diff options
Diffstat (limited to 'compiler/rustc_borrowck')
12 files changed, 144 insertions, 197 deletions
diff --git a/compiler/rustc_borrowck/src/borrow_set.rs b/compiler/rustc_borrowck/src/borrow_set.rs index ee2ce1d3f74..e30d6c7fca7 100644 --- a/compiler/rustc_borrowck/src/borrow_set.rs +++ b/compiler/rustc_borrowck/src/borrow_set.rs @@ -315,9 +315,7 @@ impl<'a, 'tcx> GatherBorrows<'a, 'tcx> { // TEMP = &foo // // so extract `temp`. - let temp = if let Some(temp) = assigned_place.as_local() { - temp - } else { + let Some(temp) = assigned_place.as_local() else { span_bug!( self.body.source_info(start_location).span, "expected 2-phase borrow to assign to a local, not `{:?}`", diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs index 37398894a20..439c728798d 100644 --- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs @@ -11,7 +11,6 @@ use rustc_middle::mir::{ }; use rustc_middle::ty::{self, suggest_constraining_type_param, Ty}; use rustc_mir_dataflow::move_paths::{InitKind, MoveOutIndex, MovePathIndex}; -use rustc_span::source_map::DesugaringKind; use rustc_span::symbol::sym; use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP}; use rustc_trait_selection::infer::InferCtxtExt; @@ -247,6 +246,36 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { place_name, partially_str, loop_message ), ); + let sess = self.infcx.tcx.sess; + let ty = used_place.ty(self.body, self.infcx.tcx).ty; + // If we have a `&mut` ref, we need to reborrow. + if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() { + // If we are in a loop this will be suggested later. + if !is_loop_move { + err.span_suggestion_verbose( + move_span.shrink_to_lo(), + &format!( + "consider creating a fresh reborrow of {} here", + self.describe_place(moved_place.as_ref()) + .map(|n| format!("`{}`", n)) + .unwrap_or_else( + || "the mutable reference".to_string() + ), + ), + "&mut *".to_string(), + Applicability::MachineApplicable, + ); + } + } else if let Ok(snippet) = + sess.source_map().span_to_snippet(move_span) + { + err.span_suggestion( + move_span, + "consider borrowing to avoid moving into the for loop", + format!("&{}", snippet), + Applicability::MaybeIncorrect, + ); + } } else { err.span_label( fn_call_span, @@ -315,35 +344,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { in_pattern = true; } } - - if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() { - let sess = self.infcx.tcx.sess; - let ty = used_place.ty(self.body, self.infcx.tcx).ty; - // If we have a `&mut` ref, we need to reborrow. - if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() { - // If we are in a loop this will be suggested later. - if !is_loop_move { - err.span_suggestion_verbose( - move_span.shrink_to_lo(), - &format!( - "consider creating a fresh reborrow of {} here", - self.describe_place(moved_place.as_ref()) - .map(|n| format!("`{}`", n)) - .unwrap_or_else(|| "the mutable reference".to_string()), - ), - "&mut *".to_string(), - Applicability::MachineApplicable, - ); - } - } else if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) { - err.span_suggestion( - move_span, - "consider borrowing to avoid moving into the for loop", - format!("&{}", snippet), - Applicability::MaybeIncorrect, - ); - } - } } use_spans.var_span_label_path_only( diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs index 855e6850b2e..692c20d7dfe 100644 --- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs @@ -5,11 +5,10 @@ use rustc_middle::ty; use rustc_mir_dataflow::move_paths::{ IllegalMoveOrigin, IllegalMoveOriginKind, LookupResult, MoveError, MovePathIndex, }; -use rustc_span::source_map::DesugaringKind; use rustc_span::{sym, Span, DUMMY_SP}; use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions; -use crate::diagnostics::UseSpans; +use crate::diagnostics::{FnSelfUseKind, UseSpans}; use crate::prefixes::PrefixSet; use crate::MirBorrowckCtxt; @@ -400,19 +399,21 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { | ty::Opaque(def_id, _) => def_id, _ => return err, }; - let is_option = self.infcx.tcx.is_diagnostic_item(sym::Option, def_id); - let is_result = self.infcx.tcx.is_diagnostic_item(sym::Result, def_id); - if (is_option || is_result) && use_spans.map_or(true, |v| !v.for_closure()) { + let diag_name = self.infcx.tcx.get_diagnostic_name(def_id); + if matches!(diag_name, Some(sym::Option | sym::Result)) + && use_spans.map_or(true, |v| !v.for_closure()) + { err.span_suggestion_verbose( span.shrink_to_hi(), - &format!( - "consider borrowing the `{}`'s content", - if is_option { "Option" } else { "Result" } - ), + &format!("consider borrowing the `{}`'s content", diag_name.unwrap()), ".as_ref()".to_string(), Applicability::MaybeIncorrect, ); - } else if matches!(span.desugaring_kind(), Some(DesugaringKind::ForLoop(_))) { + } else if let Some(UseSpans::FnSelfUse { + kind: FnSelfUseKind::Normal { implicit_into_iter: true, .. }, + .. + }) = use_spans + { let suggest = match self.infcx.tcx.get_diagnostic_item(sym::IntoIterator) { Some(def_id) => self.infcx.tcx.infer_ctxt().enter(|infcx| { type_known_to_meet_bound_modulo_regions( diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs index 246d2e3208c..d5ff4c6766f 100644 --- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs @@ -45,12 +45,12 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { let item_msg; let reason; let mut opt_source = None; - let access_place_desc = self.describe_place(access_place.as_ref()); + let access_place_desc = self.describe_any_place(access_place.as_ref()); debug!("report_mutability_error: access_place_desc={:?}", access_place_desc); match the_place_err { PlaceRef { local, projection: [] } => { - item_msg = format!("`{}`", access_place_desc.unwrap()); + item_msg = access_place_desc; if access_place.as_local().is_some() { reason = ", as it is not declared as mutable".to_string(); } else { @@ -83,7 +83,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { // If we deref an immutable ref then the suggestion here doesn't help. return; } else { - item_msg = format!("`{}`", access_place_desc.unwrap()); + item_msg = access_place_desc; if self.is_upvar_field_projection(access_place.as_ref()).is_some() { reason = ", as it is not declared as mutable".to_string(); } else { @@ -96,17 +96,17 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { PlaceRef { local, projection: [ProjectionElem::Deref] } if self.body.local_decls[local].is_ref_for_guard() => { - item_msg = format!("`{}`", access_place_desc.unwrap()); + item_msg = access_place_desc; reason = ", as it is immutable for the pattern guard".to_string(); } PlaceRef { local, projection: [ProjectionElem::Deref] } if self.body.local_decls[local].is_ref_to_static() => { if access_place.projection.len() == 1 { - item_msg = format!("immutable static item `{}`", access_place_desc.unwrap()); + item_msg = format!("immutable static item {}", access_place_desc); reason = String::new(); } else { - item_msg = format!("`{}`", access_place_desc.unwrap()); + item_msg = access_place_desc; let local_info = &self.body.local_decls[local].local_info; if let Some(box LocalInfo::StaticRef { def_id, .. }) = *local_info { let static_name = &self.infcx.tcx.item_name(def_id); @@ -121,7 +121,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { && proj_base.is_empty() && !self.upvars.is_empty() { - item_msg = format!("`{}`", access_place_desc.unwrap()); + item_msg = access_place_desc; debug_assert!( self.body.local_decls[ty::CAPTURE_STRUCT_LOCAL].ty.is_region_ptr() ); @@ -147,7 +147,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { }); let pointer_type = source.describe_for_immutable_place(self.infcx.tcx); opt_source = Some(source); - if let Some(desc) = access_place_desc { + if let Some(desc) = self.describe_place(access_place.as_ref()) { item_msg = format!("`{}`", desc); reason = match error_access { AccessKind::Mutate => format!(", which is behind {}", pointer_type), diff --git a/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs b/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs index b15e55cd667..723b57ed970 100644 --- a/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs +++ b/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs @@ -90,9 +90,7 @@ impl OutlivesSuggestionBuilder { let mut unified_already = FxHashSet::default(); for (fr, outlived) in &self.constraints_to_add { - let fr_name = if let Some(fr_name) = self.region_vid_to_name(mbcx, *fr) { - fr_name - } else { + let Some(fr_name) = self.region_vid_to_name(mbcx, *fr) else { continue; }; diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs index e6260157d11..4defa378947 100644 --- a/compiler/rustc_borrowck/src/lib.rs +++ b/compiler/rustc_borrowck/src/lib.rs @@ -2,16 +2,17 @@ #![feature(bool_to_option)] #![feature(box_patterns)] -#![cfg_attr(bootstrap, feature(const_panic))] #![feature(crate_visibility_modifier)] #![feature(format_args_capture)] #![feature(in_band_lifetimes)] #![feature(iter_zip)] +#![feature(let_else)] #![feature(min_specialization)] #![feature(stmt_expr_attributes)] #![feature(trusted_step)] #![feature(try_blocks)] #![recursion_limit = "256"] +#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))] #[macro_use] extern crate rustc_middle; diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs index 734a5b4972b..22bb3a29425 100644 --- a/compiler/rustc_borrowck/src/region_infer/mod.rs +++ b/compiler/rustc_borrowck/src/region_infer/mod.rs @@ -689,6 +689,16 @@ impl<'tcx> RegionInferenceContext<'tcx> { // them down. let mut choice_regions: Vec<ty::RegionVid> = choice_regions.to_vec(); + // Convert to the SCC representative: sometimes we have inference + // variables in the member constraint that wind up equated with + // universal regions. The scc representative is the minimal numbered + // one from the corresponding scc so it will be the universal region + // if one exists. + for c_r in &mut choice_regions { + let scc = self.constraint_sccs.scc(*c_r); + *c_r = self.scc_representatives[scc]; + } + // The 'member region' in a member constraint is part of the // hidden type, which must be in the root universe. Therefore, // it cannot have any placeholders in its value. @@ -2154,7 +2164,7 @@ impl<'tcx> RegionInferenceContext<'tcx> { // appears to be the most interesting point to report to the // user via an even more ad-hoc guess. categorized_path.sort_by(|p0, p1| p0.category.cmp(&p1.category)); - debug!("`: sorted_path={:#?}", categorized_path); + debug!("best_blame_constraint: sorted_path={:#?}", categorized_path); categorized_path.remove(0) } diff --git a/compiler/rustc_borrowck/src/region_infer/values.rs b/compiler/rustc_borrowck/src/region_infer/values.rs index 2864abde002..8819039c752 100644 --- a/compiler/rustc_borrowck/src/region_infer/values.rs +++ b/compiler/rustc_borrowck/src/region_infer/values.rs @@ -174,17 +174,19 @@ impl<N: Idx> LivenessValues<N> { self.points.contains(row, index) } + /// Returns an iterator of all the elements contained by the region `r` + crate fn get_elements(&self, row: N) -> impl Iterator<Item = Location> + '_ { + self.points + .row(row) + .into_iter() + .flat_map(|set| set.iter()) + .take_while(move |&p| self.elements.point_in_range(p)) + .map(move |p| self.elements.to_location(p)) + } + /// Returns a "pretty" string value of the region. Meant for debugging. crate fn region_value_str(&self, r: N) -> String { - region_value_str( - self.points - .row(r) - .into_iter() - .flat_map(|set| set.iter()) - .take_while(|&p| self.elements.point_in_range(p)) - .map(|p| self.elements.to_location(p)) - .map(RegionElement::Location), - ) + region_value_str(self.get_elements(r).map(RegionElement::Location)) } } diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs index 7d4df59902a..0fa72ed8241 100644 --- a/compiler/rustc_borrowck/src/type_check/canonical.rs +++ b/compiler/rustc_borrowck/src/type_check/canonical.rs @@ -94,6 +94,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { Some(ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate { trait_ref, constness: ty::BoundConstness::NotConst, + polarity: ty::ImplPolarity::Positive, }))), locations, category, diff --git a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs index 70c74940d62..f71cf09ecf6 100644 --- a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs +++ b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs @@ -1,20 +1,18 @@ use rustc_data_structures::frozen::Frozen; use rustc_data_structures::transitive_relation::TransitiveRelation; use rustc_infer::infer::canonical::QueryRegionConstraints; -use rustc_infer::infer::free_regions::FreeRegionRelations; use rustc_infer::infer::outlives; use rustc_infer::infer::region_constraints::GenericKind; use rustc_infer::infer::InferCtxt; use rustc_middle::mir::ConstraintCategory; use rustc_middle::traits::query::OutlivesBound; -use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt}; +use rustc_middle::ty::{self, RegionVid, Ty}; use rustc_span::DUMMY_SP; use rustc_trait_selection::traits::query::type_op::{self, TypeOp}; use std::rc::Rc; use type_op::TypeOpOutput; use crate::{ - nll::ToRegionVid, type_check::constraint_conversion, type_check::{Locations, MirTypeckRegionConstraints}, universal_regions::UniversalRegions, @@ -383,21 +381,3 @@ impl UniversalRegionRelationsBuilder<'cx, 'tcx> { } } } - -/// This trait is used by the `impl-trait` constraint code to abstract -/// over the `FreeRegionMap` from lexical regions and -/// `UniversalRegions` (from NLL)`. -impl<'tcx> FreeRegionRelations<'tcx> for UniversalRegionRelations<'tcx> { - fn sub_free_regions( - &self, - _tcx: TyCtxt<'tcx>, - shorter: ty::Region<'tcx>, - longer: ty::Region<'tcx>, - ) -> bool { - let shorter = shorter.to_region_vid(); - assert!(self.universal_regions.is_universal_region(shorter)); - let longer = longer.to_region_vid(); - assert!(self.universal_regions.is_universal_region(longer)); - self.outlives(longer, shorter) - } -} diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs index 55790bd2daa..7e69e710d68 100644 --- a/compiler/rustc_borrowck/src/type_check/mod.rs +++ b/compiler/rustc_borrowck/src/type_check/mod.rs @@ -36,7 +36,7 @@ use rustc_span::def_id::CRATE_DEF_ID; use rustc_span::{Span, DUMMY_SP}; use rustc_target::abi::VariantIdx; use rustc_trait_selection::infer::InferCtxtExt as _; -use rustc_trait_selection::opaque_types::{GenerateMemberConstraints, InferCtxtExt}; +use rustc_trait_selection::opaque_types::InferCtxtExt; use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; use rustc_trait_selection::traits::query::type_op; use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp; @@ -185,7 +185,6 @@ pub(crate) fn type_check<'mir, 'tcx>( ®ion_bound_pairs, implicit_region_bound, &mut borrowck_context, - &universal_region_relations, |mut cx| { cx.equate_inputs_and_outputs(&body, universal_regions, &normalized_inputs_and_output); liveness::generate(&mut cx, body, elements, flow_inits, move_data, location_table); @@ -253,15 +252,7 @@ pub(crate) fn type_check<'mir, 'tcx>( } #[instrument( - skip( - infcx, - body, - promoted, - region_bound_pairs, - borrowck_context, - universal_region_relations, - extra - ), + skip(infcx, body, promoted, region_bound_pairs, borrowck_context, extra), level = "debug" )] fn type_check_internal<'a, 'tcx, R>( @@ -272,7 +263,6 @@ fn type_check_internal<'a, 'tcx, R>( region_bound_pairs: &'a RegionBoundPairs<'tcx>, implicit_region_bound: ty::Region<'tcx>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, - universal_region_relations: &'a UniversalRegionRelations<'tcx>, extra: impl FnOnce(TypeChecker<'a, 'tcx>) -> R, ) -> R { let mut checker = TypeChecker::new( @@ -282,7 +272,6 @@ fn type_check_internal<'a, 'tcx, R>( region_bound_pairs, implicit_region_bound, borrowck_context, - universal_region_relations, ); let errors_reported = { let mut verifier = TypeVerifier::new(&mut checker, body, promoted); @@ -663,12 +652,17 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> { } self.cx.borrowck_context.constraints.outlives_constraints.push(constraint) } - for live_region in liveness_constraints.rows() { - self.cx - .borrowck_context - .constraints - .liveness_constraints - .add_element(live_region, location); + for region in liveness_constraints.rows() { + // If the region is live at at least one location in the promoted MIR, + // then add a liveness constraint to the main MIR for this region + // at the location provided as an argument to this method + if let Some(_) = liveness_constraints.get_elements(region).next() { + self.cx + .borrowck_context + .constraints + .liveness_constraints + .add_element(region, location); + } } if !closure_bounds.is_empty() { @@ -896,7 +890,6 @@ struct TypeChecker<'a, 'tcx> { implicit_region_bound: ty::Region<'tcx>, reported_errors: FxHashSet<(Ty<'tcx>, Span)>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, - universal_region_relations: &'a UniversalRegionRelations<'tcx>, } struct BorrowCheckContext<'a, 'tcx> { @@ -1045,7 +1038,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { region_bound_pairs: &'a RegionBoundPairs<'tcx>, implicit_region_bound: ty::Region<'tcx>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, - universal_region_relations: &'a UniversalRegionRelations<'tcx>, ) -> Self { let mut checker = Self { infcx, @@ -1057,7 +1049,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { implicit_region_bound, borrowck_context, reported_errors: Default::default(), - universal_region_relations, }; checker.check_user_type_annotations(); checker @@ -1153,28 +1144,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { .convert_all(data); } - /// Convenient wrapper around `relate_tys::relate_types` -- see - /// that fn for docs. - fn relate_types( - &mut self, - a: Ty<'tcx>, - v: ty::Variance, - b: Ty<'tcx>, - locations: Locations, - category: ConstraintCategory, - ) -> Fallible<()> { - relate_tys::relate_types( - self.infcx, - self.param_env, - a, - v, - b, - locations, - category, - self.borrowck_context, - ) - } - /// Try to relate `sub <: sup` fn sub_types( &mut self, @@ -1339,8 +1308,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { ), )?; - let universal_region_relations = self.universal_region_relations; - // Finally, if we instantiated the anon types successfully, we // have to solve any bounds (e.g., `-> impl Iterator` needs to // prove that `T: Iterator` where `T` is the type we @@ -1352,12 +1319,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { ConstraintCategory::OpaqueType, CustomTypeOp::new( |infcx| { - infcx.constrain_opaque_type( - opaque_type_key, - &opaque_decl, - GenerateMemberConstraints::IfNoStaticBound, - universal_region_relations, - ); + infcx.constrain_opaque_type(opaque_type_key, &opaque_decl); Ok(InferOk { value: (), obligations: vec![] }) }, || "opaque_type_map".to_string(), diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs index b788529dc1c..415d1abaa8b 100644 --- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs +++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs @@ -1,5 +1,5 @@ use rustc_infer::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRelatingDelegate}; -use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin}; +use rustc_infer::infer::NllRegionVariableOrigin; use rustc_middle::mir::ConstraintCategory; use rustc_middle::ty::relate::TypeRelation; use rustc_middle::ty::{self, Const, Ty}; @@ -7,48 +7,38 @@ use rustc_trait_selection::traits::query::Fallible; use crate::constraints::OutlivesConstraint; use crate::diagnostics::UniverseInfo; -use crate::type_check::{BorrowCheckContext, Locations}; - -/// Adds sufficient constraints to ensure that `a R b` where `R` depends on `v`: -/// -/// - "Covariant" `a <: b` -/// - "Invariant" `a == b` -/// - "Contravariant" `a :> b` -/// -/// N.B., the type `a` is permitted to have unresolved inference -/// variables, but not the type `b`. -#[instrument(skip(infcx, param_env, borrowck_context), level = "debug")] -pub(super) fn relate_types<'tcx>( - infcx: &InferCtxt<'_, 'tcx>, - param_env: ty::ParamEnv<'tcx>, - a: Ty<'tcx>, - v: ty::Variance, - b: Ty<'tcx>, - locations: Locations, - category: ConstraintCategory, - borrowck_context: &mut BorrowCheckContext<'_, 'tcx>, -) -> Fallible<()> { - TypeRelating::new( - infcx, - NllTypeRelatingDelegate::new( - infcx, - borrowck_context, - param_env, - locations, - category, - UniverseInfo::relate(a, b), - ), - v, - ) - .relate(a, b)?; - Ok(()) +use crate::type_check::{Locations, TypeChecker}; + +impl<'a, 'tcx> TypeChecker<'a, 'tcx> { + /// Adds sufficient constraints to ensure that `a R b` where `R` depends on `v`: + /// + /// - "Covariant" `a <: b` + /// - "Invariant" `a == b` + /// - "Contravariant" `a :> b` + /// + /// N.B., the type `a` is permitted to have unresolved inference + /// variables, but not the type `b`. + #[instrument(skip(self), level = "debug")] + pub(super) fn relate_types( + &mut self, + a: Ty<'tcx>, + v: ty::Variance, + b: Ty<'tcx>, + locations: Locations, + category: ConstraintCategory, + ) -> Fallible<()> { + TypeRelating::new( + self.infcx, + NllTypeRelatingDelegate::new(self, locations, category, UniverseInfo::relate(a, b)), + v, + ) + .relate(a, b)?; + Ok(()) + } } struct NllTypeRelatingDelegate<'me, 'bccx, 'tcx> { - infcx: &'me InferCtxt<'me, 'tcx>, - borrowck_context: &'me mut BorrowCheckContext<'bccx, 'tcx>, - - param_env: ty::ParamEnv<'tcx>, + type_checker: &'me mut TypeChecker<'bccx, 'tcx>, /// Where (and why) is this relation taking place? locations: Locations, @@ -63,25 +53,24 @@ struct NllTypeRelatingDelegate<'me, 'bccx, 'tcx> { impl NllTypeRelatingDelegate<'me, 'bccx, 'tcx> { fn new( - infcx: &'me InferCtxt<'me, 'tcx>, - borrowck_context: &'me mut BorrowCheckContext<'bccx, 'tcx>, - param_env: ty::ParamEnv<'tcx>, + type_checker: &'me mut TypeChecker<'bccx, 'tcx>, locations: Locations, category: ConstraintCategory, universe_info: UniverseInfo<'tcx>, ) -> Self { - Self { infcx, borrowck_context, param_env, locations, category, universe_info } + Self { type_checker, locations, category, universe_info } } } impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> { fn param_env(&self) -> ty::ParamEnv<'tcx> { - self.param_env + self.type_checker.param_env } fn create_next_universe(&mut self) -> ty::UniverseIndex { - let universe = self.infcx.create_next_universe(); - self.borrowck_context + let universe = self.type_checker.infcx.create_next_universe(); + self.type_checker + .borrowck_context .constraints .universe_causes .insert(universe, self.universe_info.clone()); @@ -90,15 +79,18 @@ impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> { fn next_existential_region_var(&mut self, from_forall: bool) -> ty::Region<'tcx> { let origin = NllRegionVariableOrigin::Existential { from_forall }; - self.infcx.next_nll_region_var(origin) + self.type_checker.infcx.next_nll_region_var(origin) } fn next_placeholder_region(&mut self, placeholder: ty::PlaceholderRegion) -> ty::Region<'tcx> { - self.borrowck_context.constraints.placeholder_region(self.infcx, placeholder) + self.type_checker + .borrowck_context + .constraints + .placeholder_region(self.type_checker.infcx, placeholder) } fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> { - self.infcx.next_nll_region_var_in_universe( + self.type_checker.infcx.next_nll_region_var_in_universe( NllRegionVariableOrigin::Existential { from_forall: false }, universe, ) @@ -110,15 +102,17 @@ impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> { sub: ty::Region<'tcx>, info: ty::VarianceDiagInfo<'tcx>, ) { - let sub = self.borrowck_context.universal_regions.to_region_vid(sub); - let sup = self.borrowck_context.universal_regions.to_region_vid(sup); - self.borrowck_context.constraints.outlives_constraints.push(OutlivesConstraint { - sup, - sub, - locations: self.locations, - category: self.category, - variance_info: info, - }); + let sub = self.type_checker.borrowck_context.universal_regions.to_region_vid(sub); + let sup = self.type_checker.borrowck_context.universal_regions.to_region_vid(sup); + self.type_checker.borrowck_context.constraints.outlives_constraints.push( + OutlivesConstraint { + sup, + sub, + locations: self.locations, + category: self.category, + variance_info: info, + }, + ); } // We don't have to worry about the equality of consts during borrow checking |