bug#44605: Support MACOSX_DEPLOYMENT_TARGET=11.0

[Ryan Schmidt]

On Nov 12, 2020, at 13:39, Isuru Fernando wrote:

> I noticed that when MACOSX_DEPLOYMENT_TARGET=11.0 is set "-Wl,-undefined" 
> flag is not set
> because of a check in m4/libtool/m4 at 
> http://git.savannah.gnu.org/cgit/libtool.git/tree/m4/libtool.m4?id=b9b44533fbf7c7752ffd255c3d09cc360e24183b#n1074
> that only checks for 10.*. A fix would be to check for both 10.* and 11.*
> 
> I can send a patch if you prefer.

An Apple engineer patched this problem in the MacPorts libtool port this way:

https://github.com/macports/macports-ports/blob/ecad44f48d8ccd74e7c2fbb86c6b0ad2c9856b78/devel/libtool/files/dynamic_lookup-11.patch

We have been needing to copy similar patches to many other ports since their 
configure scripts were infected with the problem when they were baked.

However please see my additional comments here about a change needed for 
PowerPC:

https://github.com/macports/macports-ports/commit/ecad44f48d8ccd74e7c2fbb86c6b0ad2c9856b78#r41264904

Hopefully someone else can look at both the original patch and my modification 
and come to a conclusion about what is the right fix to include in libtool.

Then hopefully a new release of libtool can be made quickly, since macOS 11 has 
been publicly released and this problem affects a *lot* of software.