[MacPorts] #52742: buildbot: add support for building variants

[MacPorts]

#52742: buildbot: add support for building variants
-----------------------------+---------------------
  Reporter:  mojca           |      Owner:  admin@…
      Type:  enhancement     |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  server/hosting  |    Version:
Resolution:                  |   Keywords:
      Port:  buildbot        |
-----------------------------+---------------------

Comment (by mojca):

 The patches are pretty outdated, but they should give the first
 impression. I wanted to fix the second one, but I should probably write
 some code to parse options between `install-port` and `<portname>` first.

 Some hints by Clemens about how to proceed:
 > `tools/dependencies.tcl` just opens all ports
 > without any specified variants. See `tools/dependencies.tcl` line 66;
 the
 > last parameter to `mportopen`, which is currently `{}`, is the list of
 > variants. The format is easy to create:
 >
 > {{{
 > array set variations {}
 > set variations(quartz) "+"
 > set variations(x11) "-"
 > mportopen ... [array get variations]
 > }}}
 >
 > gives you an mport reference as if the port was installed with
 > `+quartz-x11`. You should be able to find some suitable parsing code for
 > variants given on the command line in `src/port/port.tcl`, line 1695 and
 > following.
 >
 >> Looking at that file I have an impression that we forgot to
 >> consider global settings (`[array get global_variations]`):
 >>
 >> {{{
 >> if {!$index_only} {
 >>     # Add any global_variations to the variations
 >>     # specified for the port (so we get e.g. dependencies right)
 >>     array unset merged_variations
 >>     array set merged_variations [array get variations]
 >>     foreach { variation value } [array get global_variations] {
 >>         if { ![info exists merged_variations($variation)] } {
 >>             set merged_variations($variation) $value
 >>         }
 >>     }
 >> }}}
 >>
 >> This means that even if someone would (theoretically) set up a buildbot
 >> with `+quartz -x11` in configuration file, those setting would probably
 >> be ignored. Or do I misunderstand the concept?
 >
 > Yes, I think the file doesn't handle global variants. I think it's also
 > bad design that `port/port.tcl` has to do the merging of variant specs
 > without at least some library support from `macports1.0`, but that's a
 > story for a different refactoring.


 An additional warning:
 > However, this output will only list positive variants, it will not list
 > default variants that have been explicitly disabled. This might be a
 > problem, because specifying `-x11 +quartz` will just give you a list of
 > all dependencies with `+quartz`, but not without `+x11`, so if a port is
 > written in a way that it does not automatically disable `x11` if
 `+quartz`
 > is given (for example if both are supported simultaneously and `x11` is
 > the default), this might lead to unexpected results. I haven't tested
 > any of this, but we probably should.

--
Ticket URL: <https://trac.macports.org/ticket/52742#comment:1>
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