From 95bcca85ff9a07e70f160e4e48a67d2e70b7c207 Mon Sep 17 00:00:00 2001 From: Ali MJ Al-Nasrawy Date: Fri, 27 Jan 2023 17:22:05 +0300 Subject: [PATCH 1/4] remove obsolete `givens` from regionck --- .../src/check/compare_impl_item.rs | 5 +- .../rustc_hir_analysis/src/check/wfcheck.rs | 4 +- .../src/impl_wf_check/min_specialization.rs | 2 +- compiler/rustc_hir_typeck/src/pat.rs | 9 +--- .../src/infer/canonical/query_response.rs | 4 +- .../src/infer/lexical_region_resolve/mod.rs | 47 +------------------ compiler/rustc_infer/src/infer/mod.rs | 4 -- .../rustc_infer/src/infer/outlives/env.rs | 46 +++++++----------- .../infer/region_constraints/leak_check.rs | 3 -- .../src/infer/region_constraints/mod.rs | 44 ++--------------- .../src/traits/coherence.rs | 1 - .../rustc_trait_selection/src/traits/misc.rs | 1 - 12 files changed, 26 insertions(+), 144 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs index 5adc7a8732373..f14fb200bb0ae 100644 --- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs +++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs @@ -330,7 +330,6 @@ fn compare_method_predicate_entailment<'tcx>( // lifetime parameters. let outlives_env = OutlivesEnvironment::with_bounds( param_env, - Some(infcx), infcx.implied_bounds_tys(param_env, impl_m_def_id, wf_tys.clone()), ); infcx.process_registered_region_obligations( @@ -728,7 +727,6 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( // lifetime parameters. let outlives_environment = OutlivesEnvironment::with_bounds( param_env, - Some(infcx), infcx.implied_bounds_tys(param_env, impl_m_def_id, wf_tys), ); infcx @@ -2051,8 +2049,7 @@ pub(super) fn check_type_bounds<'tcx>( // Finally, resolve all regions. This catches wily misuses of // lifetime parameters. let implied_bounds = infcx.implied_bounds_tys(param_env, impl_ty_def_id, assumed_wf_types); - let outlives_environment = - OutlivesEnvironment::with_bounds(param_env, Some(&infcx), implied_bounds); + let outlives_environment = OutlivesEnvironment::with_bounds(param_env, implied_bounds); infcx.err_ctxt().check_region_obligations_and_report_errors( impl_ty.def_id.expect_local(), diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs index 4cccdf30c5fa6..8d9f87f89dc0a 100644 --- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs +++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs @@ -115,8 +115,7 @@ pub(super) fn enter_wf_checking_ctxt<'tcx, F>( return; } - let outlives_environment = - OutlivesEnvironment::with_bounds(param_env, Some(infcx), implied_bounds); + let outlives_environment = OutlivesEnvironment::with_bounds(param_env, implied_bounds); let _ = infcx .err_ctxt() @@ -676,7 +675,6 @@ fn resolve_regions_with_wf_tys<'tcx>( let infcx = tcx.infer_ctxt().build(); let outlives_environment = OutlivesEnvironment::with_bounds( param_env, - Some(&infcx), infcx.implied_bounds_tys(param_env, id, wf_tys.clone()), ); let region_bound_pairs = outlives_environment.region_bound_pairs(); diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs index daa5d15704d87..46a2796b3c60a 100644 --- a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs +++ b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs @@ -179,7 +179,7 @@ fn get_impl_substs( } let implied_bounds = infcx.implied_bounds_tys(param_env, impl1_def_id, assumed_wf_types); - let outlives_env = OutlivesEnvironment::with_bounds(param_env, Some(infcx), implied_bounds); + let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds); let _ = infcx.err_ctxt().check_region_obligations_and_report_errors(impl1_def_id, &outlives_env); let Ok(impl2_substs) = infcx.fully_resolve(impl2_substs) else { diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs index c36c75e444368..11ff65d0c373a 100644 --- a/compiler/rustc_hir_typeck/src/pat.rs +++ b/compiler/rustc_hir_typeck/src/pat.rs @@ -238,15 +238,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // Note that there are two tests to check that this remains true // (`regions-reassign-{match,let}-bound-pointer.rs`). // - // 2. Things go horribly wrong if we use subtype. The reason for - // THIS is a fairly subtle case involving bound regions. See the - // `givens` field in `region_constraints`, as well as the test + // 2. An outdated issue related to the old HIR borrowck. See the test // `regions-relate-bound-regions-on-closures-to-inference-variables.rs`, - // for details. Short version is that we must sometimes detect - // relationships between specific region variables and regions - // bound in a closure signature, and that detection gets thrown - // off when we substitute fresh region variables here to enable - // subtyping. } /// Compute the new expected type and default binding mode from the old ones diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs index 436d29c2449e4..90e89a187822d 100644 --- a/compiler/rustc_infer/src/infer/canonical/query_response.rs +++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs @@ -636,11 +636,9 @@ pub fn make_query_region_constraints<'tcx>( outlives_obligations: impl Iterator, ty::Region<'tcx>, ConstraintCategory<'tcx>)>, region_constraints: &RegionConstraintData<'tcx>, ) -> QueryRegionConstraints<'tcx> { - let RegionConstraintData { constraints, verifys, givens, member_constraints } = - region_constraints; + let RegionConstraintData { constraints, verifys, member_constraints } = region_constraints; assert!(verifys.is_empty()); - assert!(givens.is_empty()); debug!(?constraints); diff --git a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs index 2c480355085ef..cf657756ff534 100644 --- a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs +++ b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs @@ -13,7 +13,7 @@ use rustc_data_structures::graph::implementation::{ Direction, Graph, NodeIndex, INCOMING, OUTGOING, }; use rustc_data_structures::intern::Interned; -use rustc_index::vec::{Idx, IndexVec}; +use rustc_index::vec::IndexVec; use rustc_middle::ty::fold::TypeFoldable; use rustc_middle::ty::PlaceholderRegion; use rustc_middle::ty::{self, Ty, TyCtxt}; @@ -132,7 +132,6 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> { } let graph = self.construct_graph(); - self.expand_givens(&graph); self.expansion(&mut var_data); self.collect_errors(&mut var_data, errors); self.collect_var_errors(&var_data, &graph, errors); @@ -164,38 +163,6 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> { } } - fn expand_givens(&mut self, graph: &RegionGraph<'_>) { - // Givens are a kind of horrible hack to account for - // constraints like 'c <= '0 that are known to hold due to - // closure signatures (see the comment above on the `givens` - // field). They should go away. But until they do, the role - // of this fn is to account for the transitive nature: - // - // Given 'c <= '0 - // and '0 <= '1 - // then 'c <= '1 - - let seeds: Vec<_> = self.data.givens.iter().cloned().collect(); - for (r, vid) in seeds { - // While all things transitively reachable in the graph - // from the variable (`'0` in the example above). - let seed_index = NodeIndex(vid.index() as usize); - for succ_index in graph.depth_traverse(seed_index, OUTGOING) { - let succ_index = succ_index.0; - - // The first N nodes correspond to the region - // variables. Other nodes correspond to constant - // regions. - if succ_index < self.num_vars() { - let succ_vid = RegionVid::new(succ_index); - - // Add `'c <= '1`. - self.data.givens.insert((r, succ_vid)); - } - } - } - } - /// Gets the LUb of a given region and the empty region fn lub_empty(&self, a_region: Region<'tcx>) -> Result, PlaceholderRegion> { match *a_region { @@ -362,18 +329,6 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> { ) -> bool { debug!("expand_node({:?}, {:?} == {:?})", a_region, b_vid, b_data); - match *a_region { - // Check if this relationship is implied by a given. - ty::ReEarlyBound(_) | ty::ReFree(_) => { - if self.data.givens.contains(&(a_region, b_vid)) { - debug!("given"); - return false; - } - } - - _ => {} - } - match *b_data { VarValue::Empty(empty_ui) => { let lub = match self.lub_empty(a_region) { diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs index fb067e7ac2135..1b49843822ed7 100644 --- a/compiler/rustc_infer/src/infer/mod.rs +++ b/compiler/rustc_infer/src/infer/mod.rs @@ -855,10 +855,6 @@ impl<'tcx> InferCtxt<'tcx> { self.inner.borrow().undo_log.opaque_types_in_snapshot(&snapshot.undo_snapshot) } - pub fn add_given(&self, sub: ty::Region<'tcx>, sup: ty::RegionVid) { - self.inner.borrow_mut().unwrap_region_constraints().add_given(sub, sup); - } - pub fn can_sub(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> bool where T: at::ToTrace<'tcx>, diff --git a/compiler/rustc_infer/src/infer/outlives/env.rs b/compiler/rustc_infer/src/infer/outlives/env.rs index 24e3c34dd94fc..95f8f05ab6098 100644 --- a/compiler/rustc_infer/src/infer/outlives/env.rs +++ b/compiler/rustc_infer/src/infer/outlives/env.rs @@ -1,9 +1,9 @@ use crate::infer::free_regions::FreeRegionMap; -use crate::infer::{GenericKind, InferCtxt}; +use crate::infer::GenericKind; use crate::traits::query::OutlivesBound; use rustc_data_structures::fx::FxIndexSet; use rustc_data_structures::transitive_relation::TransitiveRelationBuilder; -use rustc_middle::ty::{self, ReEarlyBound, ReFree, ReVar, Region}; +use rustc_middle::ty::{self, Region}; use super::explicit_outlives_bounds; @@ -75,7 +75,7 @@ impl<'tcx> OutlivesEnvironment<'tcx> { region_bound_pairs: Default::default(), }; - builder.add_outlives_bounds(None, explicit_outlives_bounds(param_env)); + builder.add_outlives_bounds(explicit_outlives_bounds(param_env)); builder } @@ -89,11 +89,10 @@ impl<'tcx> OutlivesEnvironment<'tcx> { /// Create a new `OutlivesEnvironment` with extra outlives bounds. pub fn with_bounds( param_env: ty::ParamEnv<'tcx>, - infcx: Option<&InferCtxt<'tcx>>, extra_bounds: impl IntoIterator>, ) -> Self { let mut builder = Self::builder(param_env); - builder.add_outlives_bounds(infcx, extra_bounds); + builder.add_outlives_bounds(extra_bounds); builder.build() } @@ -120,12 +119,7 @@ impl<'tcx> OutlivesEnvironmentBuilder<'tcx> { } /// Processes outlives bounds that are known to hold, whether from implied or other sources. - /// - /// The `infcx` parameter is optional; if the implied bounds may - /// contain inference variables, it must be supplied, in which - /// case we will register "givens" on the inference context. (See - /// `RegionConstraintData`.) - fn add_outlives_bounds(&mut self, infcx: Option<&InferCtxt<'tcx>>, outlives_bounds: I) + fn add_outlives_bounds(&mut self, outlives_bounds: I) where I: IntoIterator>, { @@ -143,24 +137,18 @@ impl<'tcx> OutlivesEnvironmentBuilder<'tcx> { .insert(ty::OutlivesPredicate(GenericKind::Alias(alias_b), r_a)); } OutlivesBound::RegionSubRegion(r_a, r_b) => { - if let (ReEarlyBound(_) | ReFree(_), ReVar(vid_b)) = (r_a.kind(), r_b.kind()) { - infcx - .expect("no infcx provided but region vars found") - .add_given(r_a, vid_b); - } else { - // In principle, we could record (and take - // advantage of) every relationship here, but - // we are also free not to -- it simply means - // strictly less that we can successfully type - // check. Right now we only look for things - // relationships between free regions. (It may - // also be that we should revise our inference - // system to be more general and to make use - // of *every* relationship that arises here, - // but presently we do not.) - if r_a.is_free_or_static() && r_b.is_free() { - self.region_relation.add(r_a, r_b) - } + // In principle, we could record (and take + // advantage of) every relationship here, but + // we are also free not to -- it simply means + // strictly less that we can successfully type + // check. Right now we only look for things + // relationships between free regions. (It may + // also be that we should revise our inference + // system to be more general and to make use + // of *every* relationship that arises here, + // but presently we do not.) + if r_a.is_free_or_static() && r_b.is_free() { + self.region_relation.add(r_a, r_b) } } } diff --git a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs index e413b2bb570d6..89ada23c6673a 100644 --- a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs +++ b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs @@ -424,9 +424,6 @@ impl<'tcx> MiniGraph<'tcx> { &AddConstraint(Constraint::RegSubReg(a, b)) => { each_edge(a, b); } - &AddGiven(a, b) => { - each_edge(a, tcx.mk_re_var(b)); - } &AddVerify(i) => span_bug!( verifys[i].origin.span(), "we never add verifications while doing higher-ranked things", diff --git a/compiler/rustc_infer/src/infer/region_constraints/mod.rs b/compiler/rustc_infer/src/infer/region_constraints/mod.rs index 0b86d9c1fb827..7b272dfd2a454 100644 --- a/compiler/rustc_infer/src/infer/region_constraints/mod.rs +++ b/compiler/rustc_infer/src/infer/region_constraints/mod.rs @@ -7,7 +7,7 @@ use super::{ InferCtxtUndoLogs, MiscVariable, RegionVariableOrigin, Rollback, Snapshot, SubregionOrigin, }; -use rustc_data_structures::fx::{FxHashMap, FxIndexSet}; +use rustc_data_structures::fx::FxHashMap; use rustc_data_structures::intern::Interned; use rustc_data_structures::sync::Lrc; use rustc_data_structures::undo_log::UndoLogs; @@ -104,26 +104,6 @@ pub struct RegionConstraintData<'tcx> { /// An example is a `A <= B` where neither `A` nor `B` are /// inference variables. pub verifys: Vec>, - - /// A "given" is a relationship that is known to hold. In - /// particular, we often know from closure fn signatures that a - /// particular free region must be a subregion of a region - /// variable: - /// - /// foo.iter().filter(<'a> |x: &'a &'b T| ...) - /// - /// In situations like this, `'b` is in fact a region variable - /// introduced by the call to `iter()`, and `'a` is a bound region - /// on the closure (as indicated by the `<'a>` prefix). If we are - /// naive, we wind up inferring that `'b` must be `'static`, - /// because we require that it be greater than `'a` and we do not - /// know what `'a` is precisely. - /// - /// This hashmap is used to avoid that naive scenario. Basically - /// we record the fact that `'a <= 'b` is implied by the fn - /// signature, and then ignore the constraint when solving - /// equations. This is a bit of a hack but seems to work. - pub givens: FxIndexSet<(Region<'tcx>, ty::RegionVid)>, } /// Represents a constraint that influences the inference process. @@ -297,9 +277,6 @@ pub(crate) enum UndoLog<'tcx> { /// We added the given `verify`. AddVerify(usize), - /// We added the given `given`. - AddGiven(Region<'tcx>, ty::RegionVid), - /// We added a GLB/LUB "combination variable". AddCombination(CombineMapType, TwoRegions<'tcx>), } @@ -348,9 +325,6 @@ impl<'tcx> RegionConstraintStorage<'tcx> { self.data.verifys.pop(); assert_eq!(self.data.verifys.len(), index); } - AddGiven(sub, sup) => { - self.data.givens.remove(&(sub, sup)); - } AddCombination(Glb, ref regions) => { self.glbs.remove(regions); } @@ -492,15 +466,6 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> { self.undo_log.push(AddVerify(index)); } - pub(super) fn add_given(&mut self, sub: Region<'tcx>, sup: ty::RegionVid) { - // cannot add givens once regions are resolved - if self.data.givens.insert((sub, sup)) { - debug!("add_given({:?} <= {:?})", sub, sup); - - self.undo_log.push(AddGiven(sub, sup)); - } - } - pub(super) fn make_eqregion( &mut self, origin: SubregionOrigin<'tcx>, @@ -804,11 +769,8 @@ impl<'tcx> RegionConstraintData<'tcx> { /// Returns `true` if this region constraint data contains no constraints, and `false` /// otherwise. pub fn is_empty(&self) -> bool { - let RegionConstraintData { constraints, member_constraints, verifys, givens } = self; - constraints.is_empty() - && member_constraints.is_empty() - && verifys.is_empty() - && givens.is_empty() + let RegionConstraintData { constraints, member_constraints, verifys } = self; + constraints.is_empty() && member_constraints.is_empty() && verifys.is_empty() } } diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs index 6b688c322c786..19018764ba25a 100644 --- a/compiler/rustc_trait_selection/src/traits/coherence.rs +++ b/compiler/rustc_trait_selection/src/traits/coherence.rs @@ -388,7 +388,6 @@ fn resolve_negative_obligation<'tcx>( let wf_tys = ocx.assumed_wf_types(param_env, DUMMY_SP, body_def_id); let outlives_env = OutlivesEnvironment::with_bounds( param_env, - Some(&infcx), infcx.implied_bounds_tys(param_env, body_def_id, wf_tys), ); diff --git a/compiler/rustc_trait_selection/src/traits/misc.rs b/compiler/rustc_trait_selection/src/traits/misc.rs index b94346b09560a..90d8050412437 100644 --- a/compiler/rustc_trait_selection/src/traits/misc.rs +++ b/compiler/rustc_trait_selection/src/traits/misc.rs @@ -106,7 +106,6 @@ pub fn type_allowed_to_implement_copy<'tcx>( // Check regions assuming the self type of the impl is WF let outlives_env = OutlivesEnvironment::with_bounds( param_env, - Some(&infcx), infcx.implied_bounds_tys( param_env, parent_cause.body_id, From 4e441565e21a19b8d0be749e997c8b414ba185f4 Mon Sep 17 00:00:00 2001 From: Ali MJ Al-Nasrawy Date: Wed, 1 Feb 2023 13:52:44 +0300 Subject: [PATCH 2/4] resolve regions before implied bounds --- .../src/traits/outlives_bounds.rs | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs index 6cb64ad574f5b..e2c198fabde6d 100644 --- a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs +++ b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs @@ -3,7 +3,8 @@ use crate::traits::query::type_op::{self, TypeOp, TypeOpOutput}; use crate::traits::query::NoSolution; use crate::traits::ObligationCause; use rustc_data_structures::fx::FxIndexSet; -use rustc_middle::ty::{self, ParamEnv, Ty}; +use rustc_infer::infer::resolve::OpportunisticRegionResolver; +use rustc_middle::ty::{self, ParamEnv, Ty, TypeFolder, TypeVisitableExt}; use rustc_span::def_id::LocalDefId; pub use rustc_middle::traits::query::OutlivesBound; @@ -52,6 +53,10 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> { body_id: LocalDefId, ty: Ty<'tcx>, ) -> Vec> { + let ty = self.resolve_vars_if_possible(ty); + let ty = OpportunisticRegionResolver::new(self).fold_ty(ty); + assert!(!ty.needs_infer()); + let span = self.tcx.def_span(body_id); let result = param_env .and(type_op::implied_outlives_bounds::ImpliedOutlivesBounds { ty }) @@ -105,10 +110,7 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> { tys: FxIndexSet>, ) -> Bounds<'a, 'tcx> { tys.into_iter() - .map(move |ty| { - let ty = self.resolve_vars_if_possible(ty); - self.implied_outlives_bounds(param_env, body_id, ty) - }) + .map(move |ty| self.implied_outlives_bounds(param_env, body_id, ty)) .flatten() } } From 183bd97d076fa2d7bd1c4abcad6065abc17af119 Mon Sep 17 00:00:00 2001 From: Ali MJ Al-Nasrawy Date: Wed, 1 Feb 2023 14:57:17 +0300 Subject: [PATCH 3/4] add test --- tests/ui/implied-bounds/normalization.rs | 58 ++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 tests/ui/implied-bounds/normalization.rs diff --git a/tests/ui/implied-bounds/normalization.rs b/tests/ui/implied-bounds/normalization.rs new file mode 100644 index 0000000000000..f776fc98a9ede --- /dev/null +++ b/tests/ui/implied-bounds/normalization.rs @@ -0,0 +1,58 @@ +// Test that we get implied bounds from complex projections after normalization. + +// check-pass + +// implementations wil ensure that +// WF(>::Ty) implies T: 'a +trait Combine<'a> { + type Ty; +} + +impl<'a, T: 'a> Combine<'a> for Box { + type Ty = &'a T; +} + +// ======= Wrappers ====== + +// normalizes to a projection +struct WrapA(T); +impl<'a, T> Combine<'a> for WrapA +where + T: Combine<'a>, +{ + type Ty = T::Ty; +} + +// as Combine<'a>>::Ty normalizes to a type variable ?X +// with constraint `>::Ty == ?X` +struct WrapB(T); +impl<'a, X, T> Combine<'a> for WrapB +where + T: Combine<'a, Ty = X>, +{ + type Ty = X; +} + +// as Combine<'a>>::Ty normalizes to `&'a &'?x ()` +// with constraint `>::Ty == &'a &'?x ()` +struct WrapC(T); +impl<'a, 'x: 'a, T> Combine<'a> for WrapC +where + T: Combine<'a, Ty = &'a &'x ()>, +{ + type Ty = &'a &'x (); +} + +//==== Test implied bounds ====== + +fn test_wrap<'a, 'b, 'c1, 'c2, A, B>( + _: > as Combine<'a>>::Ty, // normalized: &'a A + _: > as Combine<'b>>::Ty, // normalized: &'b B + _: > as Combine<'c2>>::Ty, // normalized: &'c2 &'c1 () +) { + None::<&'a A>; + None::<&'b B>; + None::<&'c2 &'c1 ()>; +} + +fn main() {} From 211fa45d18e10f9702a1d9ef529c0f1a867f0712 Mon Sep 17 00:00:00 2001 From: Ali MJ Al-Nasrawy Date: Thu, 9 Mar 2023 11:30:49 +0300 Subject: [PATCH 4/4] exhaustive match on implied bounds regions --- .../rustc_infer/src/infer/outlives/env.rs | 23 +++++++------------ 1 file changed, 8 insertions(+), 15 deletions(-) diff --git a/compiler/rustc_infer/src/infer/outlives/env.rs b/compiler/rustc_infer/src/infer/outlives/env.rs index 95f8f05ab6098..a480ee5429eec 100644 --- a/compiler/rustc_infer/src/infer/outlives/env.rs +++ b/compiler/rustc_infer/src/infer/outlives/env.rs @@ -136,21 +136,14 @@ impl<'tcx> OutlivesEnvironmentBuilder<'tcx> { self.region_bound_pairs .insert(ty::OutlivesPredicate(GenericKind::Alias(alias_b), r_a)); } - OutlivesBound::RegionSubRegion(r_a, r_b) => { - // In principle, we could record (and take - // advantage of) every relationship here, but - // we are also free not to -- it simply means - // strictly less that we can successfully type - // check. Right now we only look for things - // relationships between free regions. (It may - // also be that we should revise our inference - // system to be more general and to make use - // of *every* relationship that arises here, - // but presently we do not.) - if r_a.is_free_or_static() && r_b.is_free() { - self.region_relation.add(r_a, r_b) - } - } + OutlivesBound::RegionSubRegion(r_a, r_b) => match (*r_a, *r_b) { + ( + ty::ReStatic | ty::ReEarlyBound(_) | ty::ReFree(_), + ty::ReStatic | ty::ReEarlyBound(_) | ty::ReFree(_), + ) => self.region_relation.add(r_a, r_b), + (ty::ReError(_), _) | (_, ty::ReError(_)) => {} + _ => bug!("add_outlives_bounds: unexpected regions"), + }, } } }