[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 kenneth.f.cunningham@…):

 Hi Ryan, - as you suspected, adding that line to the linker flags
 {{{
 configure.ldflags-append -stdlib=${configure.cxx_stdlib}
 }}}
 also allows lilypond to link. Without this line, the link fails. As you
 say, that is the more usual linker flag to add, so I'll use that from now
 on rather than "-lc++" (which also works, and I guess in the end does the
 same thing making libc++ available for linking, although admittedly less
 elegantly and less clearly.

 I don't yet understand why it is needed for only some ports, though --
 unless their configure scripts are just incorrectly / incompletely
 written.

 Isn't it the case that libc++ should be one of the 'automatically' linked
 libraries, not usually needing to be specifically added? Perhaps that is
 what lilypond and other ports are expecting.  I don't know if that's what
 the issue is here - some ports need this line added to link, others do
 not. The same port installs on a different system without modification to
 the portfile. Maybe with the libstdc++ and libc++ dichotomy on this libc++
 upgraded machine, macports-clang-3.7++ is getting "confused" about which
 standard libraries to automatically link in, and is linking in the wrong
 one, or none?

 I'm over my head at this point.

-- 
Ticket URL: <https://trac.macports.org/ticket/52002#comment:6>
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