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Don't require intercrate mode for negative coherence

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This commit is contained in:
Michael Goulet 2023-11-19 19:19:51 +00:00
parent 19a5e1dfc6
commit 253f5023c3
7 changed files with 19 additions and 41 deletions
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8
compiler/rustc_trait_selection/src/traits/coherence.rs
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@ -397,6 +397,8 @@ fn impl_intersection_has_negative_obligation(
) -> bool {
debug!("negative_impl(impl1_def_id={:?}, impl2_def_id={:?})", impl1_def_id, impl2_def_id);
// N.B. We need to unify impl headers *with* intercrate mode, even if proving negative predicates
// do not need intercrate mode enabled.
let ref infcx = tcx.infer_ctxt().intercrate(true).with_next_trait_solver(true).build();
let root_universe = infcx.universe();
assert_eq!(root_universe, ty::UniverseIndex::ROOT);
@ -554,7 +556,11 @@ fn try_prove_negated_where_clause<'tcx>(
return false;
};
let ref infcx = root_infcx.fork();
// N.B. We don't need to use intercrate mode here because we're trying to prove
// the *existence* of a negative goal, not the non-existence of a positive goal.
// Without this, we over-eagerly register coherence ambiguity candidates when
// impl candidates do exist.
let ref infcx = root_infcx.fork_with_intercrate(false);
let ocx = ObligationCtxt::new(infcx);
ocx.register_obligation(Obligation::new(