bjoernager/rust
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Point to where clause for GATs

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This commit is contained in:
jackh726 2021-07-25 22:12:34 -04:00
parent 2fc3c69e54
commit 22fc7d6e5a
7 changed files with 200 additions and 8 deletions
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98
compiler/rustc_infer/src/infer/error_reporting/mod.rs
View file

@ -2259,9 +2259,99 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}
};
let mut err = match *sub {
ty::ReEarlyBound(ty::EarlyBoundRegion { name, .. })
| ty::ReFree(ty::FreeRegion { bound_region: ty::BrNamed(_, name), .. }) => {
#[derive(Debug)]
enum SubOrigin<'hir> {
GAT(&'hir hir::Generics<'hir>),
Impl(&'hir hir::Generics<'hir>),
Trait(&'hir hir::Generics<'hir>),
Fn(&'hir hir::Generics<'hir>),
Unknown,
}
let sub_origin = 'origin: {
match *sub {
ty::ReEarlyBound(ty::EarlyBoundRegion { def_id, .. }) => {
let node = self.tcx.hir().get_if_local(def_id).unwrap();
match node {
Node::GenericParam(param) => {
for h in self.tcx.hir().parent_iter(param.hir_id) {
break 'origin match h.1 {
Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::TyAlias(..),
generics,
..
}) => SubOrigin::GAT(generics),
Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::Fn(..),
generics,
..
}) => SubOrigin::Fn(generics),
Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Type(..),
generics,
..
}) => SubOrigin::GAT(generics),
Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Fn(..),
generics,
..
}) => SubOrigin::Fn(generics),
Node::Item(hir::Item {
kind: hir::ItemKind::Trait(_, _, generics, _, _),
..
}) => SubOrigin::Trait(generics),
Node::Item(hir::Item {
kind: hir::ItemKind::Impl(hir::Impl { generics, .. }),
..
}) => SubOrigin::Impl(generics),
Node::Item(hir::Item {
kind: hir::ItemKind::Fn(_, generics, _),
..
}) => SubOrigin::Fn(generics),
_ => continue,
};
}
}
_ => {}
}
}
_ => {}
}
SubOrigin::Unknown
};
debug!(?sub_origin);
let mut err = match (*sub, sub_origin) {
// In the case of GATs, we have to be careful. If we a type parameter `T` on an impl,
// but a lifetime `'a` on an associated type, then we might need to suggest adding
// `where T: 'a`. Importantly, this is on the GAT span, not on the `T` declaration.
(ty::ReEarlyBound(ty::EarlyBoundRegion { name: _, .. }), SubOrigin::GAT(generics)) => {
// Does the required lifetime have a nice name we can print?
let mut err = struct_span_err!(
self.tcx.sess,
span,
E0309,
"{} may not live long enough",
labeled_user_string
);
let pred = format!("{}: {}", bound_kind, sub);
let suggestion = format!(
"{} {}",
if !generics.where_clause.predicates.is_empty() { "," } else { " where" },
pred,
);
err.span_suggestion(
generics.where_clause.tail_span_for_suggestion(),
"consider adding a where clause".into(),
suggestion,
Applicability::MaybeIncorrect,
);
err
}
(
ty::ReEarlyBound(ty::EarlyBoundRegion { name, .. })
| ty::ReFree(ty::FreeRegion { bound_region: ty::BrNamed(_, name), .. }),
_,
) => {
// Does the required lifetime have a nice name we can print?
let mut err = struct_span_err!(
self.tcx.sess,
@ -2278,7 +2368,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
err
}
ty::ReStatic => {
(ty::ReStatic, _) => {
// Does the required lifetime have a nice name we can print?
let mut err = struct_span_err!(
self.tcx.sess,

1
compiler/rustc_infer/src/lib.rs
View file

@ -22,6 +22,7 @@
#![feature(in_band_lifetimes)]
#![feature(control_flow_enum)]
#![feature(min_specialization)]
#![feature(label_break_value)]
#![recursion_limit = "512"] // For rustdoc
#[macro_use]