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Rollup merge of #132156 - estebank:closure-return, r=Nadrieril,compiler-errors

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When encountering unexpected closure return type, point at return type/expression

```
error[E0271]: expected `{closure@fallback-closure-wrap.rs:18:40}` to be a closure that returns `()`, but it returns `!`
  --> $DIR/fallback-closure-wrap.rs:19:9
   |
LL |     let error = Closure::wrap(Box::new(move || {
   |                                        -------
LL |         panic!("Can't connect to server.");
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `!`
   |
   = note: expected unit type `()`
                   found type `!`
   = note: required for the cast from `Box<{closure@$DIR/fallback-closure-wrap.rs:18:40: 18:47}>` to `Box<dyn FnMut()>`
```

```
error[E0271]: expected `{closure@dont-ice-for-type-mismatch-in-closure-in-async.rs:6:10}` to be a closure that returns `bool`, but it returns `Option<()>`
  --> $DIR/dont-ice-for-type-mismatch-in-closure-in-async.rs:6:16
   |
LL |     call(|| -> Option<()> {
   |     ---- ------^^^^^^^^^^
   |     |          |
   |     |          expected `bool`, found `Option<()>`
   |     required by a bound introduced by this call
   |
   = note: expected type `bool`
              found enum `Option<()>`
note: required by a bound in `call`
  --> $DIR/dont-ice-for-type-mismatch-in-closure-in-async.rs:3:25
   |
LL | fn call(_: impl Fn() -> bool) {}
   |                         ^^^^ required by this bound in `call`
```

```
error[E0271]: expected `{closure@f670.rs:28:13}` to be a closure that returns `Result<(), _>`, but it returns `!`
    --> f670.rs:28:20
     |
28   |     let c = |e| -> ! {
     |             -------^
     |                    |
     |                    expected `Result<(), _>`, found `!`
...
32   |     f().or_else(c);
     |         ------- required by a bound introduced by this call
-Ztrack-diagnostics: created at compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs:1433:28
     |
     = note: expected enum `Result<(), _>`
                found type `!`
note: required by a bound in `Result::<T, E>::or_else`
    --> /home/gh-estebank/rust/library/core/src/result.rs:1406:39
     |
1406 |     pub fn or_else<F, O: FnOnce(E) -> Result<T, F>>(self, op: O) -> Result<T, F> {
     |                                       ^^^^^^^^^^^^ required by this bound in `Result::<T, E>::or_else`
```

CC #111539.
This commit is contained in:
Jacob Pratt 2025-01-31 00:26:29 -05:00 • committed by GitHub
commit ae9dbf169f
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GPG key ID: B5690EEEBB952194
13 changed files with 189 additions and 65 deletions
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3
compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
View file

@ -653,6 +653,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
}))),
terr,
false,
None,
);
return Err(diag.emit());
}
@ -1070,6 +1071,7 @@ fn report_trait_method_mismatch<'tcx>(
}))),
terr,
false,
None,
);
diag.emit()
@ -1862,6 +1864,7 @@ fn compare_const_predicate_entailment<'tcx>(
}))),
terr,
false,
None,
);
return Err(diag.emit());
};

1
compiler/rustc_hir_analysis/src/check/mod.rs
View file

@ -649,6 +649,7 @@ pub fn check_function_signature<'tcx>(
}))),
err,
false,
None,
);
return Err(diag.emit());
}

1
compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
View file

@ -1147,6 +1147,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Some(self.param_env.and(trace.values)),
e,
true,
None,
);
}
}

1
compiler/rustc_passes/src/check_attr.rs
View file

@ -2471,6 +2471,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
}))),
terr,
false,
None,
);
diag.emit();
self.abort.set(true);

9
compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
View file

@ -1392,9 +1392,13 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
mut values: Option<ty::ParamEnvAnd<'tcx, ValuePairs<'tcx>>>,
terr: TypeError<'tcx>,
prefer_label: bool,
override_span: Option<Span>,
) {
let span = cause.span;
// We use `override_span` when we want the error to point at a `Span` other than
// `cause.span`. This is used in E0271, when a closure is passed in where the return type
// isn't what was expected. We want to point at the closure's return type (or expression),
// instead of the expression where the closure is passed as call argument.
let span = override_span.unwrap_or(cause.span);
// For some types of errors, expected-found does not make
// sense, so just ignore the values we were given.
if let TypeError::CyclicTy(_) = terr {
@ -2057,6 +2061,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
Some(param_env.and(trace.values)),
terr,
false,
None,
);
diag
}

99
compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
View file

@ -708,6 +708,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
None,
TypeError::Sorts(ty::error::ExpectedFound::new(expected_ty, ct_ty)),
false,
None,
);
diag
}
@ -931,14 +932,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
}
}
let hir_id = self.tcx.local_def_id_to_hir_id(obligation.cause.body_id);
let body_id = match self.tcx.hir_node(hir_id) {
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Fn { body: body_id, .. }, ..
}) => body_id,
_ => return false,
};
let ControlFlow::Break(expr) = (FindMethodSubexprOfTry { search_span: span })
.visit_body(self.tcx.hir().body(*body_id))
let Some(body_id) = self.tcx.hir_node(hir_id).body_id() else { return false };
let ControlFlow::Break(expr) =
(FindMethodSubexprOfTry { search_span: span }).visit_body(self.tcx.hir().body(body_id))
else {
return false;
};
@ -1385,9 +1381,14 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
_ => (None, error.err),
};
let msg = values
let (msg, span, closure_span) = values
.and_then(|(predicate, normalized_term, expected_term)| {
self.maybe_detailed_projection_msg(predicate, normalized_term, expected_term)
self.maybe_detailed_projection_msg(
obligation.cause.span,
predicate,
normalized_term,
expected_term,
)
})
.unwrap_or_else(|| {
let mut cx = FmtPrinter::new_with_limit(
@ -1395,12 +1396,39 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
Namespace::TypeNS,
rustc_session::Limit(10),
);
(
with_forced_trimmed_paths!(format!("type mismatch resolving `{}`", {
self.resolve_vars_if_possible(predicate).print(&mut cx).unwrap();
cx.into_buffer()
}))
})),
obligation.cause.span,
None,
)
});
let mut diag = struct_span_code_err!(self.dcx(), obligation.cause.span, E0271, "{msg}");
let mut diag = struct_span_code_err!(self.dcx(), span, E0271, "{msg}");
if let Some(span) = closure_span {
// Mark the closure decl so that it is seen even if we are pointing at the return
// type or expression.
//
// error[E0271]: expected `{closure@foo.rs:41:16}` to be a closure that returns
// `Unit3`, but it returns `Unit4`
// --> $DIR/foo.rs:43:17
// |
// LL | let v = Unit2.m(
// | - required by a bound introduced by this call
// ...
// LL | f: |x| {
// | --- /* this span */
// LL | drop(x);
// LL | Unit4
// | ^^^^^ expected `Unit3`, found `Unit4`
// |
diag.span_label(span, "this closure");
if !span.overlaps(obligation.cause.span) {
// Point at the binding corresponding to the closure where it is used.
diag.span_label(obligation.cause.span, "closure used here");
}
}
let secondary_span = (|| {
let ty::PredicateKind::Clause(ty::ClauseKind::Projection(proj)) =
@ -1471,6 +1499,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
}),
err,
false,
Some(span),
);
self.note_obligation_cause(&mut diag, obligation);
diag.emit()
@ -1479,34 +1508,66 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
fn maybe_detailed_projection_msg(
&self,
mut span: Span,
projection_term: ty::AliasTerm<'tcx>,
normalized_ty: ty::Term<'tcx>,
expected_ty: ty::Term<'tcx>,
) -> Option<String> {
) -> Option<(String, Span, Option<Span>)> {
let trait_def_id = projection_term.trait_def_id(self.tcx);
let self_ty = projection_term.self_ty();
with_forced_trimmed_paths! {
if self.tcx.is_lang_item(projection_term.def_id, LangItem::FnOnceOutput) {
let fn_kind = self_ty.prefix_string(self.tcx);
let (span, closure_span) = if let ty::Closure(def_id, _) = self_ty.kind() {
let def_span = self.tcx.def_span(def_id);
if let Some(local_def_id) = def_id.as_local()
&& let node = self.tcx.hir_node_by_def_id(local_def_id)
&& let Some(fn_decl) = node.fn_decl()
&& let Some(id) = node.body_id()
{
span = match fn_decl.output {
hir::FnRetTy::Return(ty) => ty.span,
hir::FnRetTy::DefaultReturn(_) => {
let body = self.tcx.hir().body(id);
match body.value.kind {
hir::ExprKind::Block(
hir::Block { expr: Some(expr), .. },
_,
) => expr.span,
hir::ExprKind::Block(
hir::Block {
expr: None, stmts: [.., last], ..
},
_,
) => last.span,
_ => body.value.span,
}
}
};
}
(span, Some(def_span))
} else {
(span, None)
};
let item = match self_ty.kind() {
ty::FnDef(def, _) => self.tcx.item_name(*def).to_string(),
_ => self_ty.to_string(),
};
Some(format!(
Some((format!(
"expected `{item}` to be a {fn_kind} that returns `{expected_ty}`, but it \
returns `{normalized_ty}`",
))
), span, closure_span))
} else if self.tcx.is_lang_item(trait_def_id, LangItem::Future) {
Some(format!(
Some((format!(
"expected `{self_ty}` to be a future that resolves to `{expected_ty}`, but it \
resolves to `{normalized_ty}`"
))
), span, None))
} else if Some(trait_def_id) == self.tcx.get_diagnostic_item(sym::Iterator) {
Some(format!(
Some((format!(
"expected `{self_ty}` to be an iterator that yields `{expected_ty}`, but it \
yields `{normalized_ty}`"
))
), span, None))
} else {
None
}

16
tests/ui/async-await/dont-ice-for-type-mismatch-in-closure-in-async.stderr
View file

@ -21,18 +21,14 @@ LL | true
found type `bool`
error[E0271]: expected `{closure@dont-ice-for-type-mismatch-in-closure-in-async.rs:6:10}` to be a closure that returns `bool`, but it returns `Option<()>`
--> $DIR/dont-ice-for-type-mismatch-in-closure-in-async.rs:6:10
--> $DIR/dont-ice-for-type-mismatch-in-closure-in-async.rs:6:16
|
LL | call(|| -> Option<()> {
| _____----_^
| | |
| | required by a bound introduced by this call
LL | |
LL | | if true {
LL | | false
... |
LL | | })
| |_____^ expected `bool`, found `Option<()>`
| ---- ------^^^^^^^^^^
| | | |
| | | expected `bool`, found `Option<()>`
| | this closure
| required by a bound introduced by this call
|
= note: expected type `bool`
found enum `Option<()>`

25
tests/ui/closures/return-type-doesnt-match-bound.rs Normal file
View file

@ -0,0 +1,25 @@
use std::error::Error;
use std::process::exit;
fn foo<F>(f: F) -> ()
where
F: FnOnce() -> Result<(), Box<dyn Error>>,
{
f().or_else(|e| -> ! { //~ ERROR to be a closure that returns
eprintln!("{:?}", e);
exit(1)
});
}
fn bar<F>(f: F) -> ()
where
F: FnOnce() -> Result<(), Box<dyn Error>>,
{
let c = |e| -> ! { //~ ERROR to be a closure that returns
eprintln!("{:?}", e);
exit(1)
};
f().or_else(c);
}
fn main() {}

37
tests/ui/closures/return-type-doesnt-match-bound.stderr Normal file
View file

@ -0,0 +1,37 @@
error[E0271]: expected `{closure@return-type-doesnt-match-bound.rs:8:17}` to be a closure that returns `Result<(), _>`, but it returns `!`
--> $DIR/return-type-doesnt-match-bound.rs:8:24
|
LL | f().or_else(|e| -> ! {
| ------- -------^
| | | |
| | | expected `Result<(), _>`, found `!`
| | this closure
| required by a bound introduced by this call
|
= note: expected enum `Result<(), _>`
found type `!`
note: required by a bound in `Result::<T, E>::or_else`
--> $SRC_DIR/core/src/result.rs:LL:COL
error[E0271]: expected `{closure@return-type-doesnt-match-bound.rs:18:13}` to be a closure that returns `Result<(), _>`, but it returns `!`
--> $DIR/return-type-doesnt-match-bound.rs:18:20
|
LL | let c = |e| -> ! {
| -------^
| | |
| | expected `Result<(), _>`, found `!`
| this closure
...
LL | f().or_else(c);
| ------- - closure used here
| |
| required by a bound introduced by this call
|
= note: expected enum `Result<(), _>`
found type `!`
note: required by a bound in `Result::<T, E>::or_else`
--> $SRC_DIR/core/src/result.rs:LL:COL
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0271`.

6
tests/ui/higher-ranked/trait-bounds/issue-62203-hrtb-ice.rs
View file

@ -36,12 +36,10 @@ trait Ty<'a> {
fn main() {
let v = Unit2.m(
L {
//~^ ERROR to be a closure that returns `Unit3`, but it returns `Unit4`
//~| ERROR type mismatch
L { //~ ERROR type mismatch
f: |x| {
drop(x);
Unit4
Unit4 //~ ERROR to be a closure that returns `Unit3`, but it returns `Unit4`
},
},
);

29
tests/ui/higher-ranked/trait-bounds/issue-62203-hrtb-ice.stderr
View file

@ -1,16 +1,15 @@
error[E0271]: type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:42:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
error[E0271]: type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:40:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
--> $DIR/issue-62203-hrtb-ice.rs:39:9
|
LL | let v = Unit2.m(
| - required by a bound introduced by this call
LL | / L {
LL | |
LL | |
LL | | f: |x| {
... |
LL | | drop(x);
LL | | Unit4
LL | | },
LL | | },
| |_________^ type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:42:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
| |_________^ type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:40:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
|
note: expected this to be `<_ as Ty<'_>>::V`
--> $DIR/issue-62203-hrtb-ice.rs:21:14
@ -30,21 +29,19 @@ LL | where
LL | F: for<'r> T0<'r, (<Self as Ty<'r>>::V,), O = <B as Ty<'r>>::V>,
| ^^^^^^^^^^^^^^^^^^^^ required by this bound in `T1::m`
error[E0271]: expected `{closure@issue-62203-hrtb-ice.rs:42:16}` to be a closure that returns `Unit3`, but it returns `Unit4`
--> $DIR/issue-62203-hrtb-ice.rs:39:9
error[E0271]: expected `{closure@issue-62203-hrtb-ice.rs:40:16}` to be a closure that returns `Unit3`, but it returns `Unit4`
--> $DIR/issue-62203-hrtb-ice.rs:42:17
|
LL | let v = Unit2.m(
| - required by a bound introduced by this call
LL | / L {
LL | |
LL | |
LL | | f: |x| {
... |
LL | | },
LL | | },
| |_________^ expected `Unit3`, found `Unit4`
LL | L {
LL | f: |x| {
| --- this closure
LL | drop(x);
LL | Unit4
| ^^^^^ expected `Unit3`, found `Unit4`
|
note: required for `L<{closure@$DIR/issue-62203-hrtb-ice.rs:42:16: 42:19}>` to implement `for<'r> T0<'r, (&'r u8,)>`
note: required for `L<{closure@$DIR/issue-62203-hrtb-ice.rs:40:16: 40:19}>` to implement `for<'r> T0<'r, (&'r u8,)>`
--> $DIR/issue-62203-hrtb-ice.rs:17:16
|
LL | impl<'a, A, T> T0<'a, A> for L<T>

11
tests/ui/never_type/fallback-closure-wrap.fallback.stderr
View file

@ -1,16 +1,15 @@
error[E0271]: expected `{closure@fallback-closure-wrap.rs:18:40}` to be a closure that returns `()`, but it returns `!`
--> $DIR/fallback-closure-wrap.rs:18:31
--> $DIR/fallback-closure-wrap.rs:19:9
|
LL | let error = Closure::wrap(Box::new(move || {
| _______________________________^
LL | |
LL | | panic!("Can't connect to server.");
LL | | }) as Box<dyn FnMut()>);
| |______^ expected `()`, found `!`
| ------- this closure
LL | panic!("Can't connect to server.");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `!`
|
= note: expected unit type `()`
found type `!`
= note: required for the cast from `Box<{closure@$DIR/fallback-closure-wrap.rs:18:40: 18:47}>` to `Box<dyn FnMut()>`
= note: this error originates in the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error

2
tests/ui/never_type/fallback-closure-wrap.rs
View file

@ -16,8 +16,8 @@ use std::marker::PhantomData;
fn main() {
let error = Closure::wrap(Box::new(move || {
//[fallback]~^ to be a closure that returns `()`, but it returns `!`
panic!("Can't connect to server.");
//[fallback]~^ to be a closure that returns `()`, but it returns `!`
}) as Box<dyn FnMut()>);
}