rusty_v8 0.104.0 build failure

[chenrui333]

👋 trying to build the latest deno 1.46.0 release, but run into some build issue with rusty_v8 0.104.0. The error log is as below:

error build log

    --- stderr
    ninja: error: '../../../../../../../opt/homebrew/opt/llvm/lib/clang/20/lib/darwin/libclang_rt.osx.a', needed by 'obj/v8/libv8_libbase.a', missing and no known rule to make it
    thread 'main' panicked at /private/tmp/deno-20240822-12060-mwfxfo/rusty_v8/build.rs:969:3:
    assertion failed: ninja(&gn_out_dir, maybe_env).arg(target).status().unwrap().success()
    note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
  error: failed to compile `deno v1.46.0 (/private/tmp/deno-20240822-12060-mwfxfo/deno/cli)`, intermediate artifacts can be found at `/private/tmp/deno-20240822-12060-mwfxfo/deno/target`.
  To reuse those artifacts with a future compilation, set the environment variable `CARGO_TARGET_DIR` to that path.

full build log, https://github.com/Homebrew/homebrew-core/actions/runs/10507035952/job/29108048297?pr=181980
relates to Homebrew/homebrew-core#181980

[devsnek]

@chenrui333 at a guess, ensure that homebrew's llvm contains libclang_rt.osx.a?

ninja: error: '../../../../../../../opt/homebrew/opt/llvm/lib/clang/20/lib/darwin/libclang_rt.osx.a', needed by 'obj/v8/libv8_libbase.a', missing and no known rule to make it

[chenrui333]

yeah, we have it

$ fd libclang_rt.osx.a /opt/homebrew/Cellar/
/opt/homebrew/Cellar/llvm/18.1.8/lib/clang/18/lib/darwin/libclang_rt.osx.a

---

but that is under 18

[devsnek]

Sounds like you need to ensure your llvm 20 installation has the needed components or switch to using your llvm 18 installation?

[avindra]

getting a similar error (in opensuse)

ninja: error: '../../../../../../../../usr/lib/clang/20/lib/x86_64-unknown-linux-gnu/libclang_rt.builtins.a', needed by 'obj/v8/libv8_libbase.a', missing and no known rule to make it
thread 'main' panicked at build.rs:965:3:
assertion failed: ninja(&gn_out_dir, maybe_env).arg(target).status().unwrap().success()

[devsnek]

I googled and found this, perhaps your llvm distributions need to be updated: https://stackoverflow.com/questions/76936217/how-to-build-libclang-rt-builtins-a

[chenrui333]

llvm 20 is not the latest release

any how that both llvm18 and 20 can be supported? if not, that would be the one supporting llvm18?

[devsnek]

I don't think the version matters, i think the issue is that you have built llvm without compiler-rt enabled. If you want the compiler-rt requirement removed you will need to implement patches in the upstream chromium repo which we could then pull into rusty_v8.

[nathanwhit]

I looked into this, I believe the issue is that the build assumes you're using clang version 20, even when you set a custom clang base path. So then it looks for that static library under the incorrect path.

We should probably be detecting the clang version and passing it along in build.rs.

For now, to fix the build you can try adding the env var

GN_ARGS='clang_version=18 use_lld=false'

(assuming the version in homebrew is 18, which it currently is).

The use_lld=false arg may not be necessary, but I found that locally I needed it to get the build working.

[felixonmars]

While packaging for Arch, we encountered this as well. Unfortunately the above workaround didn't work for us because our compiler-rt (which was built separately as a package) installs the file as /usr/lib/clang/18/lib/linux/libclang_rt.builtins-x86_64.a, which here it looks for /usr/lib/clang/18/lib/x86_64-unknown-linux-gnu/libclang_rt.builtins.a.

Any idea how can I get around this?

[devsnek]

The configuration is here: https://source.chromium.org/chromium/chromium/src/+/main:build/config/clang/BUILD.gn

Seems like you can probably follow along with chromium packaging: https://gitlab.archlinux.org/archlinux/packaging/packages/chromium/-/blob/main/compiler-rt-adjust-paths.patch?ref_type=heads

[felixonmars]

I see, thanks for the hint. Hacking this into the Rust building process is much more frustrating though...