rust-lang
Make `from_waker`, `waker` and `from_raw` unstably `const`
Make
-
Context::from_waker -
Context::waker -
Waker::from_raw
const.
Also added a small test.
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The job mingw-check failed! Check out the build log: (web) (plain)
Click to see the possible cause of the failure (guessed by this bot)
Checking rand v0.7.3
Checking alloc v0.0.0 (/checkout/library/alloc)
Checking std v0.0.0 (/checkout/library/std)
Checking core v0.0.0 (/checkout/library/core)
error[E0412]: cannot find type `RawWakerVTable` in this scope
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18 | const VOID_TABLE: RawWakerVTable = RawWakerVTable::new(|_| VOID_WAKER, |_| {}, |_| {}, |_| {});
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help: consider importing one of these items
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1 | use core::task::RawWakerVTable;
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1 | use std::task::RawWakerVTable;
error[E0433]: failed to resolve: use of undeclared type `RawWakerVTable`
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18 | const VOID_TABLE: RawWakerVTable = RawWakerVTable::new(|_| VOID_WAKER, |_| {}, |_| {}, |_| {});
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help: consider importing one of these items
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1 | use core::task::RawWakerVTable;
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1 | use std::task::RawWakerVTable;
error[E0412]: cannot find type `RawWaker` in this scope
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20 | const VOID_WAKER: RawWaker = RawWaker::new(&(), &VOID_TABLE);
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help: consider importing one of these items
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1 | use core::task::RawWaker;
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1 | use std::task::RawWaker;
error[E0433]: failed to resolve: use of undeclared type `RawWaker`
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20 | const VOID_WAKER: RawWaker = RawWaker::new(&(), &VOID_TABLE);
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help: consider importing one of these items
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1 | use core::task::RawWaker;
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1 | use std::task::RawWaker;
error[E0412]: cannot find type `Waker` in this scope
--> library/core/tests/task.rs:22:18
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22 | const WAKER: Waker = unsafe { Waker::from_raw(VOID_WAKER) };
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help: consider importing one of these items
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1 | use core::task::Waker;
1 | use core::task::Waker;
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1 | use std::task::Waker;
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error[E0433]: failed to resolve: use of undeclared type `Waker`
--> library/core/tests/task.rs:22:35
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22 | const WAKER: Waker = unsafe { Waker::from_raw(VOID_WAKER) };
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help: consider importing one of these items
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1 | use core::task::Waker;
1 | use core::task::Waker;
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1 | use std::task::Waker;
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error[E0412]: cannot find type `Context` in this scope
--> library/core/tests/task.rs:24:20
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24 | const CONTEXT: Context<'static> = Context::from_waker(&WAKER);
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help: consider importing one of these items
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1 | use core::task::Context;
1 | use core::task::Context;
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1 | use std::task::Context;
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error[E0433]: failed to resolve: use of undeclared type `Context`
--> library/core/tests/task.rs:24:39
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24 | const CONTEXT: Context<'static> = Context::from_waker(&WAKER);
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help: consider importing one of these items
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1 | use core::task::Context;
1 | use core::task::Context;
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1 | use std::task::Context;
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error[E0412]: cannot find type `Waker` in this scope
--> library/core/tests/task.rs:26:31
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26 | const WAKER_REF: &'static Waker = CONTEXT.waker();
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help: consider importing one of these items
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1 | use core::task::Waker;
The job mingw-check failed! Check out the build log: (web) (plain)
Click to see the possible cause of the failure (guessed by this bot)
Checking core v0.0.0 (/checkout/library/core)
error[E0493]: destructors cannot be evaluated at compile-time
--> library/core/tests/task.rs:24:60
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24 | const CONTEXT: Context<'static> = Context::from_waker(&WAKER);
| ^^^^^- value is dropped here
| constants cannot evaluate destructors
error[E0716]: temporary value dropped while borrowed
--> library/core/tests/task.rs:24:60
--> library/core/tests/task.rs:24:60
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24 | const CONTEXT: Context<'static> = Context::from_waker(&WAKER);
| | | |
| | | temporary value is freed at the end of this statement
| | creates a temporary which is freed while still in use
| | creates a temporary which is freed while still in use
| using this value as a constant requires that borrow lasts for `'static`
Some errors have detailed explanations: E0493, E0716.
For more information about an error, try `rustc --explain E0493`.
error: could not compile `core` due to 2 previous errors
Build completed unsuccessfully in 0:01:38
r? @lcnr for wg-const-eval approval of new const-unstable APIs
(Closest reading of policy I could find suggests that wg-const-eval should approve, though I think these particular ones seem OK to my relatively uninformed opinion).
these look fine for me, please add a tracking issue, then r=me
cc @rust-lang/wg-const-eval
