Skip to content

Detect trait fulfillment in subst_and_check_impossible_predicates #96808

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
May 10, 2022
Merged

Detect trait fulfillment in subst_and_check_impossible_predicates #96808

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
8492460
Also check TraitRef with impossible predicates.
cjgillot May 7, 2022
6b34825
Cleanup opaque type storage after checking impossible predicates.
cjgillot Apr 30, 2022
69e5b2f
Do not report overflow error.
cjgillot Apr 30, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 14 additions & 0 deletions compiler/rustc_trait_selection/src/traits/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -432,6 +432,9 @@ pub fn impossible_predicates<'tcx>(
debug!("impossible_predicates(predicates={:?})", predicates);

let result = tcx.infer_ctxt().enter(|infcx| {
// HACK: Set tainted by errors to gracefully exit in case of overflow.
infcx.set_tainted_by_errors();

let param_env = ty::ParamEnv::reveal_all();
let mut selcx = SelectionContext::new(&infcx);
let mut fulfill_cx = FulfillmentContext::new();
Expand All @@ -448,6 +451,9 @@ pub fn impossible_predicates<'tcx>(

let errors = fulfill_cx.select_all_or_error(&infcx);

// Clean up after ourselves
let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();

!errors.is_empty()
});
debug!("impossible_predicates = {:?}", result);
Expand All @@ -461,6 +467,14 @@ fn subst_and_check_impossible_predicates<'tcx>(
debug!("subst_and_check_impossible_predicates(key={:?})", key);

let mut predicates = tcx.predicates_of(key.0).instantiate(tcx, key.1).predicates;

// Specifically check trait fulfillment to avoid an error when trying to resolve
// associated items.
if let Some(trait_def_id) = tcx.trait_of_item(key.0) {
let trait_ref = ty::TraitRef::from_method(tcx, trait_def_id, key.1);
predicates.push(ty::Binder::dummy(trait_ref).to_poly_trait_predicate().to_predicate(tcx));
}

predicates.retain(|predicate| !predicate.needs_subst());
let result = impossible_predicates(tcx, predicates);

Expand Down