As an interesting tangent, to maintain BeOS compatibility, Haiku is still being built with a GCC 2.95 compiler. They also build with GCC 5 and a Clang port is u

As an interesting tangent, to maintain BeOS compatibility, Haiku is still being built with a GCC 2.95 compiler. They also build with GCC 5 and a Clang port is underway, but those obviously loose compatibility.