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Auto merge of #107376 - aliemjay:remove-givens, r=lcnr

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remove obsolete `givens` from regionck

Fixes #106567

r? `@lcnr` (feel free to reassign)
This commit is contained in:
bors 2023-03-15 02:50:58 +00:00
commit e84e5ff04a
14 changed files with 87 additions and 152 deletions
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4
compiler/rustc_infer/src/infer/canonical/query_response.rs
View file

@ -636,11 +636,9 @@ pub fn make_query_region_constraints<'tcx>(
outlives_obligations: impl Iterator<Item = (Ty<'tcx>, 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);

47
compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
View file

@ -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<Region<'tcx>, 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) {

4
compiler/rustc_infer/src/infer/mod.rs
View file

@ -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<T>(&self, param_env: ty::ParamEnv<'tcx>, a: T, b: T) -> bool
where
T: at::ToTrace<'tcx>,

45
compiler/rustc_infer/src/infer/outlives/env.rs
View file

@ -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<Item = OutlivesBound<'tcx>>,
) -> 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<I>(&mut self, infcx: Option<&InferCtxt<'tcx>>, outlives_bounds: I)
fn add_outlives_bounds<I>(&mut self, outlives_bounds: I)
where
I: IntoIterator<Item = OutlivesBound<'tcx>>,
{
@ -142,27 +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) => {
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)
}
}
}
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"),
},
}
}
}

3
compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
View file

@ -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",

44
compiler/rustc_infer/src/infer/region_constraints/mod.rs
View file

@ -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<Verify<'tcx>>,
/// 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()
}
}