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Make is_self_ty a method on SelfVisitor

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This commit is contained in:
Taiki Endo 2019-05-29 17:37:28 +09:00
parent a1fd4fa848
commit 7b9a65ea6a
1 changed files with 36 additions and 33 deletions
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69
src/librustc/middle/resolve_lifetime.rs
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@ -2146,41 +2146,44 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
// First (determined here), if `self` is by-reference, then the
// implied output region is the region of the self parameter.
if has_self {
// Look for `self: &'a Self` - also desugared from `&'a self`,
// and if that matches, use it for elision and return early.
let is_self_ty = |res: Res| {
if let Res::SelfTy(..) = res {
return true;
}
// Can't always rely on literal (or implied) `Self` due
// to the way elision rules were originally specified.
let impl_self = impl_self.map(|ty| &ty.node);
if let Some(&hir::TyKind::Path(hir::QPath::Resolved(None, ref path))) = impl_self {
match path.res {
// Whitelist the types that unambiguously always
// result in the same type constructor being used
// (it can't differ between `Self` and `self`).
Res::Def(DefKind::Struct, _)
| Res::Def(DefKind::Union, _)
| Res::Def(DefKind::Enum, _)
| Res::PrimTy(_) => {
return res == path.res
}
_ => {}
}
}
false
};
struct SelfVisitor<'a, F: FnMut(Res) -> bool> {
is_self_ty: F,
struct SelfVisitor<'a> {
map: &'a NamedRegionMap,
impl_self: Option<&'a hir::TyKind>,
lifetime: Option<Region>,
}
impl<'a, F: FnMut(Res) -> bool> Visitor<'a> for SelfVisitor<'a, F> {
impl SelfVisitor<'_> {
// Look for `self: &'a Self` - also desugared from `&'a self`,
// and if that matches, use it for elision and return early.
fn is_self_ty(&self, res: Res) -> bool {
if let Res::SelfTy(..) = res {
return true;
}
// Can't always rely on literal (or implied) `Self` due
// to the way elision rules were originally specified.
if let Some(&hir::TyKind::Path(hir::QPath::Resolved(None, ref path))) =
self.impl_self
{
match path.res {
// Whitelist the types that unambiguously always
// result in the same type constructor being used
// (it can't differ between `Self` and `self`).
Res::Def(DefKind::Struct, _)
| Res::Def(DefKind::Union, _)
| Res::Def(DefKind::Enum, _)
| Res::PrimTy(_) => {
return res == path.res
}
_ => {}
}
}
false
}
}
impl<'a> Visitor<'a> for SelfVisitor<'a> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'a> {
NestedVisitorMap::None
}
@ -2189,7 +2192,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
if let hir::TyKind::Rptr(lifetime_ref, ref mt) = ty.node {
if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = mt.ty.node
{
if (self.is_self_ty)(path.res) {
if self.is_self_ty(path.res) {
self.lifetime = self.map.defs.get(&lifetime_ref.hir_id).copied();
return;
}
@ -2200,8 +2203,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
}
let mut visitor = SelfVisitor {
is_self_ty,
map: self.map,
impl_self: impl_self.map(|ty| &ty.node),
lifetime: None,
};
visitor.visit_ty(&inputs[0]);