Module region_constraint 

The bulk of the logic for implementing -Zassumptions-on-binders

Re-exports

use derive_where::derive_where; 🔒

use indexmap::IndexSet; 🔒

use rustc_data_structures::transitive_relation::TransitiveRelation; 🔒

use rustc_data_structures::transitive_relation::TransitiveRelationBuilder; 🔒

use rustc_macros::StableHash_NoContext; 🔒

use rustc_type_ir_macros::GenericTypeVisitable; 🔒

use rustc_type_ir_macros::TypeFoldable_Generic; 🔒

use rustc_type_ir_macros::TypeVisitable_Generic; 🔒

use tracing::debug; 🔒

use tracing::instrument; 🔒

use tracing::instrument; 🔒

use crate::Const; 🔒

use smallvec::SmallVec; 🔒

use crate::data_structures::IndexMap; 🔒

use crate::fold::TypeSuperFoldable; 🔒

use crate::relate::Relate; 🔒

use crate::relate::RelateResult; 🔒

use crate::relate::TypeRelation; 🔒

use crate::relate::VarianceDiagInfo; 🔒

use crate::visit::TypeVisitableExt; 🔒

use crate::AliasTy; 🔒

use crate::Binder; 🔒

use crate::BoundRegion; 🔒

use crate::BoundRegionKind; 🔒

use crate::BoundVar; 🔒

use crate::BoundVariableKind; 🔒

use crate::ClauseKind; 🔒

use crate::DebruijnIndex; 🔒

use crate::InferCtxtLike; 🔒

use crate::Interner; 🔒

use crate::IsRigid; 🔒

use crate::OutlivesClause; 🔒

use crate::Region; 🔒

use crate::RegionKind; 🔒

use crate::TyKind; 🔒

use crate::TypeFoldable; 🔒

use crate::TypeFolder; 🔒

use crate::TypingMode; 🔒

use crate::UniverseIndex; 🔒

use crate::Variance; 🔒

use crate::elaborate; 🔒

use crate::max_universe; 🔒

use crate::set_aliases_to_non_rigid; 🔒

use crate::inherent::*; 🔒

Structs

And

An AND of leaf constraints. Always in “canonical form”, meaning:

Assumptions

HigherRankedAliasMatcher 🔒

MakeHigherRankederer

NoSpan

Placeholder for constraints which do not carry a span, see ConstraintSpan.

Or

An OR of AND of LEAF constraints. Always in “canonical form” meaning:

RegionConstraint

An And and an Or constraint both in canonical forms, with two additional constraints:

RootDestructuredConstraints

Enums

AndRelation 🔒

LeafRegionConstraint

Traits

ConstraintSpan

The span stored in a RegionConstraint and friends.

Functions

alias_outlives_candidates_from_assumptions 🔒

Converts an AliasTyOutlivesViaEnv constraint into an OR of region outlives constraints by matching the alias against any Alias: 'a assumptions. This is somewhat tricky as we have a potentially higher ranked alias being equated with a potentially higher ranked assumption and we don’t handle it correctly right now (though it is a somewhat reasonable halfway step).

compute_new_region_constraints 🔒

Filter our region constraints to not include constraints between region variables from u and other regions as those are always satisfied. This requires some care to handle correctly for example: '!a_u1: '?x_u1: '!b_u1 should result in us requiring '!a_u1: '!b_u1 rather than dropping the two constraints entirely.

destructure_type_outlives_constraints_in_root

Converts type outlives constraints into region outlives constraints. This assumes the complete set of assumptions are known. This should not be called until the end of type checking.

eagerly_handle_placeholders_in_universe

Takes any constraints involving placeholders from the current universe and eagerly checks them. This can be done a few ways:

pull_region_outlives_constraints_out_of_universe 🔒

Handles converting region outlives constraints involving placeholders from u into OR constraints involving regions from smaller universes with known relationships to the placeholder. For example:

regions_outlived_by

Returns all regions r2 for which r: r2 is known to hold in the universe associated with assumptions

regions_outlived_by_placeholder

Returns all regions r for which !t: r is known to hold in the universe associated with assumptions

regions_outliving

Returns all regions r2 for which r2: r is known to hold in the universe associated with assumptions

rewrite_alias_ty_outlives_constraints_in_universe_for_eager_placeholder_handling 🔒

rewrite_placeholder_ty_outlives_constraints_in_universe_for_eager_placeholder_handling 🔒

rewrite_type_outlives_constraints_in_universe_for_eager_placeholder_handling 🔒

Converts type outlives constraints into either region outlives constraints, or type outlives constraints which do not contain anything from u.