In fact, you probably noticed I tested most trending compilers and they are all bootstrapped this way. But none of them is 1.5GB before the compiled compiler is

In fact, you probably noticed I tested most trending compilers and they are all bootstrapped this way. But none of them is 1.5GB before the compiled compiler is downloaded. My reaction was more about the unexpected overall size and process to get a basic Java compiler built from scratch. In all the above, the binary compiler can be automatically downloaded as part of the dependencies (from their own servers, not packaged for any distribution in particular), which make things simpler. Edit : Maybe other compilers were lighter because I cloned with --depth 1 on git. I don't know the equivalent on mercurial, so it downloaded more than necessary