[MacPorts] #57912: OpenBLAS compilation fails on iMac Pro MacOS 10.13

[MacPorts]

#57912: OpenBLAS compilation fails on iMac Pro MacOS 10.13
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  Reporter:  EJFielding  |      Owner:  NicosPavlov
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.5.4
Resolution:              |   Keywords:
      Port:  OpenBLAS    |
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Comment (by cjones051073):

 I was able to reproduce a very similar issue (with AVX2 not AVX512) by
 removing the patch currently in the Portfile that forcibly disables the
 use of AVX2. This is with the default cctools installed.

 If I installed reinstall cctools with +xcode variable, that at least for
 AVX2 this does fix the problem. The port then builds fine with -mavx2 used
 for both clang and fortran.

 I could be wrong, but I would guess that if this does not work for you,
 with AVX512, then this is a slightly different (but similar) issue.
 Perhaps even the Xcode provided toolkit is not up to handling this latest
 SIMD instruction set. Unfortunately I have no way to test this as I do not
 have access to an AVX512 capable machine.

 Probably though, the fix, at least until the cctools toolkit issues are
 resolved is to also disable AVX512 in the OpenBLAS portfile.

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Ticket URL: <https://trac.macports.org/ticket/57912#comment:17>
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