[MacPorts] #62004: openmpi-default should not offer gcc variants on platforms that do not support them (was: gnuplot fails to build under Catalina because gcc49 is not supported with Xcode 9 or greater)

[MacPorts]

#62004: openmpi-default should not offer gcc variants on platforms that do not
support them
------------------------------+--------------------
  Reporter:  cwmccurdy        |      Owner:  (none)
      Type:  defect           |     Status:  new
  Priority:  Normal           |  Milestone:
 Component:  ports            |    Version:
Resolution:                   |   Keywords:
      Port:  openmpi-default  |
------------------------------+--------------------
Changes (by jmroot):

 * port:   => openmpi-default


Old description:

> After installing Macports for Catalina, gnuplot build failed because it
> was trying to build gcc49.  This happened after an operating system
> update and having uninstalled and clean the old gnuplot from macports.
> The error is:
>
> sudo port install gnuplot
> Password:
> --->  Computing dependencies for gnuplot
> --->  Cleaning gnuplot
> --->  Scanning binaries for linking errors
> --->  Found 131 broken files, matching files to ports
> Warning: No port llvm-3.8 found in the index; can't rebuild
> --->  Found 1 broken port, determining rebuild order
> You can always run 'port rev-upgrade' again to fix errors.
> The following ports will be rebuilt: openmpi-default @1.10.3+gcc49
> Continue? [Y/n]: y
> Warning: Your DNS servers incorrectly claim to know the address of
> nonexistent hosts. This may cause checksum mismatches for some ports. See
> this page for more information:
> <https://trac.macports.org/wiki/MisbehavingServers>
> --->  Fetching distfiles for gcc49
> Error: building gcc49 is not supported with Xcode 9 or greater
> Error: Failed to fetch gcc49: unsupported platform

New description:

 After installing Macports for Catalina, gnuplot build failed because it
 was trying to build gcc49.  This happened after an operating system update
 and having uninstalled and clean the old gnuplot from macports.  The error
 is:
 {{{
 sudo port install gnuplot
 Password:
 --->  Computing dependencies for gnuplot
 --->  Cleaning gnuplot
 --->  Scanning binaries for linking errors
 --->  Found 131 broken files, matching files to ports
 Warning: No port llvm-3.8 found in the index; can't rebuild
 --->  Found 1 broken port, determining rebuild order
 You can always run 'port rev-upgrade' again to fix errors.
 The following ports will be rebuilt: openmpi-default @1.10.3+gcc49
 Continue? [Y/n]: y
 Warning: Your DNS servers incorrectly claim to know the address of
 nonexistent hosts. This may cause checksum mismatches for some ports. See
 this page for more information:
 <https://trac.macports.org/wiki/MisbehavingServers>
 --->  Fetching distfiles for gcc49
 Error: building gcc49 is not supported with Xcode 9 or greater
 Error: Failed to fetch gcc49: unsupported platform
 }}}

--

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Ticket URL: <https://trac.macports.org/ticket/62004#comment:2>
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