```ruby
require 'formula'

class Qca < Formula
  homepage 'http://delta.affinix.com/qca/'
  url 'http://delta.affinix.com/download/qca/2.0/qca-2.0.3.tar.bz2'
  sha1 '9c868b05b81dce172c41b813de4de68554154c60'

  depends_on 'qt'

  def install
    system "./configure", "--prefix=#{prefix}", "--disable-tests"
    system "make install"
  end
end
```

Add QCA patch to allow compiling with clang
user
```ruby
require 'formula'

class Qca < Formula
  homepage 'http://delta.affinix.com/qca/'
  url 'http://delta.affinix.com/download/qca/2.0/qca-2.0.3.tar.bz2'
  sha1 '9c868b05b81dce172c41b813de4de68554154c60'

  depends_on 'qt'

  def patches
    # Fix for clang adhering strictly to standard, see http://clang.llvm.org/compatibility.html#dep_lookup_bases
    # See upstream report: https://bugs.kde.org/show_bug.cgi?id=307470
    'https://gist.github.com/raw/3789382/516de8476304822634db5f305e209420eadd623d/qca-2.0.3-clang-fix'
  end

  def install
    system "./configure", "--prefix=#{prefix}", "--disable-tests"
    system "make install"
  end
end
```
assistant