[MacPorts] #58898: libcxx bootstrapping needs a method to upgrade to the +emulatedtls variant on 10.6 and less

[MacPorts]

#58898: libcxx bootstrapping needs a method to upgrade to the +emulatedtls variant
on 10.6 and less
---------------------------------------+----------------------
 Reporter:  kencu                      |      Owner:  kencu
     Type:  defect                     |     Status:  assigned
 Priority:  Normal                     |  Milestone:
Component:  ports                      |    Version:
 Keywords:  snowleopard leopard tiger  |       Port:  libcxx
---------------------------------------+----------------------
 during automatic bootstrapping of 10.6 and less, `libcxx` is installed as
 a first step, building with `clang-3.4`.

 As `clang-3.4` does not support building `libcxx +emulatedtls`, `libcxx`
 is first built without `+emulatedtls`. The process then leads to the
 installation of `clang-5.0` or greater, and these compilers do support
 building `libcxx +emulatedtls`.

 The `libcxx` Portfile will build `libcxx +emulatedtls` if a suitable
 compiler is installed that can build it, but it presently requires a
 manual rebuild to force the upgrade.

 For a fully functional older system, this upgrade should be automatic.

 One option might be to put a revision increase by 1 in the Portfile, in
 the block that tests if `libcxx +emulatedtls` can be built and enables it
 if so.

-- 
Ticket URL: <https://trac.macports.org/ticket/58898>
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