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Auto merge of #96268 - jackh726:remove-mutable_borrow_reservation_conflict-lint, r=nikomatsakis

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Remove mutable_borrow_reservation_conflict lint and allow the code pattern

This was the only breaking issue with the NLL stabilization PR. Lang team decided to go ahead and allow this.

r? `@nikomatsakis`
Closes #59159
Closes #56254
This commit is contained in:
bors 2022-05-06 12:32:44 +00:00
commit 9a251644fa
21 changed files with 89 additions and 380 deletions
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73
compiler/rustc_borrowck/src/lib.rs
View file

@ -34,14 +34,13 @@ use rustc_middle::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, Stat
use rustc_middle::mir::{InlineAsmOperand, Terminator, TerminatorKind};
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, CapturedPlace, ParamEnv, RegionVid, TyCtxt};
use rustc_session::lint::builtin::{MUTABLE_BORROW_RESERVATION_CONFLICT, UNUSED_MUT};
use rustc_span::{Span, Symbol, DUMMY_SP};
use rustc_session::lint::builtin::UNUSED_MUT;
use rustc_span::{Span, Symbol};
use either::Either;
use smallvec::SmallVec;
use std::cell::RefCell;
use std::collections::BTreeMap;
use std::mem;
use std::rc::Rc;
use rustc_mir_dataflow::impls::{
@ -312,7 +311,6 @@ fn do_mir_borrowck<'a, 'tcx>(
locals_are_invalidated_at_exit,
access_place_error_reported: Default::default(),
reservation_error_reported: Default::default(),
reservation_warnings: Default::default(),
uninitialized_error_reported: Default::default(),
regioncx: regioncx.clone(),
used_mut: Default::default(),
@ -344,7 +342,6 @@ fn do_mir_borrowck<'a, 'tcx>(
fn_self_span_reported: Default::default(),
access_place_error_reported: Default::default(),
reservation_error_reported: Default::default(),
reservation_warnings: Default::default(),
uninitialized_error_reported: Default::default(),
regioncx: Rc::clone(&regioncx),
used_mut: Default::default(),
@ -377,34 +374,6 @@ fn do_mir_borrowck<'a, 'tcx>(
&mut mbcx,
);
// Convert any reservation warnings into lints.
let reservation_warnings = mem::take(&mut mbcx.reservation_warnings);
for (_, (place, span, location, bk, borrow)) in reservation_warnings {
let initial_diag = mbcx.report_conflicting_borrow(location, (place, span), bk, &borrow);
let scope = mbcx.body.source_info(location).scope;
let lint_root = match &mbcx.body.source_scopes[scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
_ => tcx.hir().local_def_id_to_hir_id(def.did),
};
// Span and message don't matter; we overwrite them below anyway
mbcx.infcx.tcx.struct_span_lint_hir(
MUTABLE_BORROW_RESERVATION_CONFLICT,
lint_root,
DUMMY_SP,
|lint| {
let mut diag = lint.build("");
diag.message = initial_diag.styled_message().clone();
diag.span = initial_diag.span.clone();
mbcx.buffer_non_error_diag(diag);
},
);
initial_diag.cancel();
}
// For each non-user used mutable variable, check if it's been assigned from
// a user-declared local. If so, then put that local into the used_mut set.
// Note that this set is expected to be small - only upvars from closures
@ -539,11 +508,6 @@ struct MirBorrowckCtxt<'cx, 'tcx> {
/// used to report extra information for `FnSelfUse`, to avoid
/// unnecessarily verbose errors.
fn_self_span_reported: FxHashSet<Span>,
/// Migration warnings to be reported for #56254. We delay reporting these
/// so that we can suppress the warning if there's a corresponding error
/// for the activation of the borrow.
reservation_warnings:
FxHashMap<BorrowIndex, (Place<'tcx>, Span, Location, BorrowKind, BorrowData<'tcx>)>,
/// This field keeps track of errors reported in the checking of uninitialized variables,
/// so that we don't report seemingly duplicate errors.
uninitialized_error_reported: FxHashSet<PlaceRef<'tcx>>,
@ -995,12 +959,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let conflict_error =
self.check_access_for_conflict(location, place_span, sd, rw, flow_state);
if let (Activation(_, borrow_idx), true) = (kind.1, conflict_error) {
// Suppress this warning when there's an error being emitted for the
// same borrow: fixing the error is likely to fix the warning.
self.reservation_warnings.remove(&borrow_idx);
}
if conflict_error || mutability_error {
debug!("access_place: logging error place_span=`{:?}` kind=`{:?}`", place_span, kind);
self.access_place_error_reported.insert((place_span.0, place_span.1));
@ -1067,6 +1025,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
BorrowKind::Unique | BorrowKind::Mut { .. },
) => Control::Continue,
(Reservation(_), BorrowKind::Shallow | BorrowKind::Shared) => {
// This used to be a future compatibility warning (to be
// disallowed on NLL). See rust-lang/rust#56254
Control::Continue
}
(Write(WriteKind::Move), BorrowKind::Shallow) => {
// Handled by initialization checks.
Control::Continue
@ -1095,27 +1059,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
Control::Break
}
(
Reservation(WriteKind::MutableBorrow(bk)),
BorrowKind::Shallow | BorrowKind::Shared,
) if { tcx.migrate_borrowck() && this.borrow_set.contains(&location) } => {
let bi = this.borrow_set.get_index_of(&location).unwrap();
debug!(
"recording invalid reservation of place: {:?} with \
borrow index {:?} as warning",
place_span.0, bi,
);
// rust-lang/rust#56254 - This was previously permitted on
// the 2018 edition so we emit it as a warning. We buffer
// these separately so that we only emit a warning if borrow
// checking was otherwise successful.
this.reservation_warnings
.insert(bi, (place_span.0, place_span.1, location, bk, borrow.clone()));
// Don't suppress actual errors.
Control::Continue
}
(Reservation(kind) | Activation(kind, _) | Write(kind), _) => {
match rw {
Reservation(..) => {