clang-3.7 software package provides C, C++ and Objective-C compiler (LLVM based), you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install clang-3.7
clang-3.7 is installed in your system.
Make ensure the clang-3.7 package were installed using the commands given below,
$ sudo dpkg-query -l | grep clang-3.7 *
You will get with clang-3.7 package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | clang-3.7 |
| Version | 1:3.7.1-3+b1 [armel], 1:3.7.1- |
| Description | C, C++ and Objective-C compiler (LLVM based) |
| Sub Section | devel |