[MacPorts] #55410: gcc7 @7.2.0 does not build on Mac OS X 10.6.8, Snow Leopard, because of "Undefined symbols for architecture x86_64"

[MacPorts]

#55410: gcc7 @7.2.0 does not build on Mac OS X 10.6.8, Snow Leopard, because of
"Undefined symbols for architecture x86_64"
------------------------+--------------------
  Reporter:  ballapete  |      Owner:  (none)
      Type:  defect     |     Status:  new
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:  2.4.2
Resolution:             |   Keywords:
      Port:  gcc7       |
------------------------+--------------------

Comment (by kencu):

 The following quite simple patch makes clang-3.9 work on 10.6.8 as it does
 on newer systems, adding `stdlib=libc++` if there is none specified on the
 build or link line, which is what you want if you have your cxx_stdlib set
 to libc++. However, don't forget you have done this, as it changes default
 behaviour. For that reason I have it as a variant so I can see that I did
 that.
 {{{
 https://github.com/kencu/SnowLeopardPorts/blob/master/lang/llvm-3.9/files/9999
 -patch-clang-3.9-Toolchains-default-always-libcxx.diff
 }}}

 and this installation set is what I use:
 {{{
 https://github.com/kencu/SnowLeopardPorts/tree/master/lang/llvm-3.9
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/55410#comment:10>
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