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Const drop selection candidates

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Deadbeef 2021-09-01 16:34:28 +00:00
parent 894ce921a0
commit a13b13ff46
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GPG key ID: 027DF9338862ADDD
9 changed files with 212 additions and 25 deletions
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42
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -1038,6 +1038,24 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
it.for_each(|o| o.recursion_depth = cmp::max(min_depth, o.recursion_depth) + 1);
}
fn check_recursion_depth<T: Display + TypeFoldable<'tcx>>(
&self,
depth: usize,
error_obligation: &Obligation<'tcx, T>,
) -> Result<(), OverflowError> {
if !self.infcx.tcx.recursion_limit().value_within_limit(depth) {
match self.query_mode {
TraitQueryMode::Standard => {
self.infcx.report_overflow_error(error_obligation, true);
}
TraitQueryMode::Canonical => {
return Err(OverflowError);
}
}
}
Ok(())
}
/// Checks that the recursion limit has not been exceeded.
///
/// The weird return type of this function allows it to be used with the `try` (`?`)
@ -1047,17 +1065,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &Obligation<'tcx, T>,
error_obligation: &Obligation<'tcx, V>,
) -> Result<(), OverflowError> {
if !self.infcx.tcx.recursion_limit().value_within_limit(obligation.recursion_depth) {
match self.query_mode {
TraitQueryMode::Standard => {
self.infcx().report_overflow_error(error_obligation, true);
}
TraitQueryMode::Canonical => {
return Err(OverflowError);
}
}
}
Ok(())
self.check_recursion_depth(obligation.recursion_depth, error_obligation)
}
fn in_task<OP, R>(&mut self, op: OP) -> (R, DepNodeIndex)
@ -1079,10 +1087,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let tcx = self.tcx();
// Respect const trait obligations
if self.is_trait_predicate_const(obligation.predicate.skip_binder()) {
if Some(obligation.predicate.skip_binder().trait_ref.def_id)
!= tcx.lang_items().sized_trait()
// const Sized bounds are skipped
{
match candidate {
// const impl
ImplCandidate(def_id)
@ -1097,12 +1101,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// generator, this will raise error in other places
// or ignore error with const_async_blocks feature
GeneratorCandidate => {}
ConstDropCandidate => {}
_ => {
// reject all other types of candidates
return Err(Unimplemented);
}
}
}
}
// Treat negative impls as unimplemented, and reservation impls as ambiguity.
if let ImplCandidate(def_id) = candidate {
@ -1476,14 +1480,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
(
BuiltinCandidate { has_nested: false }
| DiscriminantKindCandidate
| PointeeCandidate,
| PointeeCandidate
| ConstDropCandidate,
_,
) => true,
(
_,
BuiltinCandidate { has_nested: false }
| DiscriminantKindCandidate
| PointeeCandidate,
| PointeeCandidate
| ConstDropCandidate,
) => false,
(ParamCandidate(other), ParamCandidate(victim)) => {