[MacPorts] #54766: Does port:clang*'s libstdcxx have to be default?

[MacPorts]

#54766: Does port:clang*'s libstdcxx have to be default?
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 Reporter:  RJVB    |      Owner:
     Type:  defect  |     Status:  new
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:
 Keywords:          |       Port:  clang-4.0 clang-5.0
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 Since a while the clang ports have a libstdcxx variant allowing to tell
 clang-mp* to use the libstdc++ provided by MacPorts.

 That adds a dependency on gcc6, which I think is a rather significant and
 IMHO inacceptable large cost at the behest of what I think must be the
 needs of a relative minority of MacPorts users.

 If I understand correctly the goal is just to add an option to the -stdlib
 argument (`-stdlib=macports-libstdc++`). I haven't tried this, but that
 option shouldn't require `port:libgcc` (sic!) as a runtime dependency
 (sic!) to be installed. After all, stock clang should already support
 `-stdlib=libstdc++`, and the port doesn't impose a gcc dependency for
 that. Rather, a build with that option will simply fail if no libstdc++ is
 present.

 I know that -stdlib=libstdc++ does more than adding -lstdc++ to the linker
 options but IMHO it should be treated the same as far as compiler port
 dependencies are concerned. If some port requires using libstdc++ and
 needs to invoke clang with `-stdlib=macports-libstdc++` it should also
 take care to add port:libgcc to its dependencies.

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Ticket URL: <https://trac.macports.org/ticket/54766>
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