[MacPorts] #61584: Use deployment target 10.16 on Big Sur

[MacPorts]

#61584: Use deployment target 10.16 on Big Sur
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 Reporter:  ryandesign   |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  High         |  Milestone:  MacPorts 2.7.0
Component:  base         |    Version:  2.6.4
 Keywords:  bigsur       |       Port:
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 libtool has a bug where it does not recognize MACOSX_DEPLOYMENT_TARGET
 being set to 11 or greater and fails to add the linker flags required to
 suppress undefined symbols, which many ports rely on. (#60794, #60937,
 #61464, #61484, #61485, #61488, but probably also hundreds of others not
 yet reported.)

 Jeremy patched this in the libtool port months ago but I'm not sure if he
 reported it to the developers of libtool. Someone else recently
 [https://debbugs.gnu.org/cgi/bugreport.cgi?bug=44605 reported it to
 libtool] and I have added a reference to Jeremy's patch there but there
 has been no acknowledgement from the developers yet. No recent version of
 libtool generates code that correctly handles deployment target 11, and
 this incorrect code is baked into tons of projects' configure scripts, so
 even once a fixed version of libtool is released it might be years or
 never before the developers of other projects update to a fixed version of
 libtool and release a new version of their software.

 I think we could save ourselves a lot of build failures by having MacPorts
 set the deployment target to 10.16 instead of 11.0 on Big Sur. As far as I
 understand, the compiler/linker/SDK/whatever should treat it identically,
 but it would let the bad libtool code work correctly.

 We have enough other problems to deal with right now (implicit declaration
 of functions) that if we can solve this entire class of problems with a
 couple-line change in MacPorts base I think that would be a win.

-- 
Ticket URL: <https://trac.macports.org/ticket/61584>
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