1.10.0 fails to build with bootstrap compiler

[the-kenny]

While trying to package rust-1.10.0 for NixOS, I ran into the following issue:

We're using a bootstrap compiler from https://static.rust-lang.org/dist/rust-1.10.0-$platforn.tar.gz to build rustc with the following configure flags (among others):

--enable-local-rust
--local-rust-root=...

While the build used to work just fine for 1.9.0, we get errors building libcore for 1.10.0:

src/libcore/lib.rs:63:1: 63:37 error: #[feature] may not be used on the stable release channel
src/libcore/lib.rs:63 #![feature(allow_internal_unstable)]
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/libcore/lib.rs:64:1: 64:17 error: #[feature] may not be used on the stable release channel
src/libcore/lib.rs:64 #![feature(asm)]
                      ^~~~~~~~~~~~~~~~
src/libcore/lib.rs:65:1: 65:38 error: #[feature] may not be used on the stable release channel
src/libcore/lib.rs:65 #![feature(associated_type_defaults)]
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/libcore/lib.rs:66:1: 66:32 error: #[feature] may not be used on the stable release channel
src/libcore/lib.rs:66 #![feature(cfg_target_feature)]
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/libcore/lib.rs:67:1: 67:27 error: #[feature] may not be used on the stable release channel
src/libcore/lib.rs:67 #![feature(concat_idents)]
...

Full output (don't worry about the strange-looking absolute paths, they're normal on NixOS):

https://gist.github.com/the-kenny/1424cd6a03467326dc1b6ad2e6480272

[nagisa]

You must use corresponding beta (i.e. 1.11 to build 1.10) when bootstraping rustc. You’re trying to bootstrap 1.10 with 1.10.

[nagisa]

cc @alexcrichton 2nd cycle we get exactly the same error reported. Maybe some sort of diagnostic is in order?

[the-kenny]

This is quite inconvenient. As far as I see, there isn't any beta of 1.11 available on static.rust-lang.net yet. Without starting a big discussion - why isn't it possible to bootstrap rustc with the previous stable version?

[alexcrichton]

Hm I'm a bit confused here, as @nagisa mentioned you can only bootstrap the 1.10 compiler with the 1.9 compiler, no other compiler in the world. @the-kenny are you trying to bootstrap 1.10 with 1.10? How is 1.11 coming into play?

[the-kenny]

@alexcrichton Yes, apparently I was trying to bootstrap 1.10 with 1.10. Did I misunderstand @nagisa? My understanding of his comment was that I have to use 1.11 as a bootstrap compiler for 1.10.

Using 1.9 from static.rust-lang.org as a bootstrap compiler for 1.10 doesn't work for me either. It's still complaining about usage of unstable library features (this time it's extended_compare_and_swap).

[alexcrichton]

@the-kenny ah yes you can neither bootstrap 1.10 with 1.10 nor 1.11, the only way it can work is with the 1.9 compiler.

Can you gist a full build log where you're using the 1.9 compiler to bootstrap? Also, where did the 1.9 compiler come from? If you're also building the 1.9 compiler manually then the bootstrap will only work if the 1.9 compiler is configured with --release-channel=stable

[the-kenny]

@alexcrichton Thanks! Full build-log is at https://gist.github.com/the-kenny/4b6dc5991771a82873ab29bbd8179692

I'm using rustc-1.9.0 from https://static.rust-lang.org/dist/rust-1.9.0-x86_64-unknown-linux-gnu.tar.gz (sha256: 288ff13efa2577e81c77fc2cb6e2b49b1ed0ceab51b4fa12f7efb87039ac49b7). Nix does some minimal after-work on the binary, all shown in https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/compilers/rust/bootstrap.nix#L46-L53 (don't worry about the wrapProgram, it's actually a no-op there)

[MagaTailor]

#33980

[alexcrichton]

@the-kenny hm that's certainly an unusual build log! You're clearly able to use unstable features because libcore succesfully compiled, but then apparently liballoc got linked to something like a stale copy? It's not clear to me what exactly could trigger that error.

There's some suspicious errors at the top though which may be relevant? Could you try it again but with VERBOSE=1 so all the commands are printed out?

[the-kenny]

Verbose build log: https://gist.github.com/the-kenny/6707ad42d1c4fe70a805198795edc905

[alexcrichton]

Hm unfortunately that didn't help me at much, I'm not actually sure what's going on here. It'd probably be best to play around with various RUST_LOG annotations to see exactly which crates are being loaded, and this may also be a situation where local_stage0.sh is totally broken (I don't think it's exercised much).

Is there a way I could easily reproduce this locally?

[the-kenny]

It should be quite easy to reproduce (with Nix). Unfortunately I'm on a mobile internet connection right now and can't download a virgin NixOS VM to check if it's reproducible and document the steps.

The other way would be to try to reproduce it on a normal Ubuntu (or whatever) installation without Nix. I can try that, but unfortunately need to download an ISO for that too.

Stay tuned, I'll update this issue as soon as I'm back on a fast and unlimited connection later today.

[the-kenny]

Dumb question: How is a channel=stable compiler of 1.9 able to build code using unstable features only stabilized in 1.10? Is this possibly a fundamental issue?