[MacPorts] #50448: Change filenames of binary packages built against libc++ on < 10.9

[MacPorts]

#50448: Change filenames of binary packages built against libc++ on < 10.9
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  Reporter:  mojca        |      Owner:  macports-tickets@…
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  base         |    Version:  2.3.4
Resolution:               |   Keywords:
      Port:               |
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Comment (by RJVB):

 Speaking of quick and "dirty" ways to implement this kind of change: I
 think that can be done using existing mechanisms:

 - the cxx11 PortGroup could detect the presence of a "system" libc++ on OS
 versions where this is not the default.
 - If that library is present, a variant could be set through
 `default_variants`

 Supposing the PortGroup already does all the required additional things
 this should give rise to distinguishable libc++ and libstdc++ packages
 provided there are ditto slaves.

 On user systems this mechanism should have the same effect: after doing
 the conversion to libc++ any port requiring C++11 will set the libc++
 variant by default, and thus request the ditto packages.

 What bothers me here is the case of older C++ software. I'm guessing it
 will continue to work if it only links to system libraries or other ports
 using older C++, but won't it get into trouble if you try to link it with
 a library from a port using the C++11 portgroup?

 In other words, shouldn't the discussion focus on ports using C++, or at
 least on some provision (through a portgroup at first) to toggle the
 default for `configure.cxx_stdlib` persistently when the first port
 requiring libc++ gets installed? (Sic, *installed*, ideally ...)

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Ticket URL: <https://trac.macports.org/ticket/50448#comment:4>
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