Re: rust support for base system rust

[Havard Eidnes <he%NetBSD.org@localhost>]

> Am 26.10.22 um 19:28 schrieb Greg Troxel:
>> (People continue to struggle with rust and I expect that to
>> continue.  That's just background.)  Right now pkgsrc can
>> build and use RUST_TYPE=src or bin.  There's no way to say
>> "use the rustc that is in /usr/bin from the OS", which is
>> different from just about everything else in pkgsrc, and feels
>> like a bug.  So it seems intuitively obvious that rust should
>> have a builtin.mk that checks for rustc and if it is good
>> enough (exists, high enough version vs RUST_REQD, not known to
>> be broken), and uses it.
>
> Furthermore, it would also be great if we could use the already
> installed rust instead of downloading the bootstrap binaries if it is
> new enough. E.g. I cross-built my own Rust for ARM64 since I do not
> consider the provided binaries trustworthy given how they are built,
> but if I rebuild Rust from source, it would download those same
> binaries I want to avoid again, so the only way for me to update Rust
> is to cross-build it every time right now.

Yes, that would be nice, wouldn't it.

If I have understood correctly, rust is so fast-moving in terms of
changes to the language and therefore annoying in that they typically
don't guarantee more than one version backward compatibility, i.e. you
typically need 1.63 to build 1.64.

Regards,

- Håvard