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Deprecate FnBox. Box<dyn FnOnce()> can be called directly, since 1.35

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FCP completion: https://github.com/rust-lang/rust/issues/28796#issuecomment-439731515
This commit is contained in:
Simon Sapin 2019-05-24 08:55:33 +02:00
parent a8fc09be39
commit 73fd3497d4
4 changed files with 52 additions and 31 deletions
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42
src/liballoc/boxed.rs
View File

@ -759,13 +759,14 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
} }
} }
/// `FnBox` is deprecated and will be removed.
/// `Box<dyn FnOnce()>` can be called directly, since Rust 1.35.0.
///
/// `FnBox` is a version of the `FnOnce` intended for use with boxed /// `FnBox` is a version of the `FnOnce` intended for use with boxed
/// closure objects. The idea is that where one would normally store a /// closure objects. The idea was that where one would normally store a
/// `Box<dyn FnOnce()>` in a data structure, you should use /// `Box<dyn FnOnce()>` in a data structure, you whould use
/// `Box<dyn FnBox()>`. The two traits behave essentially the same, except /// `Box<dyn FnBox()>`. The two traits behave essentially the same, except
/// that a `FnBox` closure can only be called if it is boxed. (Note /// that a `FnBox` closure can only be called if it is boxed.
/// that `FnBox` may be deprecated in the future if `Box<dyn FnOnce()>`
/// closures become directly usable.)
/// ///
/// # Examples /// # Examples
/// ///
@ -777,6 +778,7 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
/// ///
/// ``` /// ```
/// #![feature(fnbox)] /// #![feature(fnbox)]
/// #![allow(deprecated)]
/// ///
/// use std::boxed::FnBox; /// use std::boxed::FnBox;
/// use std::collections::HashMap; /// use std::collections::HashMap;
@ -796,16 +798,38 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
/// } /// }
/// } /// }
/// ``` /// ```
///
/// In Rust 1.35.0 or later, use `FnOnce`, `FnMut`, or `Fn` instead:
///
/// ```
/// use std::collections::HashMap;
///
/// fn make_map() -> HashMap<i32, Box<dyn FnOnce() -> i32>> {
/// let mut map: HashMap<i32, Box<dyn FnOnce() -> i32>> = HashMap::new();
/// map.insert(1, Box::new(|| 22));
/// map.insert(2, Box::new(|| 44));
/// map
/// }
///
/// fn main() {
/// let mut map = make_map();
/// for i in &[1, 2] {
/// let f = map.remove(&i).unwrap();
/// assert_eq!(f(), i * 22);
/// }
/// }
/// ```
#[rustc_paren_sugar] #[rustc_paren_sugar]
#[unstable(feature = "fnbox", #[unstable(feature = "fnbox", issue = "28796")]
reason = "will be deprecated if and when `Box<FnOnce>` becomes usable", issue = "28796")] #[rustc_deprecated(reason = "use `FnOnce`, `FnMut`, or `Fn` instead", since = "1.37.0")]
pub trait FnBox<A>: FnOnce<A> { pub trait FnBox<A>: FnOnce<A> {
/// Performs the call operation. /// Performs the call operation.
fn call_box(self: Box<Self>, args: A) -> Self::Output; fn call_box(self: Box<Self>, args: A) -> Self::Output;
} }
#[unstable(feature = "fnbox", #[unstable(feature = "fnbox", issue = "28796")]
reason = "will be deprecated if and when `Box<FnOnce>` becomes usable", issue = "28796")] #[rustc_deprecated(reason = "use `FnOnce`, `FnMut`, or `Fn` instead", since = "1.37.0")]
#[allow(deprecated, deprecated_in_future)]
impl<A, F> FnBox<A> for F impl<A, F> FnBox<A> for F
where F: FnOnce<A> where F: FnOnce<A>
{ {

1
src/test/run-pass/unsized-locals/fnbox-compat.rs
View File

@ -1,4 +1,5 @@
#![feature(fnbox)] #![feature(fnbox)]
#![allow(deprecated, deprecated_in_future)]
use std::boxed::FnBox; use std::boxed::FnBox;

12
src/test/ui/confuse-field-and-method/issue-2392.rs
View File

@ -1,7 +1,3 @@
#![feature(core, fnbox)]
use std::boxed::FnBox;
struct FuncContainer { struct FuncContainer {
f1: fn(data: u8), f1: fn(data: u8),
f2: extern "C" fn(data: u8), f2: extern "C" fn(data: u8),
@ -18,7 +14,7 @@ struct Obj<F> where F: FnOnce() -> u32 {
} }
struct BoxedObj { struct BoxedObj {
boxed_closure: Box<FnBox() -> u32>, boxed_closure: Box<FnOnce() -> u32>,
} }
struct Wrapper<F> where F: FnMut() -> u32 { struct Wrapper<F> where F: FnMut() -> u32 {
@ -29,8 +25,8 @@ fn func() -> u32 {
0 0
} }
fn check_expression() -> Obj<Box<FnBox() -> u32>> { fn check_expression() -> Obj<Box<FnOnce() -> u32>> {
Obj { closure: Box::new(|| 42_u32) as Box<FnBox() -> u32>, not_closure: 42 } Obj { closure: Box::new(|| 42_u32) as Box<FnOnce() -> u32>, not_closure: 42 }
} }
fn main() { fn main() {
@ -48,7 +44,7 @@ fn main() {
let boxed_fn = BoxedObj { boxed_closure: Box::new(func) }; let boxed_fn = BoxedObj { boxed_closure: Box::new(func) };
boxed_fn.boxed_closure();//~ ERROR no method named `boxed_closure` found boxed_fn.boxed_closure();//~ ERROR no method named `boxed_closure` found
let boxed_closure = BoxedObj { boxed_closure: Box::new(|| 42_u32) as Box<FnBox() -> u32> }; let boxed_closure = BoxedObj { boxed_closure: Box::new(|| 42_u32) as Box<FnOnce() -> u32> };
boxed_closure.boxed_closure();//~ ERROR no method named `boxed_closure` found boxed_closure.boxed_closure();//~ ERROR no method named `boxed_closure` found
// test expression writing in the notes // test expression writing in the notes

28
src/test/ui/confuse-field-and-method/issue-2392.stderr
View File

@ -1,5 +1,5 @@
error[E0599]: no method named `closure` found for type `Obj<[closure@$DIR/issue-2392.rs:39:36: 39:41]>` in the current scope error[E0599]: no method named `closure` found for type `Obj<[closure@$DIR/issue-2392.rs:35:36: 35:41]>` in the current scope
--> $DIR/issue-2392.rs:40:15 --> $DIR/issue-2392.rs:36:15
| |
LL | struct Obj<F> where F: FnOnce() -> u32 { LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `closure` not found for this | -------------------------------------- method `closure` not found for this
@ -11,8 +11,8 @@ help: to call the function stored in `closure`, surround the field access with p
LL | (o_closure.closure)(); LL | (o_closure.closure)();
| ^ ^ | ^ ^
error[E0599]: no method named `not_closure` found for type `Obj<[closure@$DIR/issue-2392.rs:39:36: 39:41]>` in the current scope error[E0599]: no method named `not_closure` found for type `Obj<[closure@$DIR/issue-2392.rs:35:36: 35:41]>` in the current scope
--> $DIR/issue-2392.rs:42:15 --> $DIR/issue-2392.rs:38:15
| |
LL | struct Obj<F> where F: FnOnce() -> u32 { LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `not_closure` not found for this | -------------------------------------- method `not_closure` not found for this
@ -23,7 +23,7 @@ LL | o_closure.not_closure();
| field, not a method | field, not a method
error[E0599]: no method named `closure` found for type `Obj<fn() -> u32 {func}>` in the current scope error[E0599]: no method named `closure` found for type `Obj<fn() -> u32 {func}>` in the current scope
--> $DIR/issue-2392.rs:46:12 --> $DIR/issue-2392.rs:42:12
| |
LL | struct Obj<F> where F: FnOnce() -> u32 { LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `closure` not found for this | -------------------------------------- method `closure` not found for this
@ -36,7 +36,7 @@ LL | (o_func.closure)();
| ^ ^ | ^ ^
error[E0599]: no method named `boxed_closure` found for type `BoxedObj` in the current scope error[E0599]: no method named `boxed_closure` found for type `BoxedObj` in the current scope
--> $DIR/issue-2392.rs:49:14 --> $DIR/issue-2392.rs:45:14
| |
LL | struct BoxedObj { LL | struct BoxedObj {
| --------------- method `boxed_closure` not found for this | --------------- method `boxed_closure` not found for this
@ -49,7 +49,7 @@ LL | (boxed_fn.boxed_closure)();
| ^ ^ | ^ ^
error[E0599]: no method named `boxed_closure` found for type `BoxedObj` in the current scope error[E0599]: no method named `boxed_closure` found for type `BoxedObj` in the current scope
--> $DIR/issue-2392.rs:52:19 --> $DIR/issue-2392.rs:48:19
| |
LL | struct BoxedObj { LL | struct BoxedObj {
| --------------- method `boxed_closure` not found for this | --------------- method `boxed_closure` not found for this
@ -62,7 +62,7 @@ LL | (boxed_closure.boxed_closure)();
| ^ ^ | ^ ^
error[E0599]: no method named `closure` found for type `Obj<fn() -> u32 {func}>` in the current scope error[E0599]: no method named `closure` found for type `Obj<fn() -> u32 {func}>` in the current scope
--> $DIR/issue-2392.rs:57:12 --> $DIR/issue-2392.rs:53:12
| |
LL | struct Obj<F> where F: FnOnce() -> u32 { LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `closure` not found for this | -------------------------------------- method `closure` not found for this
@ -75,7 +75,7 @@ LL | (w.wrap.closure)();
| ^ ^ | ^ ^
error[E0599]: no method named `not_closure` found for type `Obj<fn() -> u32 {func}>` in the current scope error[E0599]: no method named `not_closure` found for type `Obj<fn() -> u32 {func}>` in the current scope
--> $DIR/issue-2392.rs:59:12 --> $DIR/issue-2392.rs:55:12
| |
LL | struct Obj<F> where F: FnOnce() -> u32 { LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `not_closure` not found for this | -------------------------------------- method `not_closure` not found for this
@ -85,8 +85,8 @@ LL | w.wrap.not_closure();
| | | |
| field, not a method | field, not a method
error[E0599]: no method named `closure` found for type `Obj<std::boxed::Box<(dyn std::boxed::FnBox<(), Output = u32> + 'static)>>` in the current scope error[E0599]: no method named `closure` found for type `Obj<std::boxed::Box<(dyn std::ops::FnOnce() -> u32 + 'static)>>` in the current scope
--> $DIR/issue-2392.rs:62:24 --> $DIR/issue-2392.rs:58:24
| |
LL | struct Obj<F> where F: FnOnce() -> u32 { LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `closure` not found for this | -------------------------------------- method `closure` not found for this
@ -99,7 +99,7 @@ LL | (check_expression().closure)();
| ^ ^ | ^ ^
error[E0599]: no method named `f1` found for type `FuncContainer` in the current scope error[E0599]: no method named `f1` found for type `FuncContainer` in the current scope
--> $DIR/issue-2392.rs:68:31 --> $DIR/issue-2392.rs:64:31
| |
LL | struct FuncContainer { LL | struct FuncContainer {
| -------------------- method `f1` not found for this | -------------------- method `f1` not found for this
@ -112,7 +112,7 @@ LL | ((*self.container).f1)(1);
| ^ ^ | ^ ^
error[E0599]: no method named `f2` found for type `FuncContainer` in the current scope error[E0599]: no method named `f2` found for type `FuncContainer` in the current scope
--> $DIR/issue-2392.rs:69:31 --> $DIR/issue-2392.rs:65:31
| |
LL | struct FuncContainer { LL | struct FuncContainer {
| -------------------- method `f2` not found for this | -------------------- method `f2` not found for this
@ -125,7 +125,7 @@ LL | ((*self.container).f2)(1);
| ^ ^ | ^ ^
error[E0599]: no method named `f3` found for type `FuncContainer` in the current scope error[E0599]: no method named `f3` found for type `FuncContainer` in the current scope
--> $DIR/issue-2392.rs:70:31 --> $DIR/issue-2392.rs:66:31
| |
LL | struct FuncContainer { LL | struct FuncContainer {
| -------------------- method `f3` not found for this | -------------------- method `f3` not found for this