The constant name `MAX_REFCOUNT` suggests that the value is a
_hard_ limit on the amount of references to an `Arc`. This is
a more soft limit however. This commit adds a comment to the
constant to annotate this.
See also: PR #37605
Long ago we discovered that threads which outlive main and then exit while the
rest of the program is exiting causes Windows to hang (#20704). That's what was
happening in this test so let's just not run this test any more.
This allows printing pointers to unsized types with the {:p} formatting
directive. The following impls are extended to unsized types:
- impl<'a, T: ?Sized> Pointer for &'a T
- impl<'a, T: ?Sized> Pointer for &'a mut T
- impl<T: ?Sized> Pointer for *const T
- impl<T: ?Sized> Pointer for *mut T
- impl<T: ?Sized> fmt::Pointer for Box<T>
- impl<T: ?Sized> fmt::Pointer for Rc<T>
- impl<T: ?Sized> fmt::Pointer for Arc<T>
This allows printing pointers to unsized types with the {:p} formatting
directive. The following impls are extended to unsized types:
- impl<'a, T: ?Sized> Pointer for &'a T
- impl<'a, T: ?Sized> Pointer for &'a mut T
- impl<T: ?Sized> Pointer for *const T
- impl<T: ?Sized> Pointer for *mut T
- impl<T: ?Sized> fmt::Pointer for Box<T>
- impl<T: ?Sized> fmt::Pointer for Rc<T>
- impl<T: ?Sized> fmt::Pointer for Arc<T>
Changed the description of the `make_mut` copy-on-write behaviour in arc.rs
The sentence "doesn't have one strong reference and no weak references." is a
hard to understand double negative, which can be much more easily explained.
This hairy conditional doesn't need to be so. It _does_ need to be a
thin pointer, otherwise, it will fail to compile, so let's pull that out
into a temporary for future readers of the source.
/cc @nrc @SimonSapin @Gankro @durka , who brought this up on IRC
This hairy conditional doesn't need to be so. It _does_ need to be a
thin pointer, otherwise, it will fail to compile, so let's pull that out
into a temporary for future readers of the source.
Also, after a discussion with @pnkfelix and @gankro, we don't need these
null checks anymore, as zero-on-drop has been gone for a while now.
This is a standard "clean out libstd" commit which removes all 1.5-and-before
deprecated functionality as it's now all been deprecated for at least one entire
cycle.
This is a standard "clean out libstd" commit which removes all 1.5-and-before
deprecated functionality as it's now all been deprecated for at least one entire
cycle.
Sometimes when writing generic code you want to abstract over
owning/pointer type so that calling code isn't restricted by one
concrete owning/pointer type. This commit makes possible such code:
```rust
fn i_will_work_with_arc<T: Into<Arc<MyTy>>>(t: T) {
let the_arc = t.into();
// Do something
}
i_will_work_with_arc(MyTy::new());
i_will_work_with_arc(Box::new(MyTy::new()));
let arc_that_i_already_have = Arc::new(MyTy::new());
i_will_work_with_arc(arc_that_i_already_have);
```
Please note that this patch doesn't work with DSTs.
Also to mention, I made those impls stable, and I don't know whether they should be actually stable from the beginning. Please tell me if this should be feature-gated.
Sometimes when writing generic code you want to abstract over
owning/pointer type so that calling code isn't restricted by one
concrete owning/pointer type. This commit makes possible such code:
```
fn i_will_work_with_arc<T: Into<Arc<MyTy>>>(t: T) {
let the_arc = t.into();
// Do something
}
i_will_work_with_arc(MyTy::new());
i_will_work_with_arc(Box::new(MyTy::new()));
let arc_that_i_already_have = Arc::new(MyTy::new());
i_will_work_with_arc(arc_that_i_already_have);
```
Please note that this patch doesn't work with DSTs.
This change has two consequences:
1. It makes `Arc<T>` and `Rc<T>` covariant in `T`.
2. It causes the compiler to reject code that was unsound with respect
to dropck. See compile-fail/issue-29106.rs for an example of code that
no longer compiles. Because of this, this is a [breaking-change].
Fixes#29037.
Fixes#29106.
The text says it's a vector of floats, but the code actually uses a vector of integers. The type of the Vec doesn't really matter, so I just cut it from the text.
