Stage2 rustc cannot use stage2:sysroot artifacts

[yxdai-nju]

I built stage2 rustc and sysroot artifacts with buck2 build stage2:rustc -m=riscv64 and buck2 build stage2:sysroot -m=riscv64, then combined them into a sysroot directory:

ubuntu@ubuntu:~$ tree ~/sysroot
/home/ubuntu/sysroot
├── bin
│   └── rustc
└── lib
    └── rustlib
        └── riscv64gc-unknown-linux-gnu
            └── lib
                ├── libaddr2line-007f1b3c.rlib
                ├── libadler2-481b1ea5.rlib
                ├── liballoc-7b36bf29.rlib
                ├── libcfg_if-6a1fcc32.rlib
                ├── libcompiler_builtins-1f7b3e51.rlib
                ├── libcore-18493fff.rlib
                ├── libgimli-37f06244.rlib
                ├── libhashbrown-1c741dd4.rlib
                ├── liblibc-4e784e9d.rlib
                ├── libmemchr-0c482414.rlib
                ├── libminiz_oxide-575b7770.rlib
                ├── libobject-75b0e44c.rlib
                ├── libpanic_unwind-40c529f7.rlib
                ├── librustc_demangle-29879389.rlib
                ├── librustc_std_workspace_alloc-297f18d9.rlib
                ├── librustc_std_workspace_core-1b4897cf.rlib
                ├── libstd-13a80529.rlib
                ├── libstd_detect-60746bac.rlib
                └── libunwind-4d6890c1.rlib

6 directories, 20 files

When trying to compile a hello world program:

ubuntu@ubuntu:~/src$ ~/sysroot/bin/rustc hello.rs
error[E0514]: found crate `std` compiled by an incompatible version of rustc
  |
  = note: the following crate versions were found:
          crate `std` compiled by rustc 1.86.0 (buckified stage1): /home/ubuntu/sysroot/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libstd-13a80529.rlib
          crate `std` compiled by rustc 1.86.0 (buckified stage1): /home/ubuntu/sysroot/lib/rustlib/riscv64gc-unknown-linux-gnu/lib/libstd_detect-60746bac.rlib
  = help: please recompile that crate using this compiler (rustc 1.86.0 (buckified stage2)) (consider running `cargo clean` first)

error: cannot find macro `println` in this scope
 --> hello.rs:2:5
  |
2 |     println!("hello, world");
  |     ^^^^^^^

error: requires `sized` lang_item

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0514`.

The error shows that std libraries were compiled by "buckified stage1" while rustc is "buckified stage2".

Is there a correct way to build matching rustc and std artifacts? Or do I need to rebuild std with stage2 compiler?

[dtolnay]

I believe this has been fixed by #21 + #26. Here is what I tried:

$ mkdir ~/sysroot
$ mkdir ~/sysroot/bin
$ buck2 build stage2:rustc --out ~/sysroot/bin
$ buck2 build stage2:sysroot --out ~/sysroot
$ cp `buck2 build stage0:ci_llvm --show-simple-output`/lib/* ~/sysroot/lib
$ ~/sysroot/bin/rustc hello.rs