Modifying the PortInfo data from a PortGroup?

[René J . V . Bertin]

Hi,

I'm experimenting with an idea for my Linux adaptation of MacPorts "base" and 
apparently need some insights on the internal implementation. No risk for this 
to taint the Mac version!

The idea is to add a global variant like +universal, ultimately via 
portutil.tcl but for the time being in a PortGroup. This variant would conflict 
with any variant individual ports might declare, so I was hoping to modify 
those variants in a callback.
Conflicts are stored in $PortInfo(vinfo)($currentVariant)(conflicts) (assuming 
that's the correct way to address an element of an array that's an element of 
an array itself also stored in a toplevel array), and I managed to modify it in 
a way that shows up via `port variants`:

{{{
platform linux {
    variant testIdea description {Some fancy new experiment.} {}
    set newVariantName testIdea
}

proc LTO::callback {} {
    # this callback could really also handle the disable and allow switches!
    global supported_archs LTO.must_be_disabled
    global PortInfo newVariantName
    platform linux {
        if {[variant_exists ${newVariantName}] && [info exist 
PortInfo(variants)] && [info exists PortInfo(vinfo)]} {
            array unset vinfo
            array set vinfo $PortInfo(vinfo)
            foreach v $PortInfo(variants) {
                array unset variant
                array set variant $vinfo(${v})
                if {[info exists variant(conflicts)]} {
                    ui_debug "${v}: conflicts with $variant(conflicts), adding 
+${newVariantName}"
                    set conflicts [join [lsort "$variant(conflicts) 
${newVariantName}"]]
                } else {
                    ui_debug "${v}: adding conflict with +${newVariantName}"
                    set conflicts "${newVariantName}"
                }
                array set variant [list conflicts ${conflicts}]
                array set vinfo [list ${v} [array get variant]]
                array set PortInfo [list vinfo [array get vinfo]]
            }
        }
    }
#snip
}}}

{{{
> port -v variants openssl
openssl has the variants:
   LTO: build with link-time optimisation
     * conflicts with testIdea
   builtwith: Label the install with the compiler used
     * conflicts with testIdea
   cpucompat: Build using some commonly supported SIMD settings for optimal 
cross-CPU tuning
     * conflicts with cputuned testIdea
   cputuned: Build using -march=native for optimal tuning to your CPU
     * conflicts with cpucompat testIdea
   docs: install (html) documentation
     * conflicts with testIdea
   testIdea: Some fancy new experiment.
     * conflicts with testIdea
   use_lld: use the LLD linker
     * conflicts with testIdea
}}}

However, while this doesn't break existing conflict situations it does not 
actually add a functional new conflict:

{{{
> port -v variants openssl +cputuned+cpucompat
Error: openssl: Variant cputuned conflicts with cpucompat
Error: Unable to open port: Error evaluating variants
}}}

{{{
> port -v variants openssl +cputuned+testIdea
openssl has the variants:
   LTO: build with link-time optimisation
     * conflicts with testIdea
   builtwith: Label the install with the compiler used
     * conflicts with testIdea
   cpucompat: Build using some commonly supported SIMD settings for optimal 
cross-CPU tuning
     * conflicts with cputuned testIdea
  +cputuned: Build using -march=native for optimal tuning to your CPU
     * conflicts with cpucompat testIdea
   docs: install (html) documentation
     * conflicts with testIdea
  +testIdea: Some fancy new experiment.
     * conflicts with testIdea
   use_lld: use the LLD linker
     * conflicts with testIdea
}}}

My initial idea was that `PortInfo` might be a copy so modifying it would be 
pointless, but that seems unlikely since the modifications show up via `port 
variants`.

Am I overlooking something, or should I simply do the conflict detection 
myself? I realise that might be needed anyway since IIRC the `default_variants` 
feature also doesn't play nice with declared variant conflicts.

Thanks in advance,
R.