Any reason not to update to Xcode 12.2 on Catalina?

[Peter Hancock]

On 13/11/2020 10:42, Ryan Schmidt wrote:
> On macOS 10.15, you can avoid even more problems by limiting yourself to Xcode 11.7 and the Xcode 11.5 version of the command line tools. Upgrading to Xcode 12 or the Xcode 12 version of the command line tools will cause some ports to fail to build with implicit declaration of function errors or other errors that are a consequence of earlier implicit declaration of function errors. This problem is pervasive and although we have fixed many ports already, there are many many more that have yet to be identified and fixed.

Im on:
Catalina 10.15.7, with Xcode 12.2 (12B45b).
"pkgutil --pkg-info=com.apple.pkg.CLTools_Executables | grep version" gives 
"version: 12.2.0.0.1.1604628099"

I have encountered "This problem".
It was in the port "man" (that I don't actually need, on reflection). 
I found (and can't any longer...) a recent ticket on trac, closed, fixing (on big Sur?) what looked like
the same problem (an undefined use of uint_t in signal.h) but the new version doesn't build for me. 
I'll open a new ticket, with my build log, if that's the right thing to do.

However, I'd like to ask for some general advice/guidance. 
1. My machine won't upgrade beyond Catalina.
2. I need (hopefully) only the Command Line Tools, and that for MacPorts. 
   I seem to have receipts for a whole slew of ancient Xcodes, CLT's etc. It would be a joy to 
   consign them all to the Trash, and somehow to persuade "Software Updates" to 
   shutup scolding me to update to something useless and damaging.
   (ie. causing macports to fail building things actually important to me.)

What version of the CLT's should I download and install from Apple's developer site?
They are described as, eg. "Command Line Tools for Xcode 11.5", suggesting they are no
good to me without Xcode 11.5. 

But would macports, reinstalled if advisable, likely work fine if I first uninstall 
and trash all the other stuff and just install that?
(I anticipate dragging /Applications/Xcode.app" to the trash, and running a script I
found in /Library/Developer/3.0/uninstall-devtools.  I don't mind some lingering
debris if only Software Update will shutup.)