Simplify lifetimes_from_impl_trait_bounds.
This commit is contained in:
Camille GILLOT
parent
4878034c00
commit
1baac86670
1 changed files with 181 additions and 200 deletions
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@ -1497,20 +1497,50 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
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self.allocate_hir_id_counter(opaque_ty_node_id);
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self.allocate_hir_id_counter(opaque_ty_node_id);
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let hir_bounds = self.with_hir_id_owner(opaque_ty_node_id, lower_bounds);
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let collected_lifetimes = self.with_hir_id_owner(opaque_ty_node_id, move |lctx| {
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let hir_bounds = lower_bounds(lctx);
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let (lifetimes, lifetime_defs) = self.lifetimes_from_impl_trait_bounds(
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let collected_lifetimes = lifetimes_from_impl_trait_bounds(
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opaque_ty_node_id,
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opaque_ty_node_id,
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opaque_ty_def_id,
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&hir_bounds,
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&hir_bounds,
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capturable_lifetimes,
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capturable_lifetimes,
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);
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);
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debug!("lower_opaque_impl_trait: lifetimes={:#?}", lifetimes);
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let lifetime_defs =
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lctx.arena.alloc_from_iter(collected_lifetimes.iter().map(|&(name, span)| {
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let def_node_id = lctx.resolver.next_node_id();
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let hir_id = lctx.lower_node_id(def_node_id);
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lctx.resolver.create_def(
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opaque_ty_def_id,
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def_node_id,
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DefPathData::LifetimeNs(name.ident().name),
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ExpnId::root(),
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span,
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);
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debug!("lower_opaque_impl_trait: lifetime_defs={:#?}", lifetime_defs);
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let (name, kind) = match name {
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hir::LifetimeName::Underscore => (
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hir::ParamName::Plain(Ident::with_dummy_span(kw::UnderscoreLifetime)),
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hir::LifetimeParamKind::Elided,
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),
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hir::LifetimeName::Param(param_name) => {
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(param_name, hir::LifetimeParamKind::Explicit)
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}
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_ => panic!("expected `LifetimeName::Param` or `ParamName::Plain`"),
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};
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hir::GenericParam {
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hir_id,
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name,
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span,
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pure_wrt_drop: false,
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bounds: &[],
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kind: hir::GenericParamKind::Lifetime { kind },
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}
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}));
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debug!("lower_opaque_impl_trait: lifetime_defs={:#?}", lifetime_defs);
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self.with_hir_id_owner(opaque_ty_node_id, move |lctx| {
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let opaque_ty_item = hir::OpaqueTy {
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let opaque_ty_item = hir::OpaqueTy {
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generics: hir::Generics {
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generics: hir::Generics {
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params: lifetime_defs,
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params: lifetime_defs,
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@ -1525,9 +1555,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
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trace!("lower_opaque_impl_trait: {:#?}", opaque_ty_def_id);
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trace!("lower_opaque_impl_trait: {:#?}", opaque_ty_def_id);
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lctx.generate_opaque_type(opaque_ty_def_id, opaque_ty_item, span, opaque_ty_span);
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lctx.generate_opaque_type(opaque_ty_def_id, opaque_ty_item, span, opaque_ty_span);
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// `impl Trait` now just becomes `Foo<'a, 'b, ..>`.
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collected_lifetimes
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hir::TyKind::OpaqueDef(hir::ItemId { def_id: opaque_ty_def_id }, lifetimes)
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});
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})
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let lifetimes =
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self.arena.alloc_from_iter(collected_lifetimes.into_iter().map(|(name, span)| {
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hir::GenericArg::Lifetime(hir::Lifetime { hir_id: self.next_id(), span, name })
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}));
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debug!("lower_opaque_impl_trait: lifetimes={:#?}", lifetimes);
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// `impl Trait` now just becomes `Foo<'a, 'b, ..>`.
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hir::TyKind::OpaqueDef(hir::ItemId { def_id: opaque_ty_def_id }, lifetimes)
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}
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}
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/// Registers a new opaque type with the proper `NodeId`s and
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/// Registers a new opaque type with the proper `NodeId`s and
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@ -1556,193 +1595,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
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self.insert_item(opaque_ty_item);
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self.insert_item(opaque_ty_item);
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}
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}
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fn lifetimes_from_impl_trait_bounds(
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&mut self,
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opaque_ty_id: NodeId,
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parent_def_id: LocalDefId,
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bounds: hir::GenericBounds<'hir>,
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lifetimes_to_include: Option<&FxHashSet<hir::LifetimeName>>,
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) -> (&'hir [hir::GenericArg<'hir>], &'hir [hir::GenericParam<'hir>]) {
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debug!(
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"lifetimes_from_impl_trait_bounds(opaque_ty_id={:?}, \
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parent_def_id={:?}, \
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bounds={:#?})",
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opaque_ty_id, parent_def_id, bounds,
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);
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// This visitor walks over `impl Trait` bounds and creates defs for all lifetimes that
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// appear in the bounds, excluding lifetimes that are created within the bounds.
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// E.g., `'a`, `'b`, but not `'c` in `impl for<'c> SomeTrait<'a, 'b, 'c>`.
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struct ImplTraitLifetimeCollector<'r, 'a, 'hir> {
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context: &'r mut LoweringContext<'a, 'hir>,
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parent: LocalDefId,
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opaque_ty_id: NodeId,
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collect_elided_lifetimes: bool,
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currently_bound_lifetimes: Vec<hir::LifetimeName>,
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already_defined_lifetimes: FxHashSet<hir::LifetimeName>,
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output_lifetimes: Vec<hir::GenericArg<'hir>>,
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output_lifetime_params: Vec<hir::GenericParam<'hir>>,
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lifetimes_to_include: Option<&'r FxHashSet<hir::LifetimeName>>,
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}
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impl<'r, 'a, 'v, 'hir> intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a, 'hir> {
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type Map = intravisit::ErasedMap<'v>;
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fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
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intravisit::NestedVisitorMap::None
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}
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fn visit_generic_args(&mut self, span: Span, parameters: &'v hir::GenericArgs<'v>) {
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// Don't collect elided lifetimes used inside of `Fn()` syntax.
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if parameters.parenthesized {
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let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
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self.collect_elided_lifetimes = false;
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intravisit::walk_generic_args(self, span, parameters);
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self.collect_elided_lifetimes = old_collect_elided_lifetimes;
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} else {
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intravisit::walk_generic_args(self, span, parameters);
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}
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}
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fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
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// Don't collect elided lifetimes used inside of `fn()` syntax.
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if let hir::TyKind::BareFn(_) = t.kind {
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let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
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self.collect_elided_lifetimes = false;
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// Record the "stack height" of `for<'a>` lifetime bindings
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// to be able to later fully undo their introduction.
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let old_len = self.currently_bound_lifetimes.len();
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intravisit::walk_ty(self, t);
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self.currently_bound_lifetimes.truncate(old_len);
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self.collect_elided_lifetimes = old_collect_elided_lifetimes;
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} else {
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intravisit::walk_ty(self, t)
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}
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}
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fn visit_poly_trait_ref(
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&mut self,
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trait_ref: &'v hir::PolyTraitRef<'v>,
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modifier: hir::TraitBoundModifier,
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) {
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// Record the "stack height" of `for<'a>` lifetime bindings
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// to be able to later fully undo their introduction.
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let old_len = self.currently_bound_lifetimes.len();
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intravisit::walk_poly_trait_ref(self, trait_ref, modifier);
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self.currently_bound_lifetimes.truncate(old_len);
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}
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fn visit_generic_param(&mut self, param: &'v hir::GenericParam<'v>) {
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// Record the introduction of 'a in `for<'a> ...`.
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if let hir::GenericParamKind::Lifetime { .. } = param.kind {
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// Introduce lifetimes one at a time so that we can handle
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// cases like `fn foo<'d>() -> impl for<'a, 'b: 'a, 'c: 'b + 'd>`.
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let lt_name = hir::LifetimeName::Param(param.name);
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self.currently_bound_lifetimes.push(lt_name);
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}
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intravisit::walk_generic_param(self, param);
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}
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fn visit_lifetime(&mut self, lifetime: &'v hir::Lifetime) {
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let name = match lifetime.name {
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hir::LifetimeName::Implicit | hir::LifetimeName::Underscore => {
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if self.collect_elided_lifetimes {
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// Use `'_` for both implicit and underscore lifetimes in
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// `type Foo<'_> = impl SomeTrait<'_>;`.
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hir::LifetimeName::Underscore
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} else {
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return;
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}
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}
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hir::LifetimeName::Param(_) => lifetime.name,
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// Refers to some other lifetime that is "in
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// scope" within the type.
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hir::LifetimeName::ImplicitObjectLifetimeDefault => return,
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hir::LifetimeName::Error | hir::LifetimeName::Static => return,
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};
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if !self.currently_bound_lifetimes.contains(&name)
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&& !self.already_defined_lifetimes.contains(&name)
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&& self.lifetimes_to_include.map_or(true, |lifetimes| lifetimes.contains(&name))
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{
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self.already_defined_lifetimes.insert(name);
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self.output_lifetimes.push(hir::GenericArg::Lifetime(hir::Lifetime {
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hir_id: self.context.next_id(),
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span: self.context.lower_span(lifetime.span),
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name,
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}));
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let def_node_id = self.context.resolver.next_node_id();
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let hir_id =
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self.context.lower_node_id_with_owner(def_node_id, self.opaque_ty_id);
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self.context.resolver.create_def(
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self.parent,
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def_node_id,
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DefPathData::LifetimeNs(name.ident().name),
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ExpnId::root(),
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lifetime.span,
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);
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let (name, kind) = match name {
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hir::LifetimeName::Underscore => (
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hir::ParamName::Plain(Ident::with_dummy_span(kw::UnderscoreLifetime)),
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hir::LifetimeParamKind::Elided,
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),
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hir::LifetimeName::Param(param_name) => {
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(param_name, hir::LifetimeParamKind::Explicit)
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}
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_ => panic!("expected `LifetimeName::Param` or `ParamName::Plain`"),
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};
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let name = match name {
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hir::ParamName::Plain(ident) => {
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hir::ParamName::Plain(self.context.lower_ident(ident))
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}
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name => name,
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};
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self.output_lifetime_params.push(hir::GenericParam {
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hir_id,
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name,
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span: self.context.lower_span(lifetime.span),
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pure_wrt_drop: false,
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bounds: &[],
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kind: hir::GenericParamKind::Lifetime { kind },
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});
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}
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}
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}
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let mut lifetime_collector = ImplTraitLifetimeCollector {
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context: self,
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parent: parent_def_id,
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opaque_ty_id,
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collect_elided_lifetimes: true,
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currently_bound_lifetimes: Vec::new(),
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already_defined_lifetimes: FxHashSet::default(),
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output_lifetimes: Vec::new(),
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output_lifetime_params: Vec::new(),
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lifetimes_to_include,
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};
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for bound in bounds {
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intravisit::walk_param_bound(&mut lifetime_collector, &bound);
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}
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let ImplTraitLifetimeCollector { output_lifetimes, output_lifetime_params, .. } =
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lifetime_collector;
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(
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self.arena.alloc_from_iter(output_lifetimes),
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self.arena.alloc_from_iter(output_lifetime_params),
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)
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}
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fn lower_fn_params_to_names(&mut self, decl: &FnDecl) -> &'hir [Ident] {
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fn lower_fn_params_to_names(&mut self, decl: &FnDecl) -> &'hir [Ident] {
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// Skip the `...` (`CVarArgs`) trailing arguments from the AST,
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// Skip the `...` (`CVarArgs`) trailing arguments from the AST,
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// as they are not explicit in HIR/Ty function signatures.
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// as they are not explicit in HIR/Ty function signatures.
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@ -2723,3 +2575,132 @@ impl<'hir> GenericArgsCtor<'hir> {
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this.arena.alloc(ga)
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this.arena.alloc(ga)
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}
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}
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}
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}
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fn lifetimes_from_impl_trait_bounds(
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opaque_ty_id: NodeId,
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bounds: hir::GenericBounds<'_>,
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lifetimes_to_include: Option<&FxHashSet<hir::LifetimeName>>,
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) -> Vec<(hir::LifetimeName, Span)> {
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debug!(
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"lifetimes_from_impl_trait_bounds(opaque_ty_id={:?}, \
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bounds={:#?})",
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opaque_ty_id, bounds,
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);
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// This visitor walks over `impl Trait` bounds and creates defs for all lifetimes that
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// appear in the bounds, excluding lifetimes that are created within the bounds.
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// E.g., `'a`, `'b`, but not `'c` in `impl for<'c> SomeTrait<'a, 'b, 'c>`.
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struct ImplTraitLifetimeCollector<'r> {
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collect_elided_lifetimes: bool,
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currently_bound_lifetimes: Vec<hir::LifetimeName>,
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already_defined_lifetimes: FxHashSet<hir::LifetimeName>,
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lifetimes: Vec<(hir::LifetimeName, Span)>,
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lifetimes_to_include: Option<&'r FxHashSet<hir::LifetimeName>>,
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}
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impl<'r, 'v> intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r> {
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type Map = intravisit::ErasedMap<'v>;
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fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
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intravisit::NestedVisitorMap::None
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}
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fn visit_generic_args(&mut self, span: Span, parameters: &'v hir::GenericArgs<'v>) {
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// Don't collect elided lifetimes used inside of `Fn()` syntax.
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if parameters.parenthesized {
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let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
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self.collect_elided_lifetimes = false;
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intravisit::walk_generic_args(self, span, parameters);
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self.collect_elided_lifetimes = old_collect_elided_lifetimes;
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} else {
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intravisit::walk_generic_args(self, span, parameters);
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}
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}
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fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
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// Don't collect elided lifetimes used inside of `fn()` syntax.
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if let hir::TyKind::BareFn(_) = t.kind {
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let old_collect_elided_lifetimes = self.collect_elided_lifetimes;
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self.collect_elided_lifetimes = false;
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// Record the "stack height" of `for<'a>` lifetime bindings
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// to be able to later fully undo their introduction.
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let old_len = self.currently_bound_lifetimes.len();
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intravisit::walk_ty(self, t);
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self.currently_bound_lifetimes.truncate(old_len);
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self.collect_elided_lifetimes = old_collect_elided_lifetimes;
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} else {
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||||||
|
intravisit::walk_ty(self, t)
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
fn visit_poly_trait_ref(
|
||||||
|
&mut self,
|
||||||
|
trait_ref: &'v hir::PolyTraitRef<'v>,
|
||||||
|
modifier: hir::TraitBoundModifier,
|
||||||
|
) {
|
||||||
|
// Record the "stack height" of `for<'a>` lifetime bindings
|
||||||
|
// to be able to later fully undo their introduction.
|
||||||
|
let old_len = self.currently_bound_lifetimes.len();
|
||||||
|
intravisit::walk_poly_trait_ref(self, trait_ref, modifier);
|
||||||
|
self.currently_bound_lifetimes.truncate(old_len);
|
||||||
|
}
|
||||||
|
|
||||||
|
fn visit_generic_param(&mut self, param: &'v hir::GenericParam<'v>) {
|
||||||
|
// Record the introduction of 'a in `for<'a> ...`.
|
||||||
|
if let hir::GenericParamKind::Lifetime { .. } = param.kind {
|
||||||
|
// Introduce lifetimes one at a time so that we can handle
|
||||||
|
// cases like `fn foo<'d>() -> impl for<'a, 'b: 'a, 'c: 'b + 'd>`.
|
||||||
|
let lt_name = hir::LifetimeName::Param(param.name);
|
||||||
|
self.currently_bound_lifetimes.push(lt_name);
|
||||||
|
}
|
||||||
|
|
||||||
|
intravisit::walk_generic_param(self, param);
|
||||||
|
}
|
||||||
|
|
||||||
|
fn visit_lifetime(&mut self, lifetime: &'v hir::Lifetime) {
|
||||||
|
let name = match lifetime.name {
|
||||||
|
hir::LifetimeName::Implicit | hir::LifetimeName::Underscore => {
|
||||||
|
if self.collect_elided_lifetimes {
|
||||||
|
// Use `'_` for both implicit and underscore lifetimes in
|
||||||
|
// `type Foo<'_> = impl SomeTrait<'_>;`.
|
||||||
|
hir::LifetimeName::Underscore
|
||||||
|
} else {
|
||||||
|
return;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
hir::LifetimeName::Param(_) => lifetime.name,
|
||||||
|
|
||||||
|
// Refers to some other lifetime that is "in
|
||||||
|
// scope" within the type.
|
||||||
|
hir::LifetimeName::ImplicitObjectLifetimeDefault => return,
|
||||||
|
|
||||||
|
hir::LifetimeName::Error | hir::LifetimeName::Static => return,
|
||||||
|
};
|
||||||
|
|
||||||
|
if !self.currently_bound_lifetimes.contains(&name)
|
||||||
|
&& !self.already_defined_lifetimes.contains(&name)
|
||||||
|
&& self.lifetimes_to_include.map_or(true, |lifetimes| lifetimes.contains(&name))
|
||||||
|
{
|
||||||
|
self.already_defined_lifetimes.insert(name);
|
||||||
|
|
||||||
|
self.lifetimes.push((name, lifetime.span));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
let mut lifetime_collector = ImplTraitLifetimeCollector {
|
||||||
|
collect_elided_lifetimes: true,
|
||||||
|
currently_bound_lifetimes: Vec::new(),
|
||||||
|
already_defined_lifetimes: FxHashSet::default(),
|
||||||
|
lifetimes: Vec::new(),
|
||||||
|
lifetimes_to_include,
|
||||||
|
};
|
||||||
|
|
||||||
|
for bound in bounds {
|
||||||
|
intravisit::walk_param_bound(&mut lifetime_collector, &bound);
|
||||||
|
}
|
||||||
|
|
||||||
|
lifetime_collector.lifetimes
|
||||||
|
}
|
||||||
|
|
|
||||||
Loading…
Add table
Add a link
Reference in a new issue