Rust 1.12 release announcement

_posts/2016-09-29-Rust-1.12.md

@@ -32,9 +32,9 @@ what you think of them:
 
 The largest internal change in this release is moving to a new compiler backend
 based on the new Rust [MIR]. While this feature does not result in anything
-user-visible, it paves the way for a number of future compiler optimizations,
-and for some codebases it already results in improvements to compile times and
-reductions in code size.
+user-visible today, but it paves the way for a number of future compiler
+optimizations, and for some codebases it already results in improvements to
+compile times and reductions in code size.
 
 [previously talked]: https://blog.rust-lang.org/2016/08/10/Shape-of-errors-to-come.html
 [volunteer effort]: https://github.com/rust-lang/rust/issues/35233
@@ -43,9 +43,9 @@ reductions in code size.
 #### Overhauled error messages
 
 With 1.12 we're introducing a new error format which helps to surface a lot of
-the internal knowledge about why an error is occurring to you, the developer. It
-does this by focusing on your code and the points of interest in your code that
-are relevant to the error.
+the internal knowledge about why an error is occurring to you, the developer.
+It does this by putting your code front and center, highlighting the parts
+relevant to the error with annotations describing what went wrong.
 
 For example, in 1.11 if a implementation of a trait didn't match the trait
 declaration, you would see an error like the one below:
@@ -103,29 +103,6 @@ the compiler and less bloat at runtime. In addition, because MIR is a simpler
 'language' than the full AST, it's also easier to implement compiler passes on,
 and easier to verify that they are correct.
 
-The improvements in compile times of some workloads due to this change alone
-are significant:
-
-|               | 1.11   | 1.12  | compile time |
-|---------------|--------|-------|--------------|
-| inflate-0.1.0 | 10.17s | 4.32s | 2.35x faster |
-| hyper-0.5.0   | 24.03s | 5.23s | 4.58x faster |
-| helloworld    | 0.17s  | 0.14s | 1.20x faster |
-| regex 0.1.30  | 9.63s  | 2.39s | 4.03x faster |
-
-It is worth remembering that not all workloads may see this large of an
-improvement: it depends on a large number of factors.
-
-The compiler's [memory usage](https://en.wikipedia.org/wiki/Resident_set_size)
-while compiling these crates was also improved:
-
-|               | 1.11  | 1.12  | % of original size |
-|---------------|-------|-------|--------------------|
-| inflate-0.1.0 | 175MB | 135MB | 77.1%              |
-| hyper.0.5.0   | 321MB | 302MB | 94.1%              |
-| helloworld    | 127MB | 90MB  | 70.9%              |
-| regex.0.1.30  | 230MB | 194MB | 84.3%              |
-
 #### Other improvements
 
 * Many minor improvements to the documentation.
@@ -185,10 +162,18 @@ See the [detailed release notes][notes] for more.
 
 #### Cargo features
 
-Cargo has some modest improvments:
+The biggest feature added to Cargo this cycle is the ability to [override the
+source of a crate](https://github.com/rust-lang/cargo/pull/2857). Using this
+with tools like [cargo-vendor] and [cargo-local-registry] allow vendoring
+dependencies locally in a robust fashion. Eventually this support will be the
+foundation of supporting mirrors of [crates.io] as well.
+
+[cargo-vendor]: https://github.com/alexcrichton/cargo-vendor
+[cargo-local-registry]: https://github.com/alexcrichton/cargo-local-registry
+[crates.io]: https://crates.io/
+
+There are some other improvments as well:
 
-* [Support local mirrors of
-  registries](https://github.com/rust-lang/cargo/pull/2857)
 * [Speed up noop registry updates](https://github.com/rust-lang/cargo/pull/2974)
 * [Add a `--lib` flag to `cargo new`]
   (https://github.com/rust-lang/cargo/pull/2921)