/usr/bin/CC fails to install

Greetings, All.

Running on M1 Mini with case-sensitive file system, /usr/bin/CC pop up a little window telling me to install the CLI utilities. I did so (and About tells me that they are installed along with Xcode 12.4). But invoking /usr/bin/CC pops up the same window again.

Please help.
/usr/bin/CC fails to install
 
 
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