicates {
debug!("testing predicate {predicate:?}");
let obligation = traits::Obligation::new(
infcx.tcx,
traits::ObligationCause::dummy(),
param_env,
predicate,
);
match infcx.evaluate_obligation(&obligation) {
Ok(eval_result) if eval_result.may_apply() => {}
Err(traits::OverflowError::Canonical) => {}
_ => continue 'blanket_impls,
}
match infcx.evaluate_obligation(&obligation) {
Ok(eval_result) if eval_result.may_apply() => {}
Err(traits::OverflowError::Canonical) => {}
_ => continue 'blanket_impls,
}
debug!(
"get_blanket_impls: found applicable impl for trait_ref={:?}, ty={:?}",
trait_ref, ty
);
}
debug!("found applicable impl for trait ref {trait_ref:?}");

cx.generated_synthetics.insert((ty.skip_binder(), trait_def_id));
cx.generated_synthetics.insert((ty.skip_binder(), trait_def_id));

impls.push(Item {
name: None,
attrs: Default::default(),
item_id: ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id },
kind: Box::new(ImplItem(Box::new(Impl {
unsafety: hir::Unsafety::Normal,
generics: clean_ty_generics(
cx,
cx.tcx.generics_of(impl_def_id),
cx.tcx.explicit_predicates_of(impl_def_id),
),
// FIXME(eddyb) compute both `trait_` and `for_` from
// the post-inference `trait_ref`, as it's more accurate.
trait_: Some(clean_trait_ref_with_bindings(
cx,
ty::Binder::dummy(trait_ref.instantiate_identity()),
ThinVec::new(),
)),
for_: clean_middle_ty(
ty::Binder::dummy(ty.instantiate_identity()),
cx,
None,
None,
),
items: cx
.tcx
.associated_items(impl_def_id)
.in_definition_order()
.filter(|item| !item.is_impl_trait_in_trait())
.map(|item| clean_middle_assoc_item(item, cx))
.collect::<Vec<_>>(),
polarity: ty::ImplPolarity::Positive,
kind: ImplKind::Blanket(Box::new(clean_middle_ty(
ty::Binder::dummy(trait_ref.instantiate_identity().self_ty()),
cx,
None,
None,
))),
}))),
cfg: None,
inline_stmt_id: None,
});
}
blanket_impls.push(clean::Item {
name: None,
attrs: Default::default(),
item_id: clean::ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id },
kind: Box::new(clean::ImplItem(Box::new(clean::Impl {
unsafety: hir::Unsafety::Normal,
generics: clean_ty_generics(
cx,
tcx.generics_of(impl_def_id),
tcx.explicit_predicates_of(impl_def_id),
),
// FIXME(eddyb) compute both `trait_` and `for_` from
// the post-inference `trait_ref`, as it's more accurate.
trait_: Some(clean_trait_ref_with_bindings(
cx,
ty::Binder::dummy(trait_ref.instantiate_identity()),
ThinVec::new(),
)),
for_: clean_middle_ty(
ty::Binder::dummy(ty.instantiate_identity()),
cx,
None,
None,
),
items: tcx
.associated_items(impl_def_id)
.in_definition_order()
.filter(|item| !item.is_impl_trait_in_trait())
.map(|item| clean_middle_assoc_item(item, cx))
.collect(),
polarity: ty::ImplPolarity::Positive,
kind: clean::ImplKind::Blanket(Box::new(clean_middle_ty(
ty::Binder::dummy(trait_ref.instantiate_identity().self_ty()),
cx,
None,
None,
))),
}))),
cfg: None,
inline_stmt_id: None,
});
}

impls
}

blanket_impls
}
6 changes: 3 additions & 3 deletions src/librustdoc/clean/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -29,22 +29,22 @@ use rustc_middle::ty::{self, AdtKind, Ty, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_span::hygiene::{AstPass, MacroKind};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{self, ExpnKind};
use rustc_span::ExpnKind;
use rustc_trait_selection::traits::wf::object_region_bounds;

use std::borrow::Cow;
use std::collections::BTreeMap;
use std::mem;
use thin_vec::ThinVec;

use crate::core::{self, DocContext};
use crate::core::DocContext;
use crate::formats::item_type::ItemType;
use crate::visit_ast::Module as DocModule;

use utils::*;

pub(crate) use self::types::*;
pub(crate) use self::utils::{get_auto_trait_and_blanket_impls, krate, register_res};
pub(crate) use self::utils::{krate, register_res, synthesize_auto_trait_and_blanket_impls};

pub(crate) fn clean_doc_module<'tcx>(doc: &DocModule<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
let mut items: Vec<Item> = vec![];
Expand Down
9 changes: 4 additions & 5 deletions src/librustdoc/clean/utils.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
use crate::clean::auto_trait::synthesize_auto_trait_impls;
use crate::clean::blanket_impl::BlanketImplFinder;
use crate::clean::blanket_impl::synthesize_blanket_impls;
use crate::clean::render_macro_matchers::render_macro_matcher;
use crate::clean::{
clean_doc_module, clean_middle_const, clean_middle_region, clean_middle_ty, inline, Crate,
Expand Down Expand Up @@ -477,8 +477,7 @@ pub(crate) fn resolve_type(cx: &mut DocContext<'_>, path: Path) -> Type {
}
}

// FIXME(fmease): Update the `get_*` terminology to the `synthesize_` one.
pub(crate) fn get_auto_trait_and_blanket_impls(
pub(crate) fn synthesize_auto_trait_and_blanket_impls(
cx: &mut DocContext<'_>,
item_def_id: DefId,
) -> impl Iterator<Item = Item> {
Expand All @@ -490,8 +489,8 @@ pub(crate) fn get_auto_trait_and_blanket_impls(
let blanket_impls = cx
.sess()
.prof
.generic_activity("get_blanket_impls")
.run(|| BlanketImplFinder { cx }.get_blanket_impls(item_def_id));
.generic_activity("synthesize_blanket_impls")
.run(|| synthesize_blanket_impls(cx, item_def_id));
auto_impls.into_iter().chain(blanket_impls)
}

Expand Down
8 changes: 5 additions & 3 deletions src/librustdoc/passes/collect_trait_impls.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ pub(crate) fn collect_trait_impls(mut krate: Crate, cx: &mut DocContext<'_>) ->
_ => true,
}
}) {
let impls = get_auto_trait_and_blanket_impls(cx, def_id);
let impls = synthesize_auto_trait_and_blanket_impls(cx, def_id);
new_items_external.extend(impls.filter(|i| cx.inlined.insert(i.item_id)));
}
}
Expand Down Expand Up @@ -230,8 +230,10 @@ impl<'a, 'tcx> DocVisitor for SyntheticImplCollector<'a, 'tcx> {
if i.is_struct() || i.is_enum() || i.is_union() {
// FIXME(eddyb) is this `doc(hidden)` check needed?
if !self.cx.tcx.is_doc_hidden(i.item_id.expect_def_id()) {
self.impls
.extend(get_auto_trait_and_blanket_impls(self.cx, i.item_id.expect_def_id()));
self.impls.extend(synthesize_auto_trait_and_blanket_impls(
self.cx,
i.item_id.expect_def_id(),
));
}
}

Expand Down
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