As you can see, it basically consisted in "use C, unless you _really_ have too". It was also well known that C++ was heavily discouraged by Richard Stallman, so picking it could well end up in your project having a hard time being adopted by GNU.
The guidelines were relaxed afterwards, especially since GCC came to rely on C++ and every relevant C compiler was then written in C++, making the whole "we don't want to force people to install g++" even more nonsensical. In 2004 C++ was already way too ubiquitous to not have g++ installed.
https://web.archive.org/web/20041029162424/https://www.gnu.o...
As you can see, it basically consisted in "use C, unless you _really_ have too". It was also well known that C++ was heavily discouraged by Richard Stallman, so picking it could well end up in your project having a hard time being adopted by GNU.
The guidelines were relaxed afterwards, especially since GCC came to rely on C++ and every relevant C compiler was then written in C++, making the whole "we don't want to force people to install g++" even more nonsensical. In 2004 C++ was already way too ubiquitous to not have g++ installed.