rustc-1.88.0 does not build using external LLVM due to missing rust-lld

[debohman]

When building using an external LLVM, the build fails due to a missing rust-lld even when lld is present in path.

Summary

Here is the end of the build log:

Dist rust-docs-1.88.0-x86_64-apple-darwin
	finished in 27.638 seconds
Installing stage2 docs (x86_64-apple-darwin)
install: creating uninstall script at /tmp/dst.rustc/usr/local/lib/rustlib/uninstall.sh
install: installing component 'rust-docs'

    rust docs installed.

Dist rust-std-1.88.0-x86_64-apple-darwin
	finished in 0.442 seconds
Installing stage2 std (x86_64-apple-darwin)
install: creating uninstall script at /tmp/dst.rustc/usr/local/lib/rustlib/uninstall.sh
install: installing component 'rust-std-x86_64-apple-darwin'

    rust std installed.


thread 'main' panicked at src/bootstrap/src/lib.rs:1779:24:
src.symlink_metadata() failed with No such file or directory (os error 2) ("src = /tera/tera/debo/Projects/rustc/rustc-1.88.0-src/build/x86_64-apple-darwin/stage2/lib/rustlib/x86_64-apple-darwin/bin/rust-lld")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Panic was initiated from src/bootstrap/src/lib.rs:1779:24
Build completed unsuccessfully in 0:26:40

Command used

DESTDIR=/tmp/dst.rustc x.py install

Note the error from bootstrap in the log:

Warning: LLD is enabled when using external llvm-config. LLD will not be built and copied to the sysroot.

Expected behaviour

I expected it to build.

Actual behaviour

Failed to build. See above log snippet. Entire log is attached.

rustc-1.88-log.txt

Bootstrap configuration (bootstrap.toml)

I am using a system LLVM llvm-20.1.7:

llvm-config = "/usr/local/bin/llvm-config"

Operating system

macOS 10.12.6

HEAD

6b00bc3880198600130e1cf62b8f8a93494488cc

[debohman]

I was able to successfully complete the build by doing the following:

Copy ldd to build/x86_64-apple-darwin/stage2/lib/rustlib/x86_64-apple-darwin/bin/rust-lld

Create a directory build/x86_64-apple-darwin/stage2/lib/rustlib/x86_64-apple-darwin/bin/gcc-ld

Inside that directory, hardlink ld.lld, ld64.lld, lld-link, wasm-ld to rust-lld

The question is: If the build requires it, then why isn't the stage2 directory correctly populated?

[debohman]

Note that I also worked around the issue in #139400.

[jpalus]

Note: issue is not Darwin specific, I see the same on Linux using system installed llvm.

[jpalus]

In case it's useful here's full backtrace:

backtrace

thread 'main' panicked at src/bootstrap/src/lib.rs:1779:24:
src.symlink_metadata() failed with No such file or directory (os error 2) ("src = /home/users/builder/rpm/BUILD/rust-1.88.0-build/rustc-1.88.0-src/build/aarch64-unknown-linux-gnu/stage2/lib/rustlib/aarch64-unknown-linux-gnu/bin/rust-lld")
stack backtrace:
   0:     0xaaaab09917c8 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h887f38dba00b5b2a
   1:     0xaaaab09af59c - core::fmt::write::h2a34afd9df67012f
   2:     0xaaaab095d420 - std::io::Write::write_fmt::hffb2973b22859382
   3:     0xaaaab09916c4 - std::sys::backtrace::BacktraceLock::print::h9625458d31d2622b
   4:     0xaaaab0995c4c - std::panicking::default_hook::{{closure}}::h6a1a2410bed9bb2f
   5:     0xaaaab0995b44 - std::panicking::default_hook::h2781aa184b70a849
   6:     0xaaaab099618c - std::panicking::rust_panic_with_hook::h6924c0fb82d17bc5
   7:     0xaaaab0991bd4 - std::panicking::begin_panic_handler::{{closure}}::hdebafdaae531983f
   8:     0xaaaab0991a1c - std::sys::backtrace::__rust_end_short_backtrace::h9fd1b6471baf08f9
   9:     0xaaaab0995ce8 - __rustc[aaf4a02f2f9ab86b]::rust_begin_unwind
  10:     0xaaaaaff559b4 - core::panicking::panic_fmt::h60a77bb2c5cb27f3
  11:     0xaaaab01c5300 - bootstrap::Build::copy_link_internal::hdbdbd10eaa6bb9af
  12:     0xaaaab01c456c - bootstrap::Build::copy_link::h4d03dd04aad54a94
  13:     0xaaaab0200344 - <bootstrap::core::build_steps::dist::Rustc as bootstrap::core::builder::Step>::run::prepare_image::he9cfea7987feaea1
  14:     0xaaaab01ff6c4 - <bootstrap::core::build_steps::dist::Rustc as bootstrap::core::builder::Step>::run::h3031a9df80cf4512
  15:     0xaaaab00ce164 - bootstrap::core::builder::Builder::ensure::h85cf508fac3dfa57
  16:     0xaaaab01ff5b0 - <bootstrap::core::build_steps::dist::Rustc as bootstrap::core::builder::Step>::make_run::hd7eef2b4e3696bb5
  17:     0xaaaab04c3a34 - bootstrap::core::builder::StepDescription::maybe_run::h96f8253d4fbf8942
  18:     0xaaaab04c4658 - bootstrap::core::builder::StepDescription::run::h1d8ef1312383bc01
  19:     0xaaaab04c951c - bootstrap::core::builder::Builder::run_step_descriptions::hc5e4488356b98424
  20:     0xaaaab04c92dc - bootstrap::core::builder::Builder::execute_cli::hb6e5e1cdc3baf344
  21:     0xaaaab01be984 - bootstrap::Build::build::h046ecdaff4a19fca
  22:     0xaaaaaff5a530 - bootstrap::main::h06cef34dae0473b8
  23:     0xaaaaaff5d1b0 - core::ops::function::FnOnce::call_once::hf1a679c885cbfb5c
  24:     0xaaaaaff5ce58 - std::sys::backtrace::__rust_begin_short_backtrace::h28d569c780c0ed5d
  25:     0xaaaaaff5c0ec - std::rt::lang_start::{{closure}}::h4e3747e7ac742d62
  26:     0xaaaab0997ba4 - std::rt::lang_start_internal::h8706a62a5edce61c
  27:     0xaaaaaff5c0d4 - std::rt::lang_start::h4b13ebde88700676
  28:     0xaaaaaff5bab8 - main
  29:     0xffff969d2218 - <unknown>
  30:     0xffff969d22f4 - __libc_start_main
  31:     0xaaaaaff560f0 - _start

[jpalus]

#139853 might possibly be related (cc @Kobzol)

[Kobzol]

Thanks for the report, this is indeed a bootstrap bug. I'll try fixing it in #143175.

[Kobzol]

#143175 will solve this for the future. For 1.88.0, please set rust.lld = false in bootstrap.toml.

[jpalus]

@Kobzol I'm not sure if i follow linked PR but I suppose rust.lld = false will be required in later releases too, is that correct? If yes would it be possible to change rust.lld default to !system_llvm?