We are pleased to announce the release of Ruby 2.5.0-preview1.

Ruby 2.5.0-preview1 is the first preview release toward Ruby 2.5.0.
It introduces some new features and performance improvements, for example:

## New Features

* Print backtrace and error message in reverse order if STDERR is unchanged and a tty.
  [Feature #8661] [experimental]

* Top-level constant look-up is removed.  [Feature #11547]

* rescue/else/ensure are allowed inside do/end blocks.  [Feature #12906]

* yield\_self [Feature #6721]

## Other notable changes since 2.4

* Merge Onigmo to 6.1.1.
  It adds [absence operator](https://github.com/k-takata/Onigmo/issues/87)
  Note that Ruby 2.4.1 also includes this change.
* Merge bundler to standard libraries.
* Merge rubygems-2.6.13.
* Merge rdoc-6.0.0.beta2.
  Change lexer IRB based one to Ripper.
  It much improves the speed of generating document.
  https://github.com/ruby/rdoc/pull/512
  This also includes
  * Fix so many bugs in the last dozen years or so
  * Support new Ruby syntaxes in the last several years
* Update supported Unicode version to 10.0.0.

See [NEWS](https://github.com/ruby/ruby/blob/v2_5_0_preview1/NEWS)
or commit logs for details.

With those changes,
[6162 files changed, 339744 insertions(+), 28699 deletions(-)](https://github.com/ruby/ruby/compare/v2_4_0...v2_5_0_preview1)
since Ruby 2.4.0!

Enjoy Ruby 2.5.0-preview1!

## Download

* <https://cache.ruby-lang.org/pub/ruby/2.5/ruby-2.5.0-preview1.tar.gz>

      SIZE:   16088348 bytes
      SHA1:   8d1bad4faea258ac7f97ae2b4c7d76335b044c37
      SHA256: 30994fe5efbf4759a2a616f288121857c69b45665926174680387e286bb83b05
      SHA512: bcca05333e0aa09c75492ec09e4a82bf7aebef1b96e1c40000b92fa654fd96ae1d70e4f92ecf619b199cba73d754be6c6d97fc488d1e47831bc671f64ce0ab6d

* <https://cache.ruby-lang.org/pub/ruby/2.5/ruby-2.5.0-preview1.zip>

      SIZE:   20036401 bytes
      SHA1:   e1ad073a17dc814fc8ddb3cbbed761a2278dcc12
      SHA256: 1a61196a845cb9d9b5a71fd66cb77fbc215f82cb6f90371e309ceddb25e7107b
      SHA512: 35033b5426142e271d95d438b8442e73cade9462b02014371866882a4a90911b98805b7199b15bedc9847fd2560e211f015fa09b0b1d9efc31a947e41e088b30

* <https://cache.ruby-lang.org/pub/ruby/2.5/ruby-2.5.0-preview1.tar.bz2>

      SIZE:   14110768 bytes
      SHA1:   0b664c41b75d54ff88c70b5437b20b90675e3348
      SHA256: 1158e0eac184a1d8189fae985f58c9be185d6e7074b022e66567aec798fa3446
      SHA512: 2d39ef64aaf7a52014905f4ad59b53e83b71433e50a9227f9f50cbb7a2c9a5db9cd69fa7dbe01234819f7edd2216b3d915f21676f07d12bb5f0f3276358bce7f

* <https://cache.ruby-lang.org/pub/ruby/2.5/ruby-2.5.0-preview1.tar.xz>

      SIZE:   11383812 bytes
      SHA1:   eef2901270c235a97d132ebcfb275f130ba368fd
      SHA256: c2f518eb04b38bdd562ba5611abd2521248a1608fc466368563dd794ddeddd09
      SHA512: 1153a1fc4eb1a9556af2d392743998eb9cffd2a07e4648bf124dea1044bb378c7f4534dd87c0d30563ec438d2995ba1832faaaf4261db5d0840ca32ae7ea65d9