Hi,

This is pretty frustrating to be honest, why is the build process downloading a compiler when it is already installed?

Ubuntu 19.04

The issue:
$ cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=release -DCMAKE_EXPORT_COMPILE_COMMANDS=YES
-- The CXX compiler identification is GNU 8.3.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Using downloaded Clang
-- Downloading Clang 7.0.0 (https://releases.llvm.org/7.0.0/clang+llvm-7.0.0-x86_64-linux-gnu-ubuntu-14.04.tar.xz) ...

But clang-7 is already installed:
$ apt policy clang-7
clang-7:
Installed: 1:7.0.1-8
Candidate: 1:7.0.1-8
Version table:
*** 1:7.0.1-8 500
500 http://gb.archive.ubuntu.com/ubuntu disco/universe amd64 Packages
100 /var/lib/dpkg/status

Why can't the build process just use the installed version?

Thanks,
Richard.