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Extract stable_disjoint fn

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Santiago Pastorino 2022-01-21 11:02:52 -03:00
parent 052b31b587
commit b2a45f0645
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1 changed files with 41 additions and 21 deletions
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62
compiler/rustc_trait_selection/src/traits/coherence.rs
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@ -157,6 +157,9 @@ fn overlap_within_probe<'cx, 'tcx>(
impl2_def_id: DefId,
snapshot: &CombinedSnapshot<'_, 'tcx>,
) -> Option<OverlapResult<'tcx>> {
let infcx = selcx.infcx();
let tcx = infcx.tcx;
// For the purposes of this check, we don't bring any placeholder
// types into scope; instead, we replace the generic types with
// fresh type variables, and hence we do our evaluations in an
@ -166,6 +169,39 @@ fn overlap_within_probe<'cx, 'tcx>(
let impl1_header = with_fresh_ty_vars(selcx, param_env, impl1_def_id);
let impl2_header = with_fresh_ty_vars(selcx, param_env, impl2_def_id);
let strict_coherence = tcx.has_attr(impl1_def_id, sym::rustc_strict_coherence)
&& tcx.has_attr(impl2_def_id, sym::rustc_strict_coherence);
if stable_disjoint(selcx, param_env, &impl1_header, impl2_header, strict_coherence) {
return None;
}
if !skip_leak_check.is_yes() {
if infcx.leak_check(true, snapshot).is_err() {
debug!("overlap: leak check failed");
return None;
}
}
let intercrate_ambiguity_causes = selcx.take_intercrate_ambiguity_causes();
debug!("overlap: intercrate_ambiguity_causes={:#?}", intercrate_ambiguity_causes);
let involves_placeholder =
matches!(selcx.infcx().region_constraints_added_in_snapshot(snapshot), Some(true));
let impl_header = selcx.infcx().resolve_vars_if_possible(impl1_header);
Some(OverlapResult { impl_header, intercrate_ambiguity_causes, involves_placeholder })
}
/// Given impl1 and impl2 check if both impls can be satisfied by a common type (including
/// where-clauses) If so, return false, otherwise return true, they are disjoint.
fn stable_disjoint<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
param_env: ty::ParamEnv<'tcx>,
impl1_header: &ty::ImplHeader<'tcx>,
impl2_header: ty::ImplHeader<'tcx>,
strict_coherence: bool,
) -> bool {
debug!("overlap: impl1_header={:?}", impl1_header);
debug!("overlap: impl2_header={:?}", impl2_header);
@ -177,7 +213,7 @@ fn overlap_within_probe<'cx, 'tcx>(
{
Ok(InferOk { obligations, value: () }) => obligations,
Err(_) => {
return None;
return true;
}
};
@ -222,9 +258,7 @@ fn overlap_within_probe<'cx, 'tcx>(
.find(|o| {
// if both impl headers are set to strict coherence it means that this will be accepted
// only if it's stated that T: !Trait. So only prove that the negated obligation holds.
if tcx.has_attr(impl1_def_id, sym::rustc_strict_coherence)
&& tcx.has_attr(impl2_def_id, sym::rustc_strict_coherence)
{
if strict_coherence {
strict_check(selcx, o)
} else {
loose_check(selcx, o) || tcx.features().negative_impls && strict_check(selcx, o)
@ -236,24 +270,10 @@ fn overlap_within_probe<'cx, 'tcx>(
if let Some(failing_obligation) = opt_failing_obligation {
debug!("overlap: obligation unsatisfiable {:?}", failing_obligation);
return None;
true
} else {
false
}
if !skip_leak_check.is_yes() {
if infcx.leak_check(true, snapshot).is_err() {
debug!("overlap: leak check failed");
return None;
}
}
let impl_header = selcx.infcx().resolve_vars_if_possible(impl1_header);
let intercrate_ambiguity_causes = selcx.take_intercrate_ambiguity_causes();
debug!("overlap: intercrate_ambiguity_causes={:#?}", intercrate_ambiguity_causes);
let involves_placeholder =
matches!(selcx.infcx().region_constraints_added_in_snapshot(snapshot), Some(true));
Some(OverlapResult { impl_header, intercrate_ambiguity_causes, involves_placeholder })
}
fn loose_check<'cx, 'tcx>(