[MacPorts] #56817: `port activate`: error selecting already active variant

[MacPorts]

#56817: `port activate`: error selecting already active variant
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 Reporter:  chrstphrchvz  |      Owner:  (none)
     Type:  defect        |     Status:  new
 Priority:  Normal        |  Milestone:
Component:  base          |    Version:  2.5.3
 Keywords:                |       Port:
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 If there are multiple variants of a port installed, using `port activate
 portname` brings up an interactive prompt to select which variant to
 activate. If the one marked `(active)` is selected, it exits with an
 `Image error`. However, if there was only one variant installed, there is
 no prompt and no error, so this behavior is somewhat inconsistent.

 As discussed with jmr_mp this morning on IRC:

 {{{
 Sunday, July 15th, 2018 (CDT)
 1:35 AM <chrstphrchvz> I notice that activating an already-active port
 with one variant installed exits without error, but activating an already
 active variant of a port with multiple variants installed exits *with* an
 error. Is this right?
 4:06 AM <jmr_mp> chrstphrchvz: with or without specifying which one you
 mean unambiguously?
 4:28 AM <chrstphrchvz> jmr_mp, Unambiguously? I'm not sure I understand.
 To clarify, if I run `port activate portname` and am prompted with a list
 of installed variants, it will error if I select the one marked `active`
 4:43 AM <jmr_mp> chrstphrchvz: ah, interactive mode - yeah that sounds
 like a bug
 4:44 AM if you say 'port activate portname' in a non-interactive context,
 that's ambiguous when there is more than one version of portname
 installed, and an error is appropriate
 4:45 AM the solution being to say portname @1.0_0+foo or whatever instead
 4:49 AM interactive mode gets to resolve the ambiguity with user input, so
 it shouldn't ever error for that reason
 4:49 AM it arguably shouldn't even offer the one that's currently active
 4:50 AM although then you might accidentally activate a version you didn't
 really want active, if it just assumed the inactive one
 4:51 AM (in the case where there's only one active and one inactive)
 4:57 AM <chrstphrchvz> jmr_mp: ahh, I was missing the `@version`, so that
 led to the promot. Though it probably is nice for the prompt to indicate
 which variant is currently active
 4:58 AM <jmr_mp> yeah, should probably just be labelled a bit differently
 4:58 AM anyway definitely shouldn't error because you selected one of the
 choices offered
 }}}

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Ticket URL: <https://trac.macports.org/ticket/56817>
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