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use rustc_middle::traits::query::NoSolution;
use rustc_middle::traits::solve::{Certainty, Goal, QueryResult};
use rustc_middle::traits::Reveal;
use rustc_middle::ty;
use rustc_middle::ty::util::NotUniqueParam;
use super::{EvalCtxt, SolverMode};
impl<'tcx> EvalCtxt<'_, 'tcx> {
pub(super) fn normalize_opaque_type(
&mut self,
goal: Goal<'tcx, ty::ProjectionPredicate<'tcx>>,
) -> QueryResult<'tcx> {
let tcx = self.tcx();
let opaque_ty = goal.predicate.projection_ty;
let expected = goal.predicate.term.ty().expect("no such thing as an opaque const");
match (goal.param_env.reveal(), self.solver_mode()) {
(Reveal::UserFacing, SolverMode::Normal) => {
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".
if !self.can_define_opaque_ty(opaque_ty_def_id) {
return Err(NoSolution);
}
// FIXME: This may have issues when the substs contain aliases...
match self.tcx().uses_unique_placeholders_ignoring_regions(opaque_ty.substs) {
Err(NotUniqueParam::NotParam(param)) if param.is_non_region_infer() => {
return self.evaluate_added_goals_and_make_canonical_response(
Certainty::AMBIGUOUS,
);
}
Err(_) => {
return Err(NoSolution);
}
Ok(()) => {}
}
// Prefer opaques registered already.
let matches = self.unify_existing_opaque_tys(goal.param_env, opaque_ty, expected);
if !matches.is_empty() {
if let Some(response) = self.try_merge_responses(&matches) {
return Ok(response);
} else {
return self.flounder(&matches);
}
}
// Otherwise, define a new opaque type
self.register_opaque_ty(opaque_ty, expected, goal.param_env)?;
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
}
(Reveal::UserFacing, SolverMode::Coherence) => {
self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS)
}
(Reveal::All, _) => {
// FIXME: Add an assertion that opaque type storage is empty.
let actual = tcx.type_of(opaque_ty.def_id).subst(tcx, opaque_ty.substs);
self.eq(goal.param_env, expected, actual)?;
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
}
}
}
}
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