[MacPorts] #51097: gcc5 -- xgcc internal compiler error: Illegal instruction: 4

[MacPorts]

#51097: gcc5 -- xgcc internal compiler error: Illegal instruction: 4
-----------------------+-------------------
  Reporter:  gnwiii@…  |      Owner:  mww@…
      Type:  defect    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:  2.3.4
Resolution:            |   Keywords:
      Port:  gcc5      |
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Comment (by gnwiii@…):

 This is not a gcc bug but a mismatch between the macports binary gmp
 library and older CPU's.  Installing "gmp +core2" should avoid the
 problem.  I think gcc5 is built with "-march=core2", but gmp provides a
 "+core2" variant that was not used to build the macports "officila"
 binaries.

 Several existing GCC bug reports were helpful in understanding the issue:

 [https://gcc.gnu.org/bugzilla/show_bug.cgi?id=6326 GCC Bug #6326] appears
 to be the same underlying bug and was traced to libgmp compiled for a CPU
 that was newer than the one being used to run gcc.

 Another helpful report with a minimal example in C is
 [https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68040 gcc bug 68040] where
 it is suggested:

 {{{
 "This is probably an ICE that occurs earlier than reported with
  `--enabled-checking=release`. Configure with `--enable-checking=yes`."
 }}}

 I created a "gcc5ec" Portfile.  The build failed at the same place, but
 gave a much more useful error message which led me to GCC Bug 6326.

 This is serious issue for macports users because I often hear "macports
 gfortran doesn't work so I installed gfortran from <some unrelable
 source>" which then causes nasty problems for ports that need a particular
 gcc.

 I suggest making "gmp +core2" the default, and adding a gcc* variant
 "+enable-checking" to be used for ICE bug reporting.

-- 
Ticket URL: <https://trac.macports.org/ticket/51097#comment:2>
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