Skip to content

Commit

Permalink
Rollup merge of #82021 - csmoe:issue-78600, r=tmandry
Browse files Browse the repository at this point in the history
Spell out nested Self type in lint message

Closes #78600
r? `@tmandry`
  • Loading branch information
Dylan-DPC authored Feb 17, 2021
2 parents 0b2f2b9 + 5385a3d commit f7501b6
Show file tree
Hide file tree
Showing 3 changed files with 62 additions and 13 deletions.
52 changes: 39 additions & 13 deletions compiler/rustc_typeck/src/check/check.rs
Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,9 @@ use rustc_attr as attr;
use rustc_errors::{Applicability, ErrorReported};
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 @@ -513,10 +514,11 @@ 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 @@ -533,6 +535,29 @@ 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 @@ -544,17 +569,20 @@ 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() {
visitor.visit_item(&item);
let is_async = match item.kind {
ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => {
matches!(origin, hir::OpaqueTyOrigin::AsyncFn)
Expand All @@ -571,15 +599,13 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
if is_async { "async fn" } else { "impl Trait" },
);

if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(span) {
if snippet == "Self" {
err.span_suggestion(
span,
"consider spelling out the type instead",
format!("{:?}", ty),
Applicability::MaybeIncorrect,
);
}
for (span, name) in visitor.selftys {
err.span_suggestion(
span,
"consider spelling out the type instead",
name.unwrap_or_else(|| format!("{:?}", ty)),
Applicability::MaybeIncorrect,
);
}
err.emit();
}
Expand Down
12 changes: 12 additions & 0 deletions src/test/ui/async-await/issues/issue-78600.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
// edition:2018

struct S<'a>(&'a i32);

impl<'a> S<'a> {
async fn new(i: &'a i32) -> Result<Self, ()> {
//~^ ERROR: `async fn`
Ok(S(&22))
}
}

fn main() {}
11 changes: 11 additions & 0 deletions src/test/ui/async-await/issues/issue-78600.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
error[E0760]: `async fn` return type cannot contain a projection or `Self` that references lifetimes from a parent scope
--> $DIR/issue-78600.rs:6:33
|
LL | async fn new(i: &'a i32) -> Result<Self, ()> {
| ^^^^^^^----^^^^^
| |
| help: consider spelling out the type instead: `S<'a>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0760`.

0 comments on commit f7501b6

Please sign in to comment.