use rustc_middle::hir::map::Map;
use rustc_middle::hir::nested_filter;
use rustc_middle::middle::resolve_lifetime::*;
-use rustc_middle::ty::{self, DefIdTree, TyCtxt};
+use rustc_middle::ty::{self, DefIdTree, TyCtxt, TypeSuperVisitable, TypeVisitor};
use rustc_span::def_id::DefId;
use rustc_span::symbol::{sym, Ident};
use rustc_span::Span;
tcx: TyCtxt<'tcx>,
map: &'a mut NamedRegionMap,
scope: ScopeRef<'a>,
-
- /// Indicates that we only care about the definition of a trait. This should
- /// be false if the `Item` we are resolving lifetimes for is not a trait or
- /// we eventually need lifetimes resolve for trait items.
- trait_definition_only: bool,
}
#[derive(Debug)]
s: ScopeRef<'a>,
},
- Root,
+ Root {
+ opt_parent_item: Option<LocalDefId>,
+ },
}
#[derive(Copy, Clone, Debug)]
.field("s", &"..")
.finish(),
Scope::TraitRefBoundary { s: _ } => f.debug_struct("TraitRefBoundary").finish(),
- Scope::Root => f.debug_struct("Root").finish(),
+ Scope::Root { opt_parent_item } => {
+ f.debug_struct("Root").field("opt_parent_item", &opt_parent_item).finish()
+ }
}
}
}
type ScopeRef<'a> = &'a Scope<'a>;
-const ROOT_SCOPE: ScopeRef<'static> = &Scope::Root;
-
pub(crate) fn provide(providers: &mut ty::query::Providers) {
*providers = ty::query::Providers {
- resolve_lifetimes_trait_definition,
resolve_lifetimes,
- named_region_map: |tcx, id| resolve_lifetimes_for(tcx, id).defs.get(&id),
+ named_region_map: |tcx, id| tcx.resolve_lifetimes(id).defs.get(&id),
is_late_bound_map,
object_lifetime_default,
- late_bound_vars_map: |tcx, id| resolve_lifetimes_for(tcx, id).late_bound_vars.get(&id),
+ late_bound_vars_map: |tcx, id| tcx.resolve_lifetimes(id).late_bound_vars.get(&id),
..*providers
};
}
-/// Like `resolve_lifetimes`, but does not resolve lifetimes for trait items.
-/// Also does not generate any diagnostics.
-///
-/// This is ultimately a subset of the `resolve_lifetimes` work. It effectively
-/// resolves lifetimes only within the trait "header" -- that is, the trait
-/// and supertrait list. In contrast, `resolve_lifetimes` resolves all the
-/// lifetimes within the trait and its items. There is room to refactor this,
-/// for example to resolve lifetimes for each trait item in separate queries,
-/// but it's convenient to do the entire trait at once because the lifetimes
-/// from the trait definition are in scope within the trait items as well.
-///
-/// The reason for this separate call is to resolve what would otherwise
-/// be a cycle. Consider this example:
-///
-/// ```ignore UNSOLVED (maybe @jackh726 knows what lifetime parameter to give Sub)
-/// trait Base<'a> {
-/// type BaseItem;
-/// }
-/// trait Sub<'b>: for<'a> Base<'a> {
-/// type SubItem: Sub<BaseItem = &'b u32>;
-/// }
-/// ```
-///
-/// When we resolve `Sub` and all its items, we also have to resolve `Sub<BaseItem = &'b u32>`.
-/// To figure out the index of `'b`, we have to know about the supertraits
-/// of `Sub` so that we can determine that the `for<'a>` will be in scope.
-/// (This is because we -- currently at least -- flatten all the late-bound
-/// lifetimes into a single binder.) This requires us to resolve the
-/// *trait definition* of `Sub`; basically just enough lifetime information
-/// to look at the supertraits.
-#[instrument(level = "debug", skip(tcx))]
-fn resolve_lifetimes_trait_definition(
- tcx: TyCtxt<'_>,
- local_def_id: LocalDefId,
-) -> ResolveLifetimes {
- convert_named_region_map(do_resolve(tcx, local_def_id, true))
-}
-
/// Computes the `ResolveLifetimes` map that contains data for an entire `Item`.
/// You should not read the result of this query directly, but rather use
/// `named_region_map`, `is_late_bound_map`, etc.
#[instrument(level = "debug", skip(tcx))]
-fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> ResolveLifetimes {
- convert_named_region_map(do_resolve(tcx, local_def_id, false))
-}
-
-fn do_resolve(
- tcx: TyCtxt<'_>,
- local_def_id: LocalDefId,
- trait_definition_only: bool,
-) -> NamedRegionMap {
- let item = tcx.hir().expect_item(local_def_id);
+fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: hir::OwnerId) -> ResolveLifetimes {
let mut named_region_map =
NamedRegionMap { defs: Default::default(), late_bound_vars: Default::default() };
let mut visitor = LifetimeContext {
tcx,
map: &mut named_region_map,
- scope: ROOT_SCOPE,
- trait_definition_only,
+ scope: &Scope::Root { opt_parent_item: None },
};
- visitor.visit_item(item);
-
- named_region_map
-}
+ match tcx.hir().owner(local_def_id) {
+ hir::OwnerNode::Item(item) => visitor.visit_item(item),
+ hir::OwnerNode::ForeignItem(item) => visitor.visit_foreign_item(item),
+ hir::OwnerNode::TraitItem(item) => {
+ let scope =
+ Scope::Root { opt_parent_item: Some(tcx.local_parent(item.owner_id.def_id)) };
+ visitor.scope = &scope;
+ visitor.visit_trait_item(item)
+ }
+ hir::OwnerNode::ImplItem(item) => {
+ let scope =
+ Scope::Root { opt_parent_item: Some(tcx.local_parent(item.owner_id.def_id)) };
+ visitor.scope = &scope;
+ visitor.visit_impl_item(item)
+ }
+ hir::OwnerNode::Crate(_) => {}
+ }
-fn convert_named_region_map(named_region_map: NamedRegionMap) -> ResolveLifetimes {
let mut rl = ResolveLifetimes::default();
for (hir_id, v) in named_region_map.defs {
rl
}
-/// Given `any` owner (structs, traits, trait methods, etc.), does lifetime resolution.
-/// There are two important things this does.
-/// First, we have to resolve lifetimes for
-/// the entire *`Item`* that contains this owner, because that's the largest "scope"
-/// where we can have relevant lifetimes.
-/// Second, if we are asking for lifetimes in a trait *definition*, we use `resolve_lifetimes_trait_definition`
-/// instead of `resolve_lifetimes`, which does not descend into the trait items and does not emit diagnostics.
-/// This allows us to avoid cycles. Importantly, if we ask for lifetimes for lifetimes that have an owner
-/// other than the trait itself (like the trait methods or associated types), then we just use the regular
-/// `resolve_lifetimes`.
-fn resolve_lifetimes_for<'tcx>(tcx: TyCtxt<'tcx>, def_id: hir::OwnerId) -> &'tcx ResolveLifetimes {
- let item_id = item_for(tcx, def_id.def_id);
- let local_def_id = item_id.owner_id.def_id;
- if item_id.owner_id == def_id {
- let item = tcx.hir().item(item_id);
- match item.kind {
- hir::ItemKind::Trait(..) => tcx.resolve_lifetimes_trait_definition(local_def_id),
- _ => tcx.resolve_lifetimes(local_def_id),
- }
- } else {
- tcx.resolve_lifetimes(local_def_id)
- }
-}
-
-/// Finds the `Item` that contains the given `LocalDefId`
-fn item_for(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> hir::ItemId {
- match tcx.hir().find_by_def_id(local_def_id) {
- Some(Node::Item(item)) => {
- return item.item_id();
- }
- _ => {}
- }
- let item = {
- let hir_id = tcx.hir().local_def_id_to_hir_id(local_def_id);
- let mut parent_iter = tcx.hir().parent_iter(hir_id);
- loop {
- let node = parent_iter.next().map(|n| n.1);
- match node {
- Some(hir::Node::Item(item)) => break item.item_id(),
- Some(hir::Node::Crate(_)) | None => bug!("Called `item_for` on an Item."),
- _ => {}
- }
- }
- };
- item
-}
-
fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::BoundVariableKind {
match region {
Region::LateBound(_, _, def_id) => {
let mut supertrait_lifetimes = vec![];
loop {
match scope {
- Scope::Body { .. } | Scope::Root => {
+ Scope::Body { .. } | Scope::Root { .. } => {
break (vec![], BinderScopeType::Normal);
}
}
}
impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
- type NestedFilter = nested_filter::All;
+ type NestedFilter = nested_filter::OnlyBodies;
fn nested_visit_map(&mut self) -> Self::Map {
self.tcx.hir()
}
- // We want to nest trait/impl items in their parent, but nothing else.
- fn visit_nested_item(&mut self, _: hir::ItemId) {}
-
- fn visit_trait_item_ref(&mut self, ii: &'tcx hir::TraitItemRef) {
- if !self.trait_definition_only {
- intravisit::walk_trait_item_ref(self, ii)
- }
- }
-
fn visit_nested_body(&mut self, body: hir::BodyId) {
let body = self.tcx.hir().body(body);
self.with(Scope::Body { id: body.id(), s: self.scope }, |this| {
intravisit::walk_item(this, item)
});
}
- hir::ItemKind::OpaqueTy(hir::OpaqueTy { .. }) => {
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy {
+ origin: hir::OpaqueTyOrigin::TyAlias, ..
+ }) => {
// Opaque types are visited when we visit the
// `TyKind::OpaqueDef`, so that they have the lifetimes from
// their parent opaque_ty in scope.
// their owner, we can keep going until we find the Item that owns that. We then
// conservatively add all resolved lifetimes. Otherwise we run into problems in
// cases like `type Foo<'a> = impl Bar<As = impl Baz + 'a>`.
- for (_hir_id, node) in self.tcx.hir().parent_iter(item.owner_id.into()) {
- match node {
- hir::Node::Item(parent_item) => {
- let resolved_lifetimes: &ResolveLifetimes = self.tcx.resolve_lifetimes(
- item_for(self.tcx, parent_item.owner_id.def_id).owner_id.def_id,
- );
- // We need to add *all* deps, since opaque tys may want them from *us*
- for (&owner, defs) in resolved_lifetimes.defs.iter() {
- defs.iter().for_each(|(&local_id, region)| {
- self.map.defs.insert(hir::HirId { owner, local_id }, *region);
- });
- }
- for (&owner, late_bound_vars) in
- resolved_lifetimes.late_bound_vars.iter()
- {
- late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| {
- self.record_late_bound_vars(
- hir::HirId { owner, local_id },
- late_bound_vars.clone(),
- );
- });
- }
- break;
+ let parent_item = self.tcx.hir().get_parent_item(item.hir_id());
+ let resolved_lifetimes: &ResolveLifetimes = self.tcx.resolve_lifetimes(parent_item);
+ // We need to add *all* deps, since opaque tys may want them from *us*
+ for (&owner, defs) in resolved_lifetimes.defs.iter() {
+ defs.iter().for_each(|(&local_id, region)| {
+ self.map.defs.insert(hir::HirId { owner, local_id }, *region);
+ });
+ }
+ for (&owner, late_bound_vars) in resolved_lifetimes.late_bound_vars.iter() {
+ late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| {
+ self.record_late_bound_vars(
+ hir::HirId { owner, local_id },
+ late_bound_vars.clone(),
+ );
+ });
+ }
+ }
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy {
+ origin: hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_),
+ generics,
+ ..
+ }) => {
+ // We want to start our early-bound indices at the end of the parent scope,
+ // not including any parent `impl Trait`s.
+ let mut lifetimes = FxIndexMap::default();
+ debug!(?generics.params);
+ for param in generics.params {
+ match param.kind {
+ GenericParamKind::Lifetime { .. } => {
+ let (def_id, reg) = Region::early(self.tcx.hir(), ¶m);
+ lifetimes.insert(def_id, reg);
}
- hir::Node::Crate(_) => bug!("No Item about an OpaqueTy"),
- _ => {}
+ GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {}
}
}
+
+ let scope = Scope::Binder {
+ hir_id: item.hir_id(),
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ let scope = Scope::TraitRefBoundary { s: this.scope };
+ this.with(scope, |this| intravisit::walk_item(this, item))
+ });
}
hir::ItemKind::TyAlias(_, ref generics)
| hir::ItemKind::Enum(_, ref generics)
hir_id: item.hir_id(),
lifetimes,
scope_type: BinderScopeType::Normal,
- s: ROOT_SCOPE,
+ s: self.scope,
where_bound_origin: None,
};
self.with(scope, |this| {
// ^ ^ this gets resolved in the scope of
// the opaque_ty generics
let opaque_ty = self.tcx.hir().item(item_id);
- let (generics, bounds) = match opaque_ty.kind {
+ match opaque_ty.kind {
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias,
..
}
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
- ref generics,
- bounds,
..
- }) => (generics, bounds),
+ }) => {}
ref i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i),
};
// Ensure that the parent of the def is an item, not HRTB
let parent_id = self.tcx.hir().get_parent_node(hir_id);
if !parent_id.is_owner() {
- if !self.trait_definition_only {
- struct_span_err!(
- self.tcx.sess,
- lifetime.span,
- E0657,
- "`impl Trait` can only capture lifetimes \
- bound at the fn or impl level"
- )
- .emit();
- }
+ struct_span_err!(
+ self.tcx.sess,
+ lifetime.span,
+ E0657,
+ "`impl Trait` can only capture lifetimes bound at the fn or impl level"
+ )
+ .emit();
self.uninsert_lifetime_on_error(lifetime, def.unwrap());
}
if let hir::Node::Item(hir::Item {
kind: hir::ItemKind::OpaqueTy { .. }, ..
}) = self.tcx.hir().get(parent_id)
{
- if !self.trait_definition_only {
- let mut err = self.tcx.sess.struct_span_err(
- lifetime.span,
- "higher kinded lifetime bounds on nested opaque types are not supported yet",
- );
- err.span_note(self.tcx.def_span(def_id), "lifetime declared here");
- err.emit();
- }
+ let mut err = self.tcx.sess.struct_span_err(
+ lifetime.span,
+ "higher kinded lifetime bounds on nested opaque types are not supported yet",
+ );
+ err.span_note(self.tcx.def_span(def_id), "lifetime declared here");
+ err.emit();
self.uninsert_lifetime_on_error(lifetime, def.unwrap());
}
}
-
- // We want to start our early-bound indices at the end of the parent scope,
- // not including any parent `impl Trait`s.
- let mut lifetimes = FxIndexMap::default();
- debug!(?generics.params);
- for param in generics.params {
- match param.kind {
- GenericParamKind::Lifetime { .. } => {
- let (def_id, reg) = Region::early(self.tcx.hir(), ¶m);
- lifetimes.insert(def_id, reg);
- }
- GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {}
- }
- }
- self.record_late_bound_vars(ty.hir_id, vec![]);
-
- let scope = Scope::Binder {
- hir_id: ty.hir_id,
- lifetimes,
- s: self.scope,
- scope_type: BinderScopeType::Normal,
- where_bound_origin: None,
- };
- self.with(scope, |this| {
- let scope = Scope::TraitRefBoundary { s: this.scope };
- this.with(scope, |this| {
- this.visit_generics(generics);
- for bound in bounds {
- this.visit_param_bound(bound);
- }
- })
- });
}
_ => intravisit::walk_ty(self, ty),
}
F: for<'b> FnOnce(&mut LifetimeContext<'b, 'tcx>),
{
let LifetimeContext { tcx, map, .. } = self;
- let mut this = LifetimeContext {
- tcx: *tcx,
- map,
- scope: &wrap_scope,
- trait_definition_only: self.trait_definition_only,
- };
+ let mut this = LifetimeContext { tcx: *tcx, map, scope: &wrap_scope };
let span = debug_span!("scope", scope = ?TruncatedScopeDebug(&this.scope));
{
let _enter = span.enter();
scope = s;
}
- Scope::Root => {
+ Scope::Root { opt_parent_item } => {
+ if let Some(parent_item) = opt_parent_item
+ && let parent_generics = self.tcx.generics_of(parent_item)
+ && parent_generics.param_def_id_to_index.contains_key(®ion_def_id.to_def_id())
+ {
+ break Some(Region::EarlyBound(region_def_id.to_def_id()));
+ }
break None;
}
err.emit();
return;
}
- Scope::Root => break,
+ Scope::Root { .. } => break,
Scope::Binder { s, .. }
| Scope::Body { s, .. }
| Scope::Elision { s, .. }
let mut scope = self.scope;
loop {
match *scope {
- Scope::Root => break false,
+ Scope::Root { .. } => break false,
Scope::Body { .. } => break true,
scope = s;
}
- Scope::Root | Scope::Elision { .. } => break Region::Static,
+ Scope::Root { .. } | Scope::Elision { .. } => break Region::Static,
Scope::Body { .. } | Scope::ObjectLifetimeDefault { lifetime: None, .. } => return,
let mut late_bound = FxIndexSet::default();
- let mut constrained_by_input = ConstrainedCollector::default();
+ let mut constrained_by_input = ConstrainedCollector { regions: Default::default(), tcx };
for arg_ty in decl.inputs {
constrained_by_input.visit_ty(arg_ty);
}
debug!(?late_bound);
return Some(tcx.arena.alloc(late_bound));
- #[derive(Default)]
- struct ConstrainedCollector {
+ /// Visits a `ty::Ty` collecting information about what generic parameters are constrained.
+ ///
+ /// The visitor does not operate on `hir::Ty` so that it can be called on the rhs of a `type Alias<...> = ...;`
+ /// which may live in a separate crate so there would not be any hir available. Instead we use the `type_of`
+ /// query to obtain a `ty::Ty` which will be present even in cross crate scenarios. It also naturally
+ /// handles cycle detection as we go through the query system.
+ ///
+ /// This is necessary in the first place for the following case:
+ /// ```
+ /// type Alias<'a, T> = <T as Trait<'a>>::Assoc;
+ /// fn foo<'a>(_: Alias<'a, ()>) -> Alias<'a, ()> { ... }
+ /// ```
+ ///
+ /// If we conservatively considered `'a` unconstrained then we could break users who had written code before
+ /// we started correctly handling aliases. If we considered `'a` constrained then it would become late bound
+ /// causing an error during astconv as the `'a` is not constrained by the input type `<() as Trait<'a>>::Assoc`
+ /// but appears in the output type `<() as Trait<'a>>::Assoc`.
+ ///
+ /// We must therefore "look into" the `Alias` to see whether we should consider `'a` constrained or not.
+ ///
+ /// See #100508 #85533 #47511 for additional context
+ struct ConstrainedCollectorPostAstConv {
+ arg_is_constrained: Box<[bool]>,
+ }
+
+ use std::ops::ControlFlow;
+ use ty::Ty;
+ impl<'tcx> TypeVisitor<'tcx> for ConstrainedCollectorPostAstConv {
+ fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<!> {
+ match t.kind() {
+ ty::Param(param_ty) => {
+ self.arg_is_constrained[param_ty.index as usize] = true;
+ }
+ ty::Projection(_) => return ControlFlow::Continue(()),
+ _ => (),
+ }
+ t.super_visit_with(self)
+ }
+
+ fn visit_const(&mut self, _: ty::Const<'tcx>) -> ControlFlow<!> {
+ ControlFlow::Continue(())
+ }
+
+ fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<!> {
+ debug!("r={:?}", r.kind());
+ if let ty::RegionKind::ReEarlyBound(region) = r.kind() {
+ self.arg_is_constrained[region.index as usize] = true;
+ }
+
+ ControlFlow::Continue(())
+ }
+ }
+
+ struct ConstrainedCollector<'tcx> {
+ tcx: TyCtxt<'tcx>,
regions: FxHashSet<LocalDefId>,
}
- impl<'v> Visitor<'v> for ConstrainedCollector {
+ impl<'v> Visitor<'v> for ConstrainedCollector<'_> {
fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
match ty.kind {
hir::TyKind::Path(
// (defined above)
}
+ hir::TyKind::Path(hir::QPath::Resolved(
+ None,
+ hir::Path { res: Res::Def(DefKind::TyAlias, alias_def), segments, span },
+ )) => {
+ // See comments on `ConstrainedCollectorPostAstConv` for why this arm does not just consider
+ // substs to be unconstrained.
+ let generics = self.tcx.generics_of(alias_def);
+ let mut walker = ConstrainedCollectorPostAstConv {
+ arg_is_constrained: vec![false; generics.params.len()].into_boxed_slice(),
+ };
+ walker.visit_ty(self.tcx.type_of(alias_def));
+
+ match segments.last() {
+ Some(hir::PathSegment { args: Some(args), .. }) => {
+ let tcx = self.tcx;
+ for constrained_arg in
+ args.args.iter().enumerate().flat_map(|(n, arg)| {
+ match walker.arg_is_constrained.get(n) {
+ Some(true) => Some(arg),
+ Some(false) => None,
+ None => {
+ tcx.sess.delay_span_bug(
+ *span,
+ format!(
+ "Incorrect generic arg count for alias {:?}",
+ alias_def
+ ),
+ );
+ None
+ }
+ }
+ })
+ {
+ self.visit_generic_arg(constrained_arg);
+ }
+ }
+ Some(_) => (),
+ None => bug!("Path with no segments or self type"),
+ }
+ }
+
hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
// consider only the lifetimes on the final
// segment; I am not sure it's even currently
projects / rust.git / blobdiff