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Implement defaults for associated types #25796

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May 28, 2015
Merged

Implement defaults for associated types #25796

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ae10e47
Implement defaults for associated types
May 26, 2015
65a3245
Add tests for fixed issues
May 26, 2015
c68e652
test fixes
May 27, 2015
699fc80
Address review comments
May 27, 2015
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35 changes: 22 additions & 13 deletions src/librustc/metadata/decoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -252,6 +252,13 @@ fn doc_type<'tcx>(doc: rbml::Doc, tcx: &ty::ctxt<'tcx>, cdata: Cmd) -> Ty<'tcx>
|_, did| translate_def_id(cdata, did))
}

fn maybe_doc_type<'tcx>(doc: rbml::Doc, tcx: &ty::ctxt<'tcx>, cdata: Cmd) -> Option<Ty<'tcx>> {
reader::maybe_get_doc(doc, tag_items_data_item_type).map(|tp| {
parse_ty_data(tp.data, cdata.cnum, tp.start, tcx,
|_, did| translate_def_id(cdata, did))
})
}

fn doc_method_fty<'tcx>(doc: rbml::Doc, tcx: &ty::ctxt<'tcx>,
cdata: Cmd) -> ty::BareFnTy<'tcx> {
let tp = reader::get_doc(doc, tag_item_method_fty);
Expand Down Expand Up @@ -875,24 +882,24 @@ pub fn get_impl_or_trait_item<'tcx>(intr: Rc<IdentInterner>,
id: ast::NodeId,
tcx: &ty::ctxt<'tcx>)
-> ty::ImplOrTraitItem<'tcx> {
let method_doc = lookup_item(id, cdata.data());
let item_doc = lookup_item(id, cdata.data());

let def_id = item_def_id(method_doc, cdata);
let def_id = item_def_id(item_doc, cdata);

let container_id = item_require_parent_item(cdata, method_doc);
let container_id = item_require_parent_item(cdata, item_doc);
let container_doc = lookup_item(container_id.node, cdata.data());
let container = match item_family(container_doc) {
Trait => TraitContainer(container_id),
_ => ImplContainer(container_id),
};

let name = item_name(&*intr, method_doc);
let vis = item_visibility(method_doc);
let name = item_name(&*intr, item_doc);
let vis = item_visibility(item_doc);

match item_sort(method_doc) {
match item_sort(item_doc) {
Some('C') => {
let ty = doc_type(method_doc, tcx, cdata);
let default = get_provided_source(method_doc, cdata);
let ty = doc_type(item_doc, tcx, cdata);
let default = get_provided_source(item_doc, cdata);
ty::ConstTraitItem(Rc::new(ty::AssociatedConst {
name: name,
ty: ty,
Expand All @@ -903,11 +910,11 @@ pub fn get_impl_or_trait_item<'tcx>(intr: Rc<IdentInterner>,
}))
}
Some('r') | Some('p') => {
let generics = doc_generics(method_doc, tcx, cdata, tag_method_ty_generics);
let predicates = doc_predicates(method_doc, tcx, cdata, tag_method_ty_generics);
let fty = doc_method_fty(method_doc, tcx, cdata);
let explicit_self = get_explicit_self(method_doc);
let provided_source = get_provided_source(method_doc, cdata);
let generics = doc_generics(item_doc, tcx, cdata, tag_method_ty_generics);
let predicates = doc_predicates(item_doc, tcx, cdata, tag_method_ty_generics);
let fty = doc_method_fty(item_doc, tcx, cdata);
let explicit_self = get_explicit_self(item_doc);
let provided_source = get_provided_source(item_doc, cdata);

ty::MethodTraitItem(Rc::new(ty::Method::new(name,
generics,
Expand All @@ -920,8 +927,10 @@ pub fn get_impl_or_trait_item<'tcx>(intr: Rc<IdentInterner>,
provided_source)))
}
Some('t') => {
let ty = maybe_doc_type(item_doc, tcx, cdata);
ty::TypeTraitItem(Rc::new(ty::AssociatedType {
name: name,
ty: ty,
vis: vis,
def_id: def_id,
container: container,
Expand Down
23 changes: 14 additions & 9 deletions src/librustc/metadata/encoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -894,12 +894,12 @@ fn encode_info_for_method<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
rbml_w.end_tag();
}

fn encode_info_for_associated_type(ecx: &EncodeContext,
rbml_w: &mut Encoder,
associated_type: &ty::AssociatedType,
impl_path: PathElems,
parent_id: NodeId,
impl_item_opt: Option<&ast::ImplItem>) {
fn encode_info_for_associated_type<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
rbml_w: &mut Encoder,
associated_type: &ty::AssociatedType<'tcx>,
impl_path: PathElems,
parent_id: NodeId,
impl_item_opt: Option<&ast::ImplItem>) {
debug!("encode_info_for_associated_type({:?},{:?})",
associated_type.def_id,
token::get_name(associated_type.name));
Expand All @@ -913,8 +913,6 @@ fn encode_info_for_associated_type(ecx: &EncodeContext,
encode_parent_item(rbml_w, local_def(parent_id));
encode_item_sort(rbml_w, 't');

encode_bounds_and_type_for_item(rbml_w, ecx, associated_type.def_id.local_id());

let stab = stability::lookup(ecx.tcx, associated_type.def_id);
encode_stability(rbml_w, stab);

Expand All @@ -923,7 +921,14 @@ fn encode_info_for_associated_type(ecx: &EncodeContext,

if let Some(ii) = impl_item_opt {
encode_attributes(rbml_w, &ii.attrs);
encode_type(ecx, rbml_w, ty::node_id_to_type(ecx.tcx, ii.id));
} else {
encode_predicates(rbml_w, ecx,
&ty::lookup_predicates(ecx.tcx, associated_type.def_id),
tag_item_generics);
}

if let Some(ty) = associated_type.ty {
encode_type(ecx, rbml_w, ty);
}

rbml_w.end_tag();
Expand Down
52 changes: 28 additions & 24 deletions src/librustc/middle/traits/project.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -857,37 +857,41 @@ fn confirm_impl_candidate<'cx,'tcx>(
-> (Ty<'tcx>, Vec<PredicateObligation<'tcx>>)
{
// there don't seem to be nicer accessors to these:
let impl_items_map = selcx.tcx().impl_items.borrow();
let impl_or_trait_items_map = selcx.tcx().impl_or_trait_items.borrow();

let impl_items = impl_items_map.get(&impl_vtable.impl_def_id).unwrap();
let mut impl_ty = None;
for impl_item in impl_items {
let assoc_type = match *impl_or_trait_items_map.get(&impl_item.def_id()).unwrap() {
ty::TypeTraitItem(ref assoc_type) => assoc_type.clone(),
ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => { continue; }
};

if assoc_type.name != obligation.predicate.item_name {
continue;
// Look for the associated type in the impl
for impl_item in &selcx.tcx().impl_items.borrow()[&impl_vtable.impl_def_id] {
if let ty::TypeTraitItem(ref assoc_ty) = impl_or_trait_items_map[&impl_item.def_id()] {
if assoc_ty.name == obligation.predicate.item_name {
return (assoc_ty.ty.unwrap().subst(selcx.tcx(), &impl_vtable.substs),
impl_vtable.nested.into_vec());
}
}

let impl_poly_ty = ty::lookup_item_type(selcx.tcx(), assoc_type.def_id);
impl_ty = Some(impl_poly_ty.ty.subst(selcx.tcx(), &impl_vtable.substs));
break;
}

match impl_ty {
Some(ty) => (ty, impl_vtable.nested.into_vec()),
None => {
// This means that the impl is missing a
// definition for the associated type. This error
// ought to be reported by the type checker method
// `check_impl_items_against_trait`, so here we
// just return ty_err.
(selcx.tcx().types.err, vec!())
// It is not in the impl - get the default from the trait.
let trait_ref = obligation.predicate.trait_ref;
for trait_item in ty::trait_items(selcx.tcx(), trait_ref.def_id).iter() {
if let &ty::TypeTraitItem(ref assoc_ty) = trait_item {
if assoc_ty.name == obligation.predicate.item_name {
if let Some(ty) = assoc_ty.ty {
return (ty.subst(selcx.tcx(), trait_ref.substs),
impl_vtable.nested.into_vec());
} else {
// This means that the impl is missing a
// definition for the associated type. This error
// ought to be reported by the type checker method
// `check_impl_items_against_trait`, so here we
// just return ty_err.
return (selcx.tcx().types.err, vec!());
}
}
}
}

selcx.tcx().sess.span_bug(obligation.cause.span,
&format!("No associated type for {}",
trait_ref.repr(selcx.tcx())));
}

impl<'tcx> Repr<'tcx> for ProjectionTyError<'tcx> {
Expand Down
5 changes: 3 additions & 2 deletions src/librustc/middle/ty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ impl ImplOrTraitItemContainer {
pub enum ImplOrTraitItem<'tcx> {
ConstTraitItem(Rc<AssociatedConst<'tcx>>),
MethodTraitItem(Rc<Method<'tcx>>),
TypeTraitItem(Rc<AssociatedType>),
TypeTraitItem(Rc<AssociatedType<'tcx>>),
}

impl<'tcx> ImplOrTraitItem<'tcx> {
Expand Down Expand Up @@ -267,8 +267,9 @@ pub struct AssociatedConst<'tcx> {
}

#[derive(Clone, Copy, Debug)]
pub struct AssociatedType {
pub struct AssociatedType<'tcx> {
pub name: ast::Name,
pub ty: Option<Ty<'tcx>>,
pub vis: ast::Visibility,
pub def_id: ast::DefId,
pub container: ImplOrTraitItemContainer,
Expand Down
2 changes: 1 addition & 1 deletion src/librustc/util/ppaux.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1077,7 +1077,7 @@ impl<'tcx> Repr<'tcx> for ty::AssociatedConst<'tcx> {
}
}

impl<'tcx> Repr<'tcx> for ty::AssociatedType {
impl<'tcx> Repr<'tcx> for ty::AssociatedType<'tcx> {
fn repr(&self, tcx: &ctxt<'tcx>) -> String {
format!("AssociatedType(name: {}, vis: {}, def_id: {})",
self.name.repr(tcx),
Expand Down
17 changes: 9 additions & 8 deletions src/librustc_typeck/check/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1070,7 +1070,7 @@ fn check_impl_items_against_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
// Check for missing items from trait
let provided_methods = ty::provided_trait_methods(tcx, impl_trait_ref.def_id);
let associated_consts = ty::associated_consts(tcx, impl_trait_ref.def_id);
let mut missing_methods = Vec::new();
let mut missing_items = Vec::new();
for trait_item in &*trait_items {
match *trait_item {
ty::ConstTraitItem(ref associated_const) => {
Expand All @@ -1086,8 +1086,8 @@ fn check_impl_items_against_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
associated_consts.iter().any(|ac| ac.default.is_some() &&
ac.name == associated_const.name);
if !is_implemented && !is_provided {
missing_methods.push(format!("`{}`",
token::get_name(associated_const.name)));
missing_items.push(format!("`{}`",
token::get_name(associated_const.name)));
}
}
ty::MethodTraitItem(ref trait_method) => {
Expand All @@ -1103,7 +1103,7 @@ fn check_impl_items_against_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
let is_provided =
provided_methods.iter().any(|m| m.name == trait_method.name);
if !is_implemented && !is_provided {
missing_methods.push(format!("`{}`", token::get_name(trait_method.name)));
missing_items.push(format!("`{}`", token::get_name(trait_method.name)));
}
}
ty::TypeTraitItem(ref associated_type) => {
Expand All @@ -1115,17 +1115,18 @@ fn check_impl_items_against_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
_ => false,
}
});
if !is_implemented {
missing_methods.push(format!("`{}`", token::get_name(associated_type.name)));
let is_provided = associated_type.ty.is_some();
if !is_implemented && !is_provided {
missing_items.push(format!("`{}`", token::get_name(associated_type.name)));
}
}
}
}

if !missing_methods.is_empty() {
if !missing_items.is_empty() {
span_err!(tcx.sess, impl_span, E0046,
"not all trait items implemented, missing: {}",
missing_methods.connect(", "));
missing_items.connect(", "));
}
}

Expand Down
48 changes: 24 additions & 24 deletions src/librustc_typeck/collect.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -718,15 +718,17 @@ fn convert_associated_const<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
.insert(local_def(id), ty::ConstTraitItem(associated_const));
}

fn as_refsociated_type<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
container: ImplOrTraitItemContainer,
ident: ast::Ident,
id: ast::NodeId,
vis: ast::Visibility)
fn convert_associated_type<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
container: ImplOrTraitItemContainer,
ident: ast::Ident,
id: ast::NodeId,
vis: ast::Visibility,
ty: Option<Ty<'tcx>>)
{
let associated_type = Rc::new(ty::AssociatedType {
name: ident.name,
vis: vis,
ty: ty,
def_id: local_def(id),
container: container
});
Expand Down Expand Up @@ -876,21 +878,14 @@ fn convert_item(ccx: &CrateCtxt, it: &ast::Item) {
if let ast::TypeImplItem(ref ty) = impl_item.node {
if opt_trait_ref.is_none() {
span_err!(tcx.sess, impl_item.span, E0202,
"associated items are not allowed in inherent impls");
"associated types are not allowed in inherent impls");
}

as_refsociated_type(ccx, ImplContainer(local_def(it.id)),
impl_item.ident, impl_item.id, impl_item.vis);

let typ = ccx.icx(&ty_predicates).to_ty(&ExplicitRscope, ty);
tcx.tcache.borrow_mut().insert(local_def(impl_item.id),
TypeScheme {
generics: ty::Generics::empty(),
ty: typ,
});
tcx.predicates.borrow_mut().insert(local_def(impl_item.id),
ty::GenericPredicates::empty());
write_ty_to_tcx(tcx, impl_item.id, typ);

convert_associated_type(ccx, ImplContainer(local_def(it.id)),
impl_item.ident, impl_item.id, impl_item.vis,
Some(typ));
}
}

Expand Down Expand Up @@ -973,9 +968,14 @@ fn convert_item(ccx: &CrateCtxt, it: &ast::Item) {
// Convert all the associated types.
for trait_item in trait_items {
match trait_item.node {
ast::TypeTraitItem(..) => {
as_refsociated_type(ccx, TraitContainer(local_def(it.id)),
trait_item.ident, trait_item.id, ast::Public);
ast::TypeTraitItem(_, ref opt_ty) => {
let typ = opt_ty.as_ref().map({
|ty| ccx.icx(&trait_predicates).to_ty(&ExplicitRscope, &ty)
});

convert_associated_type(ccx, TraitContainer(local_def(it.id)),
trait_item.ident, trait_item.id, ast::Public,
typ);
}
_ => {}
}
Expand Down Expand Up @@ -2292,10 +2292,10 @@ fn enforce_impl_params_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,

let lifetimes_in_associated_types: HashSet<_> =
impl_items.iter()
.filter_map(|item| match item.node {
ast::TypeImplItem(..) => Some(ty::node_id_to_type(tcx, item.id)),
ast::ConstImplItem(..) | ast::MethodImplItem(..) |
ast::MacImplItem(..) => None,
.map(|item| ty::impl_or_trait_item(tcx, local_def(item.id)))
.filter_map(|item| match item {
ty::TypeTraitItem(ref assoc_ty) => assoc_ty.ty,
ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => None
})
.flat_map(|ty| ctp::parameters_for_type(ty).into_iter())
.filter_map(|p| match p {
Expand Down
8 changes: 5 additions & 3 deletions src/librustdoc/clean/inline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -362,11 +362,13 @@ pub fn build_impl(cx: &DocContext,
}
ty::TypeTraitItem(ref assoc_ty) => {
let did = assoc_ty.def_id;
let type_scheme = ty::lookup_item_type(tcx, did);
let predicates = ty::lookup_predicates(tcx, did);
let type_scheme = ty::TypeScheme {
ty: assoc_ty.ty.unwrap(),
generics: ty::Generics::empty()
};
// Not sure the choice of ParamSpace actually matters here,
// because an associated type won't have generics on the LHS
let typedef = (type_scheme, predicates,
let typedef = (type_scheme, ty::GenericPredicates::empty(),
subst::ParamSpace::TypeSpace).clean(cx);
Some(clean::Item {
name: Some(assoc_ty.name.clean(cx)),
Expand Down
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