xargo build error

[chaozju]

I am trying out nightly xargo for further customizing target riscv64gc-unknown-linux-musl for cross building inspired by this issue
but I failed at the very beginning :)

I want a statically linked executable so targetting x86_64-unknown-linux-musl
with

xargo build --release --target x86_64-unknown-linux-musl

then got

xargo build --release --target x86_64-unknown-linux-musl
   Compiling hello v0.1.0 (/home/chao/rust_playground/hello)
error[E0463]: can't find crate for `std`
  |
  = note: the `x86_64-unknown-linux-musl` target may not be installed

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: could not compile `hello`.

To learn more, run the command again with --verbose.
Makefile:3: recipe for target 'x86-musl' failed
make: *** [x86-musl] Error 101

my rustup show

chao@DESKTOP-B79IRTG:~/rust_playground/hello$ rustup show
Default host: x86_64-unknown-linux-gnu
rustup home:  /home/chao/.rustup

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)
1.40.0-x86_64-unknown-linux-gnu

installed targets for active toolchain
--------------------------------------

wasm32-unknown-unknown
x86_64-unknown-linux-gnu
x86_64-unknown-linux-musl

active toolchain
----------------

nightly-x86_64-unknown-linux-gnu (default)
rustc 1.44.0-nightly (f509b26a7 2020-03-18)

Things work fine without nightly but with getting WARNING: the sysroot can't be built for the Stable channel. Switch to nightly. in customizing sysroot and target

[RalfJung]

Looks like something is wrong with your Xargo.toml then.

But note that xargo is basically unmaintained. Maybe try using the build-std support that is native in cargo these days? https://github.com/rust-lang/wg-cargo-std-aware

[chaozju]

@RalfJung
When assigning build-std to cargo build, some dep will be auto-configed into #!cfg[not[has_std]] where Hashmap is no-longer available.

Is there a way to build std ahead of other dep?

Multi-stage builds seems to be a Xargo feature?

[RalfJung]

Sorry, I don't understand the question. HashMap is in std, so if you use no_std ("[not[has_std]]" doesn't exist so I have no idea what you mean) then you do not have a HashMap, that is expected.

If -Zbuild-std does not work, please report a bug at https://github.com/rust-lang/wg-cargo-std-aware/issues. I have never used that feature, nor have I ever worked with musl, so I'm afraid I don't think I can help you here.