[MacPorts] #53226: gcc5 @5.4: error: 'std::log2' has not been declared (was: PowerMac, GCC 5.4 and "error: 'std::log2' has not been declared")

[MacPorts]

#53226: gcc5 @5.4: error: 'std::log2' has not been declared
-----------------------+----------------------
  Reporter:  noloader  |      Owner:  mww@…
      Type:  defect    |     Status:  assigned
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:  2.3.5
Resolution:            |   Keywords:  powerpc
      Port:  gcc5      |
-----------------------+----------------------
Changes (by ryandesign):

 * status:  new => assigned
 * cc: ryandesign (added)
 * owner:   => mww@…
 * keywords:  c++11 cmath log2 => powerpc
 * port:  g++-mp-5 => gcc5


Comment:

 I'm the one who has been updating the gcc ports for a few years, but I
 don't know C++ or the internals of gcc well enough to be able to help you
 with this. Markus is the maintainer, but he has been unresponsive for
 awhile. I suggest you test with gcc6 and gcc7. If the problem persists
 there, report the problem to the developers of gcc directly.

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Ticket URL: <https://trac.macports.org/ticket/53226#comment:2>
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