This upcast coercion currently preserves the vtable for the object, but
eventually it can be used to create a derived vtable. The upcast
coercion is not introduced into method dispatch; see comment on #18737
for information about why. Fixes#18737.
This commit is an implementation of [RFC 565][rfc] which is a stabilization of
the `std::fmt` module and the implementations of various formatting traits.
Specifically, the following changes were performed:
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0565-show-string-guidelines.md
* The `Show` trait is now deprecated, it was renamed to `Debug`
* The `String` trait is now deprecated, it was renamed to `Display`
* Many `Debug` and `Display` implementations were audited in accordance with the
RFC and audited implementations now have the `#[stable]` attribute
* Integers and floats no longer print a suffix
* Smart pointers no longer print details that they are a smart pointer
* Paths with `Debug` are now quoted and escape characters
* The `unwrap` methods on `Result` now require `Display` instead of `Debug`
* The `Error` trait no longer has a `detail` method and now requires that
`Display` must be implemented. With the loss of `String`, this has moved into
libcore.
* `impl<E: Error> FromError<E> for Box<Error>` now exists
* `derive(Show)` has been renamed to `derive(Debug)`. This is not currently
warned about due to warnings being emitted on stage1+
While backwards compatibility is attempted to be maintained with a blanket
implementation of `Display` for the old `String` trait (and the same for
`Show`/`Debug`) this is still a breaking change due to primitives no longer
implementing `String` as well as modifications such as `unwrap` and the `Error`
trait. Most code is fairly straightforward to update with a rename or tweaks of
method calls.
[breaking-change]
Closes#21436
This commit aims to stabilize the `TypeId` abstraction by moving it out of the
`intrinsics` module into the `any` module of the standard library. Specifically,
* `TypeId` is now defined at `std::any::TypeId`
* `TypeId::hash` has been removed in favor of an implementation of `Hash`.
This commit also performs a final pass over the `any` module, confirming the
following:
* `Any::get_type_id` remains unstable as *usage* of the `Any` trait will likely
never require this, and the `Any` trait does not need to be implemented for
any other types. As a result, this implementation detail can remain unstable
until associated statics are implemented.
* `Any::downcast_ref` is now stable
* `Any::downcast_mut` is now stable
* `BoxAny` remains unstable. While a direct impl on `Box<Any>` is allowed today
it does not allow downcasting of trait objects like `Box<Any + Send>` (those
returned from `Thread::join`). This is covered by #18737.
* `BoxAny::downcast` is now stable.
This gets rid of the 'experimental' level, removes the non-staged_api
case (i.e. stability levels for out-of-tree crates), and lets the
staged_api attributes use 'unstable' and 'deprecated' lints.
This makes the transition period to the full feature staging design
a bit nicer.
fmt::Show is for debugging, and can and should be implemented for
all public types. This trait is used with `{:?}` syntax. There still
exists #[derive(Show)].
fmt::String is for types that faithfully be represented as a String.
Because of this, there is no way to derive fmt::String, all
implementations must be purposeful. It is used by the default format
syntax, `{}`.
This will break most instances of `{}`, since that now requires the type
to impl fmt::String. In most cases, replacing `{}` with `{:?}` is the
correct fix. Types that were being printed specifically for users should
receive a fmt::String implementation to fix this.
Part of #20013
[breaking-change]
In regards to:
https://github.com/rust-lang/rust/issues/19253#issuecomment-64836729
This commit:
* Changes the #deriving code so that it generates code that utilizes fewer
reexports (in particur Option::* and Result::*), which is necessary to
remove those reexports in the future
* Changes other areas of the codebase so that fewer reexports are utilized
A recent change turned off inheritance for the #[stable] by default, but
failed to catch all the cases where this was being used in std. This
patch fixes that problem.
Spring cleaning is here! In the Fall! This commit removes quite a large amount
of deprecated functionality from the standard libraries. I tried to ensure that
only old deprecated functionality was removed.
This is removing lots and lots of deprecated features, so this is a breaking
change. Please consult the deprecation messages of the deleted code to see how
to migrate code forward if it still needs migration.
[breaking-change]
[Previously](e5da6a71a6),
the `Any` trait was split into a private portion and an (empty) public
portion, in order to hide the implementation strategy used for
downcasting. However, the [new
rules](e9ad12c0ca)
for privacy forbid `AnyPrivate` from actually being private.
This patch thus reverts the introduction of `AnyPrivate`.
Although this is unlikely to break any real code, it removes a public
trait and is therefore a:
[breaking-change]
This bound is already implicit through the AnyPrivate trait,
but since it is not explicit, you still have to write Box<Any + 'static>,
even though Any can only be 'static.
Introducing the 'static bound here makes this bound explicit, making
Box<Any> legal.
This breaks code like:
struct Foo {
...
}
pub fn make_foo() -> Foo {
...
}
Change this code to:
pub struct Foo { // note `pub`
...
}
pub fn make_foo() -> Foo {
...
}
The `visible_private_types` lint has been removed, since it is now an
error to attempt to expose a private type in a public API. In its place
a `#[feature(visible_private_types)]` gate has been added.
Closes#16463.
RFC #48.
[breaking-change]
This commit applies stability attributes to the contents of these modules,
summarized here:
* The `unit` and `bool` modules have become #[unstable] as they are purely meant
for documentation purposes and are candidates for removal.
* The `ty` module has been deprecated, and the inner `Unsafe` type has been
renamed to `UnsafeCell` and moved to the `cell` module. The `marker1` field
has been removed as the compiler now always infers `UnsafeCell` to be
invariant. The `new` method i stable, but the `value` field, `get` and
`unwrap` methods are all unstable.
* The `tuple` module has its name as stable, the naming of the `TupleN` traits
as stable while the methods are all #[unstable]. The other impls in the module
have appropriate stability for the corresponding trait.
* The `arc` module has received the exact same treatment as the `rc` module
previously did.
* The `any` module has its name as stable. The `Any` trait is also stable, with
a new private supertrait which now contains the `get_type_id` method. This is
to make the method a private implementation detail rather than a public-facing
detail.
The two extension traits in the module are marked #[unstable] as they will not
be necessary with DST. The `is` method is #[stable], the as_{mut,ref} methods
have been renamed to downcast_{mut,ref} and are #[unstable].
The extension trait `BoxAny` has been clarified as to why it is unstable as it
will not be necessary with DST.
This is a breaking change because the `marker1` field was removed from the
`UnsafeCell` type. To deal with this change, you can simply delete the field and
only specify the value of the `data` field in static initializers.
[breaking-change]
method calls are involved.
This breaks code like:
impl<T:Copy> Foo for T { ... }
fn take_param<T:Foo>(foo: &T) { ... }
fn main() {
let x = box 3i; // note no `Copy` bound
take_param(&x);
}
Change this code to not contain a type error. For example:
impl<T:Copy> Foo for T { ... }
fn take_param<T:Foo>(foo: &T) { ... }
fn main() {
let x = 3i; // satisfies `Copy` bound
take_param(&x);
}
Closes#15860.
[breaking-change]
Libcore's test infrastructure is complicated by the fact that many lang
items are defined in the crate. The current approach (realcore/realstd
imports) is hacky and hard to work with (tests inside of core::cmp
haven't been run for months!).
Moving tests to a separate crate does mean that they can only test the
public API of libcore, but I don't feel that that is too much of an
issue. The only tests that I had to get rid of were some checking the
various numeric formatters, but those are also exercised through normal
format! calls in other tests.
This will break code like:
fn f(x: &mut int) {}
let mut a = box 1i;
f(a);
Change it to:
fn f(x: &mut int) {}
let mut a = box 1i;
f(&mut *a);
RFC 33; issue #10504.
[breaking-change]
This breaks a fair amount of code. The typical patterns are:
* `for _ in range(0, 10)`: change to `for _ in range(0u, 10)`;
* `println!("{}", 3)`: change to `println!("{}", 3i)`;
* `[1, 2, 3].len()`: change to `[1i, 2, 3].len()`.
RFC #30. Closes#6023.
[breaking-change]
This commit fixes a bug in the calculation of the hash of a type which didn't
factor in the length of a constant-sized vector. As a result of this, a type
placed into an Any of a fixed length could be peeled out with any other fixed
length in a safe manner.
This is part of the ongoing renaming of the equality traits. See #12517 for more
details. All code using Eq/Ord will temporarily need to move to Partial{Eq,Ord}
or the Total{Eq,Ord} traits. The Total traits will soon be renamed to {Eq,Ord}.
cc #12517
[breaking-change]
This commit shuffles around some of the `rand` code, along with some
reorganization. The new state of the world is as follows:
* The librand crate now only depends on libcore. This interface is experimental.
* The standard library has a new module, `std::rand`. This interface will
eventually become stable.
Unfortunately, this entailed more of a breaking change than just shuffling some
names around. The following breaking changes were made to the rand library:
* Rng::gen_vec() was removed. This has been replaced with Rng::gen_iter() which
will return an infinite stream of random values. Previous behavior can be
regained with `rng.gen_iter().take(n).collect()`
* Rng::gen_ascii_str() was removed. This has been replaced with
Rng::gen_ascii_chars() which will return an infinite stream of random ascii
characters. Similarly to gen_iter(), previous behavior can be emulated with
`rng.gen_ascii_chars().take(n).collect()`
* {IsaacRng, Isaac64Rng, XorShiftRng}::new() have all been removed. These all
relied on being able to use an OSRng for seeding, but this is no longer
available in librand (where these types are defined). To retain the same
functionality, these types now implement the `Rand` trait so they can be
generated with a random seed from another random number generator. This allows
the stdlib to use an OSRng to create seeded instances of these RNGs.
* Rand implementations for `Box<T>` and `@T` were removed. These seemed to be
pretty rare in the codebase, and it allows for librand to not depend on
liballoc. Additionally, other pointer types like Rc<T> and Arc<T> were not
supported. If this is undesirable, librand can depend on liballoc and regain
these implementations.
* The WeightedChoice structure is no longer built with a `Vec<Weighted<T>>`,
but rather a `&mut [Weighted<T>]`. This means that the WeightedChoice
structure now has a lifetime associated with it.
* The `sample` method on `Rng` has been moved to a top-level function in the
`rand` module due to its dependence on `Vec`.
cc #13851
[breaking-change]
The compiler was updated to recognize that implementations for ty_uniq(..) are
allowed if the Box lang item is located in the current crate. This enforces the
idea that libcore cannot allocated, and moves all related trait implementations
from libcore to libstd.
This is a breaking change in that the AnyOwnExt trait has moved from the any
module to the owned module. Any previous users of std::any::AnyOwnExt should now
use std::owned::AnyOwnExt instead. This was done because the trait is intended
for Box traits and only Box traits.
[breaking-change]
This commit revisits the `cast` module in libcore and libstd, and scrutinizes
all functions inside of it. The result was to remove the `cast` module entirely,
folding all functionality into the `mem` module. Specifically, this is the fate
of each function in the `cast` module.
* transmute - This function was moved to `mem`, but it is now marked as
#[unstable]. This is due to planned changes to the `transmute`
function and how it can be invoked (see the #[unstable] comment).
For more information, see RFC 5 and #12898
* transmute_copy - This function was moved to `mem`, with clarification that is
is not an error to invoke it with T/U that are different
sizes, but rather that it is strongly discouraged. This
function is now #[stable]
* forget - This function was moved to `mem` and marked #[stable]
* bump_box_refcount - This function was removed due to the deprecation of
managed boxes as well as its questionable utility.
* transmute_mut - This function was previously deprecated, and removed as part
of this commit.
* transmute_mut_unsafe - This function doesn't serve much of a purpose when it
can be achieved with an `as` in safe code, so it was
removed.
* transmute_lifetime - This function was removed because it is likely a strong
indication that code is incorrect in the first place.
* transmute_mut_lifetime - This function was removed for the same reasons as
`transmute_lifetime`
* copy_lifetime - This function was moved to `mem`, but it is marked
`#[unstable]` now due to the likelihood of being removed in
the future if it is found to not be very useful.
* copy_mut_lifetime - This function was also moved to `mem`, but had the same
treatment as `copy_lifetime`.
* copy_lifetime_vec - This function was removed because it is not used today,
and its existence is not necessary with DST
(copy_lifetime will suffice).
In summary, the cast module was stripped down to these functions, and then the
functions were moved to the `mem` module.
transmute - #[unstable]
transmute_copy - #[stable]
forget - #[stable]
copy_lifetime - #[unstable]
copy_mut_lifetime - #[unstable]
[breaking-change]
This mostly involved frobbing imports between realstd, realcore, and the core
being test. Some of the imports are a little counterintuitive, but it mainly
focuses around libcore's types not implementing Show while libstd's types
implement Show.
