bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Consider principal trait ref's auto-trait super-traits in dyn upcasting

Browse source
This commit is contained in:
Michael Goulet 2023-12-27 03:17:37 +00:00
parent fa9f77ff35
commit ec8e898193
4 changed files with 93 additions and 52 deletions
Download patch file Download diff file Expand all files Collapse all files

23
compiler/rustc_trait_selection/src/solve/trait_goals.rs
View file

@ -1,7 +1,10 @@
//! Dealing with trait goals, i.e. `T: Trait<'a, U>`.
use crate::traits::supertrait_def_ids;
use super::assembly::{self, structural_traits, Candidate};
use super::{EvalCtxt, GoalSource, SolverMode};
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir::def_id::DefId;
use rustc_hir::{LangItem, Movability};
use rustc_infer::traits::query::NoSolution;
@ -663,13 +666,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
let tcx = self.tcx();
let Goal { predicate: (a_ty, _b_ty), .. } = goal;
// All of a's auto traits need to be in b's auto traits.
let auto_traits_compatible =
b_data.auto_traits().all(|b| a_data.auto_traits().any(|a| a == b));
if !auto_traits_compatible {
return vec![];
}
let mut responses = vec![];
// If the principal def ids match (or are both none), then we're not doing
// trait upcasting. We're just removing auto traits (or shortening the lifetime).
@ -757,6 +753,17 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
) -> QueryResult<'tcx> {
let param_env = goal.param_env;
// We may upcast to auto traits that are either explicitly listed in
// the object type's bounds, or implied by the principal trait ref's
// supertraits.
let a_auto_traits: FxIndexSet<DefId> = a_data
.auto_traits()
.chain(a_data.principal_def_id().into_iter().flat_map(|principal_def_id| {
supertrait_def_ids(self.tcx(), principal_def_id)
.filter(|def_id| self.tcx().trait_is_auto(*def_id))
}))
.collect();
// More than one projection in a_ty's bounds may match the projection
// in b_ty's bound. Use this to first determine *which* apply without
// having any inference side-effects. We process obligations because
@ -806,7 +813,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
}
// Check that b_ty's auto traits are present in a_ty's bounds.
ty::ExistentialPredicate::AutoTrait(def_id) => {
if !a_data.auto_traits().any(|source_def_id| source_def_id == def_id) {
if !a_auto_traits.contains(&def_id) {
return Err(NoSolution);
}
}