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Rollup merge of #109748 - compiler-errors:new-solver-discr-kind-ice, r=lcnr

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Don't ICE on `DiscriminantKind` projection in new solver

As title says, since we now actually call `Ty::discriminant_kind` on placeholder types 😃

Also drive-by simplify `Pointee::Metadata` projection logic, and fix the UI test because the `<T as Pointee>::Metadata` tests weren't actually exercising the new projection logic, since we still eagerly normalize (which hits `project.rs` in the old solver) in HIR typeck.

r? `@lcnr` tho feel free to re-roll, this pr is very low-priority and not super specific to the new trait solver.

Fixes compiler-errors/next-solver-hir-issues#14
This commit is contained in:
Yuki Okushi 2023-03-30 21:07:02 +09:00 • committed by GitHub
commit c1b28c3435
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5 changed files with 94 additions and 15 deletions
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48
compiler/rustc_trait_selection/src/solve/project_goals.rs
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@ -344,10 +344,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
LangItem::Sized,
[ty::GenericArg::from(goal.predicate.self_ty())],
));
ecx.add_goal(goal.with(tcx, sized_predicate));
ecx.eq(goal.param_env, goal.predicate.term, tcx.types.unit.into())?;
return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
tcx.types.unit
}
ty::Adt(def, substs) if def.is_struct() => {
@ -483,9 +481,49 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
) -> QueryResult<'tcx> {
let discriminant = goal.predicate.self_ty().discriminant_ty(ecx.tcx());
let self_ty = goal.predicate.self_ty();
let discriminant_ty = match *self_ty.kind() {
ty::Bool
| ty::Char
| ty::Int(..)
| ty::Uint(..)
| ty::Float(..)
| ty::Array(..)
| ty::RawPtr(..)
| ty::Ref(..)
| ty::FnDef(..)
| ty::FnPtr(..)
| ty::Closure(..)
| ty::Infer(ty::IntVar(..) | ty::FloatVar(..))
| ty::Generator(..)
| ty::GeneratorWitness(..)
| ty::GeneratorWitnessMIR(..)
| ty::Never
| ty::Foreign(..)
| ty::Adt(_, _)
| ty::Str
| ty::Slice(_)
| ty::Dynamic(_, _, _)
| ty::Tuple(_)
| ty::Error(_) => self_ty.discriminant_ty(ecx.tcx()),
// We do not call `Ty::discriminant_ty` on alias, param, or placeholder
// types, which return `<self_ty as DiscriminantKind>::Discriminant`
// (or ICE in the case of placeholders). Projecting a type to itself
// is never really productive.
ty::Alias(_, _) | ty::Param(_) | ty::Placeholder(..) => {
return Err(NoSolution);
}
ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_))
| ty::Bound(..) => bug!(
"unexpected self ty `{:?}` when normalizing `<T as DiscriminantKind>::Discriminant`",
goal.predicate.self_ty()
),
};
ecx.probe(|ecx| {
ecx.eq(goal.param_env, goal.predicate.term, discriminant.into())?;
ecx.eq(goal.param_env, goal.predicate.term, discriminant_ty.into())?;
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
})
}