error[E0463]: can't find crate for `core`

[KokoseiJ]

I'm using Fedora 32 x86_64. using pre-installed Rustup. Set default toolchain to nightly, installed xargo as what README says.

Now when I run make, This thing happens:

 kokoseij@KKSJ-devlaptop  ~/git/rust3ds-template   master  make
RUST_TARGET_PATH=/home/kokoseij/git/rust3ds-template xargo build --release
warning: Patch `rustc-std-workspace-alloc v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-alloc)` was not used in the crate graph.
Patch `rustc-std-workspace-std v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-std)` was not used in the crate graph.
Check that the patched package version and available features are compatible
with the dependency requirements. If the patch has a different version from
what is locked in the Cargo.lock file, run `cargo update` to use the new
version. This may also occur with an optional dependency that is not enabled.
   Compiling compiler_builtins v0.1.32
   Compiling core v0.0.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore)
   Compiling rustc-std-workspace-core v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-core)
   Compiling alloc v0.0.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/liballoc)
    Finished release [optimized] target(s) in 13.59s
warning: Patch `rustc-std-workspace-alloc v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-alloc)` was not used in the crate graph.
Patch `rustc-std-workspace-std v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-std)` was not used in the crate graph.
Check that the patched package version and available features are compatible
with the dependency requirements. If the patch has a different version from
what is locked in the Cargo.lock file, run `cargo update` to use the new
version. This may also occur with an optional dependency that is not enabled.
   Compiling libc v0.2.71
   Compiling panic_abort v0.0.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libpanic_abort)
    Finished release [optimized] target(s) in 0.77s
warning: Patch `rustc-std-workspace-alloc v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-alloc)` was not used in the crate graph.
Patch `rustc-std-workspace-std v1.99.0 (/home/kokoseij/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/tools/rustc-std-workspace-std)` was not used in the crate graph.
Check that the patched package version and available features are compatible
with the dependency requirements. If the patch has a different version from
what is locked in the Cargo.lock file, run `cargo update` to use the new
version. This may also occur with an optional dependency that is not enabled.
   Compiling cc v1.0.54
   Compiling cfg-if v0.1.10
error[E0463]: can't find crate for `core`
  |
  = note: the `3ds` 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 `cfg-if`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed
error: `"cargo" "build" "--release" "--manifest-path" "/tmp/xargo.Rv7Tjxt4GUJ6/Cargo.toml" "--target" "3ds" "-p" "panic_unwind"` failed with exit code: Some(101)
note: run with `RUST_BACKTRACE=1` for a backtrace
make: *** [Makefile:20: target/3ds/release/rust3ds-template.elf] Error 1

[FenrirWolf]

Hiya! Sorry you're running into problems with the project. Unfortunately this hasn't been maintained in quite a while, so if you're using a a modern nightly build (which I imagine you are) then the compile failures are expected. If you switch to nightly version nightly-2018-08-18 then you might be able to make it work, but note that's a nearly 2 year old version of the language so you won't be able to use some of the more recent stuff like async/await

I've been thinking about coming back to this and fixing it up to work for recent rust versions, but I haven't done it yet because the current system is... well, suboptimal. Mostly because I don't have a good way of easily updating things whenever new nightly releases come out. But if I find a better way to do things then hopefully I can get the project back into shape.

[KokoseiJ]

Oh, alright. I totally understand your situation.

I'll try to find a workaround, and post it if It works.

EDIT: By the way, May I ask you why did you make this project to be nightly-only from the first place?

EDIT2: Nvm, You have to use Nightly build to cross-compile.