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Version 1.44.0 (2020-06-04)
==========================
Language
--------
- [You can now use `async/.await` with `#[no_std]` enabled.][69033]
- [Added the `unused_braces` lint.][70081]
**Syntax-only changes**
- [Expansion-driven outline module parsing][69838]
```rust
#[cfg(FALSE)]
mod foo {
mod bar {
mod baz; // `foo/bar/baz.rs` doesn't exist, but no error!
}
}
```
These are still rejected semantically, so you will likely receive an error but
these changes can be seen and parsed by macros and conditional compilation.
Compiler
--------
- [Rustc now respects the `-C codegen-units` flag in incremental mode.][70156]
Additionally when in incremental mode rustc defaults to 256 codegen units.
- [Refactored `catch_unwind` to have zero-cost, unless unwinding is enabled and
a panic is thrown.][67502]
- [Added tier 3\* support for the `aarch64-unknown-none` and
`aarch64-unknown-none-softfloat` targets.][68334]
- [Added tier 3 support for `arm64-apple-tvos` and
`x86_64-apple-tvos` targets.][68191]
Libraries
---------
- [Special cased `vec![]` to map directly to `Vec::new()`.][70632] This allows
`vec![]` to be able to be used in `const` contexts.
- [`convert::Infallible` now implements `Hash`.][70281]
- [`OsString` now implements `DerefMut` and `IndexMut` returning
a `&mut OsStr`.][70048]
- [Unicode 13 is now supported.][69929]
- [`String` now implements `From<&mut str>`.][69661]
- [`IoSlice` now implements `Copy`.][69403]
- [`Vec<T>` now implements `From<[T; N]>`.][68692] Where `N` is at most 32.
- [`proc_macro::LexError` now implements `fmt::Display` and `Error`.][68899]
- [`from_le_bytes`, `to_le_bytes`, `from_be_bytes`, `to_be_bytes`,
`from_ne_bytes`, and `to_ne_bytes` methods are now `const` for all
integer types.][69373]
Stabilized APIs
---------------
- [`PathBuf::with_capacity`]
- [`PathBuf::capacity`]
- [`PathBuf::clear`]
- [`PathBuf::reserve`]
- [`PathBuf::reserve_exact`]
- [`PathBuf::shrink_to_fit`]
- [`f32::to_int_unchecked`]
- [`f64::to_int_unchecked`]
- [`Layout::align_to`]
- [`Layout::pad_to_align`]
- [`Layout::array`]
- [`Layout::extend`]
Cargo
-----
- [Added the `cargo tree` command which will print a tree graph of
your dependencies.][cargo/8062] E.g.
```
mdbook v0.3.2 (/Users/src/rust/mdbook)
├── ammonia v3.0.0
│ ├── html5ever v0.24.0
│ │ ├── log v0.4.8
│ │ │ └── cfg-if v0.1.9
│ │ ├── mac v0.1.1
│ │ └── markup5ever v0.9.0
│ │ ├── log v0.4.8 (*)
│ │ ├── phf v0.7.24
│ │ │ └── phf_shared v0.7.24
│ │ │ ├── siphasher v0.2.3
│ │ │ └── unicase v1.4.2
│ │ │ [build-dependencies]
│ │ │ └── version_check v0.1.5
...
```
You can also display dependencies on multiple versions of the same crate with
`cargo tree -d` (short for `cargo tree --duplicates`).
Misc
----
- [Rustdoc now allows you to specify `--crate-version` to have rustdoc include
the version in the sidebar.][69494]
Compatibility Notes
-------------------
- [Rustc now correctly generates static libraries on Windows GNU targets with
the `.a` extension, rather than the previous `.lib`.][70937]
- [Removed the `-C no_integrated_as` flag from rustc.][70345]
- [The `file_name` property in JSON output of macro errors now points the actual
source file rather than the previous format of `<NAME macros>`.][70969]
**Note:** this may not point to a file that actually exists on the user's system.
- [The minimum required external LLVM version has been bumped to LLVM 8.][71147]
- [`mem::{zeroed, uninitialised}` will now panic when used with types that do
not allow zero initialization such as `NonZeroU8`.][66059] This was
previously a warning.
- [In 1.45.0 (the next release) converting a `f64` to `u32` using the `as`
operator has been defined as a saturating operation.][71269] This was previously
undefined behaviour, but you can use the `{f64, f32}::to_int_unchecked` methods to
continue using the current behaviour, which may be desirable in rare performance
sensitive situations.
Internal Only
-------------
These changes provide no direct user facing benefits, but represent significant
improvements to the internals and overall performance of rustc and
related tools.
- [dep_graph Avoid allocating a set on when the number reads are small.][69778]
- [Replace big JS dict with JSON parsing.][71250]
[69373]: rust-lang/rust#69373
[66059]: rust-lang/rust#66059
[68191]: rust-lang/rust#68191
[68899]: rust-lang/rust#68899
[71147]: rust-lang/rust#71147
[71250]: rust-lang/rust#71250
[70937]: rust-lang/rust#70937
[70969]: rust-lang/rust#70969
[70632]: rust-lang/rust#70632
[70281]: rust-lang/rust#70281
[70345]: rust-lang/rust#70345
[70048]: rust-lang/rust#70048
[70081]: rust-lang/rust#70081
[70156]: rust-lang/rust#70156
[71269]: rust-lang/rust#71269
[69838]: rust-lang/rust#69838
[69929]: rust-lang/rust#69929
[69661]: rust-lang/rust#69661
[69778]: rust-lang/rust#69778
[69494]: rust-lang/rust#69494
[69403]: rust-lang/rust#69403
[69033]: rust-lang/rust#69033
[68692]: rust-lang/rust#68692
[68334]: rust-lang/rust#68334
[67502]: rust-lang/rust#67502
[cargo/8062]: rust-lang/cargo#8062
[`PathBuf::with_capacity`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.with_capacity
[`PathBuf::capacity`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.capacity
[`PathBuf::clear`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.clear
[`PathBuf::reserve`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.reserve
[`PathBuf::reserve_exact`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.reserve_exact
[`PathBuf::shrink_to_fit`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.shrink_to_fit
[`f32::to_int_unchecked`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_int_unchecked
[`f64::to_int_unchecked`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_int_unchecked
[`Layout::align_to`]: https://doc.rust-lang.org/std/alloc/struct.Layout.html#method.align_to
[`Layout::pad_to_align`]: https://doc.rust-lang.org/std/alloc/struct.Layout.html#method.pad_to_align
[`Layout::array`]: https://doc.rust-lang.org/std/alloc/struct.Layout.html#method.array
[`Layout::extend`]: https://doc.rust-lang.org/std/alloc/struct.Layout.html#method.extend- Loading branch information
