mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

review

Browse Source
This commit is contained in:
lcnr 2023-09-21 08:56:23 +02:00
parent 8167a25e4e
commit 614760f612
1 changed files with 75 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
compiler/rustc_trait_selection/src/traits/coherence.rs
View File

@ -214,21 +214,13 @@ fn overlap<'tcx>(
let mut obligations = equate_impl_headers(selcx.infcx, &impl1_header, &impl2_header)?;
debug!("overlap: unification check succeeded");
if !overlap_mode.use_implicit_negative() {
let impl_header = selcx.infcx.resolve_vars_if_possible(impl1_header);
return Some(OverlapResult {
impl_header,
intercrate_ambiguity_causes: Default::default(),
involves_placeholder: false,
});
};
obligations.extend(
[&impl1_header.predicates, &impl2_header.predicates].into_iter().flatten().map(
|&predicate| Obligation::new(infcx.tcx, ObligationCause::dummy(), param_env, predicate),
),
);
if overlap_mode.use_implicit_negative() {
for mode in [TreatInductiveCycleAs::Ambig, TreatInductiveCycleAs::Recur] {
if let Some(failing_obligation) = selcx.with_treat_inductive_cycle_as(mode, |selcx| {
impl_intersection_has_impossible_obligation(selcx, &obligations)
@ -286,6 +278,7 @@ fn overlap<'tcx>(
return None;
}
}
}
// We toggle the `leak_check` by using `skip_leak_check` when constructing the
// inference context, so this may be a noop.
@ -294,7 +287,9 @@ fn overlap<'tcx>(
return None;
}
let intercrate_ambiguity_causes = if infcx.next_trait_solver() {
let intercrate_ambiguity_causes = if !overlap_mode.use_implicit_negative() {
Default::default()
} else if infcx.next_trait_solver() {
compute_intercrate_ambiguity_causes(&infcx, &obligations)
} else {
selcx.take_intercrate_ambiguity_causes()
@ -932,6 +927,8 @@ fn visit_goal(&mut self, goal: &InspectGoal<'_, 'tcx>) -> ControlFlow<Self::Brea
let Goal { param_env, predicate } = goal.goal();
// For bound predicates we simply call `infcx.replace_bound_vars_with_placeholders`
// and then prove the resulting predicate as a nested goal.
let trait_ref = match predicate.kind().no_bound_vars() {
Some(ty::PredicateKind::Clause(ty::ClauseKind::Trait(tr))) => tr.trait_ref,
Some(ty::PredicateKind::Clause(ty::ClauseKind::Projection(proj))) => {
@ -942,21 +939,6 @@ fn visit_goal(&mut self, goal: &InspectGoal<'_, 'tcx>) -> ControlFlow<Self::Brea
let mut ambiguity_cause = None;
for cand in goal.candidates() {
match cand.result() {
Ok(Certainty::Maybe(_)) => {}
// We only add intercrate ambiguity causes if the goal would
// otherwise result in an error.
//
// FIXME: this isn't quite right. Changing a goal from YES with
// inference contraints to AMBIGUOUS can also cause a goal to not
// fail.
Ok(Certainty::Yes) => {
ambiguity_cause = None;
break;
}
Err(NoSolution) => continue,
}
// FIXME: boiiii, using string comparisions here sure is scuffed.
if let inspect::ProbeKind::MiscCandidate { name: "coherence unknowable", result: _ } =
cand.kind()
@ -1011,6 +993,21 @@ fn visit_goal(&mut self, goal: &InspectGoal<'_, 'tcx>) -> ControlFlow<Self::Brea
}
}
})
} else {
match cand.result() {
// We only add an ambiguity cause if the goal would otherwise
// result in an error.
//
// FIXME: While this matches the behavior of the
// old solver, it is not the only way in which the unknowable
// candidates *weaken* coherence, they can also force otherwise
// sucessful normalization to be ambiguous.
Ok(Certainty::Maybe(_) | Certainty::Yes) => {
ambiguity_cause = None;
break;
}
Err(NoSolution) => continue,
}
}
}