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use util::nodemap::{FxHashMap, FxHashSet};
use ty::context::TyCtxt;
use ty::{AdtDef, VariantDef, FieldDef, TyS};
use ty::{DefId, Substs};
use ty::{AdtKind, Visibility};
use ty::TypeVariants::*;
pub use self::def_id_forest::DefIdForest;
mod def_id_forest;
impl<'a, 'gcx, 'tcx> AdtDef {
pub fn uninhabited_from(
&self,
visited: &mut FxHashMap<DefId, FxHashSet<&'tcx Substs<'tcx>>>,
tcx: TyCtxt<'a, 'gcx, 'tcx>,
substs: &'tcx Substs<'tcx>) -> DefIdForest
{
DefIdForest::intersection(tcx, self.variants.iter().map(|v| {
v.uninhabited_from(visited, tcx, substs, self.adt_kind())
}))
}
}
impl<'a, 'gcx, 'tcx> VariantDef {
pub fn uninhabited_from(
&self,
visited: &mut FxHashMap<DefId, FxHashSet<&'tcx Substs<'tcx>>>,
tcx: TyCtxt<'a, 'gcx, 'tcx>,
substs: &'tcx Substs<'tcx>,
adt_kind: AdtKind) -> DefIdForest
{
match adt_kind {
AdtKind::Union => {
DefIdForest::intersection(tcx, self.fields.iter().map(|f| {
f.uninhabited_from(visited, tcx, substs, false)
}))
},
AdtKind::Struct => {
DefIdForest::union(tcx, self.fields.iter().map(|f| {
f.uninhabited_from(visited, tcx, substs, false)
}))
},
AdtKind::Enum => {
DefIdForest::union(tcx, self.fields.iter().map(|f| {
f.uninhabited_from(visited, tcx, substs, true)
}))
},
}
}
}
impl<'a, 'gcx, 'tcx> FieldDef {
pub fn uninhabited_from(
&self,
visited: &mut FxHashMap<DefId, FxHashSet<&'tcx Substs<'tcx>>>,
tcx: TyCtxt<'a, 'gcx, 'tcx>,
substs: &'tcx Substs<'tcx>,
is_enum: bool) -> DefIdForest
{
let mut data_uninhabitedness = move || {
self.ty(tcx, substs).uninhabited_from(visited, tcx)
};
if is_enum {
data_uninhabitedness()
} else {
match self.vis {
Visibility::Invisible => DefIdForest::empty(),
Visibility::Restricted(from) => {
let forest = DefIdForest::from_id(from);
let iter = Some(forest).into_iter().chain(Some(data_uninhabitedness()));
DefIdForest::intersection(tcx, iter)
},
Visibility::Public => data_uninhabitedness(),
}
}
}
}
impl<'a, 'gcx, 'tcx> TyS<'tcx> {
pub fn uninhabited_from(
&self,
visited: &mut FxHashMap<DefId, FxHashSet<&'tcx Substs<'tcx>>>,
tcx: TyCtxt<'a, 'gcx, 'tcx>) -> DefIdForest
{
match tcx.lift_to_global(&self) {
Some(global_ty) => {
{
let cache = tcx.inhabitedness_cache.borrow();
if let Some(forest) = cache.get(&global_ty) {
return forest.clone();
}
}
let forest = global_ty.uninhabited_from_inner(visited, tcx);
let mut cache = tcx.inhabitedness_cache.borrow_mut();
cache.insert(global_ty, forest.clone());
forest
},
None => {
let forest = self.uninhabited_from_inner(visited, tcx);
forest
},
}
}
fn uninhabited_from_inner(
&self,
visited: &mut FxHashMap<DefId, FxHashSet<&'tcx Substs<'tcx>>>,
tcx: TyCtxt<'a, 'gcx, 'tcx>) -> DefIdForest
{
match self.sty {
TyAdt(def, substs) => {
{
let mut substs_set = visited.entry(def.did).or_insert(FxHashSet::default());
if !substs_set.insert(substs) {
return DefIdForest::empty();
}
if substs_set.len() >= tcx.sess.recursion_limit.get() / 4 {
let error = format!("reached recursion limit while checking \
inhabitedness of `{}`", self);
tcx.sess.fatal(&error);
}
}
let ret = def.uninhabited_from(visited, tcx, substs);
let mut substs_set = visited.get_mut(&def.did).unwrap();
substs_set.remove(substs);
ret
},
TyNever => DefIdForest::full(tcx),
TyTuple(ref tys, _) => {
DefIdForest::union(tcx, tys.iter().map(|ty| {
ty.uninhabited_from(visited, tcx)
}))
},
TyArray(ty, len) => {
if len == 0 {
DefIdForest::empty()
} else {
ty.uninhabited_from(visited, tcx)
}
}
TyRef(_, ref tm) => {
tm.ty.uninhabited_from(visited, tcx)
}
_ => DefIdForest::empty(),
}
}
}