How to install Clang 11 on Debian

Question

I am trying to compile a C++ project on a PC with "Debian GNU/Linux 10". The project requires clang, so I installed it with:

sudo apt-get install clang

But I run into the following error:

Clang version must be at least 11, the version used is 7.0.1

How can I install clang 11?

Note: I do not want to install the entire LLVM package again. Just want to upgrade Clang from version 7 to 11, preferably via command-line.

Answer 1

I found the solution after some searching. Here is what I did to make it work:

1. Add the following lines to your /etc/apt/sources.list:

deb http://apt.llvm.org/buster/ llvm-toolchain-buster main 
deb-src http://apt.llvm.org/buster/ llvm-toolchain-buster main 
deb http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main 
deb-src http://apt.llvm.org/buster/ llvm-toolchain-buster-10 main 
deb http://apt.llvm.org/buster/ llvm-toolchain-buster-11 main 
deb-src http://apt.llvm.org/buster/ llvm-toolchain-buster-11 main

2. Add signatures for these repos (otherwise apt-get update will complain in the next step)

wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -

3. Run apt-get update to add these new repos to the apt-get:

sudo apt-get update

4. Install clang-11:

sudo apt-get install clang-11

5. Make sure now "clang-11" is used by the compiler and not the older "clang":

export CMAKE_C_COMPILER=clang-11
export CMAKE_CXX_COMPILER=clang++-11

6. Compile your project.
7. Enjoy!

For documentation: https://apt.llvm.org/