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rustc: add Spans to inferred_outlives_of predicates. #65541

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Oct 27, 2019
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rustc: add Spans to inferred_outlives_of predicates. #65541

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93cac9c
rustc: add `Span`s to `inferred_outlives_of` predicates.
eddyb Oct 18, 2019
1ca8da4
rustc_typeck: compute better spans for inferred_outlives.
eddyb Oct 19, 2019
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2 changes: 1 addition & 1 deletion src/librustc/query/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,7 @@ rustc_queries! {

/// Returns the inferred outlives predicates (e.g., for `struct
/// Foo<'a, T> { x: &'a T }`, this would return `T: 'a`).
query inferred_outlives_of(_: DefId) -> &'tcx [ty::Predicate<'tcx>] {}
query inferred_outlives_of(_: DefId) -> &'tcx [(ty::Predicate<'tcx>, Span)] {}

/// Maps from the `DefId` of a trait to the list of
/// super-predicates. This is a subset of the full list of
Expand Down
2 changes: 1 addition & 1 deletion src/librustc/ty/mod.rs
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Expand Up @@ -1136,7 +1136,7 @@ pub struct CratePredicatesMap<'tcx> {
/// For each struct with outlive bounds, maps to a vector of the
/// predicate of its outlive bounds. If an item has no outlives
/// bounds, it will have no entry.
pub predicates: FxHashMap<DefId, &'tcx [ty::Predicate<'tcx>]>,
pub predicates: FxHashMap<DefId, &'tcx [(ty::Predicate<'tcx>, Span)]>,
}

impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
Expand Down
10 changes: 5 additions & 5 deletions src/librustc_lint/builtin.rs
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Expand Up @@ -1497,10 +1497,10 @@ declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMEN

impl ExplicitOutlivesRequirements {
fn lifetimes_outliving_lifetime<'tcx>(
inferred_outlives: &'tcx [ty::Predicate<'tcx>],
inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
index: u32,
) -> Vec<ty::Region<'tcx>> {
inferred_outlives.iter().filter_map(|pred| {
inferred_outlives.iter().filter_map(|(pred, _)| {
match pred {
ty::Predicate::RegionOutlives(outlives) => {
let outlives = outlives.skip_binder();
Expand All @@ -1517,10 +1517,10 @@ impl ExplicitOutlivesRequirements {
}

fn lifetimes_outliving_type<'tcx>(
inferred_outlives: &'tcx [ty::Predicate<'tcx>],
inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
index: u32,
) -> Vec<ty::Region<'tcx>> {
inferred_outlives.iter().filter_map(|pred| {
inferred_outlives.iter().filter_map(|(pred, _)| {
match pred {
ty::Predicate::TypeOutlives(outlives) => {
let outlives = outlives.skip_binder();
Expand All @@ -1539,7 +1539,7 @@ impl ExplicitOutlivesRequirements {
&self,
param: &'tcx hir::GenericParam,
tcx: TyCtxt<'tcx>,
inferred_outlives: &'tcx [ty::Predicate<'tcx>],
inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)],
ty_generics: &'tcx ty::Generics,
) -> Vec<ty::Region<'tcx>> {
let index = ty_generics.param_def_id_to_index[
Expand Down
8 changes: 8 additions & 0 deletions src/librustc_metadata/encoder.rs
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Expand Up @@ -197,6 +197,13 @@ impl<'tcx> SpecializedEncoder<Span> for EncodeContext<'tcx> {
return TAG_INVALID_SPAN.encode(self)
}

// HACK(eddyb) there's no way to indicate which crate a Span is coming
// from right now, so decoding would fail to find the SourceFile if
// it's not local to the crate the Span is found in.
if self.source_file_cache.is_imported() {
return TAG_INVALID_SPAN.encode(self)
}
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cc @petrochenkov I had to add this because decoding assumes Spans are always from each crate's own files, not some transitive dependency.

I wonder if this should be an assert instead - I could enforce that the Spans computed for inferred_outlives_of are always from the definition of the type, not some other type (which is how the last commit in this PR triggered the problem).


TAG_VALID_SPAN.encode(self)?;
span.lo.encode(self)?;

Expand Down Expand Up @@ -379,6 +386,7 @@ impl<'tcx> EncodeContext<'tcx> {
.filter(|source_file| {
// No need to re-export imported source_files, as any downstream
// crate will import them from their original source.
// FIXME(eddyb) the `Span` encoding should take that into account.
!source_file.is_imported()
})
.map(|source_file| {
Expand Down
15 changes: 7 additions & 8 deletions src/librustc_typeck/collect.rs
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Expand Up @@ -1970,19 +1970,18 @@ fn predicates_defined_on(
);
let inferred_outlives = tcx.inferred_outlives_of(def_id);
if !inferred_outlives.is_empty() {
let span = tcx.def_span(def_id);
debug!(
"predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
def_id,
inferred_outlives,
);
result.predicates = tcx.arena.alloc_from_iter(
result.predicates.iter().copied().chain(
// FIXME(eddyb) use better spans - maybe add `Span`s
// to `inferred_outlives_of` predicates as well?
inferred_outlives.iter().map(|&p| (p, span)),
),
);
if result.predicates.is_empty() {
result.predicates = inferred_outlives;
} else {
result.predicates = tcx.arena.alloc_from_iter(
result.predicates.iter().chain(inferred_outlives).copied(),
);
}
}
debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
result
Expand Down
13 changes: 10 additions & 3 deletions src/librustc_typeck/outlives/explicit.rs
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Expand Up @@ -30,11 +30,17 @@ impl<'tcx> ExplicitPredicatesMap<'tcx> {
let mut required_predicates = RequiredPredicates::default();

// process predicates and convert to `RequiredPredicates` entry, see below
for (pred, _) in predicates.predicates {
match pred {
for &(predicate, span) in predicates.predicates {
match predicate {
ty::Predicate::TypeOutlives(predicate) => {
let OutlivesPredicate(ref ty, ref reg) = predicate.skip_binder();
insert_outlives_predicate(tcx, (*ty).into(), reg, &mut required_predicates)
insert_outlives_predicate(
tcx,
(*ty).into(),
reg,
span,
&mut required_predicates,
)
}

ty::Predicate::RegionOutlives(predicate) => {
Expand All @@ -43,6 +49,7 @@ impl<'tcx> ExplicitPredicatesMap<'tcx> {
tcx,
(*reg1).into(),
reg2,
span,
&mut required_predicates,
)
}
Expand Down
13 changes: 9 additions & 4 deletions src/librustc_typeck/outlives/implicit_infer.rs
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Expand Up @@ -4,6 +4,7 @@ use rustc::hir::itemlikevisit::ItemLikeVisitor;
use rustc::ty::subst::{GenericArg, Subst, GenericArgKind};
use rustc::ty::{self, Ty, TyCtxt};
use rustc::util::nodemap::FxHashMap;
use syntax_pos::Span;

use super::explicit::ExplicitPredicatesMap;
use super::utils::*;
Expand Down Expand Up @@ -79,9 +80,11 @@ impl<'cx, 'tcx> ItemLikeVisitor<'tcx> for InferVisitor<'cx, 'tcx> {
// (struct/enum/union) there will be outlive
// requirements for adt_def.
let field_ty = self.tcx.type_of(field_def.did);
let field_span = self.tcx.def_span(field_def.did);
insert_required_predicates_to_be_wf(
self.tcx,
field_ty,
field_span,
self.global_inferred_outlives,
&mut item_required_predicates,
&mut self.explicit_map,
Expand Down Expand Up @@ -118,6 +121,7 @@ impl<'cx, 'tcx> ItemLikeVisitor<'tcx> for InferVisitor<'cx, 'tcx> {
fn insert_required_predicates_to_be_wf<'tcx>(
tcx: TyCtxt<'tcx>,
field_ty: Ty<'tcx>,
field_span: Span,
global_inferred_outlives: &FxHashMap<DefId, RequiredPredicates<'tcx>>,
required_predicates: &mut RequiredPredicates<'tcx>,
explicit_map: &mut ExplicitPredicatesMap<'tcx>,
Expand All @@ -130,7 +134,7 @@ fn insert_required_predicates_to_be_wf<'tcx>(
// We also want to calculate potential predicates for the T
ty::Ref(region, rty, _) => {
debug!("Ref");
insert_outlives_predicate(tcx, rty.into(), region, required_predicates);
insert_outlives_predicate(tcx, rty.into(), region, field_span, required_predicates);
}

// For each Adt (struct/enum/union) type `Foo<'a, T>`, we
Expand Down Expand Up @@ -158,7 +162,7 @@ fn insert_required_predicates_to_be_wf<'tcx>(
// 'a` holds for `Foo`.
debug!("Adt");
if let Some(unsubstituted_predicates) = global_inferred_outlives.get(&def.did) {
for unsubstituted_predicate in unsubstituted_predicates {
for (unsubstituted_predicate, &span) in unsubstituted_predicates {
// `unsubstituted_predicate` is `U: 'b` in the
// example above. So apply the substitution to
// get `T: 'a` (or `predicate`):
Expand All @@ -167,6 +171,7 @@ fn insert_required_predicates_to_be_wf<'tcx>(
tcx,
predicate.0,
predicate.1,
span,
required_predicates,
);
}
Expand Down Expand Up @@ -272,7 +277,7 @@ pub fn check_explicit_predicates<'tcx>(
);
let explicit_predicates = explicit_map.explicit_predicates_of(tcx, def_id);

for outlives_predicate in explicit_predicates.iter() {
for (outlives_predicate, &span) in explicit_predicates {
debug!("outlives_predicate = {:?}", &outlives_predicate);

// Careful: If we are inferring the effects of a `dyn Trait<..>`
Expand Down Expand Up @@ -320,6 +325,6 @@ pub fn check_explicit_predicates<'tcx>(

let predicate = outlives_predicate.subst(tcx, substs);
debug!("predicate = {:?}", &predicate);
insert_outlives_predicate(tcx, predicate.0.into(), predicate.1, required_predicates);
insert_outlives_predicate(tcx, predicate.0.into(), predicate.1, span, required_predicates);
}
}
19 changes: 10 additions & 9 deletions src/librustc_typeck/outlives/mod.rs
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Expand Up @@ -5,6 +5,7 @@ use rustc::ty::query::Providers;
use rustc::ty::subst::GenericArgKind;
use rustc::ty::{self, CratePredicatesMap, TyCtxt};
use syntax::symbol::sym;
use syntax_pos::Span;

mod explicit;
mod implicit_infer;
Expand All @@ -23,7 +24,7 @@ pub fn provide(providers: &mut Providers<'_>) {
fn inferred_outlives_of(
tcx: TyCtxt<'_>,
item_def_id: DefId,
) -> &[ty::Predicate<'_>] {
) -> &[(ty::Predicate<'_>, Span)] {
let id = tcx
.hir()
.as_local_hir_id(item_def_id)
Expand All @@ -43,7 +44,7 @@ fn inferred_outlives_of(
if tcx.has_attr(item_def_id, sym::rustc_outlives) {
let mut pred: Vec<String> = predicates
.iter()
.map(|out_pred| match out_pred {
.map(|(out_pred, _)| match out_pred {
ty::Predicate::RegionOutlives(p) => p.to_string(),
ty::Predicate::TypeOutlives(p) => p.to_string(),
err => bug!("unexpected predicate {:?}", err),
Expand Down Expand Up @@ -96,27 +97,27 @@ fn inferred_outlives_crate(
let predicates = global_inferred_outlives
.iter()
.map(|(&def_id, set)| {
let predicates = tcx.arena.alloc_from_iter(set
let predicates = &*tcx.arena.alloc_from_iter(set
.iter()
.filter_map(
|ty::OutlivesPredicate(kind1, region2)| match kind1.unpack() {
|(ty::OutlivesPredicate(kind1, region2), &span)| match kind1.unpack() {
GenericArgKind::Type(ty1) => {
Some(ty::Predicate::TypeOutlives(ty::Binder::bind(
Some((ty::Predicate::TypeOutlives(ty::Binder::bind(
ty::OutlivesPredicate(ty1, region2)
)))
)), span))
}
GenericArgKind::Lifetime(region1) => {
Some(ty::Predicate::RegionOutlives(
Some((ty::Predicate::RegionOutlives(
ty::Binder::bind(ty::OutlivesPredicate(region1, region2))
))
), span))
}
GenericArgKind::Const(_) => {
// Generic consts don't impose any constraints.
None
}
},
));
(def_id, &*predicates)
(def_id, predicates)
}).collect();

tcx.arena.alloc(ty::CratePredicatesMap {
Expand Down
16 changes: 11 additions & 5 deletions src/librustc_typeck/outlives/utils.rs
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Expand Up @@ -2,19 +2,21 @@ use rustc::ty::outlives::Component;
use rustc::ty::subst::{GenericArg, GenericArgKind};
use rustc::ty::{self, Region, RegionKind, Ty, TyCtxt};
use smallvec::smallvec;
use std::collections::BTreeSet;
use std::collections::BTreeMap;
use syntax_pos::Span;

/// Tracks the `T: 'a` or `'a: 'a` predicates that we have inferred
/// must be added to the struct header.
pub type RequiredPredicates<'tcx> =
BTreeSet<ty::OutlivesPredicate<GenericArg<'tcx>, ty::Region<'tcx>>>;
BTreeMap<ty::OutlivesPredicate<GenericArg<'tcx>, ty::Region<'tcx>>, Span>;

/// Given a requirement `T: 'a` or `'b: 'a`, deduce the
/// outlives_component and add it to `required_predicates`
pub fn insert_outlives_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
kind: GenericArg<'tcx>,
outlived_region: Region<'tcx>,
span: Span,
required_predicates: &mut RequiredPredicates<'tcx>,
) {
// If the `'a` region is bound within the field type itself, we
Expand Down Expand Up @@ -53,6 +55,7 @@ pub fn insert_outlives_predicate<'tcx>(
tcx,
r.into(),
outlived_region,
span,
required_predicates,
);
}
Expand All @@ -73,7 +76,8 @@ pub fn insert_outlives_predicate<'tcx>(
// where clause that `U: 'a`.
let ty: Ty<'tcx> = param_ty.to_ty(tcx);
required_predicates
.insert(ty::OutlivesPredicate(ty.into(), outlived_region));
.entry(ty::OutlivesPredicate(ty.into(), outlived_region))
.or_insert(span);
}

Component::Projection(proj_ty) => {
Expand All @@ -88,7 +92,8 @@ pub fn insert_outlives_predicate<'tcx>(
// Here we want to add an explicit `where <T as Iterator>::Item: 'a`.
let ty: Ty<'tcx> = tcx.mk_projection(proj_ty.item_def_id, proj_ty.substs);
required_predicates
.insert(ty::OutlivesPredicate(ty.into(), outlived_region));
.entry(ty::OutlivesPredicate(ty.into(), outlived_region))
.or_insert(span);
}

Component::EscapingProjection(_) => {
Expand Down Expand Up @@ -117,7 +122,8 @@ pub fn insert_outlives_predicate<'tcx>(
if !is_free_region(tcx, r) {
return;
}
required_predicates.insert(ty::OutlivesPredicate(kind, outlived_region));
required_predicates.entry(ty::OutlivesPredicate(kind, outlived_region))
.or_insert(span);
}

GenericArgKind::Const(_) => {
Expand Down