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Comment by Vecrios | Hacker News Reader

So, if I'm understanding this correctly, they are to re-write the Go compiler in Go, and compile it using the currently published compiler (i.e. 1.4)?

Could someone, kindly, explain how future versions would be built? Thanks!

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Future versions will still be built with any current published compiler. There are binary releases for each major release, and it's not hard to avoid using new language features in the compiler, so building from source only requires the most recent binary release (at worst).

My understanding is that they wrote code that translated the C code for the original Go compiler into Go code. This translation wasn't fully general -- it made assumptions about how the C code was written -- but it allowed the port from C to Go to be very precise (i.e. bug for bug). So now that the Go compiler written in Go can compile Go, that's what they'll use going forward, and they will slowly work to make it into more idiomatic Go instead of machine-generated Go.

So to answer your question, this new Go-written-in-Go compiler will initially be compiled by the Go-written-in-C compiler. The output from that will be an executable Go-written-in-Go compiler, and _that_ will be used to compile itself in the future. I.e. Go compiler version 1.4 will be used to compile Go version 1.5 will be used to compile Go version 1.6...

Keep in mind that this is not at all unusual. The C compiler GCC has been compiled using older versions of GCC for a long time. Having a compiler compile itself is a sort of milestone that many languages aspire to as a way of showing that the language is "ready."

Its generally called "self-hosting" when a compiler can compile itself[1]. It was a pretty big deal when Clang became self-hosting[2] in 2010.

[1] https://en.wikipedia.org/wiki/Self-hosting

[2] http://blog.llvm.org/2010/02/clang-successfully-self-hosts.h...

Thank you both for your inputs.

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