Thanks for your reply. See my replies below.
It’s possible. I used Migration Assistant to copy files, about 750GB, from my 2015 MacBook Pro to my new 2018 MacBook Pro. Various things didn’t work right, so I reinstalled both XCode and XQuartz 2.7.11. I did not delete the existing XQuartz before reinstalling, so that would probably be where the overwrite occurred.
What's the output of 'codesign -vvv -d /opt/X11/lib/libXft.2.dylib’?
Executable=/opt/X11/lib/libXft.2.dylib
Identifier=libXft.2
Format=Mach-O universal (i386 x86_64)
CodeDirectory v=20200 size=808 flags=0x0(none) hashes=21+2 location=embedded
Hash type=sha256 size=32
CandidateCDHash sha1=ea79e144d73ab253e83f9c4274a98a2eee12930e
CandidateCDHash sha256=964d0ca307ce031fd4f16346419e4906ed54ac8f
Hash choices=sha1,sha256
CDHash=964d0ca307ce031fd4f16346419e4906ed54ac8f
Signature size=8927
Authority=Developer ID Application: Apple Inc. - XQuartz (NA574AWV7E)
Authority=Developer ID Certification Authority
Authority=Apple Root CA
Timestamp=Oct 29, 2016 at 1:02:09 AM
Info.plist=not bound
TeamIdentifier=NA574AWV7E
Sealed Resources=none
Internal requirements count=1 size=168
Why do you have /usr/bin/xterm on your system?
It’s a different code, not part of XQuartz, which was sent to me by a friend, who thought it might be a workaround for the XQuartz problem. It didn’t solve the problem. I could delete it.
My hope is that you will send me detailed instructions for deleting and reinstalling XQuartz.
Alan