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Author: steveklabnik

_posts/2018-03-29-Rust-1.25.md

@@ -23,8 +23,9 @@ appropriate page on our website, and check out the [detailed release notes for
 
 ## What's in 1.25.0 stable
 
-Rust 1.25 contains a bunch of stuff! The first one is straightforward: we've
-[upgraded to LLVM 6] from LLVM 4. This has a number of effects, a major one
+The last few releases have been relatively minor, but Rust 1.25 contains a
+bunch of stuff! The first one is straightforward: we've [upgraded to LLVM 6]
+from LLVM 4. This has a number of effects, a major one
 being a step closer to AVR support.
 
 A new way to write `use` statements has landed: [nested import groups]. If you've
@@ -56,7 +57,7 @@ use std::{
 This can reduce some repetition, and make things a bit more clear.
 
 There are two big documentation changes in this release: first, [Rust By
-Example is now included on doc.rust-lang.org]! We'll be redirecing the old
+Example is now included on doc.rust-lang.org]! We'll be redirecting the old
 domain there shortly. We hope this will bring more attention to a great
 resource, and you'll get a local copy with your local documentation.
 
@@ -97,15 +98,57 @@ See the [detailed release notes][notes] for more.
 
 ### Library stabilizations
 
+The biggest story in libraries this release is [`std::ptr::NonNull<T>`]. This type
+is similar to `*mut T`, but is non-null and covariant. This blog post isn't the right
+place to explain variance, but in a nutshell, `NonNull<T>`, well, guarantees that it
+won't be null, which means that `Option<NonNull<T>>` is the same size as `Option<T>`.
+If you're building a data structure with unsafe code, `NonNull<T>` is often the right
+type for you!
 
-Additionally, a few new APIs were stabilized this release:
+[`std::ptr::NonNull<T>`]: https://doc.rust-lang.org/std/ptr/struct.NonNull.html
 
-* [] ()
+`libcore` has [gained a `time` module](https://doc.rust-lang.org/core/time/),
+containing the `Duration` type previously only available in `libstd`.
+
+Additionally, the `new`, `from_secs`, `from_milis`, `from_micros`, and `from_nanos`
+functions associated with `Duration` were made `const fn`s, allowing them to be used
+to create a `Duration` as a constant expression.
 
 See the [detailed release notes][notes] for more.
 
 ### Cargo features
 
+Cargo's CLI has one really important change this release: `cargo new` will
+[now default](https://github.com/rust-lang/cargo/pull/5029) to generating a
+binary, rather than a library. We try to keep Cargo's CLI quite stable, but
+this change is important, and is unlikely to cause breakage.
+
+For some background, `cargo new` accepts two flags: `--lib`, for creating libraries,
+and `--bin`, for creating binaries, or executables. If you don't pass one of these
+flags, in previous versions of Cargo, it would default to `--lib`. We made this
+decision because each binary (often) depends on many libraries, and so the library
+case is more common. However, this is incorrect; each library is *depended upon* by
+many binaries. Furthermore, when getting stated, what you often want is a program
+you can run and play around with. It's not just new Rustaceans though; even very
+long-time community members have said that they find this default surprising.
+As such, we're changing it.
+
+Similarly, `cargo new` previously would be a bit opinionated around the names
+of packages it would create. Specifically, if your package began with `rust-`
+or ended with `-rs`, Cargo would rename it. The intention was that well,
+it's a Rust package, this information is redundant. However, people feel
+quite strongly about naming, and when they bump into this, they're surprised
+and often upset. As such, [we're not going to do that any
+more](https://github.com/rust-lang/cargo/pull/5013).
+
+Many users love `cargo doc`, a way to generate local documentation for their
+Cargo projects. [It's getting a huge speed
+bump](https://github.com/rust-lang/cargo/pull/5013) in this release, as now,
+it uses `cargo check`, rather than a full `cargo build`.
+
+Additionally, checkouts of git dependencies [should be a lot
+faster](https://github.com/rust-lang/cargo/pull/4919), thanks to the use of
+hard links where possible.
 
 See the [detailed release notes][notes] for more.