Skip to content

Unexpected error: the associated type <U as util::async::Async>::Value may not live long enough #21150

New issue
New issue
Closed
#21252
Closed
Unexpected error: the associated type <U as util::async::Async>::Value may not live long enough#21150
#21252
Labels
A-associated-itemsArea: Associated items (types, constants & functions)
@carllerche

Description

@carllerche
carllerche
opened on Jan 14, 2015

I have been attempting to switch my Future / Stream lib to use associated types, however I have been hitting snags. Even though all the types (as far as I can tell) are bound by Send (and some by 'static too), I have been getting a lot of error messages:

/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85:43: 90:26 error: the associated type `<U as util::async::Async>::Value` may not live long enough
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:88                                 Err(_) => unimplemented!(),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:89                             }
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:90                         });
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85:43: 90:26 help: consider adding an explicit lifetime bound `<U as util::async::Async>::Value: 'static`...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:88                                 Err(_) => unimplemented!(),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:89                             }
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:90                         });
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85:43: 90:26 note: ...so that captured variable `c` does not outlive the enclosing closure
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:88                                 Err(_) => unimplemented!(),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:89                             }
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:90                         });
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85:30: 90:27 error: the associated type `<U as util::async::Async>::Value` may not live long enough
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:88                                 Err(_) => unimplemented!(),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:89                             }
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:90                         });
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85:30: 90:27 help: consider adding an explicit lifetime bound `<U as util::async::Async>::Value: 'static`...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:88                                 Err(_) => unimplemented!(),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:89                             }
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:90                         });
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85:30: 90:27 note: ...so that the declared lifetime parameter bounds are satisfied
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:88                                 Err(_) => unimplemented!(),
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:89                             }
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:90                         });
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:31: 94:14 error: the associated type `<U as util::async::Async>::Value` may not live long enough
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:31: 94:14 help: consider adding an explicit lifetime bound `<U as util::async::Async>::Value: 'static`...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:31: 94:14 note: ...so that captured variable `c` does not outlive the enclosing closure
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 error: the associated type `<U as util::async::Async>::Value` may not live long enough
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 help: consider adding an explicit lifetime bound `<U as util::async::Async>::Value: 'static`...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 note: ...so that the declared lifetime parameter bounds are satisfied
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 error: the associated type `<U as util::async::Async>::Value` may not live long enough
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 help: consider adding an explicit lifetime bound `<U as util::async::Async>::Value: 'static`...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 note: ...so that the declared lifetime parameter bounds are satisfied
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 error: the associated type `<U as util::async::Async>::Value` may not live long enough
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 help: consider adding an explicit lifetime bound `<U as util::async::Async>::Value: 'static`...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),
                                                                ...
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82:18: 94:15 note: ...so that the declared lifetime parameter bounds are satisfied
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:82             self.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:83                 match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:84                     Ok(_) => {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:85                         next.receive(move |res| {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:86                             match res {
/Users/carllerche/Code/mine/syncbox/src/util/async/future.rs:87                                 Ok(u) => c.complete(u),

The repro is trying to compile syncbox on the async-associated-type branch. Sorry for not reducing more 😢

https://github.com/carllerche/syncbox/tree/async-associated-type

cc @nikomatsakis

Metadata

Metadata

Assignees

No one assigned

    Labels

    A-associated-itemsArea: Associated items (types, constants & functions)

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions