Rust binary rust-bin, binary-free, binary chains experience

[trickygnome]

I have been doing “emerge --update” recently and noticed installation
of dev-lang/rust-bin package.

Bootstrapping compiler is a multi-stage compilation of compiler that
is written in the same programming language (self-hosting).

GCC is the default C, C++ compiler in Gentoo that installed with Stage 1 tarball.

The initial step version of compiler:
- Rust = OCaml, but this approach was abandoned long ago.
- Go = C
- LLVM/Clang = C++
- GCC = C
- Python = C

As you can see, all compilers, except of Rust, may be build from sources.

Today, Rust bootstrap with an existing Rust compiler, typically a beta
or stable version of “rustc”. Alternatives:
- OCaml :: this method is no longer practical or maintained.
- mrustc and dtolnay/bootstrap :: not an official part of the Rust
project. C++-based Rust compiler that can compile an early version
of the Rust compiler.
- gccrs and Cranelift :: experimental and not yet fully developed.

But the main problem I faced is not Rust, but Gentoo emerge that
download binary rust-bin and run it *without my approvement*. I see
that Gentoo is getting old and lazy, that is not right. I don't know
for shure, but manually installing “dev-lang/rust” package will use
old version to update.

One solution to block binaries is to use file “/etc/portage/package.mask/all” with:
: */*-bin
: */*-bootstrap

“-bin” suffix for binary package naming is not strict and just recommended:
https://devmanual.gentoo.org/ebuild-writing/file-format/index.html
Who knows which packages have binaries, also? Ex. google-chrome.

For updating GCC, Gentoo don't download a binary
version of the compiler. Instead, it update GCC by compiling the new
version from source code.

From this perspective *Go compiler* looks better, because may be build with help of “gcc-go” or
“gollvm” parts of GCC and LLVM. But Gentoo download binary Go 1.20 dev-lang/go-bootstrap from
https://dev.gentoo.org/~williamh/dist

[b]I suggest: to make “-bin” strict and always ask before installing such things.[/b]
_________________
if posts > 50 then; eat(shit); fi

[eschwartz]

[sam_]

Eli is, of course, completely right. If this situation causes you distress, please donate or otherwise contribute to the gccrs effort.

In future, please start with asking a question in good faith, rather than presuming "laziness".

I'll also note the following:

• I think there's an inconsistency between it being supposedly lazy to have the status quo (which it decidedly is not, not least because of the progress made here actually facilitates a proper bootstrap chain) and also noting the difficulty, as you did, in your post wrt the messy and poor situation even outside of Gentoo wrt bootstrapping Rust.
  
• The truly "lazy" thing for us to do would've been to: a) not slot Rust; b) not make this system-bootstrap change so that dev-lang/rust continued to download a binary and nobody would complain.
  
• We've not always packaged every single version of Rust given Rust requires work to maintain. Occasionally because of people being busy, a version wasn't packaged, so this will have happened (several times) before, just nobody noticed because of the behaviour of dev-lang/rust in the past.
  
• Prior to slotting, there was no real way to have a proper chain because you couldn't have multiple Rusts installed, nor could you control properly which ones are available for use to bootstrap.
  
• I have a proposal I need to finish wrt making it easier to identify binaries, see bug 885827.
  
• GCC is not the same as Rust, given that (for one) to include Rust in stages would inevitably make various people upset, and would also imply we need something in stage3s that hard-require Rust. That has obvious downsides I'm sure I don't need to repeat.
  
• The situation was described in detail in the commit message that made this change. See also bug 943144. I recommend checking git log if you're interested in process and rationale.
  
• bug 943706 was filed earlier to handle adding the missing slots for the current range of Rust versions in Gentoo and also to discuss going back to mrustc and having a path from there. Perhaps you're interested in volunteering?
  
• Within that same bug, I explain the issue with Go, and I note that I'd like to get that fixed too. I also filed bug 941769 to that end.
  
• With regard to Go, I've no idea how viable gollvm for this, although gccgo is indeed viable for bootstrapping once slotting is sorted.