llvm-3.7 release and OpenMP

[Sean Farley]

Jeremy Huddleston Sequoia <jeremyhu at macports.org> writes:

>> On Sep 3, 2015, at 09:21, Jack Howarth <howarth.at.macports at gmail.com> wrote:
>> 
>>   You really will want to rewrite the llvm37 Portfile to use a cmake
>> build.
>
> Not unless we can depend on cmake existing out-of-tree.  If we need to depend on port:cmake, that introduces cycles.


How? I only see these as dependencies for cmake:

$ port rdeps cmake
The following ports are dependencies of cmake @3.3.1_0:
  curl
    pkgconfig
      libiconv
        gperf
    zlib
      xz
        gettext
          expat
          ncurses
    openssl
    curl-ca-bundle
      perl5
        perl5.16
          gdbm
  bzip2
  libarchive
    libxml2
    lzo2

I see that libomp depends on cmake but cmake doesn't depend on libomp
nor llvm so how is it a cycle?