[MacPorts] #44129: cmake: fix build against libc++ on Lion

[MacPorts]

#44129: cmake: fix build against libc++ on Lion
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  Reporter:  mojca@…  |      Owner:  michaelld@…
      Type:  defect   |     Status:  new
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:
Resolution:           |   Keywords:  lion
      Port:  cmake    |
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Comment (by michaelld@…):

 Mojca: thanks & understood & agreed. It would be fascinating, but there's
 only so much time in the day. Interesting results; I was not expecteding
 clang++-mp-3.4 to fix an issue with libc++; just to use it. Maybe I don't
 understand how MP builds clang / llvm &  hence how it uses libcxx /
 libc++. Anyway, if what you say is universally true, then it seems like we
 could do the following in the cmake Portfile:
 {{{
 # when using libc++, require Clang 3.4 or newer; Clang 3.3 produces
 # bad stream reading code. See also MP ticket #44129:
 # < https://trac.macports.org/ticket/44129 >

 if {${configure.cxx_stdlib} eq "libc++"} {
     compiler.blacklist-append *gcc* {clang < 500} macports-clang-3.3
     compiler.fallback-append macports-clang-3.4 macports-clang-3.5
 }
 }}}

 Is the fallback really necessary? Could also use whitelist.

 I don't think we need a "platform darwin 11" around that, since it's
 universally true; maybe around the fallback list only?

-- 
Ticket URL: <https://trac.macports.org/ticket/44129#comment:27>
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