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by inferiorhuman 688 days ago
Last year I got sucked into poking at some of the cross building rust issues (specifically issues targeting Solaris and BSD and issues cross hosting on macOS). Illumos isn't terribly exotic but the rust bootstrapping process has a few rough edges that will cut you. Illumos suffers mainly because it's not popular enough to get a ton of attention by the rustc folks and because it's not quite Solaris.

That said, for CI, cross building is much easier to scale than tracking down every permutation. For something like Illumos, that's not too bad. But for Solaris/SPARC? Heh.

  Since cranelift-codegen was an optional component that can be disabled,
  the x.py tooling could notice if a build failed in such a component
I think there's quite a bit of utility in ensuring that as much of the rust core builds. As cranelift-codegen is optional, the scripts should be able to bundle up a distribution with everything that succeeded.

Edit: Just took a quick look, and it sure looks like cranelift isn't built by default (at least that's what config.example.toml says and the none of the defaults available via 'x setup' seem to override that).
1 comments
sunshowers 688 days ago
Setting the library profile did build cranelift-codegen for me.
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inferiorhuman 688 days ago
Weird. I'm looking at master right now and `config.example.toml` has this comment:

  # This is an array of the codegen backends that will be compiled for the rustc
  # that's being compiled. The default is to only build the LLVM codegen backend,
  # and currently the only standard options supported are `"llvm"`, `"cranelift"`
  # and `"gcc"`. The first backend in this list will be used as default by rustc
  # when no explicit backend is specified.
  #codegen-backends = ["llvm"]
Now I've not messed with the build profiles at all, and I don't have the repo checked out so digging through it is tedious, but my assumption is the library profiles work by copying everything from src/bootstrap/defaults/config.library.toml into a config.toml at the current directory. There's nothing overriding the default codegen-backends value that I can see.

The defaults for the Config struct are set in src/bootstrap/src/core/config/config.rs and codegen-backends is indeed just "llvm" (line 1167).

Nothing in src/bootstrap/src/core/build_steps/compile.rs appears to override that list.

So that's all very curious (to me). Did the gcc backend get built as well?

Tangentially: a year on and the Github interface is still nasty to use – and one of the big motivating factor for me backing off of hacking on the cross build stuff. Every day seems to bring a new WTF moment. If I could get one thing for my birthday it would be for Rust to wean itself off of Github.

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