Can't link to rustc_driver with latest nightly

[bjorn3]

I tried this code:

#![feature(rustc_private)]
extern crate rustc_driver;
fn main() {}

I expected to see this happen: Compiles fine.

Instead, this happened:

error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-m64" "-L" "/home/bjorn/.rustup/toolchains/nightly-2020-05-25-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "rust_out.rust_out.7rcbfp3g-cgu.0.rcgu.o" "rust_out.rust_out.7rcbfp3g-cgu.1.rcgu.o" "rust_out.rust_out.7rcbfp3g-cgu.2.rcgu.o" "rust_out.rust_out.7rcbfp3g-cgu.3.rcgu.o" "rust_out.rust_out.7rcbfp3g-cgu.4.rcgu.o" "-o" "rust_out" "-Wl,--gc-sections" "-pie" "-Wl,-zrelro" "-Wl,-znow" "-nodefaultlibs" "-L" "/home/bjorn/.rustup/toolchains/nightly-2020-05-25-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/home/bjorn/.rustup/toolchains/nightly-2020-05-25-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-lrustc_driver-fefef43299f39010" "-Wl,--start-group" "-L" "/home/bjorn/.rustup/toolchains/nightly-2020-05-25-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-lstd-265ff16c7b6b86f9" "-Wl,--end-group" "-Wl,-Bstatic" "/home/bjorn/.rustup/toolchains/nightly-2020-05-25-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-a1755b3e88842f5d.rlib" "-Wl,-Bdynamic" "-lLLVM-10-rust-1.45.0-nightly" "-lutil" "-ldl" "-lutil" "-ldl" "-lrt" "-lpthread" "-lgcc_s" "-lc" "-lm" "-lrt" "-lpthread" "-lutil" "-ldl" "-lutil"
  = note: /usr/bin/ld: cannot find -lLLVM-10-rust-1.45.0-nightly
          collect2: error: ld returned 1 exit status

Meta

rustc --version --verbose:

rustc 1.45.0-nightly (46e85b432 2020-05-24)
binary: rustc
commit-hash: 46e85b4328fe18492894093c1092dfe509df4370
commit-date: 2020-05-24
host: x86_64-unknown-linux-gnu
release: 1.45.0-nightly
LLVM version: 10.0

[jonas-schievink]

Presumably expected breakage due to #72000?

[bjorn3]

We'll move it to the llvm-tools-preview component directly,
and rustc-dev will have an implicit dependency on it.

That implicit dependency seems to be missing.

[jonas-schievink]

Looks like it was dropped #72000 (comment)

[Mark-Simulacrum]

Yes, closing as expected breakage. If llvm-tools-preview doesn't work for you, we can reopen.

The dependency is implicit, i.e. you need to manage it yourself, as rustup doesn't currently support dependencies.

[regexident]

The dependency is implicit, i.e. you need to manage it yourself, as rustup doesn't currently support dependencies.

From a user's perspective what would that entail exactly?
I'm struggling to make this work. 😔

When creating a new project via:

cargo new rustc_driver_test

cd rustc_driver_test

echo "nightly-2020-06-16\n" > ./rust-toolchain

printf "\
#![feature(rustc_private)]\n\
extern crate rustc_driver;\n\
fn main() {}\n\
" > ./src/main.rs

rustup component add rust-src rustc-dev llvm-tools-preview

cargo +nightly build

… all I'm getting is this:

   Compiling rustc_driver_test v0.1.0 (…/emit-ffi)
error[E0463]: can't find crate for `rustc_driver`
 --> src/main.rs:2:1
  |
2 | extern crate rustc_driver;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

error: aborting due to previous error

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

To learn more, run the command again with --verbose.

rustup run nightly rustc --version --verbose

rustc 1.46.0-nightly (feb3536eb 2020-06-09)
binary: rustc
commit-hash: feb3536eba10c2e4585d066629598f03d5ddc7c6
commit-date: 2020-06-09
host: x86_64-apple-darwin
release: 1.46.0-nightly
LLVM version: 10.0

[bjorn3]

rustup component add rust-src rustc-dev llvm-tools-preview

You need to specify that you want to add it to the nightly toolchain: rustup component add --toolchain nightly rust-src rustc-dev llvm-tools-preview.

[regexident]

Thanks @bjorn3! Now it's kinda obvious. 🙈