Skip to content

Add help for #![feature(impl_trait_in_fn_trait_return)] #105408

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Dec 9, 2022
Merged

Add help for #![feature(impl_trait_in_fn_trait_return)] #105408

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
32 changes: 21 additions & 11 deletions compiler/rustc_ast_lowering/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -259,6 +259,8 @@ enum ImplTraitContext {
},
/// Impl trait in type aliases.
TypeAliasesOpaqueTy,
/// `impl Trait` is unstably accepted in this position.
FeatureGated(ImplTraitPosition, Symbol),
/// `impl Trait` is not accepted in this position.
Disallowed(ImplTraitPosition),
}
Expand Down Expand Up @@ -1372,25 +1374,23 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}
path
}
ImplTraitContext::Disallowed(
position @ (ImplTraitPosition::TraitReturn | ImplTraitPosition::ImplReturn),
) => {
ImplTraitContext::FeatureGated(position, feature) => {
self.tcx
.sess
.create_feature_err(
MisplacedImplTrait {
span: t.span,
position: DiagnosticArgFromDisplay(&position),
position: DiagnosticArgFromDisplay(position),
},
sym::return_position_impl_trait_in_trait,
*feature,
)
.emit();
hir::TyKind::Err
}
ImplTraitContext::Disallowed(position) => {
self.tcx.sess.emit_err(MisplacedImplTrait {
span: t.span,
position: DiagnosticArgFromDisplay(&position),
position: DiagnosticArgFromDisplay(position),
});
hir::TyKind::Err
}
Expand Down Expand Up @@ -1739,14 +1739,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
} else {
match &decl.output {
FnRetTy::Ty(ty) => {
let mut context = if kind.return_impl_trait_allowed(self.tcx) {
let context = if kind.return_impl_trait_allowed(self.tcx) {
let fn_def_id = self.local_def_id(fn_node_id);
ImplTraitContext::ReturnPositionOpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
in_trait: matches!(kind, FnDeclKind::Trait),
}
} else {
ImplTraitContext::Disallowed(match kind {
let position = match kind {
FnDeclKind::Fn | FnDeclKind::Inherent => {
unreachable!("fn should allow in-band lifetimes")
}
Expand All @@ -1755,9 +1755,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
FnDeclKind::Pointer => ImplTraitPosition::PointerReturn,
FnDeclKind::Trait => ImplTraitPosition::TraitReturn,
FnDeclKind::Impl => ImplTraitPosition::ImplReturn,
})
};
match kind {
FnDeclKind::Trait | FnDeclKind::Impl => ImplTraitContext::FeatureGated(
position,
sym::return_position_impl_trait_in_trait,
),
_ => ImplTraitContext::Disallowed(position),
}
};
hir::FnRetTy::Return(self.lower_ty(ty, &mut context))
hir::FnRetTy::Return(self.lower_ty(ty, &context))
}
FnRetTy::Default(span) => hir::FnRetTy::DefaultReturn(self.lower_span(*span)),
}
Expand Down Expand Up @@ -1938,7 +1945,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
output,
span,
if in_trait && !this.tcx.features().return_position_impl_trait_in_trait {
ImplTraitContext::Disallowed(ImplTraitPosition::TraitReturn)
ImplTraitContext::FeatureGated(
ImplTraitPosition::TraitReturn,
sym::return_position_impl_trait_in_trait,
)
} else {
ImplTraitContext::ReturnPositionOpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
Expand Down
19 changes: 13 additions & 6 deletions compiler/rustc_ast_lowering/src/path.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use rustc_ast::{self as ast, *};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, PartialRes, Res};
use rustc_hir::GenericArg;
use rustc_span::symbol::{kw, Ident};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{BytePos, Span, DUMMY_SP};

use smallvec::{smallvec, SmallVec};
Expand Down Expand Up @@ -352,11 +352,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
// fn f(_: impl Fn() -> impl Debug) -> impl Fn() -> impl Debug
// // disallowed --^^^^^^^^^^ allowed --^^^^^^^^^^
// ```
FnRetTy::Ty(ty)
if matches!(itctx, ImplTraitContext::ReturnPositionOpaqueTy { .. })
&& self.tcx.features().impl_trait_in_fn_trait_return =>
{
self.lower_ty(&ty, itctx)
FnRetTy::Ty(ty) if matches!(itctx, ImplTraitContext::ReturnPositionOpaqueTy { .. }) => {
if self.tcx.features().impl_trait_in_fn_trait_return {
self.lower_ty(&ty, itctx)
} else {
self.lower_ty(
&ty,
&ImplTraitContext::FeatureGated(
ImplTraitPosition::FnTraitReturn,
sym::impl_trait_in_fn_trait_return,
),
)
}
}
FnRetTy::Ty(ty) => {
self.lower_ty(&ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FnTraitReturn))
Expand Down
6 changes: 6 additions & 0 deletions src/test/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,18 @@ error[E0562]: `impl Trait` only allowed in function and inherent method return t
|
LL | fn f() -> impl Fn() -> impl Sized { || () }
| ^^^^^^^^^^
|
= note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
= help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable

error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
--> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:3:32
|
LL | fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
| ^^^^^^^^^^
|
= note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
= help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable

error: aborting due to 2 previous errors

Expand Down