[MacPorts] #70257: isl, isl-devel are not substitutes: gcc* ports, perhaps, need explicit variants instead of path-style dependency

[MacPorts]

#70257: isl, isl-devel are not substitutes: gcc* ports, perhaps, need explicit
variants instead of path-style dependency
-------------------------+-------------------------------------------------
 Reporter:               |      Owner:  (none)
  barracuda156           |
     Type:  defect       |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:  2.9.3
 Keywords:               |       Port:  gcc13, gcc12, gcc11, isl, isl-devel
-------------------------+-------------------------------------------------
 gcc* ports treat `isl` and `isl-devel` as substitutes, however if you
 build libgcc against `isl-devel` and then activate `isl` instead, the port
 is broken, since `libisl` version does not match. I did not check the
 reverse case.

 Also, FWIW, I could not build gcc6 earlier against `isl-devel`.

 It looks like we should rather make two co-existing `isl` ports or at
 least make conflicting variants for gcc* ports, so that the port remembers
 which `isl` is was built against.

 What do you think?

-- 
Ticket URL: <https://trac.macports.org/ticket/70257>
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