[MacPorts] #49903: libcxx: undo changes to system directories when deactivating

[MacPorts]

#49903: libcxx: undo changes to system directories when deactivating
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  Reporter:  ryandesign@…  |      Owner:  jeremyhu@…
      Type:  enhancement   |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.3.4
Resolution:                |   Keywords:
      Port:  libcxx        |
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Comment (by jeremyhu@…):

 The reason that the port is setup this way is to specifically prevent
 deactivation from removing contents of system directories.  What you
 suggest could be *extremely* dangerous, especially if some bug causes that
 code to accidentally remove them in the Lion+ case.

 libc++ and libc++abi first appeared in Lion, so that is why the ports
 default to +replacemnt_libcxx on SL and earlier and -replacemnt_libcxx on
 Lion and later.  The port never replaces system files on its own.  On
 Lion+, we tell the users that if they want to replace the system
 libraries, they should use darwinup to do so, so darwinup can be used to
 roll back their changes.  On SL-, we just update the host ourselves using
 the same technique (tarball root rather than destroot directly) because of
 this case:

 1. User installs libcxx on Snow Leopard
 2. User updates to Lion+
 3. User uninstalls all ports in order to update them

 We specifically don't want to remove the (now-system-provided)
 libc++abi.dylib and libc++.dylib

 The disk space cost of having 2 dylibs (libc++abi and libc++) that the
 user might not need any more on their system is far less than the
 potential risk of things going wrong because we removed the dylibs.

 I'd feel more comfortable giving instructions in deactivate than actually
 doing the work there.  Would that be acceptable?

-- 
Ticket URL: <https://trac.macports.org/ticket/49903#comment:3>
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