This commit marks as `#[stable]`:
* The `Index` and `IndexMut` traits. These are stabilized as taking the
index itself *by reference*; after extensive discussion it was
determined that this is a better match with our choices
elsewhere (e.g. making comparison operators auto-reference), and that
the use cases for by-value indices are better handled through
`IndexSet`.
* The `Range`, `RangeFrom` and `RangeTo` structs, introduced for range
notation.
* Various impls of `Index` and `IndexMut`.
The `FullRange` struct is left unstable as we may wish to rename it to
`RangeFull` in the future.
This commit also *removes* the `Step` trait in favor of direct
implementation of iterator traits on ranges for integers. The `Step`
trait was not a terribly useful factoring internally, and it is likely
that external integer types are best off implementing range iterators
directly. It was removed to simplify the API surface. We can always
reintroduce `Step` later if it turns out to be useful.
Due to this removal, this is a:
[breaking-change]
As discussed with @aturon I added implementations of various op traits for references to built-in types which was already suggested by the ops reform RFC.
The 2nd commit updates the module documentation of core::ops to fully reflect the recent change from pass-by-reference to pass-by-value and expands on the implications for generic code.
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
The example of the `Index` and `IndexMut` trait contained too much `Foo`.
It now contains a bit more `Bar` to make things clearer which parts are
defining the type of the index.
* Not all traits are part of the prelude anymore
* We switched from pass-by-reference to pass-by-value for most traits
* Add some explanations around pass-by-value traits in the context of
generic code and additional implementations for reference types.
This commit marks as stable those parts of `core::ops` that are in their
final planned form: `Drop`, all of the mathematical operators (`Add`,
`Sub`, etc), `Deref`/`DerefMut`. It leaves the `Index*`, `Slice*` and
`Fn*` traits unstable, as they are still undergoing active changes.
This commit is an implementation of [RFC 503][rfc] which is a stabilization
story for the prelude. Most of the RFC was directly applied, removing reexports.
Some reexports are kept around, however:
* `range` remains until range syntax has landed to reduce churn.
* `Path` and `GenericPath` remain until path reform lands. This is done to
prevent many imports of `GenericPath` which will soon be removed.
* All `io` traits remain until I/O reform lands so imports can be rewritten all
at once to `std::io::prelude::*`.
This is a breaking change because many prelude reexports have been removed, and
the RFC can be consulted for the exact list of removed reexports, as well as to
find the locations of where to import them.
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0503-prelude-stabilization.md
[breaking-change]
Closes#20068
