ace: fails to build about legacy-linuxbrew HOT 5 CLOSED

$ brew install ace -d
/home/deploy/linuxbrew/Library/brew.rb: loading /home/deploy/linuxbrew/Library/Formula/ace.rb
Warning: Xcode not installed
Most stuff needs Xcode to build: http://developer.apple.com/xcode/
==> Downloading http://download.dre.vanderbilt.edu/previous_versions/ACE-6.0.3.tar.bz2
Already downloaded: /home/deploy/linuxbrew/Library/Caches/Homebrew/ace-6.0.3.tar.bz2
Warning: MD5 support is deprecated and will be removed in a future version.
Please switch this formula to SHA1 or SHA256.
/home/deploy/linuxbrew/Library/Formula/ace.rb:16:in ``'
Errno::ENOENT: No such file or directory - sw_vers -productVersion
1. raise
2. ignore
3. backtrace
4. irb
5. shell
Choose an action: 3
/home/deploy/linuxbrew/Library/Formula/ace.rb:16:in ``'
/home/deploy/linuxbrew/Library/Formula/ace.rb:16:in `install'
/home/deploy/linuxbrew/Library/Homebrew/build.rb:142:in `block in install'
/home/deploy/linuxbrew/Library/Homebrew/formula.rb:250:in `block in brew'
/home/deploy/linuxbrew/Library/Homebrew/formula.rb:635:in `block in stage'
/home/deploy/linuxbrew/Library/Homebrew/extend/fileutils.rb:21:in `mktemp'
/home/deploy/linuxbrew/Library/Homebrew/formula.rb:631:in `stage'
/home/deploy/linuxbrew/Library/Homebrew/formula.rb:245:in `brew'
/home/deploy/linuxbrew/Library/Homebrew/build.rb:121:in `install'
/home/deploy/linuxbrew/Library/Homebrew/build.rb:43:in `main'
/home/deploy/linuxbrew/Library/Homebrew/build.rb:12:in `block in <top (required)>'