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//! Various code related to computing outlives relations.
use self::env::OutlivesEnvironment;
use super::region_constraints::RegionConstraintData;
use super::{InferCtxt, RegionResolutionError};
use crate::infer::free_regions::RegionRelations;
use crate::infer::lexical_region_resolve::{self, LexicalRegionResolutions};
use rustc_middle::traits::query::OutlivesBound;
use rustc_middle::ty;
pub mod components;
pub mod env;
pub mod obligations;
pub mod test_type_match;
pub mod verify;
#[instrument(level = "debug", skip(param_env), ret)]
pub fn explicit_outlives_bounds<'tcx>(
param_env: ty::ParamEnv<'tcx>,
) -> impl Iterator<Item = OutlivesBound<'tcx>> + 'tcx {
param_env
.caller_bounds()
.into_iter()
.map(ty::Predicate::kind)
.filter_map(ty::Binder::no_bound_vars)
.filter_map(move |kind| match kind {
ty::PredicateKind::Clause(ty::Clause::Projection(..))
| ty::PredicateKind::Clause(ty::Clause::Trait(..))
| ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..))
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::Coerce(..)
| ty::PredicateKind::Subtype(..)
| ty::PredicateKind::WellFormed(..)
| ty::PredicateKind::ObjectSafe(..)
| ty::PredicateKind::ClosureKind(..)
| ty::PredicateKind::Clause(ty::Clause::TypeOutlives(..))
| ty::PredicateKind::ConstEvaluatable(..)
| ty::PredicateKind::ConstEquate(..)
| ty::PredicateKind::Ambiguous
| ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
ty::PredicateKind::Clause(ty::Clause::RegionOutlives(ty::OutlivesPredicate(
r_a,
r_b,
))) => Some(OutlivesBound::RegionSubRegion(r_b, r_a)),
})
}
impl<'tcx> InferCtxt<'tcx> {
pub fn skip_region_resolution(&self) {
let (var_infos, _) = {
let mut inner = self.inner.borrow_mut();
let inner = &mut *inner;
// Note: `inner.region_obligations` may not be empty, because we
// didn't necessarily call `process_registered_region_obligations`.
// This is okay, because that doesn't introduce new vars.
inner
.region_constraint_storage
.take()
.expect("regions already resolved")
.with_log(&mut inner.undo_log)
.into_infos_and_data()
};
let lexical_region_resolutions = LexicalRegionResolutions {
values: rustc_index::IndexVec::from_elem_n(
crate::infer::lexical_region_resolve::VarValue::Value(self.tcx.lifetimes.re_erased),
var_infos.len(),
),
};
let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
assert!(old_value.is_none());
}
/// Process the region constraints and return any errors that
/// result. After this, no more unification operations should be
/// done -- or the compiler will panic -- but it is legal to use
/// `resolve_vars_if_possible` as well as `fully_resolve`.
#[must_use]
pub fn resolve_regions(
&self,
outlives_env: &OutlivesEnvironment<'tcx>,
) -> Vec<RegionResolutionError<'tcx>> {
self.process_registered_region_obligations(outlives_env);
let (var_infos, data) = {
let mut inner = self.inner.borrow_mut();
let inner = &mut *inner;
assert!(
self.tainted_by_errors().is_some() || inner.region_obligations.is_empty(),
"region_obligations not empty: {:#?}",
inner.region_obligations
);
inner
.region_constraint_storage
.take()
.expect("regions already resolved")
.with_log(&mut inner.undo_log)
.into_infos_and_data()
};
let region_rels = &RegionRelations::new(self.tcx, outlives_env.free_region_map());
let (lexical_region_resolutions, errors) =
lexical_region_resolve::resolve(outlives_env.param_env, region_rels, var_infos, data);
let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
assert!(old_value.is_none());
errors
}
/// Obtains (and clears) the current set of region
/// constraints. The inference context is still usable: further
/// unifications will simply add new constraints.
///
/// This method is not meant to be used with normal lexical region
/// resolution. Rather, it is used in the NLL mode as a kind of
/// interim hack: basically we run normal type-check and generate
/// region constraints as normal, but then we take them and
/// translate them into the form that the NLL solver
/// understands. See the NLL module for mode details.
pub fn take_and_reset_region_constraints(&self) -> RegionConstraintData<'tcx> {
assert!(
self.inner.borrow().region_obligations.is_empty(),
"region_obligations not empty: {:#?}",
self.inner.borrow().region_obligations
);
self.inner.borrow_mut().unwrap_region_constraints().take_and_reset_data()
}
/// Gives temporary access to the region constraint data.
pub fn with_region_constraints<R>(
&self,
op: impl FnOnce(&RegionConstraintData<'tcx>) -> R,
) -> R {
let mut inner = self.inner.borrow_mut();
op(inner.unwrap_region_constraints().data())
}
}
|
