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spell the real selftype
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csmoe committed Feb 13, 2021
1 parent ed40b95 commit 5385a3d
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Showing 2 changed files with 33 additions and 36 deletions.
67 changes: 32 additions & 35 deletions compiler/rustc_typeck/src/check/check.rs
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use rustc_hir as hir;
use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
use rustc_hir::intravisit::Visitor;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{ItemKind, Node};
use rustc_hir::{def::Res, ItemKind, Node, PathSegment};
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
use rustc_middle::ty::fold::TypeFoldable;
Expand Down Expand Up @@ -516,10 +516,11 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
}
}

#[derive(Debug)]
struct ProhibitOpaqueVisitor<'tcx> {
opaque_identity_ty: Ty<'tcx>,
generics: &'tcx ty::Generics,
tcx: TyCtxt<'tcx>,
selftys: Vec<(Span, Option<String>)>,
}

impl<'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueVisitor<'tcx> {
Expand All @@ -536,6 +537,29 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
}
}

impl Visitor<'tcx> for ProhibitOpaqueVisitor<'tcx> {
type Map = rustc_middle::hir::map::Map<'tcx>;

fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
hir::intravisit::NestedVisitorMap::OnlyBodies(self.tcx.hir())
}

fn visit_ty(&mut self, arg: &'tcx hir::Ty<'tcx>) {
match arg.kind {
hir::TyKind::Path(hir::QPath::Resolved(None, path)) => match &path.segments {
[PathSegment { res: Some(Res::SelfTy(_, impl_ref)), .. }] => {
let impl_ty_name =
impl_ref.map(|(def_id, _)| self.tcx.def_path_str(def_id));
self.selftys.push((path.span, impl_ty_name));
}
_ => {}
},
_ => {}
}
hir::intravisit::walk_ty(self, arg);
}
}

if let ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::AsyncFn | hir::OpaqueTyOrigin::FnReturn,
..
Expand All @@ -547,18 +571,19 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
InternalSubsts::identity_for_item(tcx, def_id.to_def_id()),
),
generics: tcx.generics_of(def_id),
tcx,
selftys: vec![],
};
let prohibit_opaque = tcx
.explicit_item_bounds(def_id)
.iter()
.try_for_each(|(predicate, _)| predicate.visit_with(&mut visitor));
debug!(
"check_opaque_for_inheriting_lifetimes: prohibit_opaque={:?}, visitor={:?}",
prohibit_opaque, visitor
"check_opaque_for_inheriting_lifetimes: prohibit_opaque={:?}, visitor.opaque_identity_ty={:?}, visitor.generics={:?}",
prohibit_opaque, visitor.opaque_identity_ty, visitor.generics
);

if let Some(ty) = prohibit_opaque.break_value() {
let mut visitor = SelfTySpanVisitor { tcx, selfty_spans: vec![] };
visitor.visit_item(&item);
let is_async = match item.kind {
ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => {
Expand All @@ -576,11 +601,11 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
if is_async { "async fn" } else { "impl Trait" },
);

for span in visitor.selfty_spans {
for (span, name) in visitor.selftys {
err.span_suggestion(
span,
"consider spelling out the type instead",
format!("{:?}", ty),
name.unwrap_or_else(|| format!("{:?}", ty)),
Applicability::MaybeIncorrect,
);
}
Expand Down Expand Up @@ -1591,31 +1616,3 @@ fn opaque_type_cycle_error(tcx: TyCtxt<'tcx>, def_id: LocalDefId, span: Span) {
}
err.emit();
}

struct SelfTySpanVisitor<'tcx> {
tcx: TyCtxt<'tcx>,
selfty_spans: Vec<Span>,
}

impl Visitor<'tcx> for SelfTySpanVisitor<'tcx> {
type Map = rustc_middle::hir::map::Map<'tcx>;

fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
hir::intravisit::NestedVisitorMap::OnlyBodies(self.tcx.hir())
}

fn visit_ty(&mut self, arg: &'tcx hir::Ty<'tcx>) {
match arg.kind {
hir::TyKind::Path(hir::QPath::Resolved(None, path)) => match &path.segments {
[segment]
if segment.res.map(|res| matches!(res, Res::SelfTy(_, _))).unwrap_or(false) =>
{
self.selfty_spans.push(path.span);
}
_ => {}
},
_ => {}
}
hir::intravisit::walk_ty(self, arg);
}
}
2 changes: 1 addition & 1 deletion src/test/ui/async-await/issues/issue-78600.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ error[E0760]: `async fn` return type cannot contain a projection or `Self` that
LL | async fn new(i: &'a i32) -> Result<Self, ()> {
| ^^^^^^^----^^^^^
| |
| help: consider spelling out the type instead: `std::result::Result<S<'a>, ()>`
| help: consider spelling out the type instead: `S<'a>`

error: aborting due to previous error

Expand Down

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