Skip to content

Commit

Permalink
Rollup merge of rust-lang#79298 - lcnr:new-elysium, r=matthewjasper
Browse files Browse the repository at this point in the history
correctly deal with late-bound lifetimes in anon consts

adds support for using late bound lifetimes of the parent context in anon consts.
```rust
#![feature(const_generics)]
const fn inner<'a>() -> usize where &'a (): Sized { 3 }

fn test<'a>() {
    let _: [u8; inner::<'a>()];
}
```
The lifetime `'a` is late bound in `test` so it's not included in its generics but is instead dealt with separately in borrowck.
This didn't previously work for anon consts as they have to use the late bound lifetimes of their parent which has
to be explicitly handled.

r? `@matthewjasper` cc `@varkor` `@eddyb`
  • Loading branch information
m-ou-se authored Jan 16, 2021
2 parents 8a65184 + 15f0921 commit f6f754a
Show file tree
Hide file tree
Showing 6 changed files with 71 additions and 8 deletions.
2 changes: 1 addition & 1 deletion compiler/rustc_middle/src/query/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1316,7 +1316,7 @@ rustc_queries! {
desc { "looking up a named region" }
}
query is_late_bound_map(_: LocalDefId) ->
Option<&'tcx FxHashSet<ItemLocalId>> {
Option<(LocalDefId, &'tcx FxHashSet<ItemLocalId>)> {
desc { "testing if a region is late bound" }
}
query object_lifetime_defaults_map(_: LocalDefId)
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_middle/src/ty/context.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2578,7 +2578,8 @@ impl<'tcx> TyCtxt<'tcx> {
}

pub fn is_late_bound(self, id: HirId) -> bool {
self.is_late_bound_map(id.owner).map_or(false, |set| set.contains(&id.local_id))
self.is_late_bound_map(id.owner)
.map_or(false, |(owner, set)| owner == id.owner && set.contains(&id.local_id))
}

pub fn object_lifetime_defaults(self, id: HirId) -> Option<&'tcx [ObjectLifetimeDefault]> {
Expand Down
8 changes: 4 additions & 4 deletions compiler/rustc_mir/src/borrow_check/universal_regions.rs
Original file line number Diff line number Diff line change
Expand Up @@ -788,13 +788,13 @@ fn for_each_late_bound_region_defined_on<'tcx>(
fn_def_id: DefId,
mut f: impl FnMut(ty::Region<'tcx>),
) {
if let Some(late_bounds) = tcx.is_late_bound_map(fn_def_id.expect_local()) {
for late_bound in late_bounds.iter() {
let hir_id = HirId { owner: fn_def_id.expect_local(), local_id: *late_bound };
if let Some((owner, late_bounds)) = tcx.is_late_bound_map(fn_def_id.expect_local()) {
for &late_bound in late_bounds.iter() {
let hir_id = HirId { owner, local_id: late_bound };
let name = tcx.hir().name(hir_id);
let region_def_id = tcx.hir().local_def_id(hir_id);
let liberated_region = tcx.mk_region(ty::ReFree(ty::FreeRegion {
scope: fn_def_id,
scope: owner.to_def_id(),
bound_region: ty::BoundRegionKind::BrNamed(region_def_id.to_def_id(), name),
}));
f(liberated_region);
Expand Down
32 changes: 30 additions & 2 deletions compiler/rustc_resolve/src/late/lifetimes.rs
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,8 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LOCAL_CRATE};
use rustc_hir::def_id::{CrateNum, DefIdMap, LOCAL_CRATE};
use rustc_hir::hir_id::ItemLocalId;
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::{GenericArg, GenericParam, LifetimeName, Node, ParamName, QPath};
use rustc_hir::{GenericParamKind, HirIdMap, HirIdSet, LifetimeParamKind};
Expand All @@ -20,6 +21,7 @@ use rustc_middle::middle::resolve_lifetime::*;
use rustc_middle::ty::{self, DefIdTree, GenericParamDefKind, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_session::lint;
use rustc_span::def_id::{DefId, LocalDefId};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::Span;
use std::borrow::Cow;
Expand Down Expand Up @@ -284,7 +286,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
resolve_lifetimes,

named_region_map: |tcx, id| tcx.resolve_lifetimes(LOCAL_CRATE).defs.get(&id),
is_late_bound_map: |tcx, id| tcx.resolve_lifetimes(LOCAL_CRATE).late_bound.get(&id),
is_late_bound_map,
object_lifetime_defaults_map: |tcx, id| {
tcx.resolve_lifetimes(LOCAL_CRATE).object_lifetime_defaults.get(&id)
},
Expand Down Expand Up @@ -320,6 +322,32 @@ fn resolve_lifetimes(tcx: TyCtxt<'_>, for_krate: CrateNum) -> ResolveLifetimes {
rl
}

fn is_late_bound_map<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: LocalDefId,
) -> Option<(LocalDefId, &'tcx FxHashSet<ItemLocalId>)> {
match tcx.def_kind(def_id) {
DefKind::AnonConst => {
let mut def_id = tcx
.parent(def_id.to_def_id())
.unwrap_or_else(|| bug!("anon const or closure without a parent"));
// We search for the next outer anon const or fn here
// while skipping closures.
//
// Note that for `AnonConst` we still just recurse until we
// find a function body, but who cares :shrug:
while tcx.is_closure(def_id) {
def_id = tcx
.parent(def_id)
.unwrap_or_else(|| bug!("anon const or closure without a parent"));
}

tcx.is_late_bound_map(def_id.expect_local())
}
_ => tcx.resolve_lifetimes(LOCAL_CRATE).late_bound.get(&def_id).map(|lt| (def_id, lt)),
}
}

fn krate(tcx: TyCtxt<'_>) -> NamedRegionMap {
let krate = tcx.hir().krate();
let mut map = NamedRegionMap {
Expand Down
18 changes: 18 additions & 0 deletions src/test/ui/const-generics/late-bound-vars/in_closure.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
// run-pass
#![feature(const_generics)]
#![allow(incomplete_features)]

const fn inner<'a>() -> usize where &'a (): Sized {
3
}

fn test<'a>() {
let _ = || {
let _: [u8; inner::<'a>()];
let _ = [0; inner::<'a>()];
};
}

fn main() {
test();
}
16 changes: 16 additions & 0 deletions src/test/ui/const-generics/late-bound-vars/simple.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
// run-pass
#![feature(const_generics)]
#![allow(incomplete_features)]

const fn inner<'a>() -> usize where &'a (): Sized {
3
}

fn test<'a>() {
let _: [u8; inner::<'a>()];
let _ = [0; inner::<'a>()];
}

fn main() {
test();
}

0 comments on commit f6f754a

Please sign in to comment.