Rollup merge of rust-lang#74744 - XAMPPRocky:relnotes-1.46.0, r=Mark-Simulacrum

Update RELEASES.md for 1.46.0

### [Rendered](https://github.com/XAMPPRocky/rust/blob/relnotes-1.46.0/RELEASES.md)

r? @Mark-Simulacrum

cc @rust-lang/release

Author: JohnTitor

RELEASES.md

@@ -1,3 +1,104 @@
+Version 1.46.0 (2020-08-27)
+==========================
+
+Language
+--------
+- [`if`, `match`, and `loop` expressions can now be used in const functions.][72437]
+- [Additionally you are now also able to coerce and cast to slices (`&[T]`) in
+  const functions.][73862]
+- [The `#[track_caller]` attribute can now be added to functions to use the
+  function's caller's location information for panic messages.][72445]
+- [Recursively indexing into tuples no longer needs parentheses.][71322] E.g.
+  `x.0.0` over `(x.0).0`.
+- [`mem::transmute` can now be used in static and constants.][72920] **Note**
+  You currently can't use `mem::transmute` in constant functions.
+
+Compiler
+--------
+- [You can now use the `cdylib` target on Apple iOS and tvOS platforms.][73516]
+- [Enabled static "Position Independent Executables" by default
+  for `x86_64-unknown-linux-musl`.][70740]
+
+Libraries
+---------
+- [`mem::forget` is now a `const fn`.][73887]
+- [`String` now implements `From<char>`.][73466]
+- [The `leading_ones`, and `trailing_ones` methods have been stabilised for all
+  integer types.][73032]
+- [`vec::IntoIter<T>` now implements `AsRef<[T]>`.][72583]
+- [All non-zero integer types (`NonZeroU8`) now implement `TryFrom` for their
+  zero-able equivalent (e.g. `TryFrom<u8>`).][72717]
+- [`&[T]` and `&mut [T]` now implement `PartialEq<Vec<T>>`.][71660]
+- [`(String, u16)` now implements `ToSocketAddrs`.][73007]
+- [`vec::Drain<'_, T>` now implements `AsRef<[T]>`.][72584]
+
+Stabilized APIs
+---------------
+- [`Option::zip`]
+- [`vec::Drain::as_slice`]
+
+Cargo
+-----
+Added a number of new environment variables that are now available when
+compiling your crate.
+
+- [`CARGO_BIN_NAME` and `CARGO_CRATE_NAME`][cargo/8270] Providing the name of
+  the specific binary being compiled and the name of the crate.
+- [`CARGO_PKG_LICENSE`][cargo/8325] The license from the manifest of the package.
+- [`CARGO_PKG_LICENSE_FILE`][cargo/8387] The path to the license file.
+
+Compatibility Notes
+-------------------
+- [The target configuration option `abi_blacklist` has been renamed
+  to `unsupported_abis`.][74150] The old name will still continue to work.
+- [Rustc will now warn if you have a C-like enum that implements `Drop`.][72331]
+  This was previously accepted but will become a hard error in a future release.
+- [Rustc will fail to compile if you have a struct with
+  `#[repr(i128)]` or `#[repr(u128)]`.][74109] This representation is currently only
+  allowed on `enum`s.
+- [Tokens passed to `macro_rules!` are now always captured.][73293] This helps
+  ensure that spans have the correct information, and may cause breakage if you
+  were relying on receiving spans with dummy information.
+- [The InnoSetup installer for Windows is no longer available.][72569] This was
+  a legacy installer that was replaced by a MSI installer a few years ago but
+  was still being built.
+- [`{f32, f64}::asinh` now returns the correct values for negative numbers.][72486]
+- [Rustc will no longer accept overlapping trait implementations that only
+  differ in how the lifetime was bound.][72493]
+- [Rustc now correctly relates the lifetime of an existential associated
+  type.][71896] This fixes some edge cases where `rustc` would erroneously allow
+  you to pass a shorter lifetime than expected.
+
+[74109]: https://github.com/rust-lang/rust/pull/74109/
+[74150]: https://github.com/rust-lang/rust/pull/74150/
+[73862]: https://github.com/rust-lang/rust/pull/73862/
+[73887]: https://github.com/rust-lang/rust/pull/73887/
+[73466]: https://github.com/rust-lang/rust/pull/73466/
+[73516]: https://github.com/rust-lang/rust/pull/73516/
+[73293]: https://github.com/rust-lang/rust/pull/73293/
+[73007]: https://github.com/rust-lang/rust/pull/73007/
+[73032]: https://github.com/rust-lang/rust/pull/73032/
+[72920]: https://github.com/rust-lang/rust/pull/72920/
+[72569]: https://github.com/rust-lang/rust/pull/72569/
+[72583]: https://github.com/rust-lang/rust/pull/72583/
+[72584]: https://github.com/rust-lang/rust/pull/72584/
+[72717]: https://github.com/rust-lang/rust/pull/72717/
+[72437]: https://github.com/rust-lang/rust/pull/72437/
+[72445]: https://github.com/rust-lang/rust/pull/72445/
+[72486]: https://github.com/rust-lang/rust/pull/72486/
+[72493]: https://github.com/rust-lang/rust/pull/72493/
+[72331]: https://github.com/rust-lang/rust/pull/72331/
+[71896]: https://github.com/rust-lang/rust/pull/71896/
+[71660]: https://github.com/rust-lang/rust/pull/71660/
+[71322]: https://github.com/rust-lang/rust/pull/71322/
+[70740]: https://github.com/rust-lang/rust/pull/70740/
+[cargo/8270]: https://github.com/rust-lang/cargo/pull/8270/
+[cargo/8325]: https://github.com/rust-lang/cargo/pull/8325/
+[cargo/8387]: https://github.com/rust-lang/cargo/pull/8387/
+[`Option::zip`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.zip
+[`vec::Drain::as_slice`]: https://doc.rust-lang.org/stable/std/vec/struct.Drain.html#method.as_slice
+
+
 Version 1.45.2 (2020-08-03)
 ==========================
 
@@ -7,6 +108,7 @@ Version 1.45.2 (2020-08-03)
 [74954]: https://github.com/rust-lang/rust/issues/74954
 [74784]: https://github.com/rust-lang/rust/issues/74784
 
+
 Version 1.45.1 (2020-07-30)
 ==========================
 
@@ -20,6 +122,7 @@ Version 1.45.1 (2020-07-30)
 [74509]: https://github.com/rust-lang/rust/pull/74509
 [74457]: https://github.com/rust-lang/rust/pull/74457
 
+
 Version 1.45.0 (2020-07-16)
 ==========================