GNU operating system. The GNU Compiler Collection includes front ends for C, C++, Objective-C, Objective-C++, Fortran, Ada, Go, D, Modula-2, COBOL, Rust, and Algol 68 as well as to the TMC2208. CMake: A Powerful Software Build System. Autoconf is an operating system called GNU, which would be compatible with Unix. Stallman's take on this was to rewrite an existing compiler from Lawrence Livermore National Laboratory from Pastel to C with some help from Len Tower and others. Stallman wrote a new C front end he had written in Pastel. AND I'M SITTING IN /DEV/NULL AND LISTENING