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use hir::def_id::DefId;
use middle::resolve_lifetime as rl;
use rustc::ty::subst::Substs;
use rustc::ty::{self, Ty, TyCtxt};
use rustc::hir::map as hir_map;
use syntax::ast;
use rustc::hir;
use rustc::hir::itemlikevisit::ItemLikeVisitor;
use super::terms::*;
use super::terms::VarianceTerm::*;
use super::xform::*;
use dep_graph::DepNode::ItemSignature as VarianceDepNode;
pub struct ConstraintContext<'a, 'tcx: 'a> {
pub terms_cx: TermsContext<'a, 'tcx>,
covariant: VarianceTermPtr<'a>,
contravariant: VarianceTermPtr<'a>,
invariant: VarianceTermPtr<'a>,
bivariant: VarianceTermPtr<'a>,
pub constraints: Vec<Constraint<'a>>,
}
#[derive(Copy, Clone)]
pub struct Constraint<'a> {
pub inferred: InferredIndex,
pub variance: &'a VarianceTerm<'a>,
}
pub fn add_constraints_from_crate<'a, 'tcx>(terms_cx: TermsContext<'a, 'tcx>)
-> ConstraintContext<'a, 'tcx> {
let tcx = terms_cx.tcx;
let covariant = terms_cx.arena.alloc(ConstantTerm(ty::Covariant));
let contravariant = terms_cx.arena.alloc(ConstantTerm(ty::Contravariant));
let invariant = terms_cx.arena.alloc(ConstantTerm(ty::Invariant));
let bivariant = terms_cx.arena.alloc(ConstantTerm(ty::Bivariant));
let mut constraint_cx = ConstraintContext {
terms_cx: terms_cx,
covariant: covariant,
contravariant: contravariant,
invariant: invariant,
bivariant: bivariant,
constraints: Vec::new(),
};
tcx.visit_all_item_likes_in_krate(VarianceDepNode, &mut constraint_cx);
constraint_cx
}
impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for ConstraintContext<'a, 'tcx> {
fn visit_item(&mut self, item: &hir::Item) {
let tcx = self.terms_cx.tcx;
let did = tcx.hir.local_def_id(item.id);
debug!("visit_item item={}", tcx.hir.node_to_string(item.id));
match item.node {
hir::ItemEnum(..) |
hir::ItemStruct(..) |
hir::ItemUnion(..) => {
let generics = tcx.item_generics(did);
for field in tcx.lookup_adt_def(did).all_fields() {
self.add_constraints_from_ty(generics,
tcx.item_type(field.did),
self.covariant);
}
}
hir::ItemTrait(..) => {
let generics = tcx.item_generics(did);
let trait_ref = ty::TraitRef {
def_id: did,
substs: Substs::identity_for_item(tcx, did)
};
self.add_constraints_from_trait_ref(generics,
trait_ref,
self.invariant);
}
hir::ItemExternCrate(_) |
hir::ItemUse(..) |
hir::ItemStatic(..) |
hir::ItemConst(..) |
hir::ItemFn(..) |
hir::ItemMod(..) |
hir::ItemForeignMod(..) |
hir::ItemTy(..) |
hir::ItemImpl(..) |
hir::ItemDefaultImpl(..) => {}
}
}
fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
}
fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
}
}
fn is_lifetime(map: &hir_map::Map, param_id: ast::NodeId) -> bool {
match map.find(param_id) {
Some(hir_map::NodeLifetime(..)) => true,
_ => false,
}
}
impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
fn tcx(&self) -> TyCtxt<'a, 'tcx, 'tcx> {
self.terms_cx.tcx
}
fn inferred_index(&self, param_id: ast::NodeId) -> InferredIndex {
match self.terms_cx.inferred_map.get(¶m_id) {
Some(&index) => index,
None => {
bug!("no inferred index entry for {}",
self.tcx().hir.node_to_string(param_id));
}
}
}
fn find_binding_for_lifetime(&self, param_id: ast::NodeId) -> ast::NodeId {
let tcx = self.terms_cx.tcx;
assert!(is_lifetime(&tcx.hir, param_id));
match tcx.named_region_map.defs.get(¶m_id) {
Some(&rl::Region::EarlyBound(_, lifetime_decl_id)) => lifetime_decl_id,
Some(_) => bug!("should not encounter non early-bound cases"),
None => param_id,
}
}
fn is_to_be_inferred(&self, param_id: ast::NodeId) -> bool {
let result = self.terms_cx.inferred_map.contains_key(¶m_id);
let check_result = |this: &ConstraintContext| -> bool {
let tcx = this.terms_cx.tcx;
let decl_id = this.find_binding_for_lifetime(param_id);
assert!(is_lifetime(&tcx.hir, param_id));
let parent_id = tcx.hir.get_parent(decl_id);
let parent = tcx.hir
.find(parent_id)
.unwrap_or_else(|| bug!("tcx.hir missing entry for id: {}", parent_id));
let is_inferred;
macro_rules! cannot_happen { () => { {
bug!("invalid parent: {} for {}",
tcx.hir.node_to_string(parent_id),
tcx.hir.node_to_string(param_id));
} } }
match parent {
hir_map::NodeItem(p) => {
match p.node {
hir::ItemTy(..) |
hir::ItemEnum(..) |
hir::ItemStruct(..) |
hir::ItemUnion(..) |
hir::ItemTrait(..) => is_inferred = true,
hir::ItemFn(..) => is_inferred = false,
_ => cannot_happen!(),
}
}
hir_map::NodeTraitItem(..) => is_inferred = false,
hir_map::NodeImplItem(..) => is_inferred = false,
_ => cannot_happen!(),
}
return is_inferred;
};
assert_eq!(result, check_result(self));
return result;
}
fn declared_variance(&self,
param_def_id: DefId,
item_def_id: DefId,
index: usize)
-> VarianceTermPtr<'a> {
assert_eq!(param_def_id.krate, item_def_id.krate);
if let Some(param_node_id) = self.tcx().hir.as_local_node_id(param_def_id) {
let InferredIndex(index) = self.inferred_index(param_node_id);
self.terms_cx.inferred_infos[index].term
} else {
let variances = self.tcx().item_variances(item_def_id);
self.constant_term(variances[index])
}
}
fn add_constraint(&mut self,
InferredIndex(index): InferredIndex,
variance: VarianceTermPtr<'a>) {
debug!("add_constraint(index={}, variance={:?})", index, variance);
self.constraints.push(Constraint {
inferred: InferredIndex(index),
variance: variance,
});
}
fn contravariant(&mut self, variance: VarianceTermPtr<'a>) -> VarianceTermPtr<'a> {
self.xform(variance, self.contravariant)
}
fn invariant(&mut self, variance: VarianceTermPtr<'a>) -> VarianceTermPtr<'a> {
self.xform(variance, self.invariant)
}
fn constant_term(&self, v: ty::Variance) -> VarianceTermPtr<'a> {
match v {
ty::Covariant => self.covariant,
ty::Invariant => self.invariant,
ty::Contravariant => self.contravariant,
ty::Bivariant => self.bivariant,
}
}
fn xform(&mut self, v1: VarianceTermPtr<'a>, v2: VarianceTermPtr<'a>) -> VarianceTermPtr<'a> {
match (*v1, *v2) {
(_, ConstantTerm(ty::Covariant)) => {
v1
}
(ConstantTerm(c1), ConstantTerm(c2)) => self.constant_term(c1.xform(c2)),
_ => &*self.terms_cx.arena.alloc(TransformTerm(v1, v2)),
}
}
fn add_constraints_from_trait_ref(&mut self,
generics: &ty::Generics,
trait_ref: ty::TraitRef<'tcx>,
variance: VarianceTermPtr<'a>) {
debug!("add_constraints_from_trait_ref: trait_ref={:?} variance={:?}",
trait_ref,
variance);
let trait_generics = self.tcx().item_generics(trait_ref.def_id);
self.tcx().dep_graph.read(VarianceDepNode(trait_ref.def_id));
self.add_constraints_from_substs(generics,
trait_ref.def_id,
&trait_generics.types,
&trait_generics.regions,
trait_ref.substs,
variance);
}
fn add_constraints_from_ty(&mut self,
generics: &ty::Generics,
ty: Ty<'tcx>,
variance: VarianceTermPtr<'a>) {
debug!("add_constraints_from_ty(ty={:?}, variance={:?})",
ty,
variance);
match ty.sty {
ty::TyBool | ty::TyChar | ty::TyInt(_) | ty::TyUint(_) | ty::TyFloat(_) |
ty::TyStr | ty::TyNever => {
}
ty::TyClosure(..) |
ty::TyAnon(..) => {
bug!("Unexpected closure type in variance computation");
}
ty::TyRef(region, ref mt) => {
let contra = self.contravariant(variance);
self.add_constraints_from_region(generics, region, contra);
self.add_constraints_from_mt(generics, mt, variance);
}
ty::TyArray(typ, _) |
ty::TySlice(typ) => {
self.add_constraints_from_ty(generics, typ, variance);
}
ty::TyRawPtr(ref mt) => {
self.add_constraints_from_mt(generics, mt, variance);
}
ty::TyTuple(subtys, _) => {
for &subty in subtys {
self.add_constraints_from_ty(generics, subty, variance);
}
}
ty::TyAdt(def, substs) => {
let adt_generics = self.tcx().item_generics(def.did);
self.tcx().dep_graph.read(VarianceDepNode(def.did));
self.add_constraints_from_substs(generics,
def.did,
&adt_generics.types,
&adt_generics.regions,
substs,
variance);
}
ty::TyProjection(ref data) => {
let trait_ref = &data.trait_ref;
let trait_generics = self.tcx().item_generics(trait_ref.def_id);
self.tcx().dep_graph.read(VarianceDepNode(trait_ref.def_id));
self.add_constraints_from_substs(generics,
trait_ref.def_id,
&trait_generics.types,
&trait_generics.regions,
trait_ref.substs,
variance);
}
ty::TyDynamic(ref data, r) => {
let contra = self.contravariant(variance);
self.add_constraints_from_region(generics, r, contra);
if let Some(p) = data.principal() {
let poly_trait_ref = p.with_self_ty(self.tcx(), self.tcx().types.err);
self.add_constraints_from_trait_ref(generics, poly_trait_ref.0, variance);
}
for projection in data.projection_bounds() {
self.add_constraints_from_ty(generics, projection.0.ty, self.invariant);
}
}
ty::TyParam(ref data) => {
assert_eq!(generics.parent, None);
let mut i = data.idx as usize;
if !generics.has_self || i > 0 {
i -= generics.regions.len();
}
let def_id = generics.types[i].def_id;
let node_id = self.tcx().hir.as_local_node_id(def_id).unwrap();
match self.terms_cx.inferred_map.get(&node_id) {
Some(&index) => {
self.add_constraint(index, variance);
}
None => {
}
}
}
ty::TyFnDef(.., sig) |
ty::TyFnPtr(sig) => {
self.add_constraints_from_sig(generics, sig, variance);
}
ty::TyError => {
}
ty::TyInfer(..) => {
bug!("unexpected type encountered in \
variance inference: {}",
ty);
}
}
}
fn add_constraints_from_substs(&mut self,
generics: &ty::Generics,
def_id: DefId,
type_param_defs: &[ty::TypeParameterDef],
region_param_defs: &[ty::RegionParameterDef],
substs: &Substs<'tcx>,
variance: VarianceTermPtr<'a>) {
debug!("add_constraints_from_substs(def_id={:?}, substs={:?}, variance={:?})",
def_id,
substs,
variance);
for p in type_param_defs {
let variance_decl = self.declared_variance(p.def_id, def_id, p.index as usize);
let variance_i = self.xform(variance, variance_decl);
let substs_ty = substs.type_for_def(p);
debug!("add_constraints_from_substs: variance_decl={:?} variance_i={:?}",
variance_decl,
variance_i);
self.add_constraints_from_ty(generics, substs_ty, variance_i);
}
for p in region_param_defs {
let variance_decl = self.declared_variance(p.def_id, def_id, p.index as usize);
let variance_i = self.xform(variance, variance_decl);
let substs_r = substs.region_for_def(p);
self.add_constraints_from_region(generics, substs_r, variance_i);
}
}
fn add_constraints_from_sig(&mut self,
generics: &ty::Generics,
sig: ty::PolyFnSig<'tcx>,
variance: VarianceTermPtr<'a>) {
let contra = self.contravariant(variance);
for &input in sig.0.inputs() {
self.add_constraints_from_ty(generics, input, contra);
}
self.add_constraints_from_ty(generics, sig.0.output(), variance);
}
fn add_constraints_from_region(&mut self,
generics: &ty::Generics,
region: &'tcx ty::Region,
variance: VarianceTermPtr<'a>) {
match *region {
ty::ReEarlyBound(ref data) => {
assert_eq!(generics.parent, None);
let i = data.index as usize - generics.has_self as usize;
let def_id = generics.regions[i].def_id;
let node_id = self.tcx().hir.as_local_node_id(def_id).unwrap();
if self.is_to_be_inferred(node_id) {
let index = self.inferred_index(node_id);
self.add_constraint(index, variance);
}
}
ty::ReStatic => {}
ty::ReLateBound(..) => {
}
ty::ReFree(..) |
ty::ReScope(..) |
ty::ReVar(..) |
ty::ReSkolemized(..) |
ty::ReEmpty |
ty::ReErased => {
bug!("unexpected region encountered in variance \
inference: {:?}",
region);
}
}
}
fn add_constraints_from_mt(&mut self,
generics: &ty::Generics,
mt: &ty::TypeAndMut<'tcx>,
variance: VarianceTermPtr<'a>) {
match mt.mutbl {
hir::MutMutable => {
let invar = self.invariant(variance);
self.add_constraints_from_ty(generics, mt.ty, invar);
}
hir::MutImmutable => {
self.add_constraints_from_ty(generics, mt.ty, variance);
}
}
}
}