bjoernager/rust
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new solver cleanup + coherence

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This commit is contained in:
lcnr 2023-03-21 16:26:23 +01:00
parent a01b4cc9f3
commit 47f24a881b
18 changed files with 203 additions and 52 deletions
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19
compiler/rustc_trait_selection/src/solve/mod.rs
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@ -9,10 +9,6 @@
//! FIXME(@lcnr): Write that section. If you read this before then ask me
//! about it on zulip.
// FIXME: Instead of using `infcx.canonicalize_query` we have to add a new routine which
// preserves universes and creates a unique var (in the highest universe) for each
// appearance of a region.
// FIXME: uses of `infcx.at` need to enable deferred projection equality once that's implemented.
use rustc_hir::def_id::DefId;
@ -41,6 +37,19 @@ mod trait_goals;
pub use eval_ctxt::{EvalCtxt, InferCtxtEvalExt};
pub use fulfill::FulfillmentCtxt;
#[derive(Debug, Clone, Copy)]
enum SolverMode {
/// Ordinary trait solving, using everywhere except for coherence.
Normal,
/// Trait solving during coherence. There are a few notable differences
/// between coherence and ordinary trait solving.
///
/// Most importantly, trait solving during coherence must not be incomplete,
/// i.e. return `Err(NoSolution)` for goals for which a solution exists.
/// This means that we must not make any guesses or arbitrary choices.
Coherence,
}
trait CanonicalResponseExt {
fn has_no_inference_or_external_constraints(&self) -> bool;
}
@ -255,7 +264,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
return Err(NoSolution);
}
// FIXME(-Ztreat-solver=next): We should instead try to find a `Certainty::Yes` response with
// FIXME(-Ztrait-solver=next): We should instead try to find a `Certainty::Yes` response with
// a subset of the constraints that all the other responses have.
let one = candidates[0];
if candidates[1..].iter().all(|resp| resp == &one) {