[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
--------------------------+----------------------
  Reporter:  kencu        |      Owner:  kencu
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  libcxx       |
--------------------------+----------------------

Comment (by kencu):

 to use dylib linking, you do it like this:
 {{{
 /usr/bin/clang++ -std=c++17 -D_LIBCPP_DISABLE_AVAILABILITY
 -L/opt/local/libexec/llvm-11/lib/
 -Wl,-rpath,/opt/local/libexec/llvm-11/lib/ fstest.cpp
 }}}

 Then the binary comes with this:
 {{{
 $ otool -L a.out
 a.out:
         @rpath/libc++.1.dylib (compatibility version 1.0.0, current
 version 1.0.0)
         /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current
 version 1252.250.1)
 }}}

 The @rpath search path is set correctly:
 {{{
 Load command 12
           cmd LC_LOAD_DYLIB
       cmdsize 48
          name @rpath/libc++.1.dylib (offset 24)
    time stamp 2 Wed Dec 31 16:00:02 1969
       current version 1.0.0
 compatibility version 1.0.0
 Load command 13
           cmd LC_LOAD_DYLIB
       cmdsize 56
          name /usr/lib/libSystem.B.dylib (offset 24)
    time stamp 2 Wed Dec 31 16:00:02 1969
       current version 1252.250.1
 compatibility version 1.0.0
 Load command 14
           cmd LC_RPATH
       cmdsize 48
          path /opt/local/libexec/llvm-11/lib/ (offset 12)
 }}}

 and the binary works:
 {{{
 $ ./a.out
 Displaying path info for: "/Users/kencu"
 path part: 0 = "/"
 path part: 1 = "Users"
 path part: 2 = "kencu"
 exists() = 1
 root_name() = ""
 root_path() = "/"
 relative_path() = "Users/kencu"
 parent_path() = "/Users"
 filename() = "kencu"
 stem() = "kencu"
 extension() = ""
 canonical() = "/Users/kencu"
 path concat/append:
 "C:\\temp/user/data"
 "C:\\temp\\userdata"
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/62426#comment:7>
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