rust-lang · bors · Nov 3, 2023 · Oct 5, 2023
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
@@ -316,6 316,7 @@ symbols! {
  ToOwned,
  ToString,
  TokenStream,
  Trait,
  Try,
  TryCaptureGeneric,
  TryCapturePrintable,

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
@@ -53,6 53,7 @@ static ALLOWED_FORMAT_SYMBOLS: &[Symbol] = &[
  sym::float,
  sym::_Self,
  sym::crate_local,
  sym::Trait,
 ];
 
 impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
@@ -183,6 184,19 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
  flags.push((sym::cause, Some("MainFunctionType".to_string())));
  }
 
  if let Some(kind) = self.tcx.fn_trait_kind_from_def_id(trait_ref.def_id)
  && let ty::Tuple(args) = trait_ref.args.type_at(1).kind()
  {
  let args = args
  .iter()
  .map(|ty| ty.to_string())
  .collect::<Vec<_>>()
  .join(", ");
  flags.push((sym::Trait, Some(format!("{}({args})", kind.as_str()))));
  } else {
  flags.push((sym::Trait, Some(trait_ref.print_only_trait_path().to_string())));
  }
 
  // Add all types without trimmed paths or visible paths, ensuring they end up with
  // their "canonical" def path.
  ty::print::with_no_trimmed_paths!(ty::print::with_no_visible_paths!({

diff --git a/library/core/src/ops/function.rs b/library/core/src/ops/function.rs
@@ -56,7 56,7 @@ use crate::marker::Tuple;
 #[lang = "fn"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_paren_sugar]
-#[rustc_on_unimplemented(
 #[cfg_attr(not(bootstrap), rustc_on_unimplemented(
  on(
  Args = "()",
  note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
@@ -67,9 67,9 @@ use crate::marker::Tuple;
  // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
  label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
  ),
- message = "expected a `{Fn}<{Args}>` closure, found `{Self}`",
- label = "expected an `Fn<{Args}>` closure, found `{Self}`"
-)]
  message = "expected a `{Trait}` closure, found `{Self}`",
  label = "expected an `{Trait}` closure, found `{Self}`"
 ))]
 #[fundamental] // so that regex can rely that `&str: !FnMut`
 #[must_use = "closures are lazy and do nothing unless called"]
 // FIXME(effects) #[const_trait]
@@ -143,7 143,7 @@ pub trait Fn<Args: Tuple>: FnMut<Args> {
 #[lang = "fn_mut"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_paren_sugar]
-#[rustc_on_unimplemented(
 #[cfg_attr(not(bootstrap), rustc_on_unimplemented(
  on(
  Args = "()",
  note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
@@ -154,9 154,9 @@ pub trait Fn<Args: Tuple>: FnMut<Args> {
  // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
  label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
  ),
- message = "expected a `{FnMut}<{Args}>` closure, found `{Self}`",
- label = "expected an `FnMut<{Args}>` closure, found `{Self}`"
-)]
  message = "expected a `{Trait}` closure, found `{Self}`",
  label = "expected an `{Trait}` closure, found `{Self}`"
 ))]
 #[fundamental] // so that regex can rely that `&str: !FnMut`
 #[must_use = "closures are lazy and do nothing unless called"]
 // FIXME(effects) #[const_trait]
@@ -222,7 222,7 @@ pub trait FnMut<Args: Tuple>: FnOnce<Args> {
 #[lang = "fn_once"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_paren_sugar]
-#[rustc_on_unimplemented(
 #[cfg_attr(not(bootstrap), rustc_on_unimplemented(
  on(
  Args = "()",
  note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
@@ -233,9 233,9 @@ pub trait FnMut<Args: Tuple>: FnOnce<Args> {
  // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
  label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
  ),
- message = "expected a `{FnOnce}<{Args}>` closure, found `{Self}`",
- label = "expected an `FnOnce<{Args}>` closure, found `{Self}`"
-)]
  message = "expected a `{Trait}` closure, found `{Self}`",
  label = "expected an `{Trait}` closure, found `{Self}`"
 ))]
 #[fundamental] // so that regex can rely that `&str: !FnMut`
 #[must_use = "closures are lazy and do nothing unless called"]
 // FIXME(effects) #[const_trait]

diff --git a/tests/ui/closures/closure-expected.rs b/tests/ui/closures/closure-expected.rs
@@ -1,5 1,5 @@
 fn main() {
  let x = Some(1);
  let y = x.or_else(4);
- //~^ ERROR expected a `FnOnce<()>` closure, found `{integer}`
  //~^ ERROR expected a `FnOnce()` closure, found `{integer}`
 }
diff --git a/tests/ui/closures/closure-expected.stderr b/tests/ui/closures/closure-expected.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `FnOnce<()>` closure, found `{integer}`
 error[E0277]: expected a `FnOnce()` closure, found `{integer}`
  --> $DIR/closure-expected.rs:3:23
  |
 LL | let y = x.or_else(4);
- | ------- ^ expected an `FnOnce<()>` closure, found `{integer}`
  | ------- ^ expected an `FnOnce()` closure, found `{integer}`
  | |
  | required by a bound introduced by this call
  |

diff --git a/tests/ui/closures/coerce-unsafe-to-closure.stderr b/tests/ui/closures/coerce-unsafe-to-closure.stderr
@@ -1,4 1,4 @@
-error[E0277]: expected a `FnOnce<(&str,)>` closure, found `unsafe extern "rust-intrinsic" fn(_) -> _ {transmute::<_, _>}`
 error[E0277]: expected a `FnOnce(&str)` closure, found `unsafe extern "rust-intrinsic" fn(_) -> _ {transmute::<_, _>}`
  --> $DIR/coerce-unsafe-to-closure.rs:2:44
  |
 LL | let x: Option<&[u8]> = Some("foo").map(std::mem::transmute);

diff --git a/tests/ui/expr/malformed_closure/block_instead_of_closure_in_arg.rs b/tests/ui/expr/malformed_closure/block_instead_of_closure_in_arg.rs
@@ -1,6 1,6 @@
 fn main() {
  let number = 2;
- Some(true).filter({ //~ ERROR expected a `FnOnce<(&bool,)>` closure, found `bool`
  Some(true).filter({ //~ ERROR expected a `FnOnce(&bool)` closure, found `bool`
  if number % 2 == 0 {
  number == 0
  } else {

diff --git a/tests/ui/expr/malformed_closure/block_instead_of_closure_in_arg.stderr b/tests/ui/expr/malformed_closure/block_instead_of_closure_in_arg.stderr
@@ -1,4 1,4 @@
-error[E0277]: expected a `FnOnce<(&bool,)>` closure, found `bool`
 error[E0277]: expected a `FnOnce(&bool)` closure, found `bool`
  --> $DIR/block_instead_of_closure_in_arg.rs:3:23
  |
 LL | Some(true).filter({
@@ -12,7 12,7 @@ LL | || number != 0
 LL | || }
  | ||_________- this tail expression is of type `bool`
 LL | | });
- | |______^ expected an `FnOnce<(&bool,)>` closure, found `bool`
  | |______^ expected an `FnOnce(&bool)` closure, found `bool`
  |
  = help: the trait `for<'a> FnOnce<(&'a bool,)>` is not implemented for `bool`
 note: required by a bound in `Option::<T>::filter`

diff --git a/tests/ui/expr/malformed_closure/ruby_style_closure_successful_parse.rs b/tests/ui/expr/malformed_closure/ruby_style_closure_successful_parse.rs
@@ -1,6 1,6 @@
 const x: usize =42;
 fn main() {
- let p = Some(45).and_then({|x| //~ ERROR expected a `FnOnce<({integer},)>` closure, found `Option<usize>`
  let p = Some(45).and_then({|x| //~ ERROR expected a `FnOnce({integer})` closure, found `Option<usize>`
  1 1;
  Some(x * 2)
  });

diff --git a/tests/ui/expr/malformed_closure/ruby_style_closure_successful_parse.stderr b/tests/ui/expr/malformed_closure/ruby_style_closure_successful_parse.stderr
@@ -1,4 1,4 @@
-error[E0277]: expected a `FnOnce<({integer},)>` closure, found `Option<usize>`
 error[E0277]: expected a `FnOnce({integer})` closure, found `Option<usize>`
  --> $DIR/ruby_style_closure_successful_parse.rs:3:31
  |
 LL | let p = Some(45).and_then({|x|
@@ -9,7 9,7 @@ LL | | 1 1;
 LL | | Some(x * 2)
  | | ----------- this tail expression is of type `Option<usize>`
 LL | | });
- | |_____^ expected an `FnOnce<({integer},)>` closure, found `Option<usize>`
  | |_____^ expected an `FnOnce({integer})` closure, found `Option<usize>`
  |
  = help: the trait `FnOnce<({integer},)>` is not implemented for `Option<usize>`
 note: required by a bound in `Option::<T>::and_then`

diff --git a/tests/ui/extern/extern-wrong-value-type.rs b/tests/ui/extern/extern-wrong-value-type.rs
@@ -7,5 7,5 @@ fn main() {
  // extern functions are extern "C" fn
  let _x: extern "C" fn() = f; // OK
  is_fn(f);
- //~^ ERROR expected a `Fn<()>` closure, found `extern "C" fn() {f}`
  //~^ ERROR expected a `Fn()` closure, found `extern "C" fn() {f}`
 }
diff --git a/tests/ui/extern/extern-wrong-value-type.stderr b/tests/ui/extern/extern-wrong-value-type.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<()>` closure, found `extern "C" fn() {f}`
 error[E0277]: expected a `Fn()` closure, found `extern "C" fn() {f}`
  --> $DIR/extern-wrong-value-type.rs:9:11
  |
 LL | is_fn(f);
- | ----- ^ expected an `Fn<()>` closure, found `extern "C" fn() {f}`
  | ----- ^ expected an `Fn()` closure, found `extern "C" fn() {f}`
  | |
  | required by a bound introduced by this call
  |

diff --git a/tests/ui/fn/fn-trait-formatting.rs b/tests/ui/fn/fn-trait-formatting.rs
@@ -17,5 17,5 @@ fn main() {
  //~| found struct `Box<dyn FnMut() -> isize>`
 
  needs_fn(1);
- //~^ ERROR expected a `Fn<(isize,)>` closure, found `{integer}`
  //~^ ERROR expected a `Fn(isize)` closure, found `{integer}`
 }
diff --git a/tests/ui/fn/fn-trait-formatting.stderr b/tests/ui/fn/fn-trait-formatting.stderr
@@ -39,11 39,11 @@ LL | let _: () = Box::new(|| -> isize { unimplemented!() }) as Box<dyn FnMut
  = note: expected unit type `()`
  found struct `Box<dyn FnMut() -> isize>`
 
-error[E0277]: expected a `Fn<(isize,)>` closure, found `{integer}`
 error[E0277]: expected a `Fn(isize)` closure, found `{integer}`
  --> $DIR/fn-trait-formatting.rs:19:14
  |
 LL | needs_fn(1);
- | -------- ^ expected an `Fn<(isize,)>` closure, found `{integer}`
  | -------- ^ expected an `Fn(isize)` closure, found `{integer}`
  | |
  | required by a bound introduced by this call
  |

diff --git a/tests/ui/generic-associated-types/issue-68642-broken-llvm-ir.rs b/tests/ui/generic-associated-types/issue-68642-broken-llvm-ir.rs
@@ -10,7 10,7 @@ trait Fun {
 
 impl<T> Fun for T {
  type F<'a> = Self;
- //~^ ERROR expected a `Fn<()>` closure, found `T`
  //~^ ERROR expected a `Fn()` closure, found `T`
 }
 
 fn main() {

diff --git a/tests/ui/generic-associated-types/issue-68642-broken-llvm-ir.stderr b/tests/ui/generic-associated-types/issue-68642-broken-llvm-ir.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<()>` closure, found `T`
 error[E0277]: expected a `Fn()` closure, found `T`
  --> $DIR/issue-68642-broken-llvm-ir.rs:12:18
  |
 LL | type F<'a> = Self;
- | ^^^^ expected an `Fn<()>` closure, found `T`
  | ^^^^ expected an `Fn()` closure, found `T`
  |
  = note: wrap the `T` in a closure with no arguments: `|| { /* code */ }`
 note: required by a bound in `Fun::F`

diff --git a/tests/ui/generic-associated-types/issue-68643-broken-mir.rs b/tests/ui/generic-associated-types/issue-68643-broken-mir.rs
@@ -10,7 10,7 @@ trait Fun {
 
 impl<T> Fun for T {
  type F<'a> = Self;
- //~^ ERROR expected a `Fn<()>` closure, found `T`
  //~^ ERROR expected a `Fn()` closure, found `T`
 }
 
 pub fn main() {

diff --git a/tests/ui/generic-associated-types/issue-68643-broken-mir.stderr b/tests/ui/generic-associated-types/issue-68643-broken-mir.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<()>` closure, found `T`
 error[E0277]: expected a `Fn()` closure, found `T`
  --> $DIR/issue-68643-broken-mir.rs:12:18
  |
 LL | type F<'a> = Self;
- | ^^^^ expected an `Fn<()>` closure, found `T`
  | ^^^^ expected an `Fn()` closure, found `T`
  |
  = note: wrap the `T` in a closure with no arguments: `|| { /* code */ }`
 note: required by a bound in `Fun::F`

diff --git a/tests/ui/generic-associated-types/issue-68644-codegen-selection.rs b/tests/ui/generic-associated-types/issue-68644-codegen-selection.rs
@@ -10,7 10,7 @@ trait Fun {
 
 impl<T> Fun for T {
  type F<'a> = Self;
- //~^ ERROR expected a `Fn<()>` closure, found `T`
  //~^ ERROR expected a `Fn()` closure, found `T`
 }
 
 fn main() {

diff --git a/tests/ui/generic-associated-types/issue-68644-codegen-selection.stderr b/tests/ui/generic-associated-types/issue-68644-codegen-selection.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<()>` closure, found `T`
 error[E0277]: expected a `Fn()` closure, found `T`
  --> $DIR/issue-68644-codegen-selection.rs:12:18
  |
 LL | type F<'a> = Self;
- | ^^^^ expected an `Fn<()>` closure, found `T`
  | ^^^^ expected an `Fn()` closure, found `T`
  |
  = note: wrap the `T` in a closure with no arguments: `|| { /* code */ }`
 note: required by a bound in `Fun::F`

diff --git a/tests/ui/generic-associated-types/issue-68645-codegen-fulfillment.rs b/tests/ui/generic-associated-types/issue-68645-codegen-fulfillment.rs
@@ -10,7 10,7 @@ trait Fun {
 
 impl<T> Fun for T {
  type F<'a> = Self;
- //~^ ERROR expected a `Fn<()>` closure, found `T`
  //~^ ERROR expected a `Fn()` closure, found `T`
 }
 
 fn main() {

diff --git a/tests/ui/generic-associated-types/issue-68645-codegen-fulfillment.stderr b/tests/ui/generic-associated-types/issue-68645-codegen-fulfillment.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<()>` closure, found `T`
 error[E0277]: expected a `Fn()` closure, found `T`
  --> $DIR/issue-68645-codegen-fulfillment.rs:12:18
  |
 LL | type F<'a> = Self;
- | ^^^^ expected an `Fn<()>` closure, found `T`
  | ^^^^ expected an `Fn()` closure, found `T`
  |
  = note: wrap the `T` in a closure with no arguments: `|| { /* code */ }`
 note: required by a bound in `Fun::F`

diff --git a/tests/ui/higher-ranked/trait-bounds/fn-ptr.classic.stderr b/tests/ui/higher-ranked/trait-bounds/fn-ptr.classic.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<(&'w (),)>` closure, found `fn(&'w ())`
 error[E0277]: expected a `Fn(&'w ())` closure, found `fn(&'w ())`
  --> $DIR/fn-ptr.rs:12:5
  |
 LL | ice();
- | ^^^ expected an `Fn<(&'w (),)>` closure, found `fn(&'w ())`
  | ^^^ expected an `Fn(&'w ())` closure, found `fn(&'w ())`
  |
  = help: the trait `for<'w> Fn<(&'w (),)>` is not implemented for `fn(&'w ())`
 note: required by a bound in `ice`

diff --git a/tests/ui/higher-ranked/trait-bounds/fn-ptr.rs b/tests/ui/higher-ranked/trait-bounds/fn-ptr.rs
@@ -10,5 10,5 @@ where
 
 fn main() {
  ice();
- //[classic]~^ ERROR expected a `Fn<(&'w (),)>` closure, found `fn(&'w ())`
  //[classic]~^ ERROR expected a `Fn(&'w ())` closure, found `fn(&'w ())`
 }
diff --git a/tests/ui/higher-ranked/trait-bounds/normalize-under-binder/issue-62529-3.stderr b/tests/ui/higher-ranked/trait-bounds/normalize-under-binder/issue-62529-3.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<(<_ as ATC<'a>>::Type,)>` closure, found `F`
 error[E0277]: expected a `Fn(<_ as ATC<'a>>::Type)` closure, found `F`
  --> $DIR/issue-62529-3.rs:25:14
  |
 LL | call(f, ());
- | ---- ^ expected an `Fn<(<_ as ATC<'a>>::Type,)>` closure, found `F`
  | ---- ^ expected an `Fn(<_ as ATC<'a>>::Type)` closure, found `F`
  | |
  | required by a bound introduced by this call
  |

diff --git a/tests/ui/implied-bounds/issue-100690.rs b/tests/ui/implied-bounds/issue-100690.rs
@@ -35,8 35,8 @@ impl<'a, T: 'a> Handle<'a, T, UIView<'a, T>, Result<(), io::Error>> for TUIHandl
  F: FnOnce(&mut UIView<'a, T>) -> Result<(), io::Error> Send 'static,
  {
  real_dispatch(f)
- //~^ ERROR expected a `FnOnce<(&mut UIView<'_, T>,)>` closure, found `F`
- //~| NOTE expected an `FnOnce<(&mut UIView<'_, T>,)>` closure, found `F`
  //~^ ERROR expected a `FnOnce(&mut UIView<'_, T>)` closure, found `F`
  //~| NOTE expected an `FnOnce(&mut UIView<'_, T>)` closure, found `F`
  //~| NOTE expected a closure with arguments
  //~| NOTE required by a bound introduced by this call
  }

diff --git a/tests/ui/implied-bounds/issue-100690.stderr b/tests/ui/implied-bounds/issue-100690.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `FnOnce<(&mut UIView<'_, T>,)>` closure, found `F`
 error[E0277]: expected a `FnOnce(&mut UIView<'_, T>)` closure, found `F`
  --> $DIR/issue-100690.rs:37:23
  |
 LL | real_dispatch(f)
- | ------------- ^ expected an `FnOnce<(&mut UIView<'_, T>,)>` closure, found `F`
  | ------------- ^ expected an `FnOnce(&mut UIView<'_, T>)` closure, found `F`
  | |
  | required by a bound introduced by this call
  |

diff --git a/tests/ui/intrinsics/const-eval-select-bad.rs b/tests/ui/intrinsics/const-eval-select-bad.rs
@@ -8,8 8,8 @@ const fn not_fn_items() {
  //~^ ERROR this argument must be a function item
  //~| ERROR this argument must be a function item
  const_eval_select((), 42, 0xDEADBEEF);
- //~^ ERROR expected a `FnOnce<()>` closure
- //~| ERROR expected a `FnOnce<()>` closure
  //~^ ERROR expected a `FnOnce()` closure
  //~| ERROR expected a `FnOnce()` closure
  //~| ERROR this argument must be a function item
  //~| ERROR this argument must be a function item
 }

diff --git a/tests/ui/intrinsics/const-eval-select-bad.stderr b/tests/ui/intrinsics/const-eval-select-bad.stderr
@@ -25,11 25,11 @@ LL | const_eval_select((), 42, 0xDEADBEEF);
  = note: expected a function item, found {integer}
  = help: consult the documentation on `const_eval_select` for more information
 
-error[E0277]: expected a `FnOnce<()>` closure, found `{integer}`
 error[E0277]: expected a `FnOnce()` closure, found `{integer}`
  --> $DIR/const-eval-select-bad.rs:10:27
  |
 LL | const_eval_select((), 42, 0xDEADBEEF);
- | ----------------- ^^ expected an `FnOnce<()>` closure, found `{integer}`
  | ----------------- ^^ expected an `FnOnce()` closure, found `{integer}`
  | |
  | required by a bound introduced by this call
  |
@@ -47,11 47,11 @@ LL | const_eval_select((), 42, 0xDEADBEEF);
  = note: expected a function item, found {integer}
  = help: consult the documentation on `const_eval_select` for more information
 
-error[E0277]: expected a `FnOnce<()>` closure, found `{integer}`
 error[E0277]: expected a `FnOnce()` closure, found `{integer}`
  --> $DIR/const-eval-select-bad.rs:10:31
  |
 LL | const_eval_select((), 42, 0xDEADBEEF);
- | ----------------- ^^^^^^^^^^ expected an `FnOnce<()>` closure, found `{integer}`
  | ----------------- ^^^^^^^^^^ expected an `FnOnce()` closure, found `{integer}`
  | |
  | required by a bound introduced by this call
  |

diff --git a/tests/ui/issues/issue-22034.rs b/tests/ui/issues/issue-22034.rs
@@ -6,6 6,6 @@ fn main() {
  let ptr: *mut () = core::ptr::null_mut();
  let _: &mut dyn Fn() = unsafe {
  &mut *(ptr as *mut dyn Fn())
- //~^ ERROR expected a `Fn<()>` closure, found `()`
  //~^ ERROR expected a `Fn()` closure, found `()`
  };
 }
diff --git a/tests/ui/issues/issue-22034.stderr b/tests/ui/issues/issue-22034.stderr
@@ -1,8 1,8 @@
-error[E0277]: expected a `Fn<()>` closure, found `()`
 error[E0277]: expected a `Fn()` closure, found `()`
  --> $DIR/issue-22034.rs:8:16
  |
 LL | &mut *(ptr as *mut dyn Fn())
- | ^^^ expected an `Fn<()>` closure, found `()`
  | ^^^ expected an `Fn()` closure, found `()`
  |
  = help: the trait `Fn<()>` is not implemented for `()`
  = note: wrap the `()` in a closure with no arguments: `|| { /* code */ }`