diff options
Diffstat (limited to 'compiler/rustc_middle/src/ty/inhabitedness')
| -rw-r--r-- | compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs | 19 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/ty/inhabitedness/mod.rs | 2 |
2 files changed, 16 insertions, 5 deletions
diff --git a/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs b/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs index ac42d6e05..295cb1464 100644 --- a/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs +++ b/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs @@ -62,7 +62,18 @@ impl<'tcx> InhabitedPredicate<'tcx> { Some(1..) => Ok(false), }, Self::NotInModule(id) => in_module(id).map(|in_mod| !in_mod), - Self::GenericType(_) => Ok(true), + // `t` may be a projection, for which `inhabited_predicate` returns a `GenericType`. As + // we have a param_env available, we can do better. + Self::GenericType(t) => { + let normalized_pred = tcx + .try_normalize_erasing_regions(param_env, t) + .map_or(self, |t| t.inhabited_predicate(tcx)); + match normalized_pred { + // We don't have more information than we started with, so consider inhabited. + Self::GenericType(_) => Ok(true), + pred => pred.apply_inner(tcx, param_env, in_module), + } + } Self::And([a, b]) => try_and(a, b, |x| x.apply_inner(tcx, param_env, in_module)), Self::Or([a, b]) => try_or(a, b, |x| x.apply_inner(tcx, param_env, in_module)), } @@ -158,8 +169,8 @@ impl<'tcx> InhabitedPredicate<'tcx> { fn subst_opt(self, tcx: TyCtxt<'tcx>, substs: ty::SubstsRef<'tcx>) -> Option<Self> { match self { Self::ConstIsZero(c) => { - let c = ty::EarlyBinder(c).subst(tcx, substs); - let pred = match c.kind().try_to_target_usize(tcx) { + let c = ty::EarlyBinder::bind(c).subst(tcx, substs); + let pred = match c.try_to_target_usize(tcx) { Some(0) => Self::True, Some(1..) => Self::False, None => Self::ConstIsZero(c), @@ -167,7 +178,7 @@ impl<'tcx> InhabitedPredicate<'tcx> { Some(pred) } Self::GenericType(t) => { - Some(ty::EarlyBinder(t).subst(tcx, substs).inhabited_predicate(tcx)) + Some(ty::EarlyBinder::bind(t).subst(tcx, substs).inhabited_predicate(tcx)) } Self::And(&[a, b]) => match a.subst_opt(tcx, substs) { None => b.subst_opt(tcx, substs).map(|b| a.and(tcx, b)), diff --git a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs index 422350284..b92d84152 100644 --- a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs +++ b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs @@ -197,7 +197,7 @@ fn inhabited_predicate_type<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> InhabitedP // If we can evaluate the array length before having a `ParamEnv`, then // we can simplify the predicate. This is an optimization. - Array(ty, len) => match len.kind().try_to_target_usize(tcx) { + Array(ty, len) => match len.try_to_target_usize(tcx) { Some(0) => InhabitedPredicate::True, Some(1..) => ty.inhabited_predicate(tcx), None => ty.inhabited_predicate(tcx).or(tcx, InhabitedPredicate::ConstIsZero(len)), |