[MacPorts] #54215: gcc7, libgcc: broken on powerpc

[MacPorts]

#54215: gcc7, libgcc: broken on powerpc
---------------------------+----------------------
  Reporter:  mojca         |      Owner:  kencu
      Type:  defect        |     Status:  closed
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:
Resolution:  fixed         |   Keywords:  haspatch
      Port:  gcc7, libgcc  |
---------------------------+----------------------

Comment (by ccorn):

 I agree that {{{gcc6}}} should remain default, although the contrast with
 {{{gcc7}}} is not that stark in my tests. For me, the point is that the
 buildfix itself seems to have introduced its own problems.

 Meanwhile, I have added the variant defs for {{{+defaultabi4}}} and
 {{{+staticlibgcc}}} to the {{{gcc6}}} Portfile, rebuilt {{{libgcc6}}} and
 rebuilt and tested {{{gcc6}}}.

 With {{{gcc6}}}, things are clearer: The variant {{{+staticlibgcc}}}
 causes 24 {{{g++}}} exception-handling testsuite failures not encountered
 with {{{+defaultabi4}}}, no other differences.
 Attaching the diff. This result makes me favor {{{+defaultabi4}}} over
 {{{+staticlibgcc}}}.

 Comparing test summaries of
 * {{{---}}} {{{gcc6+defaultabi4+universal}}}
 * {{{+++}}} {{{gcc7+defaultabi4+universal}}}
 and counting diff patterns yields:
 {{{
 -FAIL: 21
 +FAIL: 111
 -UNRESOLVED: 1
 +UNRESOLVED: 12
 -WARNING: 1
 -XPASS: 1
 +XPASS: 3
 }}}
 That's about one hundred more failures. Attaching the summary diff.

 I also made an incomplete attempt to backport some of the patches in
 {{{patch-darwin-ppc-2017-01-msg02971.diff}}} (the {{{gcc7 buildfix}}}) to
 {{{gcc6}}}. This resulted in 15 //additional// {{{gcc6}}} testsuite
 failures, see (yet another) attached diff. And those failures are present
 in the {{{gcc7}}} test summaries too. I am tempted to conclude that the
 buildfix is not clean (unless the tests themselves are broken).

 So the {{{gcc7}}} build is still in murky waters. {{{gcc6}}} should remain
 default compiler.

--
Ticket URL: <https://trac.macports.org/ticket/54215#comment:42>
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