[MacPorts] #62426: libc++: using a newer libc++ to build software on older macos systems

[MacPorts]

#62426: libc++: using a newer libc++ to build software on older macos systems
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  Reporter:  kencu                   |      Owner:  kencu
      Type:  enhancement             |     Status:  closed
  Priority:  Normal                  |  Milestone:
 Component:  ports                   |    Version:
Resolution:  fixed                   |   Keywords:
      Port:  libcxx macports-libcxx  |
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Comment (by RJVB):

 I'll play around with this, but using the newest llvm versions I have
 installed (9 and 12). Do you prevent the availability check in these
 tests, and have you tried with the PER_TU macro discussed above?

 Why is libc++ being built and installed with the newer clang versions?
 From what I understand it shouldn't be used and will not under normal
 circumstances provide new functionality anyway?

 BTW, did you notice that you have both

 `       /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current
 version 1.0.0)`

 and

 `/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version
 1200.3.0)`

 (look at the current_version!) which seems a bit odd?

 I realise that Apple's stubborn use of unrelated version numbers could
 wreak havoc on appropriate use of self-built library versioning; do we
 have a table mapping their version numbers to/from the stock LLVM/libc++
 versions?

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Ticket URL: <https://trac.macports.org/ticket/62426#comment:66>
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