Can't compile `lilypond-devel`

[Werner LEMBERG]

[This has already been reported as

   https://trac.macports.org/ticket/58717

 but no solution was found yet.  To have a broader discussion I'm also
 writing to this list.]

[I'm using the current git version of both `macports-base' and
 `macports-port' on macOS 10.7.5; according to the recently posted
 instructions from Joshua I no longer have the lines

   cxx_stdlib            libc++
   default_compilers     macports-clang-5.0

 in my `macports.conf' file.]


The `lilypond-devel' port can only be built with a non-ancient version
of gcc; the Portfile comes with a blacklist to disable all
incompatible compilers and a whitelist to enforce gcc.  Since
approx. two months there are problems with MacPorts – this is, the
unmodified Portfile suddenly fails to work correctly.

I only have `gcc8 @8.3.0_4' installed.

After a successful build and installation, I get the message

  lilypond-devel is using libstdc++
    (this installation is configured to use libc++)

in the `rev-upgrade' phase, which triggers a re-build again and again
until `port install' gives up.

To me, this looks like a bug in `macports-base'...


    Werner