When building something from source code using cmake, you probably will see it fail with an error that looks like this:
CMake Error: your CXX compiler: "CMAKE_CXX_COMPILER-NOTFOUND" was not found. Please set CMAKE_CXX_COMPILER to a valid compiler path or name.
To fix this, install gcc-c++
apt-get install gcc-c++
After I came across the problem, I saw a couple old, unsolved threads mentioning this error while investigating how to fix it. Figured it would be nice to post the fix somewhere so anybody searching for an answer will see this. A better solution might be to make gcc-c++ a dependency of cmake since every app I tried building that used cmake wouldn't work without gcc-c++ on a vanilla system, but that ain't my decision to make