[MacPorts] #59292: base request: have a method to prepopulate environment variables for the build and destroot phases

[MacPorts]

#59292: base request: have a method to prepopulate environment variables for the
build and destroot phases
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 Reporter:  kencu        |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  base         |    Version:
 Keywords:               |       Port:
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 When setting up a port for a build, base does a very careful job of pre-
 populating the environment variables prior to running `./configure` with
 carefully planned out defaults.

 Appropriately, base does not by default recalculate and reset all those
 environment variables prior to the build phase, in deference to what the
 `./configure` script has set up. This has worked well for many years.

 However, there are quite a few ports that do not run a `./configure`
 phase, and those builds enter the build phase with a very empty set of
 environment variables. As things have become more complicated with
 building ports in general, the deficiencies in building these ports has
 become more obvious.

 So I'd like to suggest that in cases where ports are not using a configure
 phase, having base prepopulate the build (and perhaps destroot)
 environment variables with same defaults it sets up prior to the
 `./configure` phase could be very helpful.

-- 
Ticket URL: <https://trac.macports.org/ticket/59292>
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