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NiceRegionError: Use written return type for async fn
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@tmandry
tmandry committed Jan 19, 2022
1 parent 6487845 commit 5c15ad7
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Showing 13 changed files with 181 additions and 165 deletions.
15 changes: 14 additions & 1 deletion compiler/rustc_hir/src/hir.rs
View file
Expand Up @@ -2726,6 +2726,10 @@ pub struct FnHeader {
}

impl FnHeader {
pub fn is_async(&self) -> bool {
matches!(&self.asyncness, IsAsync::Async)
}

pub fn is_const(&self) -> bool {
matches!(&self.constness, Constness::Const)
}
Expand Down Expand Up @@ -3169,7 +3173,7 @@ impl<'hir> Node<'hir> {
}
}

pub fn fn_decl(&self) -> Option<&FnDecl<'hir>> {
pub fn fn_decl(&self) -> Option<&'hir FnDecl<'hir>> {
match self {
Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(fn_sig, _), .. })
| Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(fn_sig, _), .. })
Expand All @@ -3181,6 +3185,15 @@ impl<'hir> Node<'hir> {
}
}

pub fn fn_sig(&self) -> Option<&'hir FnSig<'hir>> {
match self {
Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(fn_sig, _), .. })
| Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(fn_sig, _), .. })
| Node::Item(Item { kind: ItemKind::Fn(fn_sig, _, _), .. }) => Some(fn_sig),
_ => None,
}
}

pub fn body_id(&self) -> Option<BodyId> {
match self {
Node::TraitItem(TraitItem {
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_infer/src/infer/error_reporting/mod.rs
View file
Expand Up @@ -65,9 +65,9 @@ use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{Item, ItemKind, Node};
use rustc_middle::dep_graph::DepContext;
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::{
self,
error::TypeError,
subst::{GenericArgKind, Subst, SubstsRef},
Binder, Region, Ty, TyCtxt, TypeFoldable,
};
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
View file
Expand Up @@ -171,6 +171,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {

self.suggest_adding_lifetime_params(sub, ty_sup, ty_sub, &mut err);

// TODO: This is only helpful if the lifetime more visible in the impl Future type than in the signature.
if let Some(t) = future_return_type {
let snip = self
.tcx()
Expand Down
19 changes: 6 additions & 13 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs
View file
@@ -1,6 +1,5 @@
use rustc_hir as hir;
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::Node;
use rustc_middle::hir::map::Map;
use rustc_middle::hir::nested_filter;
use rustc_middle::middle::resolve_lifetime as rl;
Expand All @@ -25,25 +24,19 @@ pub(crate) fn find_anon_type<'tcx>(
tcx: TyCtxt<'tcx>,
region: Region<'tcx>,
br: &ty::BoundRegionKind,
) -> Option<(&'tcx hir::Ty<'tcx>, &'tcx hir::FnDecl<'tcx>)> {
) -> Option<(&'tcx hir::Ty<'tcx>, &'tcx hir::FnSig<'tcx>)> {
if let Some(anon_reg) = tcx.is_suitable_region(region) {
let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
let fndecl = match tcx.hir().get(hir_id) {
Node::Item(&hir::Item { kind: hir::ItemKind::Fn(ref m, ..), .. })
| Node::TraitItem(&hir::TraitItem {
kind: hir::TraitItemKind::Fn(ref m, ..), ..
})
| Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(ref m, ..), .. }) => {
&m.decl
}
_ => return None,
let Some(fn_sig) = tcx.hir().get(hir_id).fn_sig() else {
return None
};

fndecl
fn_sig
.decl
.inputs
.iter()
.find_map(|arg| find_component_for_bound_region(tcx, arg, br))
.map(|ty| (ty, &**fndecl))
.map(|ty| (ty, fn_sig))
} else {
None
}
Expand Down
37 changes: 26 additions & 11 deletions compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs
View file
Expand Up @@ -4,7 +4,7 @@
use crate::infer::error_reporting::nice_region_error::NiceRegionError;
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
use rustc_middle::ty::{self, DefIdTree, Region, Ty};
use rustc_middle::ty::{self, Binder, DefIdTree, Region, Ty, TypeFoldable};
use rustc_span::Span;

/// Information about the anonymous region we are searching for.
Expand Down Expand Up @@ -149,26 +149,41 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
}

// Here, we check for the case where the anonymous region
// is in the return type.
// is in the return type as written by the user.
// FIXME(#42703) - Need to handle certain cases here.
pub(super) fn is_return_type_anon(
&self,
scope_def_id: LocalDefId,
br: ty::BoundRegionKind,
decl: &hir::FnDecl<'_>,
hir_sig: &hir::FnSig<'_>,
) -> Option<Span> {
let ret_ty = self.tcx().type_of(scope_def_id);
if let ty::FnDef(_, _) = ret_ty.kind() {
let sig = ret_ty.fn_sig(self.tcx());
let late_bound_regions =
self.tcx().collect_referenced_late_bound_regions(&sig.output());
if late_bound_regions.iter().any(|r| *r == br) {
return Some(decl.output.span());
}
let fn_ty = self.tcx().type_of(scope_def_id);
if let ty::FnDef(_, _) = fn_ty.kind() {
let ret_ty = fn_ty.fn_sig(self.tcx()).output();
let span = hir_sig.decl.output.span();
let future_output = if hir_sig.header.is_async() {
ret_ty.map_bound(|ty| self.infcx.get_impl_future_output_ty(ty)).transpose()
} else {
None
};
return match future_output {
Some(output) if self.includes_region(output, br) => Some(span),
None if self.includes_region(ret_ty, br) => Some(span),
_ => None,
};
}
None
}

fn includes_region(
&self,
ty: Binder<'tcx, impl TypeFoldable<'tcx>>,
region: ty::BoundRegionKind,
) -> bool {
let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(&ty);
late_bound_regions.iter().any(|r| *r == region)
}

// Here we check for the case where anonymous region
// corresponds to self and if yes, we display E0312.
// FIXME(#42700) - Need to format self properly to
Expand Down
14 changes: 4 additions & 10 deletions src/test/ui/async-await/issue-76547.stderr
View file
Expand Up @@ -2,23 +2,17 @@ error[E0623]: lifetime mismatch
--> $DIR/issue-76547.rs:20:13
|
LL | async fn fut(bufs: &mut [&mut [u8]]) {
| --------- -
| | |
| | this `async fn` implicitly returns an `impl Future<Output = ()>`
| this parameter and the returned future are declared with different lifetimes...
| ---------------- these two types are declared with different lifetimes...
LL | ListFut(bufs).await
| ^^^^ ...but data from `bufs` is held across an await point here
| ^^^^ ...but data from `bufs` flows into `bufs` here

error[E0623]: lifetime mismatch
--> $DIR/issue-76547.rs:34:14
|
LL | async fn fut2(bufs: &mut [&mut [u8]]) -> i32 {
| --------- ---
| | |
| | this `async fn` implicitly returns an `impl Future<Output = i32>`
| this parameter and the returned future are declared with different lifetimes...
| ---------------- these two types are declared with different lifetimes...
LL | ListFut2(bufs).await
| ^^^^ ...but data from `bufs` is held across an await point here
| ^^^^ ...but data from `bufs` flows into `bufs` here

error: aborting due to 2 previous errors

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/async-await/issues/issue-63388-1.stderr
View file
Expand Up @@ -2,7 +2,7 @@ error[E0623]: lifetime mismatch
--> $DIR/issue-63388-1.rs:14:9
|
LL | &'a self, foo: &dyn Foo
| -------- this parameter and the returned future are declared with different lifetimes...
| -------- this parameter and the returned future are declared with different lifetimes...
LL | ) -> &dyn Foo
| --------
| |
Expand Down
24 changes: 12 additions & 12 deletions src/test/ui/self/arbitrary_self_types_pin_lifetime_mismatch-async.stderr
View file
Expand Up @@ -2,28 +2,28 @@ error[E0623]: lifetime mismatch
--> $DIR/arbitrary_self_types_pin_lifetime_mismatch-async.rs:8:52
|
LL | async fn a(self: Pin<&Foo>, f: &Foo) -> &Foo { f }
| ---- ---- ^ ...but data from `f` is held across an await point here
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &Foo>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ---- ^ ...but data from `f` is held across an await point here
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &Foo>`
| this parameter and the returned future are declared with different lifetimes...

error[E0623]: lifetime mismatch
--> $DIR/arbitrary_self_types_pin_lifetime_mismatch-async.rs:11:82
|
LL | async fn c(self: Pin<&Self>, f: &Foo, g: &Foo) -> (Pin<&Foo>, &Foo) { (self, f) }
| ----- ----------------- ^ ...but data from `f` is held across an await point here
| | |
| | this `async fn` implicitly returns an `impl Future<Output = (Pin<&Foo>, &Foo)>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----------------- ^ ...but data from `f` is held across an await point here
| | |
| | this `async fn` implicitly returns an `impl Future<Output = (Pin<&Foo>, &Foo)>`
| this parameter and the returned future are declared with different lifetimes...

error[E0623]: lifetime mismatch
--> $DIR/arbitrary_self_types_pin_lifetime_mismatch-async.rs:17:64
|
LL | async fn bar<'a>(self: Alias<&Self>, arg: &'a ()) -> &() { arg }
| ----- --- ^^^ ...but data from `arg` is held across an await point here
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &()>`
| this parameter and the returned future are declared with different lifetimes...
| ------ --- ^^^ ...but data from `arg` is held across an await point here
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &()>`
| this parameter and the returned future are declared with different lifetimes...

error: aborting due to 3 previous errors

Expand Down
48 changes: 24 additions & 24 deletions src/test/ui/self/elision/lt-ref-self-async.stderr
View file
Expand Up @@ -2,65 +2,65 @@ error[E0623]: lifetime mismatch
--> $DIR/lt-ref-self-async.rs:13:9
|
LL | async fn ref_self(&self, f: &u32) -> &u32 {
| ----- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
LL | f
| ^ ...but data from `f` is held across an await point here

error[E0623]: lifetime mismatch
--> $DIR/lt-ref-self-async.rs:19:9
|
LL | async fn ref_Self(self: &Self, f: &u32) -> &u32 {
| ----- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
LL | f
| ^ ...but data from `f` is held across an await point here

error[E0623]: lifetime mismatch
--> $DIR/lt-ref-self-async.rs:23:9
|
LL | async fn box_ref_Self(self: Box<&Self>, f: &u32) -> &u32 {
| ----- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
LL | f
| ^ ...but data from `f` is held across an await point here

error[E0623]: lifetime mismatch
--> $DIR/lt-ref-self-async.rs:27:9
|
LL | async fn pin_ref_Self(self: Pin<&Self>, f: &u32) -> &u32 {
| ----- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
LL | f
| ^ ...but data from `f` is held across an await point here

error[E0623]: lifetime mismatch
--> $DIR/lt-ref-self-async.rs:31:9
|
LL | async fn box_box_ref_Self(self: Box<Box<&Self>>, f: &u32) -> &u32 {
| ----- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
LL | f
| ^ ...but data from `f` is held across an await point here

error[E0623]: lifetime mismatch
--> $DIR/lt-ref-self-async.rs:35:9
|
LL | async fn box_pin_Self(self: Box<Pin<&Self>>, f: &u32) -> &u32 {
| ----- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
| ---- ----
| | |
| | this `async fn` implicitly returns an `impl Future<Output = &u32>`
| this parameter and the returned future are declared with different lifetimes...
LL | f
| ^ ...but data from `f` is held across an await point here

Expand Down

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