Use rustup now that it's the official installation method

[paul-english]

Using rustup to install would allow us to run nightly only things like rustfmt alongside the stable build.

[bbigras]

could base this on 83f68b9

[mathroc]

@bbigras have you tried it on alpine ?

I have this error :

/ # curl https://sh.rustup.rs -sSf | sh -s -- -y
info: downloading installer
sh: /tmp/tmp.PfDcdK/rustup-init: not found

[bbigras]

have you tried it on alpine ?

No. rustup-init seems to need libc. I don't know if it works with libc6-compat or musl libc. With libc6-compat I got:

~ # /tmp/tmp.KJgKFh/rustup-init 
Error relocating /tmp/tmp.KJgKFh/rustup-init: __register_atfork: symbol not found
Error relocating /tmp/tmp.KJgKFh/rustup-init: __rawmemchr: symbol not found
Error relocating /tmp/tmp.KJgKFh/rustup-init: __strtok_r: symbol not found