Auto merge of #44741 - qmx:trans_fulfill_obligation_should_not_crash, r=nikomatsakis

use param_env on the trait_cache key

We bailed from making trans_fulfill_obligation return `Option` or `Result`, just made it less prone to crashing outside trans

r? @nikomatsakis
This commit is contained in:
bors 2017-09-26 18:29:57 +00:00
commit 930d3b17dd
3 changed files with 11 additions and 8 deletions

View File

@ -19,7 +19,7 @@ use std::cell::RefCell;
use std::marker::PhantomData;
use syntax::ast;
use syntax_pos::Span;
use traits::{FulfillmentContext, Obligation, ObligationCause, Reveal, SelectionContext, Vtable};
use traits::{FulfillmentContext, Obligation, ObligationCause, SelectionContext, Vtable};
use ty::{self, Ty, TyCtxt};
use ty::subst::{Subst, Substs};
use ty::fold::{TypeFoldable, TypeFolder};
@ -31,24 +31,25 @@ impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
/// (necessarily) resolve all nested obligations on the impl. Note
/// that type check should guarantee to us that all nested
/// obligations *could be* resolved if we wanted to.
/// Assumes that this is run after the entire crate has been successfully type-checked.
pub fn trans_fulfill_obligation(self,
span: Span,
param_env: ty::ParamEnv<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>)
-> Vtable<'tcx, ()>
{
// Remove any references to regions; this helps improve caching.
let trait_ref = self.erase_regions(&trait_ref);
self.trans_trait_caches.trait_cache.memoize(trait_ref, || {
self.trans_trait_caches.trait_cache.memoize((param_env, trait_ref), || {
debug!("trans::fulfill_obligation(trait_ref={:?}, def_id={:?})",
trait_ref, trait_ref.def_id());
(param_env, trait_ref), trait_ref.def_id());
// Do the initial selection for the obligation. This yields the
// shallow result we are looking for -- that is, what specific impl.
self.infer_ctxt().enter(|infcx| {
let mut selcx = SelectionContext::new(&infcx);
let param_env = ty::ParamEnv::empty(Reveal::All);
let obligation_cause = ObligationCause::misc(span,
ast::DUMMY_NODE_ID);
let obligation = Obligation::new(obligation_cause,
@ -167,7 +168,7 @@ pub struct TraitSelectionCache<'tcx> {
}
impl<'tcx> DepTrackingMapConfig for TraitSelectionCache<'tcx> {
type Key = ty::PolyTraitRef<'tcx>;
type Key = (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>);
type Value = Vtable<'tcx, ()>;
fn to_dep_kind() -> DepKind {
DepKind::TraitSelect

View File

@ -112,7 +112,8 @@ fn resolve_associated_item<'a, 'tcx>(
def_id, trait_id, rcvr_substs);
let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
let vtbl = tcx.trans_fulfill_obligation(DUMMY_SP, ty::Binder(trait_ref));
let vtbl = tcx.trans_fulfill_obligation(
DUMMY_SP, ty::ParamEnv::empty(traits::Reveal::All), ty::Binder(trait_ref));
// Now that we know which impl is being used, we can dispatch to
// the actual function:
@ -226,7 +227,8 @@ pub fn custom_coerce_unsize_info<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
substs: tcx.mk_substs_trait(source_ty, &[target_ty])
});
match tcx.trans_fulfill_obligation(DUMMY_SP, trait_ref) {
match tcx.trans_fulfill_obligation(
DUMMY_SP, ty::ParamEnv::empty(traits::Reveal::All), trait_ref) {
traits::VtableImpl(traits::VtableImplData { impl_def_id, .. }) => {
tcx.coerce_unsized_info(impl_def_id).custom_kind.unwrap()
}

View File

@ -23,7 +23,7 @@
# Each tool has a list of people to ping
# ping @oli-obk @RalfJung @eddyb
miri = "Testing"
miri = "Broken"
# ping @Manishearth @llogiq @mcarton @oli-obk
clippy = "Broken"