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Auto merge of #50397 - sgrif:sg-smaller-universe-refactorings, r=niko…
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…matsakis

Refactorings in preparation for the removal of the leak check

This contains all of the commits from #48407 that I was able to pull out on their own. This has most of the refactoring/ground work to unblock other work, but without the behavior changes that still need a crater run and NLL changes.

r? @nikomatsakis
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@bors
bors committed May 4, 2018
2 parents e82261d + 68a1fdf commit 1eab9c5
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Showing 12 changed files with 168 additions and 156 deletions.
4 changes: 2 additions & 2 deletions src/librustc/infer/combine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -407,7 +407,7 @@ impl<'cx, 'gcx, 'tcx> TypeRelation<'cx, 'gcx, 'tcx> for Generalizer<'cx, 'gcx, '
drop(variables);
self.relate(&u, &u)
}
TypeVariableValue::Unknown { .. } => {
TypeVariableValue::Unknown { universe } => {
match self.ambient_variance {
// Invariant: no need to make a fresh type variable.
ty::Invariant => return Ok(t),
Expand All @@ -424,7 +424,7 @@ impl<'cx, 'gcx, 'tcx> TypeRelation<'cx, 'gcx, 'tcx> for Generalizer<'cx, 'gcx, '
}

let origin = *variables.var_origin(vid);
let new_var_id = variables.new_var(false, origin);
let new_var_id = variables.new_var(universe, false, origin);
let u = self.tcx().mk_var(new_var_id);
debug!("generalize: replacing original vid={:?} with new={:?}",
vid, u);
Expand Down
14 changes: 7 additions & 7 deletions src/librustc/infer/higher_ranked/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
// Second, we instantiate each bound region in the supertype with a
// fresh concrete region.
let (b_prime, skol_map) =
self.infcx.skolemize_late_bound_regions(b, snapshot);
self.infcx.skolemize_late_bound_regions(b);

debug!("a_prime={:?}", a_prime);
debug!("b_prime={:?}", b_prime);
Expand Down Expand Up @@ -114,7 +114,7 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
// First, we instantiate each bound region in the matcher
// with a skolemized region.
let ((a_match, a_value), skol_map) =
self.infcx.skolemize_late_bound_regions(a_pair, snapshot);
self.infcx.skolemize_late_bound_regions(a_pair);

debug!("higher_ranked_match: a_match={:?}", a_match);
debug!("higher_ranked_match: skol_map={:?}", skol_map);
Expand Down Expand Up @@ -587,14 +587,13 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
///
/// [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/trait-hrtb.html
pub fn skolemize_late_bound_regions<T>(&self,
binder: &ty::Binder<T>,
snapshot: &CombinedSnapshot<'a, 'tcx>)
binder: &ty::Binder<T>)
-> (T, SkolemizationMap<'tcx>)
where T : TypeFoldable<'tcx>
{
let (result, map) = self.tcx.replace_late_bound_regions(binder, |br| {
self.borrow_region_constraints()
.push_skolemized(self.tcx, br, &snapshot.region_constraints_snapshot)
self.universe.set(self.universe().subuniverse());
self.tcx.mk_region(ty::ReSkolemized(self.universe(), br))
});

debug!("skolemize_bound_regions(binder={:?}, result={:?}, map={:?})",
Expand Down Expand Up @@ -779,7 +778,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
debug!("pop_skolemized({:?})", skol_map);
let skol_regions: FxHashSet<_> = skol_map.values().cloned().collect();
self.borrow_region_constraints()
.pop_skolemized(self.tcx, &skol_regions, &snapshot.region_constraints_snapshot);
.pop_skolemized(self.universe(), &skol_regions, &snapshot.region_constraints_snapshot);
self.universe.set(snapshot.universe);
if !skol_map.is_empty() {
self.projection_cache.borrow_mut().rollback_skolemized(
&snapshot.projection_cache_snapshot);
Expand Down
16 changes: 8 additions & 8 deletions src/librustc/infer/lexical_region_resolve/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ use infer::RegionVariableOrigin;
use infer::region_constraints::Constraint;
use infer::region_constraints::GenericKind;
use infer::region_constraints::RegionConstraintData;
use infer::region_constraints::VarOrigins;
use infer::region_constraints::VarInfos;
use infer::region_constraints::VerifyBound;
use middle::free_region::RegionRelations;
use rustc_data_structures::indexed_vec::{Idx, IndexVec};
Expand All @@ -37,7 +37,7 @@ mod graphviz;
/// all the variables as well as a set of errors that must be reported.
pub fn resolve<'tcx>(
region_rels: &RegionRelations<'_, '_, 'tcx>,
var_origins: VarOrigins,
var_infos: VarInfos,
data: RegionConstraintData<'tcx>,
) -> (
LexicalRegionResolutions<'tcx>,
Expand All @@ -47,7 +47,7 @@ pub fn resolve<'tcx>(
let mut errors = vec![];
let mut resolver = LexicalResolver {
region_rels,
var_origins,
var_infos,
data,
};
let values = resolver.infer_variable_values(&mut errors);
Expand Down Expand Up @@ -103,7 +103,7 @@ type RegionGraph<'tcx> = graph::Graph<(), Constraint<'tcx>>;

struct LexicalResolver<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
region_rels: &'cx RegionRelations<'cx, 'gcx, 'tcx>,
var_origins: VarOrigins,
var_infos: VarInfos,
data: RegionConstraintData<'tcx>,
}

Expand Down Expand Up @@ -132,7 +132,7 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
}

fn num_vars(&self) -> usize {
self.var_origins.len()
self.var_infos.len()
}

/// Initially, the value for all variables is set to `'empty`, the
Expand Down Expand Up @@ -279,7 +279,7 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {

(&ReVar(v_id), _) | (_, &ReVar(v_id)) => {
span_bug!(
self.var_origins[v_id].span(),
self.var_infos[v_id].origin.span(),
"lub_concrete_regions invoked with non-concrete \
regions: {:?}, {:?}",
a,
Expand Down Expand Up @@ -576,7 +576,7 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
if !self.region_rels
.is_subregion_of(lower_bound.region, upper_bound.region)
{
let origin = self.var_origins[node_idx].clone();
let origin = self.var_infos[node_idx].origin.clone();
debug!(
"region inference error at {:?} for {:?}: SubSupConflict sub: {:?} \
sup: {:?}",
Expand All @@ -598,7 +598,7 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
}

span_bug!(
self.var_origins[node_idx].span(),
self.var_infos[node_idx].origin.span(),
"collect_error_for_expanding_node() could not find \
error for var {:?}, lower_bounds={:?}, \
upper_bounds={:?}",
Expand Down
52 changes: 38 additions & 14 deletions src/librustc/infer/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ use arena::SyncDroplessArena;
use self::combine::CombineFields;
use self::higher_ranked::HrMatchResult;
use self::region_constraints::{RegionConstraintCollector, RegionSnapshot};
use self::region_constraints::{GenericKind, VerifyBound, RegionConstraintData, VarOrigins};
use self::region_constraints::{GenericKind, VerifyBound, RegionConstraintData, VarInfos};
use self::lexical_region_resolve::LexicalRegionResolutions;
use self::outlives::env::OutlivesEnvironment;
use self::type_variable::TypeVariableOrigin;
Expand Down Expand Up @@ -183,6 +183,17 @@ pub struct InferCtxt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
// obligations within. This is expected to be done 'late enough'
// that all type inference variables have been bound and so forth.
pub region_obligations: RefCell<Vec<(ast::NodeId, RegionObligation<'tcx>)>>,

/// What is the innermost universe we have created? Starts out as
/// `UniverseIndex::root()` but grows from there as we enter
/// universal quantifiers.
///
/// NB: At present, we exclude the universal quantifiers on the
/// item we are type-checking, and just consider those names as
/// part of the root universe. So this would only get incremented
/// when we enter into a higher-ranked (`for<..>`) type or trait
/// bound.
universe: Cell<ty::UniverseIndex>,
}

/// A map returned by `skolemize_late_bound_regions()` indicating the skolemized
Expand Down Expand Up @@ -455,6 +466,7 @@ impl<'a, 'gcx, 'tcx> InferCtxtBuilder<'a, 'gcx, 'tcx> {
err_count_on_creation: tcx.sess.err_count(),
in_snapshot: Cell::new(false),
region_obligations: RefCell::new(vec![]),
universe: Cell::new(ty::UniverseIndex::ROOT),
}))
}
}
Expand Down Expand Up @@ -489,6 +501,7 @@ pub struct CombinedSnapshot<'a, 'tcx:'a> {
float_snapshot: ut::Snapshot<ut::InPlace<ty::FloatVid>>,
region_constraints_snapshot: RegionSnapshot,
region_obligations_snapshot: usize,
universe: ty::UniverseIndex,
was_in_snapshot: bool,
_in_progress_tables: Option<Ref<'a, ty::TypeckTables<'tcx>>>,
}
Expand Down Expand Up @@ -618,6 +631,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
float_snapshot: self.float_unification_table.borrow_mut().snapshot(),
region_constraints_snapshot: self.borrow_region_constraints().start_snapshot(),
region_obligations_snapshot: self.region_obligations.borrow().len(),
universe: self.universe(),
was_in_snapshot: in_snapshot,
// Borrow tables "in progress" (i.e. during typeck)
// to ban writes from within a snapshot to them.
Expand All @@ -635,10 +649,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
float_snapshot,
region_constraints_snapshot,
region_obligations_snapshot,
universe,
was_in_snapshot,
_in_progress_tables } = snapshot;

self.in_snapshot.set(was_in_snapshot);
self.universe.set(universe);

self.projection_cache
.borrow_mut()
Expand Down Expand Up @@ -667,6 +683,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
float_snapshot,
region_constraints_snapshot,
region_obligations_snapshot: _,
universe: _,
was_in_snapshot,
_in_progress_tables } = snapshot;

Expand Down Expand Up @@ -811,7 +828,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {

Some(self.commit_if_ok(|snapshot| {
let (ty::SubtypePredicate { a_is_expected, a, b}, skol_map) =
self.skolemize_late_bound_regions(predicate, snapshot);
self.skolemize_late_bound_regions(predicate);

let cause_span = cause.span;
let ok = self.at(cause, param_env).sub_exp(a_is_expected, a, b)?;
Expand All @@ -828,7 +845,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
{
self.commit_if_ok(|snapshot| {
let (ty::OutlivesPredicate(r_a, r_b), skol_map) =
self.skolemize_late_bound_regions(predicate, snapshot);
self.skolemize_late_bound_regions(predicate);
let origin =
SubregionOrigin::from_obligation_cause(cause,
|| RelateRegionParamBound(cause.span));
Expand All @@ -841,7 +858,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
pub fn next_ty_var_id(&self, diverging: bool, origin: TypeVariableOrigin) -> TyVid {
self.type_variables
.borrow_mut()
.new_var(diverging, origin)
.new_var(self.universe(), diverging, origin)
}

pub fn next_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
Expand Down Expand Up @@ -872,12 +889,14 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
/// during diagnostics / error-reporting.
pub fn next_region_var(&self, origin: RegionVariableOrigin)
-> ty::Region<'tcx> {
self.tcx.mk_region(ty::ReVar(self.borrow_region_constraints().new_region_var(origin)))
let region_var = self.borrow_region_constraints()
.new_region_var(self.universe(), origin);
self.tcx.mk_region(ty::ReVar(region_var))
}

/// Number of region variables created so far.
pub fn num_region_vars(&self) -> usize {
self.borrow_region_constraints().var_origins().len()
self.borrow_region_constraints().num_region_vars()
}

/// Just a convenient wrapper of `next_region_var` for using during NLL.
Expand Down Expand Up @@ -909,7 +928,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
-> Ty<'tcx> {
let ty_var_id = self.type_variables
.borrow_mut()
.new_var(false,
.new_var(self.universe(),
false,
TypeVariableOrigin::TypeParameterDefinition(span, def.name));

self.tcx.mk_var(ty_var_id)
Expand Down Expand Up @@ -1004,12 +1024,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
region_context,
region_map,
outlives_env.free_region_map());
let (var_origins, data) = self.region_constraints.borrow_mut()
let (var_infos, data) = self.region_constraints.borrow_mut()
.take()
.expect("regions already resolved")
.into_origins_and_data();
.into_infos_and_data();
let (lexical_region_resolutions, errors) =
lexical_region_resolve::resolve(region_rels, var_origins, data);
lexical_region_resolve::resolve(region_rels, var_infos, data);

let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
assert!(old_value.is_none());
Expand Down Expand Up @@ -1057,13 +1077,13 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
/// hence that `resolve_regions_and_report_errors` can never be
/// called. This is used only during NLL processing to "hand off" ownership
/// of the set of region vairables into the NLL region context.
pub fn take_region_var_origins(&self) -> VarOrigins {
let (var_origins, data) = self.region_constraints.borrow_mut()
pub fn take_region_var_origins(&self) -> VarInfos {
let (var_infos, data) = self.region_constraints.borrow_mut()
.take()
.expect("regions already resolved")
.into_origins_and_data();
.into_infos_and_data();
assert!(data.is_empty());
var_origins
var_infos
}

pub fn ty_to_string(&self, t: Ty<'tcx>) -> String {
Expand Down Expand Up @@ -1356,6 +1376,10 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
self.evaluation_cache.clear();
self.projection_cache.borrow_mut().clear();
}

fn universe(&self) -> ty::UniverseIndex {
self.universe.get()
}
}

impl<'a, 'gcx, 'tcx> TypeTrace<'tcx> {
Expand Down
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