[MacPorts] #56519: libcxx database corrupted, universal broken, weird circular dependency

[MacPorts]

#56519: libcxx database corrupted, universal broken, weird circular dependency
----------------------------+---------------------------------------------
  Reporter:  gaming-hacker  |      Owner:  (none)
      Type:  defect         |     Status:  new
  Priority:  Normal         |  Milestone:
 Component:  ports          |    Version:  2.4.3
Resolution:                 |   Keywords:  libxml2, universal, ghostscript
      Port:  libcxx         |
----------------------------+---------------------------------------------

Comment (by ryandesign):

 It's unclear what is happening here, and how much of it is due to
 modifications you've made to portfiles.

 Could you tell us what version of macOS you're running?

 Replying to [ticket:56519 gaming-hacker]:
 > {{{
 > Error: Cannot install libcxx for the archs 'i386 x86_64' because
 > Error: its dependency libxml2 only supports the arch 'x86_64'.
 > }}}

 This error message seems to be erroneous, because libxml2 has no arch
 restrictions; it builds on any arch. I suppose it could be caused by the
 circular dependency introduced by [https://github.com/macports/macports-
 ports/pull/1853 PR 1853]. MacPorts behavior is undefined when a circular
 dependency exists, so anything could happen.

 > i forced an upgrade to libxml2 by creating a revision 1 and resulting
 error is

 If you mean you edited the libxml2 portfile and increased its revision,
 you should not do that, because that would prevent you from receiving the
 "real" libxml2 @2.9.7_1 if and when we create it in the future. If you
 need to force a port to rebuild from source, the way to do that is e.g.
 `sudo port -ns upgrade --force libxml2`.

-- 
Ticket URL: <https://trac.macports.org/ticket/56519#comment:4>
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