Broken with upcoming nightly

[jethrogb]

Once a new nightly is produced, xargo will stop working because of rust-lang/rust#56092 . You can already see this behavior when using https://github.com/kennytm/rustup-toolchain-install-master

$ xargo build --target x86_64-fortanix-unknown-sgx
   Compiling core v0.0.0 (/home/jethro/.rustup/toolchains/9fe5cb5342244a716055fa0162e795deabd4985c/lib/rustlib/src/rust/src/libcore)
    Finished release [optimized] target(s) in 22.12s
error: failed to load source for a dependency on `compiler_builtins`

Caused by:
  Unable to update /home/jethro/.rustup/toolchains/9fe5cb5342244a716055fa0162e795deabd4985c/lib/rustlib/src/rust/src/libcompiler_builtins

Caused by:
  failed to read `/home/jethro/.rustup/toolchains/9fe5cb5342244a716055fa0162e795deabd4985c/lib/rustlib/src/rust/src/libcompiler_builtins/Cargo.toml`

Caused by:
  No such file or directory (os error 2)
error: `"cargo" "build" "--release" "--manifest-path" "/tmp/xargo.MmX2uglNXWpA/Cargo.toml" "--target" "x86_64-fortanix-unknown-sgx" "-p" "compiler_builtins"` failed with exit code: Some(101)
note: run with `RUST_BACKTRACE=1` for a backtrace
`` 

[jethrogb]

Once a new nightly is produced

Yay we finally got a new nightly 🎉 Boo, xargo is now broken 😞

[bruceloco]

Is this fixed in xargo 0.3.13?
I am trying for 3 days to build an arm-none-eabi for arm7 targets for kernel development and I am left scratching my head. First its create the target, its fun, but hard to find the info, then it fails because there are no binaries for it or libs even though you have the compiler(and this is in windows as well) then xargo shows as a suggestion and you move to nightly, and what not and the end result is this bug
If I wasnt a grown man I would cry :D

[RalfJung]

Yeah this is long fixed. So if you have 0.3.13, whatever you are hitting is not this bug.

[jethrogb]

Well, it's only fixed if you use the rust-src component or the XARGO_RUST_SRC envvar. If you use one of the other methods to specify the source, it's still broken. A PR has been open to fix that for a long time.

[bruceloco]

I am.on windows, I tried to pass that as a command line argument but it fails, also setting in the windows environment it also fails using set, haven't tried manually on the system settings
But the command line argument should work...

[jethrogb]

@bruceloco There is no way to set the source using a command-line argument

[RalfJung]

@jethrogb

Well, it's only fixed if you use the rust-src component or the XARGO_RUST_SRC envvar. If you use one of the other methods to specify the source, it's still broken. A PR has been open to fix that for a long time.

Fair. Xargo is unfortunately not maintained currently. But it seems like we both have an interest in it -- so how about we suggest to @japaric that we could co-maintain it? I basically care only about case of building a custom libstd for the host architecture, but xargo currently is the only tool I know of that can do that -- and it's not like I intend to break the cross-building part (and it seems you have some interest in that?). I also don't have much time to spare, so I won't be able to review anything big or go through the backlog of PRs or issues, but between the two of us it seems like we should be able to get stuff like your PR landed and keep xargo at the level of functionality it is at right now.

[jethrogb]

@RalfJung Sure I can review PRs that keep Xargo's pre-existing functionality working until Cargo can do this.

[robert-w-gries]

@RalfJung Have you looked into cargo-xbuild? It is an actively maintained fork of xargo

[RalfJung]

@robert-w-gries it cannot build libstd though, which I require.

[RalfJung]

@jethrogb

Sure I can review PRs that keep Xargo's pre-existing functionality working until Cargo can do this.

Okay, let's do this!

@japaric we'd like to take over basic maintenance of xargo, if that's okay for you.