[MacPorts] #52002: lilypond build fails due to missing reference to libc++ on some Darwin systems - fix attached

[MacPorts]

#52002: lilypond build fails due to missing reference to libc++ on some Darwin
systems - fix attached
-------------------------------------+--------------------
  Reporter:  kenneth.f.cunningham@…  |      Owner:  snc@…
      Type:  defect                  |     Status:  closed
  Priority:  Normal                  |  Milestone:
 Component:  ports                   |    Version:  2.3.4
Resolution:  fixed                   |   Keywords:
      Port:  lilypond                |
-------------------------------------+--------------------

Comment (by ryandesign@…):

 Replying to [comment:8 kenneth.f.cunningham@…]:
 > Replying to [comment:7 ryandesign@…]:
 > > libc++ isn't the default C++ library on Snow Leopard.
 >
 > The crux of the issue. Much current software will assume libc++ is the
 default, and not specifically link it.

 Certainly, much current software will assume C++11 features are available
 in the C++ library. That's fine. Software developers are certainly free to
 make that decision for their own projects.  If we offer that software in
 MacPorts, we will use the cxx11 1.0 port group to indicate this
 requirement.


 > I wonder if this can be changed somewhere in the guts of the clang-3.7
 linker scripts where mortals should not venture...

 There's nothing really to be changed there. The compiler and linker must
 respect the operating system's choice of default C++ library,  unless told
 to do otherwise.


 > > The other system where it worked was also using Snow Leopard?
 >
 > No - one of my El Cap machines.

 Then that makes perfect sense, since El Capitan defaults to libc++.

 The problem is that MacPorts informs the lilypond build system that it
 should use libc++, by way of adding the `-stdlib=...` flag to CXXFLAGS,
 and lilypond's build system is ignoring that request during the link step.
 The lilypond build system needs to be fixed to respect the value of
 CXXFLAGS at every step that involves C++ files.

-- 
Ticket URL: <https://trac.macports.org/ticket/52002#comment:9>
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