Making G'MIC Qt GIMP plug-in work in the 2.10.30 Mac version

If you are using the G'MIC-Qt plug-in for GIMP on Mac OS, especially the one from aferrero2707, you may have encountered this error after upgrading to a recent GIMP build:

GIMP says: “Plug-in crashed: "gmic_gimp_qt",” and warns about the dying plug-in possibly messing up GIMP's internal state.

Running GIMP from the Terminal yields a bit more information:

dyld: Library not loaded: @rpath/libintl.9.dylib

  Referenced from: /Users/username/Library/Application Support/GIMP/2.10/plug-ins/gmic_gimp_qt

  Reason: image not found

The Resynthesizer plug-in build from the same author suffers from the same problem.

It seems that these builds of the plug-ins rely on the presence of a dynamic library file ‘libintl.9.dylib,’ most likely in the GIMP application bundle itself. But, my current build of GIMP only includes libintl.8.dylib. Judging from a related issue report on GitLab, there never has been a true version 9 of this library and the number 9 was due to a mistake in the gettext library, which explains why the version number seemingly decreased.

Until someone creates a new build of the plug-ins, there is a relatively straightforward workaround: shove a copy of the libintl file into the G'MIC and Resynthesizer plug-in library folders, and give it the expected name. This ensures the plug-ins will always find this library regardless of what is in the particular build of GIMP.

There are 2 ways to obtain the dylib file:

1. [Slightly harder for those unfamiliar with low-level workings of Mac OS]
   Open your GIMP application bundle (either by right-clicking the app icon, or by using the Terminal), and find the libintl.8.dylib file, normally in Contents/Resources/lib/.
   Copy this file and rename the copy to libintl.9.dylib.
   This works because there is no significant difference between the version 8 and purported version 9 of the file.
2. [Easier but not that safe]
   Directly download it from wherever you find it on the web, and hope it is trustworthy. (This particular one works for me, it is 77584 bytes in size and has an MD5sum of 2a88ed7a2d8901fd0e75401e761b24d2.)

Place the libintl.9.dylib file inside the GMIC/lib folder where you installed the G'MIC plug-in, most likely ~/Library/Application Support/GIMP/2.10/plug-ins/GMIC/lib/, then restart GIMP and it might work.
Same for ResynthesizerPlugin/lib/.