Skip to content

Commit

Permalink
Rollup merge of rust-lang#112781 - compiler-errors:new-solver-tait-ov…
Browse files Browse the repository at this point in the history
…erlaps-hidden, r=lcnr

Don't consider TAIT normalizable to hidden ty if it would result in impossible item bounds

See test for example where we shouldn't consider it possible to alias-relate a TAIT and hidden type.

r? `@lcnr`
  • Loading branch information
jyn514 authored Jun 19, 2023
2 parents 7fe7a98 + 48ad6e3 commit bc61d6f
Show file tree
Hide file tree
Showing 5 changed files with 39 additions and 13 deletions.
3 changes: 2 additions & 1 deletion compiler/rustc_borrowck/src/type_check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1065,7 +1065,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
)?;

ocx.infcx.add_item_bounds_for_hidden_type(
opaque_type_key,
opaque_type_key.def_id.to_def_id(),
opaque_type_key.substs,
cause,
param_env,
hidden_ty.ty,
Expand Down
10 changes: 6 additions & 4 deletions compiler/rustc_infer/src/infer/opaque_types.rs
Original file line number Diff line number Diff line change
Expand Up @@ -536,7 +536,8 @@ impl<'tcx> InferCtxt<'tcx> {
)?;

self.add_item_bounds_for_hidden_type(
opaque_type_key,
opaque_type_key.def_id.to_def_id(),
opaque_type_key.substs,
cause,
param_env,
hidden_ty,
Expand Down Expand Up @@ -598,7 +599,8 @@ impl<'tcx> InferCtxt<'tcx> {

pub fn add_item_bounds_for_hidden_type(
&self,
OpaqueTypeKey { def_id, substs }: OpaqueTypeKey<'tcx>,
def_id: DefId,
substs: ty::SubstsRef<'tcx>,
cause: ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
hidden_ty: Ty<'tcx>,
Expand Down Expand Up @@ -631,7 +633,7 @@ impl<'tcx> InferCtxt<'tcx> {
// Replace all other mentions of the same opaque type with the hidden type,
// as the bounds must hold on the hidden type after all.
ty::Alias(ty::Opaque, ty::AliasTy { def_id: def_id2, substs: substs2, .. })
if def_id.to_def_id() == def_id2 && substs == substs2 =>
if def_id == def_id2 && substs == substs2 =>
{
hidden_ty
}
Expand All @@ -640,7 +642,7 @@ impl<'tcx> InferCtxt<'tcx> {
ty::Alias(
ty::Projection,
ty::AliasTy { def_id: def_id2, substs: substs2, .. },
) if def_id.to_def_id() == def_id2 && substs == substs2 => hidden_ty,
) if def_id == def_id2 && substs == substs2 => hidden_ty,
_ => ty,
},
lt_op: |lt| lt,
Expand Down
13 changes: 10 additions & 3 deletions compiler/rustc_trait_selection/src/solve/eval_ctxt.rs
Original file line number Diff line number Diff line change
Expand Up @@ -750,13 +750,15 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {

pub(super) fn add_item_bounds_for_hidden_type(
&mut self,
opaque_type_key: OpaqueTypeKey<'tcx>,
opaque_def_id: DefId,
opaque_substs: ty::SubstsRef<'tcx>,
param_env: ty::ParamEnv<'tcx>,
hidden_ty: Ty<'tcx>,
) {
let mut obligations = Vec::new();
self.infcx.add_item_bounds_for_hidden_type(
opaque_type_key,
opaque_def_id,
opaque_substs,
ObligationCause::dummy(),
param_env,
hidden_ty,
Expand Down Expand Up @@ -786,7 +788,12 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
ecx.eq(param_env, a, b)?;
}
ecx.eq(param_env, candidate_ty, ty)?;
ecx.add_item_bounds_for_hidden_type(candidate_key, param_env, candidate_ty);
ecx.add_item_bounds_for_hidden_type(
candidate_key.def_id.to_def_id(),
candidate_key.substs,
param_env,
candidate_ty,
);
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
}));
}
Expand Down
24 changes: 19 additions & 5 deletions compiler/rustc_trait_selection/src/solve/opaques.rs
Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
let Some(opaque_ty_def_id) = opaque_ty.def_id.as_local() else {
return Err(NoSolution);
};
let opaque_ty =
ty::OpaqueTypeKey { def_id: opaque_ty_def_id, substs: opaque_ty.substs };
// FIXME: at some point we should call queries without defining
// new opaque types but having the existing opaque type definitions.
// This will require moving this below "Prefer opaques registered already".
Expand All @@ -41,7 +39,10 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
Ok(()) => {}
}
// Prefer opaques registered already.
let matches = self.unify_existing_opaque_tys(goal.param_env, opaque_ty, expected);
let opaque_type_key =
ty::OpaqueTypeKey { def_id: opaque_ty_def_id, substs: opaque_ty.substs };
let matches =
self.unify_existing_opaque_tys(goal.param_env, opaque_type_key, expected);
if !matches.is_empty() {
if let Some(response) = self.try_merge_responses(&matches) {
return Ok(response);
Expand All @@ -50,11 +51,24 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
}
}
// Otherwise, define a new opaque type
self.insert_hidden_type(opaque_ty, goal.param_env, expected)?;
self.add_item_bounds_for_hidden_type(opaque_ty, goal.param_env, expected);
self.insert_hidden_type(opaque_type_key, goal.param_env, expected)?;
self.add_item_bounds_for_hidden_type(
opaque_ty.def_id,
opaque_ty.substs,
goal.param_env,
expected,
);
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
}
(Reveal::UserFacing, SolverMode::Coherence) => {
// An impossible opaque type bound is the only way this goal will fail
// e.g. assigning `impl Copy := NotCopy`
self.add_item_bounds_for_hidden_type(
opaque_ty.def_id,
opaque_ty.substs,
goal.param_env,
expected,
);
self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS)
}
(Reveal::All, _) => {
Expand Down
Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
// Regression test for issue #76202
// Tests that we don't ICE when we have a trait impl on a TAIT.

// revisions: current next
//[next] compile-flags: -Ztrait-solver=next
// check-pass

#![feature(type_alias_impl_trait)]
Expand Down

0 comments on commit bc61d6f

Please sign in to comment.