bjoernager/rust
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Auto merge of #113154 - lcnr:better-probe-check, r=compiler-errors

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change snapshot tracking in fulfillment contexts

use the exact snapshot number to prevent misuse even when created inside of a snapshot
This commit is contained in:
bors 2023-07-01 01:53:10 +00:00
commit 7383ab7378
23 changed files with 79 additions and 121 deletions
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14
compiler/rustc_trait_selection/src/solve/fulfill.rs
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@ -26,20 +26,27 @@ use super::{Certainty, InferCtxtEvalExt};
/// here as this will have to deal with far more root goals than `evaluate_all`.
pub struct FulfillmentCtxt<'tcx> {
obligations: Vec<PredicateObligation<'tcx>>,
/// The snapshot in which this context was created. Using the context
/// outside of this snapshot leads to subtle bugs if the snapshot
/// gets rolled back. Because of this we explicitly check that we only
/// use the context in exactly this snapshot.
usable_in_snapshot: usize,
}
impl<'tcx> FulfillmentCtxt<'tcx> {
pub fn new() -> FulfillmentCtxt<'tcx> {
FulfillmentCtxt { obligations: Vec::new() }
pub fn new(infcx: &InferCtxt<'tcx>) -> FulfillmentCtxt<'tcx> {
FulfillmentCtxt { obligations: Vec::new(), usable_in_snapshot: infcx.num_open_snapshots() }
}
}
impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
fn register_predicate_obligation(
&mut self,
_infcx: &InferCtxt<'tcx>,
infcx: &InferCtxt<'tcx>,
obligation: PredicateObligation<'tcx>,
) {
assert_eq!(self.usable_in_snapshot, infcx.num_open_snapshots());
self.obligations.push(obligation);
}
@ -77,6 +84,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
}
fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>> {
assert_eq!(self.usable_in_snapshot, infcx.num_open_snapshots());
let mut errors = Vec::new();
for i in 0.. {
if !infcx.tcx.recursion_limit().value_within_limit(i) {