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Revert "Auto merge of #79637 - spastorino:revert-trait-inheritance-self, r=Mark-Simulacrum" 

This reverts commit b4def89d76, reversing
changes made to 7dc1e852d4.
This commit is contained in:
Santiago Pastorino 2020-12-03 20:10:55 -03:00
parent 23adf9fd84
commit 7aa602b84c
No known key found for this signature in database
GPG Key ID: 8131A24E0C79EFAF
28 changed files with 500 additions and 152 deletions
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34
compiler/rustc_infer/src/traits/util.rs
View File

@ -1,9 +1,10 @@
use smallvec::smallvec;
use crate::traits::{Obligation, ObligationCause, PredicateObligation};
use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
use rustc_middle::ty::outlives::Component;
use rustc_middle::ty::{self, ToPredicate, TyCtxt, WithConstness};
use rustc_span::symbol::Ident;
pub fn anonymize_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
@ -282,6 +283,37 @@ pub fn transitive_bounds<'tcx>(
elaborate_trait_refs(tcx, bounds).filter_to_traits()
}
/// A specialized variant of `elaborate_trait_refs` that only elaborates trait references that may
/// define the given associated type `assoc_name`. It uses the
/// `super_predicates_that_define_assoc_type` query to avoid enumerating super-predicates that
/// aren't related to `assoc_item`. This is used when resolving types like `Self::Item` or
/// `T::Item` and helps to avoid cycle errors (see e.g. #35237).
pub fn transitive_bounds_that_define_assoc_type<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
assoc_name: Ident,
) -> FxIndexSet<ty::PolyTraitRef<'tcx>> {
let mut stack: Vec<_> = bounds.collect();
let mut trait_refs = FxIndexSet::default();
while let Some(trait_ref) = stack.pop() {
if trait_refs.insert(trait_ref) {
let super_predicates =
tcx.super_predicates_that_define_assoc_type((trait_ref.def_id(), Some(assoc_name)));
for (super_predicate, _) in super_predicates.predicates {
let bound_predicate = super_predicate.bound_atom();
let subst_predicate = super_predicate
.subst_supertrait(tcx, &bound_predicate.rebind(trait_ref.skip_binder()));
if let Some(binder) = subst_predicate.to_opt_poly_trait_ref() {
stack.push(binder.value);
}
}
}
}
trait_refs
}
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////

15
compiler/rustc_middle/src/query/mod.rs
View File

@ -443,12 +443,23 @@ rustc_queries! {
/// full predicates are available (note that supertraits have
/// additional acyclicity requirements).
query super_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
desc { |tcx| "computing the supertraits of `{}`", tcx.def_path_str(key) }
desc { |tcx| "computing the super predicates of `{}`", tcx.def_path_str(key) }
}
/// The `Option<Ident>` is the name of an associated type. If it is `None`, then this query
/// returns the full set of predicates. If `Some<Ident>`, then the query returns only the
/// subset of super-predicates that reference traits that define the given associated type.
/// This is used to avoid cycles in resolving types like `T::Item`.
query super_predicates_that_define_assoc_type(key: (DefId, Option<rustc_span::symbol::Ident>)) -> ty::GenericPredicates<'tcx> {
desc { |tcx| "computing the super traits of `{}`{}",
tcx.def_path_str(key.0),
if let Some(assoc_name) = key.1 { format!(" with associated type name `{}`", assoc_name) } else { "".to_string() },
}
}
/// To avoid cycles within the predicates of a single item we compute
/// per-type-parameter predicates for resolving `T::AssocTy`.
query type_param_predicates(key: (DefId, LocalDefId)) -> ty::GenericPredicates<'tcx> {
query type_param_predicates(key: (DefId, LocalDefId, rustc_span::symbol::Ident)) -> ty::GenericPredicates<'tcx> {
desc { |tcx| "computing the bounds for type parameter `{}`", {
let id = tcx.hir().local_def_id_to_hir_id(key.1);
tcx.hir().ty_param_name(id)

38
compiler/rustc_middle/src/ty/context.rs
View File

@ -52,7 +52,7 @@ use rustc_session::config::{BorrowckMode, CrateType, OutputFilenames};
use rustc_session::lint::{Level, Lint};
use rustc_session::Session;
use rustc_span::source_map::MultiSpan;
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{Span, DUMMY_SP};
use rustc_target::abi::{Layout, TargetDataLayout, VariantIdx};
use rustc_target::spec::abi;
@ -2053,6 +2053,42 @@ impl<'tcx> TyCtxt<'tcx> {
self.mk_fn_ptr(sig.map_bound(|sig| ty::FnSig { unsafety: hir::Unsafety::Unsafe, ..sig }))
}
/// Given the def_id of a Trait `trait_def_id` and the name of an associated item `assoc_name`
/// returns true if the `trait_def_id` defines an associated item of name `assoc_name`.
pub fn trait_may_define_assoc_type(self, trait_def_id: DefId, assoc_name: Ident) -> bool {
self.super_traits_of(trait_def_id).any(|trait_did| {
self.associated_items(trait_did)
.find_by_name_and_kind(self, assoc_name, ty::AssocKind::Type, trait_did)
.is_some()
})
}
/// Computes the def-ids of the transitive super-traits of `trait_def_id`. This (intentionally)
/// does not compute the full elaborated super-predicates but just the set of def-ids. It is used
/// to identify which traits may define a given associated type to help avoid cycle errors.
/// Returns a `DefId` iterator.
fn super_traits_of(self, trait_def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx {
let mut set = FxHashSet::default();
let mut stack = vec![trait_def_id];
set.insert(trait_def_id);
iter::from_fn(move || -> Option<DefId> {
let trait_did = stack.pop()?;
let generic_predicates = self.super_predicates_of(trait_did);
for (predicate, _) in generic_predicates.predicates {
if let ty::PredicateAtom::Trait(data, _) = predicate.skip_binders() {
if set.insert(data.def_id()) {
stack.push(data.def_id());
}
}
}
Some(trait_did)
})
}
/// Given a closure signature, returns an equivalent fn signature. Detuples
/// and so forth -- so e.g., if we have a sig with `Fn<(u32, i32)>` then
/// you would get a `fn(u32, i32)`.

24
compiler/rustc_middle/src/ty/query/keys.rs
View File

@ -7,7 +7,7 @@ use crate::ty::subst::{GenericArg, SubstsRef};
use crate::ty::{self, Ty, TyCtxt};
use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
use rustc_query_system::query::DefaultCacheSelector;
use rustc_span::symbol::Symbol;
use rustc_span::symbol::{Ident, Symbol};
use rustc_span::{Span, DUMMY_SP};
/// The `Key` trait controls what types can legally be used as the key
@ -160,6 +160,28 @@ impl Key for (LocalDefId, DefId) {
}
}
impl Key for (DefId, Option<Ident>) {
type CacheSelector = DefaultCacheSelector;
fn query_crate(&self) -> CrateNum {
self.0.krate
}
fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
tcx.def_span(self.0)
}
}
impl Key for (DefId, LocalDefId, Ident) {
type CacheSelector = DefaultCacheSelector;
fn query_crate(&self) -> CrateNum {
self.0.krate
}
fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
self.1.default_span(tcx)
}
}
impl Key for (CrateNum, DefId) {
type CacheSelector = DefaultCacheSelector;

3
compiler/rustc_trait_selection/src/traits/mod.rs
View File

@ -65,7 +65,8 @@ pub use self::util::{
get_vtable_index_of_object_method, impl_item_is_final, predicate_for_trait_def, upcast_choices,
};
pub use self::util::{
supertrait_def_ids, supertraits, transitive_bounds, SupertraitDefIds, Supertraits,
supertrait_def_ids, supertraits, transitive_bounds, transitive_bounds_that_define_assoc_type,
SupertraitDefIds, Supertraits,
};
pub use self::chalk_fulfill::FulfillmentContext as ChalkFulfillmentContext;

68
compiler/rustc_typeck/src/astconv/mod.rs
View File

@ -49,9 +49,10 @@ pub trait AstConv<'tcx> {
fn default_constness_for_trait_bounds(&self) -> Constness;
/// Returns predicates in scope of the form `X: Foo`, where `X` is
/// a type parameter `X` with the given id `def_id`. This is a
/// subset of the full set of predicates.
/// Returns predicates in scope of the form `X: Foo<T>`, where `X`
/// is a type parameter `X` with the given id `def_id` and T
/// matches `assoc_name`. This is a subset of the full set of
/// predicates.
///
/// This is used for one specific purpose: resolving "short-hand"
/// associated type references like `T::Item`. In principle, we
@ -60,7 +61,12 @@ pub trait AstConv<'tcx> {
/// but this can lead to cycle errors. The problem is that we have
/// to do this resolution *in order to create the predicates in
/// the first place*. Hence, we have this "special pass".
fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx>;
fn get_type_parameter_bounds(
&self,
span: Span,
def_id: DefId,
assoc_name: Ident,
) -> ty::GenericPredicates<'tcx>;
/// Returns the lifetime to use when a lifetime is omitted (and not elided).
fn re_infer(&self, param: Option<&ty::GenericParamDef>, span: Span)
@ -792,7 +798,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
}
// Returns `true` if a bounds list includes `?Sized`.
pub fn is_unsized(&self, ast_bounds: &[hir::GenericBound<'_>], span: Span) -> bool {
pub fn is_unsized(&self, ast_bounds: &[&hir::GenericBound<'_>], span: Span) -> bool {
let tcx = self.tcx();
// Try to find an unbound in bounds.
@ -850,7 +856,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
fn add_bounds(
&self,
param_ty: Ty<'tcx>,
ast_bounds: &[hir::GenericBound<'_>],
ast_bounds: &[&hir::GenericBound<'_>],
bounds: &mut Bounds<'tcx>,
) {
let constness = self.default_constness_for_trait_bounds();
@ -865,7 +871,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => self
.instantiate_lang_item_trait_ref(
lang_item, span, hir_id, args, param_ty, bounds,
*lang_item, *span, *hir_id, args, param_ty, bounds,
),
hir::GenericBound::Outlives(ref l) => bounds
.region_bounds
@ -896,6 +902,42 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
ast_bounds: &[hir::GenericBound<'_>],
sized_by_default: SizedByDefault,
span: Span,
) -> Bounds<'tcx> {
let ast_bounds: Vec<_> = ast_bounds.iter().collect();
self.compute_bounds_inner(param_ty, &ast_bounds, sized_by_default, span)
}
/// Convert the bounds in `ast_bounds` that refer to traits which define an associated type
/// named `assoc_name` into ty::Bounds. Ignore the rest.
pub fn compute_bounds_that_match_assoc_type(
&self,
param_ty: Ty<'tcx>,
ast_bounds: &[hir::GenericBound<'_>],
sized_by_default: SizedByDefault,
span: Span,
assoc_name: Ident,
) -> Bounds<'tcx> {
let mut result = Vec::new();
for ast_bound in ast_bounds {
if let Some(trait_ref) = ast_bound.trait_ref() {
if let Some(trait_did) = trait_ref.trait_def_id() {
if self.tcx().trait_may_define_assoc_type(trait_did, assoc_name) {
result.push(ast_bound);
}
}
}
}
self.compute_bounds_inner(param_ty, &result, sized_by_default, span)
}
fn compute_bounds_inner(
&self,
param_ty: Ty<'tcx>,
ast_bounds: &[&hir::GenericBound<'_>],
sized_by_default: SizedByDefault,
span: Span,
) -> Bounds<'tcx> {
let mut bounds = Bounds::default();
@ -1098,7 +1140,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
// parameter to have a skipped binder.
let param_ty =
tcx.mk_projection(assoc_ty.def_id, projection_ty.skip_binder().substs);
self.add_bounds(param_ty, ast_bounds, bounds);
let ast_bounds: Vec<_> = ast_bounds.iter().collect();
self.add_bounds(param_ty, &ast_bounds, bounds);
}
}
Ok(())
@ -1413,8 +1456,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
ty_param_def_id, assoc_name, span,
);
let predicates =
&self.get_type_parameter_bounds(span, ty_param_def_id.to_def_id()).predicates;
let predicates = &self
.get_type_parameter_bounds(span, ty_param_def_id.to_def_id(), assoc_name)
.predicates;
debug!("find_bound_for_assoc_item: predicates={:#?}", predicates);
@ -1422,12 +1466,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let param_name = tcx.hir().ty_param_name(param_hir_id);
self.one_bound_for_assoc_type(
|| {
traits::transitive_bounds(
traits::transitive_bounds_that_define_assoc_type(
tcx,
predicates.iter().filter_map(|(p, _)| {
p.to_opt_poly_trait_ref().map(|trait_ref| trait_ref.value)
}),
assoc_name,
)
.into_iter()
},
|| param_name.to_string(),
assoc_name,

8
compiler/rustc_typeck/src/check/fn_ctxt/mod.rs
View File

@ -20,6 +20,7 @@ use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty::{self, Const, Ty, TyCtxt};
use rustc_session::Session;
use rustc_span::symbol::Ident;
use rustc_span::{self, Span};
use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode};
@ -183,7 +184,12 @@ impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
}
}
fn get_type_parameter_bounds(&self, _: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
fn get_type_parameter_bounds(
&self,
_: Span,
def_id: DefId,
_: Ident,
) -> ty::GenericPredicates<'tcx> {
let tcx = self.tcx;
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
let item_id = tcx.hir().ty_param_owner(hir_id);

187
compiler/rustc_typeck/src/collect.rs
View File

@ -1,3 +1,4 @@
// ignore-tidy-filelength
//! "Collection" is the process of determining the type and other external
//! details of each item in Rust. Collection is specifically concerned
//! with *inter-procedural* things -- for example, for a function
@ -77,6 +78,7 @@ pub fn provide(providers: &mut Providers) {
projection_ty_from_predicates,
explicit_predicates_of,
super_predicates_of,
super_predicates_that_define_assoc_type,
trait_explicit_predicates_and_bounds,
type_param_predicates,
trait_def,
@ -308,8 +310,17 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
}
}
fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
self.tcx.at(span).type_param_predicates((self.item_def_id, def_id.expect_local()))
fn get_type_parameter_bounds(
&self,
span: Span,
def_id: DefId,
assoc_name: Ident,
) -> ty::GenericPredicates<'tcx> {
self.tcx.at(span).type_param_predicates((
self.item_def_id,
def_id.expect_local(),
assoc_name,
))
}
fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
@ -490,7 +501,7 @@ fn get_new_lifetime_name<'tcx>(
/// `X: Foo` where `X` is the type parameter `def_id`.
fn type_param_predicates(
tcx: TyCtxt<'_>,
(item_def_id, def_id): (DefId, LocalDefId),
(item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
) -> ty::GenericPredicates<'_> {
use rustc_hir::*;
@ -515,7 +526,7 @@ fn type_param_predicates(
let mut result = parent
.map(|parent| {
let icx = ItemCtxt::new(tcx, parent);
icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id())
icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
})
.unwrap_or_default();
let mut extend = None;
@ -558,12 +569,18 @@ fn type_param_predicates(
let icx = ItemCtxt::new(tcx, item_def_id);
let extra_predicates = extend.into_iter().chain(
icx.type_parameter_bounds_in_generics(ast_generics, param_id, ty, OnlySelfBounds(true))
.into_iter()
.filter(|(predicate, _)| match predicate.kind().skip_binder() {
ty::PredicateKind::Trait(data, _) => data.self_ty().is_param(index),
_ => false,
}),
icx.type_parameter_bounds_in_generics(
ast_generics,
param_id,
ty,
OnlySelfBounds(true),
Some(assoc_name),
)
.into_iter()
.filter(|(predicate, _)| match predicate.kind().skip_binder() {
ty::PredicateAtom::Trait(data, _) => data.self_ty().is_param(index),
_ => false,
}),
);
result.predicates =
tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
@ -581,6 +598,7 @@ impl ItemCtxt<'tcx> {
param_id: hir::HirId,
ty: Ty<'tcx>,
only_self_bounds: OnlySelfBounds,
assoc_name: Option<Ident>,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
let constness = self.default_constness_for_trait_bounds();
let from_ty_params = ast_generics
@ -591,6 +609,10 @@ impl ItemCtxt<'tcx> {
_ => None,
})
.flat_map(|bounds| bounds.iter())
.filter(|b| match assoc_name {
Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
None => true,
})
.flat_map(|b| predicates_from_bound(self, ty, b, constness));
let from_where_clauses = ast_generics
@ -609,12 +631,34 @@ impl ItemCtxt<'tcx> {
} else {
None
};
bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
bp.bounds
.iter()
.filter(|b| match assoc_name {
Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
None => true,
})
.filter_map(move |b| bt.map(|bt| (bt, b)))
})
.flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
from_ty_params.chain(from_where_clauses).collect()
}
fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
debug!("bound_defines_assoc_item(b={:?}, assoc_name={:?})", b, assoc_name);
match b {
hir::GenericBound::Trait(poly_trait_ref, _) => {
let trait_ref = &poly_trait_ref.trait_ref;
if let Some(trait_did) = trait_ref.trait_def_id() {
self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
} else {
false
}
}
_ => false,
}
}
}
/// Tests whether this is the AST for a reference to the type
@ -983,54 +1027,91 @@ fn adt_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::AdtDef {
/// the transitive super-predicates are converted.
fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> {
debug!("super_predicates(trait_def_id={:?})", trait_def_id);
let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
}
let item = match tcx.hir().get(trait_hir_id) {
Node::Item(item) => item,
_ => bug!("trait_node_id {} is not an item", trait_hir_id),
};
let (generics, bounds) = match item.kind {
hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
_ => span_bug!(item.span, "super_predicates invoked on non-trait"),
};
let icx = ItemCtxt::new(tcx, trait_def_id);
// Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
let self_param_ty = tcx.types.self_param;
let superbounds1 =
AstConv::compute_bounds(&icx, self_param_ty, bounds, SizedByDefault::No, item.span);
let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
// Convert any explicit superbounds in the where-clause,
// e.g., `trait Foo where Self: Bar`.
// In the case of trait aliases, however, we include all bounds in the where-clause,
// so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
// as one of its "superpredicates".
let is_trait_alias = tcx.is_trait_alias(trait_def_id);
let superbounds2 = icx.type_parameter_bounds_in_generics(
generics,
item.hir_id,
self_param_ty,
OnlySelfBounds(!is_trait_alias),
/// Ensures that the super-predicates of the trait with a `DefId`
/// of `trait_def_id` are converted and stored. This also ensures that
/// the transitive super-predicates are converted.
fn super_predicates_that_define_assoc_type(
tcx: TyCtxt<'_>,
(trait_def_id, assoc_name): (DefId, Option<Ident>),
) -> ty::GenericPredicates<'_> {
debug!(
"super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})",
trait_def_id, assoc_name
);
if trait_def_id.is_local() {
debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id);
let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
// Combine the two lists to form the complete set of superbounds:
let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
let item = match tcx.hir().get(trait_hir_id) {
Node::Item(item) => item,
_ => bug!("trait_node_id {} is not an item", trait_hir_id),
};
// Now require that immediate supertraits are converted,
// which will, in turn, reach indirect supertraits.
for &(pred, span) in superbounds {
debug!("superbound: {:?}", pred);
if let ty::PredicateKind::Trait(bound, _) = pred.kind().skip_binder() {
tcx.at(span).super_predicates_of(bound.def_id());
let (generics, bounds) = match item.kind {
hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
_ => span_bug!(item.span, "super_predicates invoked on non-trait"),
};
let icx = ItemCtxt::new(tcx, trait_def_id);
// Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
let self_param_ty = tcx.types.self_param;
let superbounds1 = if let Some(assoc_name) = assoc_name {
AstConv::compute_bounds_that_match_assoc_type(
&icx,
self_param_ty,
&bounds,
SizedByDefault::No,
item.span,
assoc_name,
)
} else {
AstConv::compute_bounds(&icx, self_param_ty, &bounds, SizedByDefault::No, item.span)
};
let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
// Convert any explicit superbounds in the where-clause,
// e.g., `trait Foo where Self: Bar`.
// In the case of trait aliases, however, we include all bounds in the where-clause,
// so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
// as one of its "superpredicates".
let is_trait_alias = tcx.is_trait_alias(trait_def_id);
let superbounds2 = icx.type_parameter_bounds_in_generics(
generics,
item.hir_id,
self_param_ty,
OnlySelfBounds(!is_trait_alias),
assoc_name,
);
// Combine the two lists to form the complete set of superbounds:
let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
// Now require that immediate supertraits are converted,
// which will, in turn, reach indirect supertraits.
if assoc_name.is_none() {
// Now require that immediate supertraits are converted,
// which will, in turn, reach indirect supertraits.
for &(pred, span) in superbounds {
debug!("superbound: {:?}", pred);
if let ty::PredicateKind::Trait(bound, _) = pred.kind().skip_binder() {
tcx.at(span).super_predicates_of(bound.def_id());
}
}
}
}
ty::GenericPredicates { parent: None, predicates: superbounds }
ty::GenericPredicates { parent: None, predicates: superbounds }
} else {
// if `assoc_name` is None, then the query should've been redirected to an
// external provider
assert!(assoc_name.is_some());
tcx.super_predicates_of(trait_def_id)
}
}
fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {

4
compiler/rustc_typeck/src/collect/item_bounds.rs
View File

@ -28,7 +28,7 @@ fn associated_type_bounds<'tcx>(
let bounds = AstConv::compute_bounds(
&ItemCtxt::new(tcx, assoc_item_def_id),
item_ty,
bounds,
&bounds,
SizedByDefault::Yes,
span,
);
@ -69,7 +69,7 @@ fn opaque_type_bounds<'tcx>(
let bounds = AstConv::compute_bounds(
&ItemCtxt::new(tcx, opaque_def_id),
item_ty,
bounds,
&bounds,
SizedByDefault::Yes,
span,
)

10
src/test/incremental/cyclic-trait-hierarchy.rs
View File

@ -3,11 +3,11 @@
// revisions: rpass1 cfail2
#[cfg(rpass1)]
pub trait T2 { }
pub trait T2 {}
#[cfg(cfail2)]
pub trait T2: T1 { }
//[cfail2]~^ ERROR cycle detected when computing the supertraits of `T2`
pub trait T2: T1 {}
//[cfail2]~^ ERROR cycle detected when computing the super predicates of `T2`
pub trait T1: T2 { }
pub trait T1: T2 {}
fn main() { }
fn main() {}

12
src/test/ui/associated-type-bounds/ambiguous-associated-type2.rs Normal file
View File

@ -0,0 +1,12 @@
// ignore-tidy-linelength
trait Foo {
type Item;
}
trait Bar<T> {
type Item;
}
trait Baz: Foo + Bar<Self::Item> {}
//~^ ERROR cycle detected when computing the super traits of `Baz` with associated type name `Item` [E0391]
fn main() {}

16
src/test/ui/associated-type-bounds/ambiguous-associated-type2.stderr Normal file
View File

@ -0,0 +1,16 @@
error[E0391]: cycle detected when computing the super traits of `Baz` with associated type name `Item`
--> $DIR/ambiguous-associated-type2.rs:9:1
|
LL | trait Baz: Foo + Bar<Self::Item> {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: ...which again requires computing the super traits of `Baz` with associated type name `Item`, completing the cycle
note: cycle used when computing the super traits of `Baz`
--> $DIR/ambiguous-associated-type2.rs:9:1
|
LL | trait Baz: Foo + Bar<Self::Item> {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0391`.

21
src/test/ui/associated-type-bounds/associated-item-through-where-clause.rs Normal file
View File

@ -0,0 +1,21 @@
// check-pass
trait Foo {
type Item;
}
trait Bar
where
Self: Foo,
{
}
#[allow(dead_code)]
fn foo<M>(_m: M)
where
M: Bar,
M::Item: Send,
{
}
fn main() {}

10
src/test/ui/associated-type-bounds/handle-predicates-that-can-define-assoc-type.rs Normal file
View File

@ -0,0 +1,10 @@
// check-pass
trait Foo<T> {}
trait Bar {
type A;
type B;
}
trait Baz: Bar<B = u32> + Foo<Self::A> {}
fn main() {}

10
src/test/ui/associated-type-bounds/missing-trait-bound-for-assoc-fails.rs Normal file
View File

@ -0,0 +1,10 @@
#[allow(dead_code)]
fn foo<M>(_m: M)
where
M::Item: Temp,
//~^ ERROR cannot find trait `Temp` in this scope [E0405]
//~| ERROR associated type `Item` not found for `M` [E0220]
{
}
fn main() {}

16
src/test/ui/associated-type-bounds/missing-trait-bound-for-assoc-fails.stderr Normal file
View File

@ -0,0 +1,16 @@
error[E0405]: cannot find trait `Temp` in this scope
--> $DIR/missing-trait-bound-for-assoc-fails.rs:4:14
|
LL | M::Item: Temp,
| ^^^^ not found in this scope
error[E0220]: associated type `Item` not found for `M`
--> $DIR/missing-trait-bound-for-assoc-fails.rs:4:8
|
LL | M::Item: Temp,
| ^^^^ associated type `Item` not found
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0220, E0405.
For more information about an error, try `rustc --explain E0220`.

12
src/test/ui/associated-type-bounds/super-trait-referencing-self.rs Normal file
View File

@ -0,0 +1,12 @@
// check-pass
trait Foo {
type Bar;
}
trait Qux: Foo + AsRef<Self::Bar> {}
trait Foo2 {}
trait Qux2: Foo2 + AsRef<Self::Bar> {
type Bar;
}
fn main() {}

19
src/test/ui/associated-type-bounds/super-trait-referencing.rs Normal file
View File

@ -0,0 +1,19 @@
// check-pass
// The goal of this test is to ensure that T: Bar<T::Item>
// in the where clause does not cycle
trait Foo {
type Item;
}
trait Bar<T> {}
fn baz<T>()
where
T: Foo,
T: Bar<T::Item>,
{
}
fn main() {}

27
src/test/ui/associated-type-bounds/super-trait-where-referencing-self.rs Normal file
View File

@ -0,0 +1,27 @@
// check-pass
// Test that we do not get a cycle due to
// resolving `Self::Bar` in the where clauses
// on a trait definition (in particular, in
// a where clause that is defining a superpredicate).
trait Foo {
type Bar;
}
trait Qux
where
Self: Foo,
Self: AsRef<Self::Bar>,
{
}
trait Foo2 {}
trait Qux2
where
Self: Foo2,
Self: AsRef<Self::Bar>,
{
type Bar;
}
fn main() {}

24
src/test/ui/cycle-projection-based-on-where-clause.rs
View File

@ -1,24 +0,0 @@
// Example cycle where a bound on `T` uses a shorthand for `T`. This
// creates a cycle because we have to know the bounds on `T` to figure
// out what trait defines `Item`, but we can't know the bounds on `T`
// without knowing how to handle `T::Item`.
//
// Note that in the future cases like this could perhaps become legal,
// if we got more fine-grained about our cycle detection or changed
// how we handle `T::Item` resolution.
use std::ops::Add;
// Preamble.
trait Trait { type Item; }
struct A<T>
where T : Trait,
T : Add<T::Item>
//~^ ERROR cycle detected
{
data: T
}
fn main() {
}

16
src/test/ui/cycle-projection-based-on-where-clause.stderr
View File

@ -1,16 +0,0 @@
error[E0391]: cycle detected when computing the bounds for type parameter `T`
--> $DIR/cycle-projection-based-on-where-clause.rs:17:19
|
LL | T : Add<T::Item>
| ^^^^^^^
|
= note: ...which again requires computing the bounds for type parameter `T`, completing the cycle
note: cycle used when computing explicit predicates of `A`
--> $DIR/cycle-projection-based-on-where-clause.rs:17:19
|
LL | T : Add<T::Item>
| ^^^^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0391`.

11
src/test/ui/cycle-trait/cycle-trait-supertrait-direct.stderr
View File

@ -1,10 +1,15 @@
error[E0391]: cycle detected when computing the supertraits of `Chromosome`
error[E0391]: cycle detected when computing the super predicates of `Chromosome`
--> $DIR/cycle-trait-supertrait-direct.rs:3:1
|
LL | trait Chromosome: Chromosome {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: ...which requires computing the super traits of `Chromosome`...
--> $DIR/cycle-trait-supertrait-direct.rs:3:19
|
LL | trait Chromosome: Chromosome {
| ^^^^^^^^^^
|
= note: ...which again requires computing the supertraits of `Chromosome`, completing the cycle
= note: ...which again requires computing the super predicates of `Chromosome`, completing the cycle
note: cycle used when collecting item types in top-level module
--> $DIR/cycle-trait-supertrait-direct.rs:3:1
|

18
src/test/ui/cycle-trait/cycle-trait-supertrait-indirect.stderr
View File

@ -1,16 +1,26 @@
error[E0391]: cycle detected when computing the supertraits of `B`
error[E0391]: cycle detected when computing the super predicates of `B`
--> $DIR/cycle-trait-supertrait-indirect.rs:7:1
|
LL | trait B: C {
| ^^^^^^^^^^
|
note: ...which requires computing the super traits of `B`...
--> $DIR/cycle-trait-supertrait-indirect.rs:7:10
|
LL | trait B: C {
| ^
note: ...which requires computing the super predicates of `C`...
--> $DIR/cycle-trait-supertrait-indirect.rs:11:1
|
note: ...which requires computing the supertraits of `C`...
LL | trait C: B { }
| ^^^^^^^^^^
note: ...which requires computing the super traits of `C`...
--> $DIR/cycle-trait-supertrait-indirect.rs:11:10
|
LL | trait C: B { }
| ^
= note: ...which again requires computing the supertraits of `B`, completing the cycle
note: cycle used when computing the supertraits of `A`
= note: ...which again requires computing the super predicates of `B`, completing the cycle
note: cycle used when computing the super traits of `A`
--> $DIR/cycle-trait-supertrait-indirect.rs:4:10
|
LL | trait A: B {

16
src/test/ui/issues/issue-12511.stderr
View File

@ -1,15 +1,25 @@
error[E0391]: cycle detected when computing the supertraits of `T1`
error[E0391]: cycle detected when computing the super predicates of `T1`
--> $DIR/issue-12511.rs:1:1
|
LL | trait T1 : T2 {
| ^^^^^^^^^^^^^
|
note: ...which requires computing the super traits of `T1`...
--> $DIR/issue-12511.rs:1:12
|
LL | trait T1 : T2 {
| ^^
note: ...which requires computing the super predicates of `T2`...
--> $DIR/issue-12511.rs:5:1
|
note: ...which requires computing the supertraits of `T2`...
LL | trait T2 : T1 {
| ^^^^^^^^^^^^^
note: ...which requires computing the super traits of `T2`...
--> $DIR/issue-12511.rs:5:12
|
LL | trait T2 : T1 {
| ^^
= note: ...which again requires computing the supertraits of `T1`, completing the cycle
= note: ...which again requires computing the super predicates of `T1`, completing the cycle
note: cycle used when collecting item types in top-level module
--> $DIR/issue-12511.rs:1:1
|

6
src/test/ui/issues/issue-20772.stderr
View File

@ -1,4 +1,4 @@
error[E0391]: cycle detected when computing the supertraits of `T`
error[E0391]: cycle detected when computing the super traits of `T` with associated type name `Item`
--> $DIR/issue-20772.rs:1:1
|
LL | / trait T : Iterator<Item=Self::Item>
@ -6,8 +6,8 @@ LL | |
LL | | {}
| |__^
|
= note: ...which again requires computing the supertraits of `T`, completing the cycle
note: cycle used when collecting item types in top-level module
= note: ...which again requires computing the super traits of `T` with associated type name `Item`, completing the cycle
note: cycle used when computing the super traits of `T`
--> $DIR/issue-20772.rs:1:1
|
LL | / trait T : Iterator<Item=Self::Item>

6
src/test/ui/issues/issue-20825.stderr
View File

@ -1,11 +1,11 @@
error[E0391]: cycle detected when computing the supertraits of `Processor`
error[E0391]: cycle detected when computing the super traits of `Processor` with associated type name `Input`
--> $DIR/issue-20825.rs:5:1
|
LL | pub trait Processor: Subscriber<Input = Self::Input> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: ...which again requires computing the supertraits of `Processor`, completing the cycle
note: cycle used when collecting item types in top-level module
= note: ...which again requires computing the super traits of `Processor` with associated type name `Input`, completing the cycle
note: cycle used when computing the super traits of `Processor`
--> $DIR/issue-20825.rs:5:1
|
LL | pub trait Processor: Subscriber<Input = Self::Input> {

5
src/test/ui/issues/issue-22673.rs
View File

@ -1,5 +1,6 @@
trait Expr : PartialEq<Self::Item> {
//~^ ERROR: cycle detected
// check-pass
trait Expr: PartialEq<Self::Item> {
type Item;
}

16
src/test/ui/issues/issue-22673.stderr
View File

@ -1,16 +0,0 @@
error[E0391]: cycle detected when computing the supertraits of `Expr`
--> $DIR/issue-22673.rs:1:1
|
LL | trait Expr : PartialEq<Self::Item> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: ...which again requires computing the supertraits of `Expr`, completing the cycle
note: cycle used when collecting item types in top-level module
--> $DIR/issue-22673.rs:1:1
|
LL | trait Expr : PartialEq<Self::Item> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0391`.