Problem compiling 0.18.7 on OS X 10.11.6 with LLVM about homebrew-crystal HOT 6 OPEN

$ brew install crystal-lang
Warning: You are using OS X 10.12.
We do not provide support for this pre-release version.
You may encounter build failures or other breakages.
Please create pull-requests instead of filing issues.
==> Downloading https://github.com/crystal-lang/crystal/archive/0.18.7.tar.gz
==> Downloading from https://codeload.github.com/crystal-lang/crystal/tar.gz/0.18.7
######################################################################## 100.0%
==> Downloading https://github.com/crystal-lang/crystal/releases/download/0.18.6/crystal-0.18.6-1-darwin-x86_64.tar.gz
Already downloaded: /Users/fibric/Library/Caches/Homebrew/crystal-lang--boot-0.18.6.tar.gz
==> make crystal release=true
Last 15 lines from /Users/fibric/Library/Logs/Homebrew/crystal-lang/01.make:
  inline ref wrap(const ty *P) {                        \
             ^
src/llvm/ext/llvm_ext.cc:149:21: error: unknown type name 'DIDescriptor'; did you mean 'llvm::Intrinsic::IITDescriptor'?
      Tag, unwrapDI<DIDescriptor>(Scope), Name, unwrapDI<DIFile>(File), Line,
                    ^~~~~~~~~~~~
                    llvm::Intrinsic::IITDescriptor
/usr/local/Cellar/llvm/3.8.1/include/llvm/IR/Intrinsics.h:80:10: note: 'llvm::Intrinsic::IITDescriptor' declared here
  struct IITDescriptor {
         ^
src/llvm/ext/llvm_ext.cc:148:21: error: no member named 'createLocalVariable' in 'llvm::DIBuilder'
  DIVariable V = D->createLocalVariable(
                 ~  ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
make: *** [src/llvm/ext/llvm_ext.o] Error 1

READ THIS: https://git.io/brew-troubleshooting
If reporting this issue please do so at (not Homebrew/brew):
  https://github.com/Homebrew/homebrew-core/issues

Warning: You are using OS X 10.12.
We do not provide support for this pre-release version.
You may encounter build failures or other breakages.
Please create pull-requests instead of filing issues.

$ command -v llvm-config-3.8 || command -v llvm-config38 || (command -v llvm-config > /dev/null && (case "$(llvm-config --version)" in 3.8*) command -v llvm-config;; *) false;; esac)) || command -v llvm-config-3.6 || command -v llvm-config36 || command -v llvm-config-3.5 || command -v llvm-config35 || command -v llvm-config

/usr/local/bin/llvm-config

$ llvm-config --version
3.8.1

$ /usr/local/bin/llvm-config --version
3.8.1

$ brew ls
antigen     cmake       gdbm        git     git-flow    libatomic_ops   libffi      libyaml     makedepend  nvm     pcre        s-lang      thefuck     zsh
bdw-gc      curl        gettext     git-extras  go      libevent    libpng      llvm        most        openssl     pkg-config  sphinx-doc  xz      zsh-completions

$ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry and just ignore them. Thanks!

Warning: You are using OS X 10.12.
We do not provide support for this pre-release version.
You may encounter build failures or other breakages.
Please create pull-requests instead of filing issues.

Warning: Some keg-only formula are linked into the Cellar.
Linking a keg-only formula, such as gettext, into the cellar with
`brew link <formula>` will cause other formulae to detect them during
the `./configure` step. This may cause problems when compiling those
other formulae.

Binaries provided by keg-only formulae may override system binaries
with other strange results.

You may wish to `brew unlink` these brews:
    llvm

$ brew install crystal-lang --HEAD
Warning: You are using OS X 10.12.
We do not provide support for this pre-release version.
You may encounter build failures or other breakages.
Please create pull-requests instead of filing issues.
==> Cloning https://github.com/crystal-lang/crystal.git
Updating /Users/fibric/Library/Caches/Homebrew/crystal-lang--git
==> Checking out branch master
==> Downloading https://github.com/crystal-lang/crystal/releases/download/0.18.6/crystal-0.18.6-1-darwin-x86_64.tar.gz
Already downloaded: /Users/fibric/Library/Caches/Homebrew/crystal-lang--boot-0.18.6.tar.gz
==> make crystal release=true
Last 15 lines from /Users/fibric/Library/Logs/Homebrew/crystal-lang/01.make:
and by not initializing it here it's not clear if the variable is supposed
to be nilable or if this is a mistake.

To fix this error, either assign nil to it here:

  @stack_top = nil

Or declare it as nilable outside at the type level:

  @stack_top : (Pointer(Void))?

  def initialize(@name : String? = nil, &@proc : ->)
      ^~~~~~~~~~

make: *** [.build/crystal] Error 1

READ THIS: https://git.io/brew-troubleshooting
If reporting this issue please do so at (not Homebrew/brew):
  https://github.com/Homebrew/homebrew-core/issues

Warning: You are using OS X 10.12.
We do not provide support for this pre-release version.
You may encounter build failures or other breakages.
Please create pull-requests instead of filing issues.