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Rollup merge of #109493 - compiler-errors:new-solver-vars-obligations, r=lcnr

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Return nested obligations from canonical response var unification

Handle alias-eq obligations being emitted from `instantiate_and_apply_query_response` in:
* `EvalCtxt` - by processing the nested obligations in the next loop by `new_goals`
* `FulfillCtxt` - by adding the nested obligations to the fulfillment's pending obligations
* `InferCtxt::evaluate_obligation` - ~~by returning `EvaluationResult::EvaluatedToAmbig` (boo 👎, see the FIXME)~~ same behavior as above, since we use fulfillment and `select_where_possible`

The only one that's truly sketchy is `evaluate_obligation`, but it's not hard to modify this behavior moving forward.

From #109037, I think a smaller repro could be crafted if I were smarter, but I am not, so I just took this from #105878.

r? `@lcnr` cc `@BoxyUwU`
This commit is contained in:
Matthias Krüger
2023-03-24 01:22:06 +01:00
committed by GitHub
parent cca2630bc9 1680334928
commit 1c7ef3b483
6 changed files with 84 additions and 46 deletions
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36
compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs
View File

@@ -1,9 +1,8 @@
use rustc_middle::traits::solve::{Certainty, Goal, MaybeCause};
use rustc_infer::traits::{TraitEngine, TraitEngineExt};
use rustc_middle::ty;
use crate::infer::canonical::OriginalQueryValues;
use crate::infer::InferCtxt;
use crate::solve::InferCtxtEvalExt;
use crate::traits::{EvaluationResult, OverflowError, PredicateObligation, SelectionContext};
pub trait InferCtxtExt<'tcx> {
@@ -81,27 +80,20 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
if self.tcx.trait_solver_next() {
self.probe(|snapshot| {
if let Ok((_, certainty)) =
self.evaluate_root_goal(Goal::new(self.tcx, param_env, obligation.predicate))
{
match certainty {
Certainty::Yes => {
if self.opaque_types_added_in_snapshot(snapshot) {
Ok(EvaluationResult::EvaluatedToOkModuloOpaqueTypes)
} else if self.region_constraints_added_in_snapshot(snapshot).is_some()
{
Ok(EvaluationResult::EvaluatedToOkModuloRegions)
} else {
Ok(EvaluationResult::EvaluatedToOk)
}
}
Certainty::Maybe(MaybeCause::Ambiguity) => {
Ok(EvaluationResult::EvaluatedToAmbig)
}
Certainty::Maybe(MaybeCause::Overflow) => Err(OverflowError::Canonical),
}
} else {
let mut fulfill_cx = crate::solve::FulfillmentCtxt::new();
fulfill_cx.register_predicate_obligation(self, obligation.clone());
// True errors
// FIXME(-Ztrait-solver=next): Overflows are reported as ambig here, is that OK?
if !fulfill_cx.select_where_possible(self).is_empty() {
Ok(EvaluationResult::EvaluatedToErr)
} else if !fulfill_cx.select_all_or_error(self).is_empty() {
Ok(EvaluationResult::EvaluatedToAmbig)
} else if self.opaque_types_added_in_snapshot(snapshot) {
Ok(EvaluationResult::EvaluatedToOkModuloOpaqueTypes)
} else if self.region_constraints_added_in_snapshot(snapshot).is_some() {
Ok(EvaluationResult::EvaluatedToOkModuloRegions)
} else {
Ok(EvaluationResult::EvaluatedToOk)
}
})
} else {

1
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -618,6 +618,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let mut fulfill_cx = crate::solve::FulfillmentCtxt::new();
fulfill_cx.register_predicate_obligations(self.infcx, predicates);
// True errors
// FIXME(-Ztrait-solver=next): Overflows are reported as ambig here, is that OK?
if !fulfill_cx.select_where_possible(self.infcx).is_empty() {
return Ok(EvaluatedToErr);
}