[MacPorts] #67592: Prevent creation of CoreSimulator caches

[MacPorts]

#67592: Prevent creation of CoreSimulator caches
-------------------------+-----------------------------
 Reporter:  ryandesign   |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:  MacPorts Future
Component:  base         |    Version:  2.8.1
 Keywords:               |       Port:
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 With Xcode 12.2 or later (or possibly 12 or later, but definitely not with
 11.x or earlier versions), something (presumably at least some instances
 of running `xcodebuild`) causes CoreSimulator caches to be created in
 Library/Developer/CoreSimulator/Caches (where this may be the Library
 folder in the user's home directory or the root user's home directory or
 the MacPorts home directory). These caches enable the simulator to run
 non-macOS (iOS, iPadOS, tvOS, watchOS) software. As such, we have no use
 for them in MacPorts. These caches are specific to the versions of the
 non-macOS operating systems supported by the installed version of Xcode.
 Upgrading Xcode causes new versions of the caches to eventually be created
 while the previous ones are not automatically removed. These caches are
 several GiB in size and multiple copies of the caches can get created, in
 each of several Library folders. The presence of these large unneeded
 files has been responsible for numerous instances of buildbot builds
 failing due to lack of disk space. MacPorts base should prevent the
 creation of these useless cache files.

 I reported this problem to Apple in FB9072613 and they advised that the
 creation of the cache files can be prevented by using:

 {{{
 defaults write com.apple.CoreSimulator DisableDyldSharedCache 1
 }}}

 I've done this on the buildbot workers and copied
 $HOME/Library/Preferences/com.apple.CoreSimulator.plist to
 /opt/local/var/macports/home/Library/Preferences and
 /opt/bblocal/var/macports/home/Library/Preferences and will see if this
 prevents the caches from being recreated during the use of MacPorts. If
 not, MacPorts base may need to copy it to
 ${workpath}/.home/Library/Preferences like it already does for
 com.apple.dt.Xcode.plist.

-- 
Ticket URL: <https://trac.macports.org/ticket/67592>
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