From 8dcb8e0759ea48df925968557bd81e37c084e2d0 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 7 Aug 2023 22:09:12 +0000
Subject: [PATCH 1/5] Unconditionally record lifetime mapping
---
compiler/rustc_ast_lowering/src/lib.rs | 6 +-----
compiler/rustc_hir/src/hir.rs | 2 +-
compiler/rustc_hir_analysis/src/collect/predicates_of.rs | 2 +-
compiler/rustc_ty_utils/src/implied_bounds.rs | 2 +-
4 files changed, 4 insertions(+), 8 deletions(-)
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index d29e9f9b3f6..a8151ccfff3 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -1663,11 +1663,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
);
debug!("lower_async_fn_ret_ty: generic_params={:#?}", generic_params);
- let lifetime_mapping = if in_trait {
- Some(&*self.arena.alloc_slice(&synthesized_lifetime_args))
- } else {
- None
- };
+ let lifetime_mapping = self.arena.alloc_slice(&synthesized_lifetime_args);
let opaque_ty_item = hir::OpaqueTy {
generics: this.arena.alloc(hir::Generics {
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index c6f8d1e211d..61353c7b1ec 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -2675,7 +2675,7 @@ pub struct OpaqueTy<'hir> {
///
/// This mapping associated a captured lifetime (first parameter) with the new
/// early-bound lifetime that was generated for the opaque.
- pub lifetime_mapping: Option<&'hir [(&'hir Lifetime, LocalDefId)]>,
+ pub lifetime_mapping: &'hir [(&'hir Lifetime, LocalDefId)],
/// Whether the opaque is a return-position impl trait (or async future)
/// originating from a trait method. This makes it so that the opaque is
/// lowered as an associated type.
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 83220be6883..f0a426722c3 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -59,7 +59,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
let opaque_ty_id = tcx.hir().local_def_id_to_hir_id(opaque_def_id.expect_local());
let opaque_ty_node = tcx.hir().get(opaque_ty_id);
let Node::Item(&Item {
- kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping: Some(lifetime_mapping), .. }),
+ kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping, .. }),
..
}) = opaque_ty_node
else {
diff --git a/compiler/rustc_ty_utils/src/implied_bounds.rs b/compiler/rustc_ty_utils/src/implied_bounds.rs
index 7eb1042d2f8..01fe3a408e8 100644
--- a/compiler/rustc_ty_utils/src/implied_bounds.rs
+++ b/compiler/rustc_ty_utils/src/implied_bounds.rs
@@ -67,7 +67,7 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'
let mut mapping = FxHashMap::default();
let generics = tcx.generics_of(def_id);
for &(lifetime, new_early_bound_def_id) in
- lifetime_mapping.expect("expected lifetime mapping for RPITIT")
+ lifetime_mapping
{
if let Some(rbv::ResolvedArg::LateBound(_, _, def_id)) =
tcx.named_bound_var(lifetime.hir_id)
From 420ee167a8fbda2a078cb3a294fa1108c0180c98 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 7 Aug 2023 23:37:57 +0000
Subject: [PATCH 2/5] Install bidirectional outlives predicates for RPITITs
(and RPITs) correctly
---
.../src/collect/predicates_of.rs | 94 ++++++-------------
compiler/rustc_middle/src/ty/context.rs | 69 ++++++++++++++
compiler/rustc_ty_utils/src/implied_bounds.rs | 35 +++----
.../in-trait/outlives-in-nested-rpit.rs | 11 +++
4 files changed, 121 insertions(+), 88 deletions(-)
create mode 100644 tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index f0a426722c3..495e663666c 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -2,16 +2,16 @@ use crate::astconv::{AstConv, OnlySelfBounds, PredicateFilter};
use crate::bounds::Bounds;
use crate::collect::ItemCtxt;
use crate::constrained_generic_params as cgp;
-use hir::{HirId, Lifetime, Node};
+use hir::{HirId, Node};
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::intravisit::{self, Visitor};
use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_middle::ty::{GenericPredicates, Generics, ImplTraitInTraitData, ToPredicate};
+use rustc_middle::ty::{GenericPredicates, ImplTraitInTraitData, ToPredicate};
use rustc_span::symbol::Ident;
-use rustc_span::{Span, Symbol, DUMMY_SP};
+use rustc_span::{Span, DUMMY_SP};
/// Returns a list of all type predicates (explicit and implicit) for the definition with
/// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
@@ -55,17 +55,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
use rustc_hir::*;
match tcx.opt_rpitit_info(def_id.to_def_id()) {
- Some(ImplTraitInTraitData::Trait { opaque_def_id, fn_def_id }) => {
- let opaque_ty_id = tcx.hir().local_def_id_to_hir_id(opaque_def_id.expect_local());
- let opaque_ty_node = tcx.hir().get(opaque_ty_id);
- let Node::Item(&Item {
- kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping, .. }),
- ..
- }) = opaque_ty_node
- else {
- bug!("unexpected {opaque_ty_node:?}")
- };
-
+ Some(ImplTraitInTraitData::Trait { fn_def_id, .. }) => {
let mut predicates = Vec::new();
// RPITITs should inherit the predicates of their parent. This is
@@ -78,13 +68,12 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
// We also install bidirectional outlives predicates for the RPITIT
// to keep the duplicates lifetimes from opaque lowering in sync.
+ // We only need to compute bidirectional outlives for the duplicated
+ // opaque lifetimes, which explains the slicing below.
compute_bidirectional_outlives_predicates(
tcx,
- def_id,
- lifetime_mapping.iter().map(|(lifetime, def_id)| {
- (**lifetime, (*def_id, lifetime.ident.name, lifetime.ident.span))
- }),
- tcx.generics_of(def_id.to_def_id()),
+ &tcx.generics_of(def_id.to_def_id()).params
+ [tcx.generics_of(fn_def_id).params.len()..],
&mut predicates,
);
@@ -351,21 +340,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
};
debug!(?lifetimes);
- let lifetime_mapping = std::iter::zip(lifetimes, ast_generics.params)
- .map(|(arg, dup)| {
- let hir::GenericArg::Lifetime(arg) = arg else { bug!() };
- (**arg, dup)
- })
- .filter(|(_, dup)| matches!(dup.kind, hir::GenericParamKind::Lifetime { .. }))
- .map(|(lifetime, dup)| (lifetime, (dup.def_id, dup.name.ident().name, dup.span)));
-
- compute_bidirectional_outlives_predicates(
- tcx,
- def_id,
- lifetime_mapping,
- generics,
- &mut predicates,
- );
+ compute_bidirectional_outlives_predicates(tcx, &generics.params, &mut predicates);
debug!(?predicates);
}
@@ -379,41 +354,28 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
/// enforce that these lifetimes stay in sync.
fn compute_bidirectional_outlives_predicates<'tcx>(
tcx: TyCtxt<'tcx>,
- item_def_id: LocalDefId,
- lifetime_mapping: impl Iterator<Item = (Lifetime, (LocalDefId, Symbol, Span))>,
- generics: &Generics,
+ opaque_own_params: &[ty::GenericParamDef],
predicates: &mut Vec<(ty::Clause<'tcx>, Span)>,
) {
- let icx = ItemCtxt::new(tcx, item_def_id);
-
- for (arg, (dup_def, name, span)) in lifetime_mapping {
- let orig_region = icx.astconv().ast_region_to_region(&arg, None);
- if !matches!(orig_region.kind(), ty::ReEarlyBound(..)) {
- // There is no late-bound lifetime to actually match up here, since the lifetime doesn't
- // show up in the opaque's parent's args.
- continue;
+ for param in opaque_own_params {
+ let orig_lifetime = tcx.map_rpit_lifetime_to_fn_lifetime(param.def_id.expect_local());
+ if let ty::ReEarlyBound(..) = *orig_lifetime {
+ let dup_lifetime = ty::Region::new_early_bound(
+ tcx,
+ ty::EarlyBoundRegion { def_id: param.def_id, index: param.index, name: param.name },
+ );
+ let span = tcx.def_span(param.def_id);
+ predicates.push((
+ ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(orig_lifetime, dup_lifetime))
+ .to_predicate(tcx),
+ span,
+ ));
+ predicates.push((
+ ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(dup_lifetime, orig_lifetime))
+ .to_predicate(tcx),
+ span,
+ ));
}
-
- let Some(dup_index) = generics.param_def_id_to_index(icx.tcx, dup_def.to_def_id()) else {
- bug!()
- };
-
- let dup_region = ty::Region::new_early_bound(
- tcx,
- ty::EarlyBoundRegion { def_id: dup_def.to_def_id(), index: dup_index, name },
- );
-
- predicates.push((
- ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(orig_region, dup_region))
- .to_predicate(tcx),
- span,
- ));
-
- predicates.push((
- ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(dup_region, orig_region))
- .to_predicate(tcx),
- span,
- ));
}
}
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 5eef3e45f32..75a2c6cbd20 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1931,6 +1931,75 @@ impl<'tcx> TyCtxt<'tcx> {
)
}
+ /// Given the def-id of an early-bound lifetime on an RPIT corresponding to
+ /// a duplicated captured lifetime, map it back to the early- or late-bound
+ /// lifetime of the function from which it originally as captured. If it is
+ /// a late-bound lifetime, this will represent the liberated (`ReFree`) lifetime
+ /// of the signature.
+ // FIXME(RPITIT): if we ever synthesize new lifetimes for RPITITs and not just
+ // re-use the generics of the opaque, this function will need to be tweaked slightly.
+ pub fn map_rpit_lifetime_to_fn_lifetime(
+ self,
+ mut rpit_lifetime_param_def_id: LocalDefId,
+ ) -> ty::Region<'tcx> {
+ debug_assert!(
+ matches!(self.def_kind(rpit_lifetime_param_def_id), DefKind::LifetimeParam),
+ "{rpit_lifetime_param_def_id:?} is a {}",
+ self.def_descr(rpit_lifetime_param_def_id.to_def_id())
+ );
+
+ loop {
+ let parent = self.local_parent(rpit_lifetime_param_def_id);
+ let hir::OpaqueTy { lifetime_mapping, .. } =
+ self.hir().get_by_def_id(parent).expect_item().expect_opaque_ty();
+
+ let Some((lifetime, _)) = lifetime_mapping
+ .iter()
+ .find(|(_, duplicated_param)| *duplicated_param == rpit_lifetime_param_def_id)
+ else {
+ bug!("duplicated lifetime param should be present");
+ };
+
+ match self.named_bound_var(lifetime.hir_id) {
+ Some(resolve_bound_vars::ResolvedArg::EarlyBound(ebv)) => {
+ let new_parent = self.parent(ebv);
+
+ // If we map to another opaque, then it should be a parent
+ // of the opaque we mapped from. Continue mapping.
+ if matches!(self.def_kind(new_parent), DefKind::OpaqueTy) {
+ debug_assert_eq!(self.parent(parent.to_def_id()), new_parent);
+ rpit_lifetime_param_def_id = ebv.expect_local();
+ continue;
+ }
+
+ let generics = self.generics_of(new_parent);
+ return ty::Region::new_early_bound(
+ self,
+ ty::EarlyBoundRegion {
+ def_id: ebv,
+ index: generics
+ .param_def_id_to_index(self, ebv)
+ .expect("early-bound var should be present in fn generics"),
+ name: self.hir().name(self.local_def_id_to_hir_id(ebv.expect_local())),
+ },
+ );
+ }
+ Some(resolve_bound_vars::ResolvedArg::LateBound(_, _, lbv)) => {
+ let new_parent = self.parent(lbv);
+ return ty::Region::new_free(
+ self,
+ new_parent,
+ ty::BoundRegionKind::BrNamed(
+ lbv,
+ self.hir().name(self.local_def_id_to_hir_id(lbv.expect_local())),
+ ),
+ );
+ }
+ _ => bug!(),
+ }
+ }
+ }
+
/// Whether the `def_id` counts as const fn in the current crate, considering all active
/// feature gates
pub fn is_const_fn(self, def_id: DefId) -> bool {
diff --git a/compiler/rustc_ty_utils/src/implied_bounds.rs b/compiler/rustc_ty_utils/src/implied_bounds.rs
index 01fe3a408e8..ec2e0daaf88 100644
--- a/compiler/rustc_ty_utils/src/implied_bounds.rs
+++ b/compiler/rustc_ty_utils/src/implied_bounds.rs
@@ -2,7 +2,6 @@ use rustc_data_structures::fx::FxHashMap;
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::LocalDefId;
-use rustc_middle::middle::resolve_bound_vars as rbv;
use rustc_middle::query::Providers;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::Span;
@@ -52,9 +51,7 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'
tcx.arena.alloc_from_iter(tys.into_iter().map(|ty| (ty, impl_spans.next().unwrap())))
}
DefKind::AssocTy if let Some(data) = tcx.opt_rpitit_info(def_id.to_def_id()) => match data {
- ty::ImplTraitInTraitData::Trait { fn_def_id, opaque_def_id } => {
- let hir::OpaqueTy { lifetime_mapping, .. } =
- *tcx.hir().expect_item(opaque_def_id.expect_local()).expect_opaque_ty();
+ ty::ImplTraitInTraitData::Trait { fn_def_id, .. } => {
// We need to remap all of the late-bound lifetimes in theassumed wf types
// of the fn (which are represented as ReFree) to the early-bound lifetimes
// of the RPITIT (which are represented by ReEarlyBound owned by the opaque).
@@ -66,28 +63,22 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'
// predicates we insert in the `explicit_predicates_of` query for RPITITs.
let mut mapping = FxHashMap::default();
let generics = tcx.generics_of(def_id);
- for &(lifetime, new_early_bound_def_id) in
- lifetime_mapping
- {
- if let Some(rbv::ResolvedArg::LateBound(_, _, def_id)) =
- tcx.named_bound_var(lifetime.hir_id)
- {
- let name = tcx.hir().name(lifetime.hir_id);
- let index = generics
- .param_def_id_to_index(tcx, new_early_bound_def_id.to_def_id())
- .unwrap();
+
+ // For each captured opaque lifetime, if it's late-bound (`ReFree` in this case,
+ // since it has been liberated), map it back to the early-bound lifetime of
+ // the GAT. Since RPITITs also have all of the fn's generics, we slice only
+ // the end of the list corresponding to the opaque's generics.
+ for param in &generics.params[tcx.generics_of(fn_def_id).params.len()..] {
+ let orig_lt = tcx.map_rpit_lifetime_to_fn_lifetime(param.def_id.expect_local());
+ if matches!(*orig_lt, ty::ReFree(..)) {
mapping.insert(
- ty::Region::new_free(
- tcx,
- fn_def_id,
- ty::BoundRegionKind::BrNamed(def_id, name),
- ),
+ orig_lt,
ty::Region::new_early_bound(
tcx,
ty::EarlyBoundRegion {
- def_id: new_early_bound_def_id.to_def_id(),
- index,
- name,
+ def_id: param.def_id,
+ index: param.index,
+ name: param.name,
},
),
);
diff --git a/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs b/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs
new file mode 100644
index 00000000000..6330242ceeb
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/outlives-in-nested-rpit.rs
@@ -0,0 +1,11 @@
+// check-pass
+
+#![feature(return_position_impl_trait_in_trait)]
+
+trait Foo {
+ fn early<'a, T: 'a>(x: &'a T) -> impl Iterator<Item = impl Into<&'a T>>;
+
+ fn late<'a, T>(x: &'a T) -> impl Iterator<Item = impl Into<&'a T>>;
+}
+
+fn main() {}
From 67703b9161e4869c5ac155e9a12317c1a2fee339 Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Mon, 7 Aug 2023 08:33:25 +0000
Subject: [PATCH 3/5] Stop using identity args for opaque type wf checks and
instead load the args from the single use of a RPIT in its parent function's
return type
---
.../rustc_hir_analysis/src/check/check.rs | 193 +++++++++++-------
.../wf-check-rpit-lifetimes.rs | 19 ++
2 files changed, 134 insertions(+), 78 deletions(-)
create mode 100644 tests/ui/type-alias-impl-trait/wf-check-rpit-lifetimes.rs
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 73627a818e5..f0a8ae9b7a8 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -13,7 +13,7 @@ use rustc_hir::intravisit::Visitor;
use rustc_hir::{ItemKind, Node, PathSegment};
use rustc_infer::infer::opaque_types::ConstrainOpaqueTypeRegionVisitor;
use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
+use rustc_infer::infer::{LateBoundRegionConversionTime, RegionVariableOrigin, TyCtxtInferExt};
use rustc_infer::traits::{Obligation, TraitEngineExt as _};
use rustc_lint_defs::builtin::REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS;
use rustc_middle::hir::nested_filter;
@@ -407,7 +407,38 @@ fn check_opaque_meets_bounds<'tcx>(
.build();
let ocx = ObligationCtxt::new(&infcx);
- let args = GenericArgs::identity_for_item(tcx, def_id.to_def_id());
+ let mut args = GenericArgs::identity_for_item(tcx, def_id.to_def_id());
+ assert!(!args.has_escaping_bound_vars(), "{args:#?}");
+ if let hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) = origin {
+ // Find use of the RPIT in the function signature and thus find the right args to
+ // convert it into the parameter space of the function signature. This is needed,
+ // because that's what `type_of` returns, against which we compare later.
+ let ret = tcx.fn_sig(defining_use_anchor).instantiate_identity().output();
+
+ let a = ret
+ .skip_binder()
+ .visit_with(&mut FindOpaqueTypeArgs {
+ tcx,
+ opaque: def_id.to_def_id(),
+ fn_def_id: defining_use_anchor.to_def_id(),
+ seen: Default::default(),
+ depth: ty::INNERMOST,
+ })
+ .break_value()
+ .ok_or_else(|| {
+ tcx.sess.delay_span_bug(
+ tcx.def_span(defining_use_anchor),
+ format!("return type of {defining_use_anchor:?} does not contain {def_id:?}"),
+ )
+ })?;
+ let a = infcx.instantiate_binder_with_fresh_vars(
+ span,
+ LateBoundRegionConversionTime::HigherRankedType,
+ ret.rebind(a),
+ );
+ assert!(!a.has_escaping_bound_vars(), "{a:#?}");
+ args = ty::EarlyBinder::bind(args).instantiate(tcx, a);
+ }
let opaque_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);
// `ReErased` regions appear in the "parent_args" of closures/generators.
@@ -468,9 +499,10 @@ fn check_opaque_meets_bounds<'tcx>(
}
}
// Check that any hidden types found during wf checking match the hidden types that `type_of` sees.
- for (key, mut ty) in infcx.take_opaque_types() {
+ for (mut key, mut ty) in infcx.take_opaque_types() {
ty.hidden_type.ty = infcx.resolve_vars_if_possible(ty.hidden_type.ty);
- sanity_check_found_hidden_type(tcx, key, ty.hidden_type, defining_use_anchor, origin)?;
+ key = infcx.resolve_vars_if_possible(key);
+ sanity_check_found_hidden_type(tcx, key, ty.hidden_type)?;
}
Ok(())
}
@@ -479,8 +511,6 @@ fn sanity_check_found_hidden_type<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::OpaqueTypeKey<'tcx>,
mut ty: ty::OpaqueHiddenType<'tcx>,
- defining_use_anchor: LocalDefId,
- origin: &hir::OpaqueTyOrigin,
) -> Result<(), ErrorGuaranteed> {
if ty.ty.is_ty_var() {
// Nothing was actually constrained.
@@ -493,29 +523,23 @@ fn sanity_check_found_hidden_type<'tcx>(
return Ok(());
}
}
+ let strip_vars = |ty: Ty<'tcx>| {
+ ty.fold_with(&mut BottomUpFolder {
+ tcx,
+ ty_op: |t| t,
+ ct_op: |c| c,
+ lt_op: |l| match l.kind() {
+ RegionKind::ReVar(_) => tcx.lifetimes.re_erased,
+ _ => l,
+ },
+ })
+ };
// Closures frequently end up containing erased lifetimes in their final representation.
// These correspond to lifetime variables that never got resolved, so we patch this up here.
- ty.ty = ty.ty.fold_with(&mut BottomUpFolder {
- tcx,
- ty_op: |t| t,
- ct_op: |c| c,
- lt_op: |l| match l.kind() {
- RegionKind::ReVar(_) => tcx.lifetimes.re_erased,
- _ => l,
- },
- });
+ ty.ty = strip_vars(ty.ty);
// Get the hidden type.
- let mut hidden_ty = tcx.type_of(key.def_id).instantiate(tcx, key.args);
- if let hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) = origin {
- if hidden_ty != ty.ty {
- hidden_ty = find_and_apply_rpit_args(
- tcx,
- hidden_ty,
- defining_use_anchor.to_def_id(),
- key.def_id.to_def_id(),
- )?;
- }
- }
+ let hidden_ty = tcx.type_of(key.def_id).instantiate(tcx, key.args);
+ let hidden_ty = strip_vars(hidden_ty);
// If the hidden types differ, emit a type mismatch diagnostic.
if hidden_ty == ty.ty {
@@ -563,67 +587,80 @@ fn sanity_check_found_hidden_type<'tcx>(
/// x
/// }
/// ```
-fn find_and_apply_rpit_args<'tcx>(
+struct FindOpaqueTypeArgs<'tcx> {
tcx: TyCtxt<'tcx>,
- mut hidden_ty: Ty<'tcx>,
- function: DefId,
opaque: DefId,
-) -> Result<Ty<'tcx>, ErrorGuaranteed> {
- // Find use of the RPIT in the function signature and thus find the right args to
- // convert it into the parameter space of the function signature. This is needed,
- // because that's what `type_of` returns, against which we compare later.
- let ret = tcx.fn_sig(function).instantiate_identity().output();
- struct Visitor<'tcx> {
- tcx: TyCtxt<'tcx>,
- opaque: DefId,
- seen: FxHashSet<DefId>,
- }
- impl<'tcx> ty::TypeVisitor<TyCtxt<'tcx>> for Visitor<'tcx> {
- type BreakTy = GenericArgsRef<'tcx>;
+ seen: FxHashSet<DefId>,
+ fn_def_id: DefId,
+ depth: ty::DebruijnIndex,
+}
+impl<'tcx> ty::TypeVisitor<TyCtxt<'tcx>> for FindOpaqueTypeArgs<'tcx> {
+ type BreakTy = GenericArgsRef<'tcx>;
- #[instrument(level = "trace", skip(self), ret)]
- fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
- trace!("{:#?}", t.kind());
- match t.kind() {
- ty::Alias(ty::Opaque, alias) => {
- trace!(?alias.def_id);
- if alias.def_id == self.opaque {
- return ControlFlow::Break(alias.args);
- } else if self.seen.insert(alias.def_id) {
- for clause in self
- .tcx
- .explicit_item_bounds(alias.def_id)
- .iter_instantiated_copied(self.tcx, alias.args)
- {
- trace!(?clause);
- clause.visit_with(self)?;
+ #[instrument(level = "trace", skip(self), ret)]
+ fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
+ &mut self,
+ t: &ty::Binder<'tcx, T>,
+ ) -> ControlFlow<Self::BreakTy> {
+ self.depth.shift_in(1);
+ let binder = t.super_visit_with(self);
+ self.depth.shift_out(1);
+ binder
+ }
+
+ #[instrument(level = "trace", skip(self), ret)]
+ fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+ trace!("{:#?}", t.kind());
+ match t.kind() {
+ ty::Alias(ty::Opaque, alias) => {
+ trace!(?alias.def_id);
+ if alias.def_id == self.opaque {
+ let args = self.tcx.fold_regions(alias.args, |re, depth| {
+ if let ty::ReLateBound(index, bv) = re.kind() {
+ if depth != ty::INNERMOST {
+ return ty::Region::new_error_with_message(
+ self.tcx,
+ self.tcx.def_span(self.opaque),
+ "opaque type behind meaningful binders are not supported yet",
+ );
+ }
+ ty::Region::new_late_bound(
+ self.tcx,
+ index.shifted_out_to_binder(self.depth),
+ bv,
+ )
+ } else {
+ re
}
+ });
+ return ControlFlow::Break(args);
+ } else if self.seen.insert(alias.def_id) {
+ for clause in self
+ .tcx
+ .explicit_item_bounds(alias.def_id)
+ .iter_instantiated_copied(self.tcx, alias.args)
+ {
+ trace!(?clause);
+ clause.visit_with(self)?;
}
}
- ty::Alias(ty::Weak, alias) => {
- self.tcx
- .type_of(alias.def_id)
- .instantiate(self.tcx, alias.args)
- .visit_with(self)?;
- }
- _ => (),
}
-
- t.super_visit_with(self)
+ ty::Alias(ty::Projection, alias) => {
+ if let Some(ty::ImplTraitInTraitData::Trait { fn_def_id, .. }) = self.tcx.opt_rpitit_info(alias.def_id) && fn_def_id == self.fn_def_id {
+ self.tcx.type_of(alias.def_id).instantiate(self.tcx, alias.args).visit_with(self)?;
+ }
+ }
+ ty::Alias(ty::Weak, alias) => {
+ self.tcx
+ .type_of(alias.def_id)
+ .instantiate(self.tcx, alias.args)
+ .visit_with(self)?;
+ }
+ _ => (),
}
+
+ t.super_visit_with(self)
}
- if let ControlFlow::Break(args) =
- ret.visit_with(&mut Visitor { tcx, opaque, seen: Default::default() })
- {
- trace!(?args);
- trace!("expected: {hidden_ty:#?}");
- hidden_ty = ty::EarlyBinder::bind(hidden_ty).instantiate(tcx, args);
- trace!("expected: {hidden_ty:#?}");
- } else {
- tcx.sess
- .delay_span_bug(tcx.def_span(function), format!("{ret:?} does not contain {opaque:?}"));
- }
- Ok(hidden_ty)
}
fn is_enum_of_nonnullable_ptr<'tcx>(
diff --git a/tests/ui/type-alias-impl-trait/wf-check-rpit-lifetimes.rs b/tests/ui/type-alias-impl-trait/wf-check-rpit-lifetimes.rs
new file mode 100644
index 00000000000..b92e15aad56
--- /dev/null
+++ b/tests/ui/type-alias-impl-trait/wf-check-rpit-lifetimes.rs
@@ -0,0 +1,19 @@
+//check-pass
+
+pub struct Key;
+#[derive(Clone)]
+pub struct Value;
+
+use std::collections::HashMap;
+
+pub struct DiagnosticBuilder<'db> {
+ inner: HashMap<&'db Key, Vec<&'db Value>>,
+}
+
+impl<'db> DiagnosticBuilder<'db> {
+ pub fn iter<'a>(&'a self) -> impl Iterator<Item = (&'db Key, impl Iterator<Item = &'a Value>)> {
+ self.inner.iter().map(|(key, values)| (*key, values.iter().map(|v| *v)))
+ }
+}
+
+fn main() {}
From ef2a611803964e50853333e34d41f4347434513c Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 7 Aug 2023 23:54:04 +0000
Subject: [PATCH 4/5] Simplify via map_rpit_lifetime_to_fn_lifetime
---
.../rustc_hir_analysis/src/check/check.rs | 155 ++----------------
compiler/rustc_middle/src/ty/context.rs | 11 +-
2 files changed, 21 insertions(+), 145 deletions(-)
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index f0a8ae9b7a8..1c4ee9a2bc3 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -13,7 +13,7 @@ use rustc_hir::intravisit::Visitor;
use rustc_hir::{ItemKind, Node, PathSegment};
use rustc_infer::infer::opaque_types::ConstrainOpaqueTypeRegionVisitor;
use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{LateBoundRegionConversionTime, RegionVariableOrigin, TyCtxtInferExt};
+use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
use rustc_infer::traits::{Obligation, TraitEngineExt as _};
use rustc_lint_defs::builtin::REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS;
use rustc_middle::hir::nested_filter;
@@ -407,38 +407,17 @@ fn check_opaque_meets_bounds<'tcx>(
.build();
let ocx = ObligationCtxt::new(&infcx);
- let mut args = GenericArgs::identity_for_item(tcx, def_id.to_def_id());
- assert!(!args.has_escaping_bound_vars(), "{args:#?}");
- if let hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) = origin {
- // Find use of the RPIT in the function signature and thus find the right args to
- // convert it into the parameter space of the function signature. This is needed,
- // because that's what `type_of` returns, against which we compare later.
- let ret = tcx.fn_sig(defining_use_anchor).instantiate_identity().output();
-
- let a = ret
- .skip_binder()
- .visit_with(&mut FindOpaqueTypeArgs {
+ let args = match *origin {
+ hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
+ GenericArgs::identity_for_item(tcx, parent).extend_to(
tcx,
- opaque: def_id.to_def_id(),
- fn_def_id: defining_use_anchor.to_def_id(),
- seen: Default::default(),
- depth: ty::INNERMOST,
- })
- .break_value()
- .ok_or_else(|| {
- tcx.sess.delay_span_bug(
- tcx.def_span(defining_use_anchor),
- format!("return type of {defining_use_anchor:?} does not contain {def_id:?}"),
- )
- })?;
- let a = infcx.instantiate_binder_with_fresh_vars(
- span,
- LateBoundRegionConversionTime::HigherRankedType,
- ret.rebind(a),
- );
- assert!(!a.has_escaping_bound_vars(), "{a:#?}");
- args = ty::EarlyBinder::bind(args).instantiate(tcx, a);
- }
+ def_id.to_def_id(),
+ |param, _| tcx.map_rpit_lifetime_to_fn_lifetime(param.def_id.expect_local()).into(),
+ )
+ }
+ hir::OpaqueTyOrigin::TyAlias { .. } => GenericArgs::identity_for_item(tcx, def_id),
+ };
+
let opaque_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);
// `ReErased` regions appear in the "parent_args" of closures/generators.
@@ -551,118 +530,6 @@ fn sanity_check_found_hidden_type<'tcx>(
}
}
-/// In case it is in a nested opaque type, find that opaque type's
-/// usage in the function signature and use the generic arguments from the usage site.
-/// We need to do because RPITs ignore the lifetimes of the function,
-/// as they have their own copies of all the lifetimes they capture.
-/// So the only way to get the lifetimes represented in terms of the function,
-/// is to look how they are used in the function signature (or do some other fancy
-/// recording of this mapping at ast -> hir lowering time).
-///
-/// As an example:
-/// ```text
-/// trait Id {
-/// type Assoc;
-/// }
-/// impl<'a> Id for &'a () {
-/// type Assoc = &'a ();
-/// }
-/// fn func<'a>(x: &'a ()) -> impl Id<Assoc = impl Sized + 'a> { x }
-/// // desugared to
-/// fn func<'a>(x: &'a () -> Outer<'a> where <Outer<'a> as Id>::Assoc = Inner<'a> {
-/// // Note that in contrast to other nested items, RPIT type aliases can
-/// // access their parents' generics.
-///
-/// // hidden type is `&'aDupOuter ()`
-/// // During wfcheck the hidden type of `Inner<'aDupOuter>` is `&'a ()`, but
-/// // `typeof(Inner<'aDupOuter>) = &'aDupOuter ()`.
-/// // So we walk the signature of `func` to find the use of `Inner<'a>`
-/// // and then use that to replace the lifetimes in the hidden type, obtaining
-/// // `&'a ()`.
-/// type Outer<'aDupOuter> = impl Id<Assoc = Inner<'aDupOuter>>;
-///
-/// // hidden type is `&'aDupInner ()`
-/// type Inner<'aDupInner> = impl Sized + 'aDupInner;
-///
-/// x
-/// }
-/// ```
-struct FindOpaqueTypeArgs<'tcx> {
- tcx: TyCtxt<'tcx>,
- opaque: DefId,
- seen: FxHashSet<DefId>,
- fn_def_id: DefId,
- depth: ty::DebruijnIndex,
-}
-impl<'tcx> ty::TypeVisitor<TyCtxt<'tcx>> for FindOpaqueTypeArgs<'tcx> {
- type BreakTy = GenericArgsRef<'tcx>;
-
- #[instrument(level = "trace", skip(self), ret)]
- fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
- &mut self,
- t: &ty::Binder<'tcx, T>,
- ) -> ControlFlow<Self::BreakTy> {
- self.depth.shift_in(1);
- let binder = t.super_visit_with(self);
- self.depth.shift_out(1);
- binder
- }
-
- #[instrument(level = "trace", skip(self), ret)]
- fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
- trace!("{:#?}", t.kind());
- match t.kind() {
- ty::Alias(ty::Opaque, alias) => {
- trace!(?alias.def_id);
- if alias.def_id == self.opaque {
- let args = self.tcx.fold_regions(alias.args, |re, depth| {
- if let ty::ReLateBound(index, bv) = re.kind() {
- if depth != ty::INNERMOST {
- return ty::Region::new_error_with_message(
- self.tcx,
- self.tcx.def_span(self.opaque),
- "opaque type behind meaningful binders are not supported yet",
- );
- }
- ty::Region::new_late_bound(
- self.tcx,
- index.shifted_out_to_binder(self.depth),
- bv,
- )
- } else {
- re
- }
- });
- return ControlFlow::Break(args);
- } else if self.seen.insert(alias.def_id) {
- for clause in self
- .tcx
- .explicit_item_bounds(alias.def_id)
- .iter_instantiated_copied(self.tcx, alias.args)
- {
- trace!(?clause);
- clause.visit_with(self)?;
- }
- }
- }
- ty::Alias(ty::Projection, alias) => {
- if let Some(ty::ImplTraitInTraitData::Trait { fn_def_id, .. }) = self.tcx.opt_rpitit_info(alias.def_id) && fn_def_id == self.fn_def_id {
- self.tcx.type_of(alias.def_id).instantiate(self.tcx, alias.args).visit_with(self)?;
- }
- }
- ty::Alias(ty::Weak, alias) => {
- self.tcx
- .type_of(alias.def_id)
- .instantiate(self.tcx, alias.args)
- .visit_with(self)?;
- }
- _ => (),
- }
-
- t.super_visit_with(self)
- }
-}
-
fn is_enum_of_nonnullable_ptr<'tcx>(
tcx: TyCtxt<'tcx>,
adt_def: AdtDef<'tcx>,
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 75a2c6cbd20..e25ca75bba8 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1995,7 +1995,16 @@ impl<'tcx> TyCtxt<'tcx> {
),
);
}
- _ => bug!(),
+ Some(resolve_bound_vars::ResolvedArg::Error(guar)) => {
+ return ty::Region::new_error(self, guar);
+ }
+ _ => {
+ return ty::Region::new_error_with_message(
+ self,
+ lifetime.ident.span,
+ "cannot resolve lifetime",
+ );
+ }
}
}
}
From 0adf7048d23649d561bb121d7e1ab00b4c0269b0 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 8 Aug 2023 00:28:17 +0000
Subject: [PATCH 5/5] add'l test
---
.../mapping-duplicated-lifetimes-issue-114597.rs | 15 +++++++++++++++
1 file changed, 15 insertions(+)
create mode 100644 tests/ui/impl-trait/mapping-duplicated-lifetimes-issue-114597.rs
diff --git a/tests/ui/impl-trait/mapping-duplicated-lifetimes-issue-114597.rs b/tests/ui/impl-trait/mapping-duplicated-lifetimes-issue-114597.rs
new file mode 100644
index 00000000000..a2dd0a9308d
--- /dev/null
+++ b/tests/ui/impl-trait/mapping-duplicated-lifetimes-issue-114597.rs
@@ -0,0 +1,15 @@
+// check-pass
+// issue: 114597
+// edition: 2021
+
+struct A<'a> {
+ dat: &'a (),
+}
+
+impl<'a> A<'a> {
+ async fn a(&self) -> impl Iterator<Item = std::iter::Repeat<()>> {
+ std::iter::repeat(()).map(|()| std::iter::repeat(()))
+ }
+}
+
+fn main() {}