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rustc_typeck: unify the impl type with the UFCS path prefix type.

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This commit is contained in:
Eduard Burtescu 2015-02-23 23:24:41 +02:00
parent f0efa2d843
commit 8501c9dee5
1 changed files with 32 additions and 7 deletions
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39
src/librustc_typeck/check/mod.rs
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@ -4748,9 +4748,7 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
assert!(segments.len() >= 1);
// In `<T as Trait<A, B>>::method`, `A` and `B` are mandatory.
let mut require_type_space = opt_self_ty.is_some();
let mut ufcs_method = None;
let mut segment_spaces: Vec<_>;
match def {
// Case 1 and 1b. Reference to a *type* or *enum variant*.
@ -4777,8 +4775,8 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
}
// Case 3. Reference to a method.
def::DefMethod(_, providence) => {
match providence {
def::DefMethod(_, provenance) => {
match provenance {
def::FromTrait(trait_did) => {
callee::check_legal_trait_for_method_call(fcx.ccx, span, trait_did)
}
@ -4791,9 +4789,9 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
segment_spaces.push(Some(subst::FnSpace));
} else {
// `<T>::method` will end up here, and so can `T::method`.
assert!(opt_self_ty.is_some());
require_type_space = false;
let self_ty = opt_self_ty.expect("UFCS sugared method missing Self");
segment_spaces = vec![Some(subst::FnSpace)];
ufcs_method = Some((provenance, self_ty));
}
}
@ -4812,6 +4810,11 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
}
assert_eq!(segment_spaces.len(), segments.len());
// In `<T as Trait<A, B>>::method`, `A` and `B` are mandatory, but
// `opt_self_ty` can also be Some for `Foo::method`, where Foo's
// type parameters are not mandatory.
let require_type_space = opt_self_ty.is_some() && ufcs_method.is_none();
debug!("segment_spaces={:?}", segment_spaces);
// Next, examine the definition, and determine how many type
@ -4879,6 +4882,28 @@ pub fn instantiate_path<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
// the referenced item.
let ty_substituted = fcx.instantiate_type_scheme(span, &substs, &type_scheme.ty);
if let Some((def::FromImpl(impl_def_id), self_ty)) = ufcs_method {
// In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
// is inherent, there is no `Self` parameter, instead, the impl needs
// type parameters, which we can infer by unifying the provided `Self`
// with the substituted impl type.
let impl_scheme = ty::lookup_item_type(fcx.tcx(), impl_def_id);
assert_eq!(substs.types.len(subst::TypeSpace),
impl_scheme.generics.types.len(subst::TypeSpace));
assert_eq!(substs.regions().len(subst::TypeSpace),
impl_scheme.generics.regions.len(subst::TypeSpace));
let impl_ty = fcx.instantiate_type_scheme(span, &substs, &impl_scheme.ty);
if fcx.mk_subty(false, infer::Misc(span), self_ty, impl_ty).is_err() {
fcx.tcx().sess.span_bug(span,
&format!(
"instantiate_path: (UFCS) {} was a subtype of {} but now is not?",
self_ty.repr(fcx.tcx()),
impl_ty.repr(fcx.tcx())));
}
}
fcx.write_ty(node_id, ty_substituted);
fcx.write_substs(node_id, ty::ItemSubsts { substs: substs });
return;