Clang/LLVM with its more permissive licence sees _much_ wider use and is written purely in C++. PlayStation, automotive, platforms and runtimes like Chromium/V8, Android, etc. are all built with Clang.
With Android, iDevices, PlayStation, Switch, and everyone that had proprietary compilers down using downstream forks from clang, due to the more appealing license.
Who is left still using GCC, other than existing projects lacking a clang backend for a snowflake embed CPU?
In any case, if it is a modern GCC release past 2012, it was compiled with C++ as well.
Regards, an embedded dev.