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Suggest move for closures and async blocks in more cases.

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This commit is contained in:
Alex Aktsipetrov 2020-04-07 23:57:26 +02:00
parent 42abbd8878
commit aaebbe196b
9 changed files with 84 additions and 68 deletions
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12
src/test/ui/async-await/async-borrowck-escaping-block-error.fixed
View file

@ -1,12 +1,18 @@
// edition:2018
// run-rustfix
fn foo() -> Box<impl std::future::Future<Output = u32>> {
fn test_boxed() -> Box<impl std::future::Future<Output = u32>> {
let x = 0u32;
Box::new(async move { x } )
//~^ ERROR E0373
}
fn main() {
let _foo = foo();
fn test_ref(x: &u32) -> impl std::future::Future<Output = u32> + '_ {
async move { *x }
//~^ ERROR E0373
}
fn main() {
let _ = test_boxed();
let _ = test_ref(&0u32);
}

12
src/test/ui/async-await/async-borrowck-escaping-block-error.rs
View file

@ -1,12 +1,18 @@
// edition:2018
// run-rustfix
fn foo() -> Box<impl std::future::Future<Output = u32>> {
fn test_boxed() -> Box<impl std::future::Future<Output = u32>> {
let x = 0u32;
Box::new(async { x } )
//~^ ERROR E0373
}
fn main() {
let _foo = foo();
fn test_ref(x: &u32) -> impl std::future::Future<Output = u32> + '_ {
async { *x }
//~^ ERROR E0373
}
fn main() {
let _ = test_boxed();
let _ = test_ref(&0u32);
}

31
src/test/ui/async-await/async-borrowck-escaping-block-error.stderr
View file

@ -1,4 +1,4 @@
error[E0373]: closure may outlive the current function, but it borrows `x`, which is owned by the current function
error[E0373]: async block may outlive the current function, but it borrows `x`, which is owned by the current function
--> $DIR/async-borrowck-escaping-block-error.rs:6:20
|
LL | Box::new(async { x } )
@ -7,16 +7,35 @@ LL | Box::new(async { x } )
| | `x` is borrowed here
| may outlive borrowed value `x`
|
note: generator is returned here
--> $DIR/async-borrowck-escaping-block-error.rs:4:13
note: async block is returned here
--> $DIR/async-borrowck-escaping-block-error.rs:4:20
|
LL | fn foo() -> Box<impl std::future::Future<Output = u32>> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | fn test_boxed() -> Box<impl std::future::Future<Output = u32>> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to force the async block to take ownership of `x` (and any other referenced variables), use the `move` keyword
|
LL | Box::new(async move { x } )
| ^^^^^^^^^^
error: aborting due to previous error
error[E0373]: async block may outlive the current function, but it borrows `x`, which is owned by the current function
--> $DIR/async-borrowck-escaping-block-error.rs:11:11
|
LL | async { *x }
| ^^^-^^
| | |
| | `x` is borrowed here
| may outlive borrowed value `x`
|
note: async block is returned here
--> $DIR/async-borrowck-escaping-block-error.rs:11:5
|
LL | async { *x }
| ^^^^^^^^^^^^
help: to force the async block to take ownership of `x` (and any other referenced variables), use the `move` keyword
|
LL | async move { *x }
| ^^^^^^^^^^^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0373`.

2
src/test/ui/async-await/async-borrowck-escaping-closure-error.rs
View file

@ -1,5 +1,5 @@
// edition:2018
#![feature(async_closure,async_await)]
#![feature(async_closure)]
fn foo() -> Box<dyn std::future::Future<Output = u32>> {
let x = 0u32;
Box::new((async || x)())

2
src/test/ui/impl-trait/does-not-live-long-enough.rs
View file

@ -4,7 +4,7 @@ struct List {
impl List {
fn started_with<'a>(&'a self, prefix: &'a str) -> impl Iterator<Item=&'a str> {
self.data.iter().filter(|s| s.starts_with(prefix)).map(|s| s.as_ref())
//~^ ERROR does not live long enough
//~^ ERROR E0373
}
}

30
src/test/ui/impl-trait/does-not-live-long-enough.stderr
View file

@ -1,21 +1,21 @@
error[E0597]: `prefix` does not live long enough
--> $DIR/does-not-live-long-enough.rs:6:51
error[E0373]: closure may outlive the current function, but it borrows `prefix`, which is owned by the current function
--> $DIR/does-not-live-long-enough.rs:6:33
|
LL | self.data.iter().filter(|s| s.starts_with(prefix)).map(|s| s.as_ref())
| ^^^ ------ `prefix` is borrowed here
| |
| may outlive borrowed value `prefix`
|
note: closure is returned here
--> $DIR/does-not-live-long-enough.rs:5:55
|
LL | fn started_with<'a>(&'a self, prefix: &'a str) -> impl Iterator<Item=&'a str> {
| -- lifetime `'a` defined here --------------------------- opaque type requires that `prefix` is borrowed for `'a`
LL | self.data.iter().filter(|s| s.starts_with(prefix)).map(|s| s.as_ref())
| --- ^^^^^^ borrowed value does not live long enough
| |
| value captured here
LL |
LL | }
| - `prefix` dropped here while still borrowed
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to force the closure to take ownership of `prefix` (and any other referenced variables), use the `move` keyword
|
help: you can add a bound to the opaque type to make it last less than `'static` and match `'a`
|
LL | fn started_with<'a>(&'a self, prefix: &'a str) -> impl Iterator<Item=&'a str> + 'a {
| ^^^^
LL | self.data.iter().filter(move |s| s.starts_with(prefix)).map(|s| s.as_ref())
| ^^^^^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0597`.
For more information about this error, try `rustc --explain E0373`.