Don't rely on CC/CXX: it make it seems like a specific version could be used (CC=clang-18 make), but the actual value is ignored and overridden with clang (same for CXX). And while make CC=clang-18 is honored, this result in ccache support being partially disabled.
Instead, use a custom dedicated variable: USE_CLANG.
Don't rely on
CC/CXX: it make it seems like a specific version could be used (CC=clang-18 make), but the actual value is ignored and overridden withclang(same forCXX). And whilemake CC=clang-18is honored, this result in ccache support being partially disabled.Instead, use a custom dedicated variable:
USE_CLANG.This change is