[MacPorts] #65934: mesa @22.1.7 +tests requires added link library to libunwind on PPC Leopard, Mac OS X 10.5.8

[MacPorts]

#65934: mesa @22.1.7 +tests requires added link library to libunwind on PPC
Leopard, Mac OS X 10.5.8
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  Reporter:  ballapete  |      Owner:  (none)
      Type:  defect     |     Status:  new
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:  2.7.2
Resolution:             |   Keywords:  leopard ppc
      Port:  mesa       |
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Comment (by kencu):

 So I think the reason that the link to the libunwind library is needed
 here is that the libunwind-headers are installed, and the build is picking
 up those headers, which then reference certain symbols that exist in
 libunwind.dylib but not in the system gcc unwinder. If the libunwind-
 headers port was not installed, then the link to libunwind.dylib would
 likely not be needed. This is to be explicitly verified, but appears
 likely.

 The reason we have libunwind at all is to allow certain Apple software
 like cctools, ld64, and probably llvm/clang/etc to find the unwinding
 symbols that are assumed to be there.

 Iain points out that this is both fragile and highly likely to be broken;
 you have to have one unwinder in use.

 So we may be in a situation where we build and install libunwind
 /libunwind-headers to allow other things to build, knowing that in so
 doing we are actually breaking unwinding.

-- 
Ticket URL: <https://trac.macports.org/ticket/65934#comment:15>
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