[MacPorts] #56369: github portgroup: don't override an already-specified version

[MacPorts]

#56369: github portgroup: don't override an already-specified version
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 Reporter:  ryandesign  |      Owner:  (none)
     Type:  defect      |     Status:  new
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:
 Keywords:              |       Port:
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 Perry recently [changeset:84e569d946c51794090465c7841c2b96e7aba1ca
 /macports-ports encountered the need] to write the following in a
 Portfile:

 {{{
 set                 _version 1.13
 github.setup        xavierleroy cryptokit [string map {. ""} $_version]
 release
 version             $_version
 }}}

 That is, the developers created the version number in the tag name lossily
 from the real version (the period was removed). Perry wanted to specify
 the real version, and compute the lossy tag version from that. But
 `github.setup` unconditionally sets `version` from that. Perry wanted that
 to be changed, so that, much as it already only sets `name` if the name
 has not already been set, it should only set `version` if the version has
 not already been set.

 It would have to be handled in the portgroup the same unusual way that
 setting `name` is handled, using `PortInfo`, because doing it the expected
 way, using `default`, does not work correctly, for reasons I have not
 fully understood. I will attach a patch of that as an example, but it
 should not be committed yet; see below.

 The more important problem is that, although the github portgroup was
 designed with the intention that `github.setup` would be invoked exactly
 once in any portfile, portfile authors have taken to running it once in
 each subport instead. And specifically, there are cases where it is called
 once unconditionally at the top of the portfile to set the main port's
 version, and then called a second time in a -devel subport to override the
 version for the subport. An example of such a port is cantera. If we were
 to implement Perry's suggestion, this usage would break, and those
 subports would then be at the wrong version.

 We either cannot implement the suggestion, or we need to identify all of
 the portfiles where `github.setup` will be called more than once and
 change them so that they no longer do that. After that is done, we could
 also modify the github portgroup to print an error if `github.setup` is
 called a second time.

 Whatever we do for the github portgroup should also be done for the
 bitbucket portgroup.

-- 
Ticket URL: <https://trac.macports.org/ticket/56369>
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