Oh absolutely it's ... interesting. And I guess kind of typical for the era to rely on the native includes, libs, assembler, linker. It reminds me of GCC on SGI, RS/6000, MacOS, etc.
I picked this version as it's much more smaller to really dive into, and I already have the old Linux GCC 1.40 with binutils running on Windows that can build Linux 0.10 & 0.11 kernels just fine. I was really interested to see if I could build the x68000 version of GCC, since all it basically does is read text files.
I was surprised to find out that HAS & HLK have source, but both were written in assembly..
I have some time functions that I used for nethack, but I was beyond lost at that libc and where to impliment them... I guess it's like fixing stdio and file handling...... I really don't know.
I see the GCC 2 stuff uses a gas to has program, so it again relies on HAS.