[MacPorts] #54773: port:libgcc/port:gcc7: proposed modifications, efficiency + libc++ support

[MacPorts]

#54773: port:libgcc/port:gcc7: proposed modifications, efficiency + libc++ support
--------------------------+----------------------
  Reporter:  RJVB         |      Owner:
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:  haspatch
      Port:  gcc7 libgcc  |
--------------------------+----------------------

Comment (by RJVB):

 Replying to [comment:23 jeremyhu]:

 > I'm confused.  Why would only one of them install the gcc runtime
 libraries into lib/libgcc?  Where would the other install the runtime?
 That doesn't really make sense to me.  Both should be conflicting as they
 should both be providing the gcc runtime in lib/libgcc.

 I must have been a bit confused too, under the assumption one could have
 libgcc6 installed in parallel to libgcc but that's clearly not the case.

 I *thought* that the latest version I just uploaded avoided the whole
 issue because it doesn't change the dependency structure.
 port:gcc+with_libgcc still  depends on port:libgcc . This is a
 surprisingly hard one to get my head around.

 It's becoming clear to me that we probably shouldn't add a +with_libgcc
 variant to all gcc ports but only to the newest stable release (gcc7)
 and/or the next release (gcc8). I'll go back to the drawing board after a
 night's sleep and see how complex the code is going to be to declare the
 appropriate conflicts. The most elegant approach would be that gcc8
 doesn't support the +with_libgcc variant if gcc7 is installed with it and
 vice versa.

 Do we even know if port:gcc8 works with port:libgcc instead of port
 :libgcc-devel?

 If this becomes too complex I'll drop the whole +with_libgcc idea. The
 "full" port:libgcc took 15 minutes to build, which is almost reasonable.

 > It should work with a deployment target of 10.7 and up as the system
 provided TLS natively in Lion.  You can see this with:

 Thanks. So I was a bit pessimistic with my (lazy) estimation that 10.8 was
 the earliest possible version where a non-bootstrap build would work.

--
Ticket URL: <https://trac.macports.org/ticket/54773#comment:24>
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