How to insist on only clang, for world/kernel?

[Chris H]

Greetings,
 A recent build/install world/kernel on a fresh 9-STABLE.
I was surprised to see that, while clang was also built,
gcc was used to perform the build for at least world.
I performed some research to definitively determine the
magic incantation for at least src.conf(5). However, I
found too many possibilities to be sure. So I'm here
to beg for the answer.

The most likely candidates I have so far

FAVORITE_COMPILER=clang
MAKE_COMPILER_TYPE=clang
WITH_CLANG=true
CC=clang
CXX=clang++
CPP=clang-cpp

Thanks you.

--Chris

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