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Use trait select logic instead of query

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Deadbeef 2021-09-02 10:59:53 +00:00
parent f0a52128ee
commit 1ca83c6451
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5 changed files with 100 additions and 31 deletions
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52
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
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@ -283,6 +283,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
if self.is_in_const_context {
self.assemble_const_drop_candidates(obligation, &mut candidates)?;
} else {
debug!("passing ~const Drop bound; in non-const context");
// `~const Drop` when we are not in a const context has no effect.
candidates.vec.push(ConstDropCandidate)
}
@ -821,6 +822,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let mut stack: Vec<(Ty<'tcx>, usize)> = vec![(obligation.self_ty().skip_binder(), 0)];
while let Some((ty, depth)) = stack.pop() {
let mut noreturn = false;
self.check_recursion_depth(depth, obligation)?;
let mut copy_candidates = SelectionCandidateSet { vec: Vec::new(), ambiguous: false };
let mut copy_obligation =
@ -836,8 +839,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let copy_conditions = self.copy_clone_conditions(&copy_obligation);
self.assemble_builtin_bound_candidates(copy_conditions, &mut copy_candidates);
if !copy_candidates.vec.is_empty() {
continue;
noreturn = true;
}
debug!(?copy_candidates.vec, "assemble_const_drop_candidates - copy");
match ty.kind() {
ty::Int(_)
@ -857,22 +861,28 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
ty::Adt(def, subst) => {
let mut set = SelectionCandidateSet { vec: Vec::new(), ambiguous: false };
self.assemble_candidates_from_impls(obligation, &mut set);
if set
.vec
.into_iter()
.find(|candidate| {
if let SelectionCandidate::ImplCandidate(did) = candidate {
matches!(self.tcx().impl_constness(*did), hir::Constness::NotConst)
} else {
false
}
})
.is_none()
{
// could not find a const impl for Drop, iterate over its fields.
stack
.extend(def.all_fields().map(|f| (f.ty(self.tcx(), subst), depth + 1)));
self.assemble_candidates_from_impls(
&obligation.with(obligation.predicate.map_bound(|mut pred| {
pred.trait_ref.substs = self.tcx().mk_substs_trait(ty, &[]);
pred
})),
&mut set,
);
stack.extend(def.all_fields().map(|f| (f.ty(self.tcx(), subst), depth + 1)));
debug!(?set.vec, "assemble_const_drop_candidates - ty::Adt");
if set.vec.into_iter().any(|candidate| {
if let SelectionCandidate::ImplCandidate(did) = candidate {
matches!(self.tcx().impl_constness(did), hir::Constness::NotConst)
} else {
false
}
}) {
if !noreturn {
// has non-const Drop
return Ok(());
}
debug!("not returning");
}
}
@ -903,8 +913,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
| ty::Infer(_)
| ty::Placeholder(_)
| ty::Projection(..)
| ty::Param(..) => return Ok(()),
| ty::Param(..) => {
if !noreturn {
return Ok(());
}
debug!("not returning");
}
}
debug!(?stack, "assemble_const_drop_candidates - in loop");
}
// all types have passed.
candidates.vec.push(ConstDropCandidate);