rust-lld doesn't support libraries with zlib-compressed debug info

[vadorovsky]

rust-lld which is shipped in rustup toolchains doesn't include zlib support. That leads to issues if it tries to link static libraries which are compressed.

In my case, I'm trying to build a crate on Alpine Linux, where /usr/lib/libc.a is compressed wit zlib.

(I also had to specify -L /lib -L /usr/lib in my RUSTFLAGS to even be able to find the library, but that's a separate issue - #130062)

77d2cb0e3483:~/aya# RUSTFLAGS="-L /lib -L /usr/lib" cargo build --target x86_64-unknown-linux-musl --config "target.x86_64-unknown-linux-musl.linker = \"rust-lld\"" --package init --profile release
   Compiling libc v0.2.158
   Compiling cfg-if v1.0.0
   Compiling bitflags v2.6.0
   Compiling anyhow v1.0.86
   Compiling nix v0.29.0
   Compiling init v0.1.0 (/root/aya/init)
error: linking with `rust-lld` failed: exit status: 1
  |
  = note: LC_ALL="C" PATH="/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/bin:/usr/loca/aya/target/x86_64-unknown-linux-musl/release/deps/init-e28d03be64389d41.init.1ff0b768912a0f5b-cgu.5.rcgu.o" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/init-e28d03be64389d41.5v5bzgpeitn8k9cw66o41lpcv.rcgu.o" "--as-needed" "-L" "/root/aya/target/x86_64-unknown-linux-musl/release/deps" "-L" "/root/aya/target/release/deps" "-L" "/lib" "-L" "/usr/lib" "-L" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib" "-Bstatic" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/libnix-58a27e1bb6f49050.rlib" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/libbitflags-3c134508527922bc.rlib" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/libcfg_if-8d8fae249b1ab972.rlib" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/liblibc-8773206ad0630d2b.rlib" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/libanyhow-892885a59fdac32f.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-1b60b176e45a0318.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_abort-30b1bb7d44aa9e0e.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libobject-0123438d987de009.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libmemchr-05f3c42b49d78619.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libaddr2line-45c700404e36c3de.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libgimli-cf5f9b37b545ed6e.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_demangle-44abbf672f21a10b.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd_detect-9b6d712a985955e4.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libhashbrown-e4ec61de4b8ef447.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_std_workspace_alloc-c72777eb88217fe3.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libminiz_oxide-b0a8429443e0fed6.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libadler-820055e0e9cc55a4.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libunwind-2ceb129e8b1d5c77.rlib" "-lunwind" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libcfg_if-8cd2ce184499d012.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/liblibc-ada011f709b467ef.rlib" "-lc" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc-67a0423d44ab989a.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/librustc_std_workspace_core-15fc71c4e52ac90f.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libcore-273f69939f389095.rlib" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/libcompiler_builtins-c8f82c72237d07e8.rlib" "-Bdynamic" "--eh-frame-hdr" "-z" "noexecstack" "-L" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib" "-L" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained" "-o" "/root/aya/target/x86_64-unknown-linux-musl/release/deps/init-e28d03be64389d41" "--gc-sections" "-static" "-pie" "--no-dynamic-linker" "-z" "text" "-z" "relro" "-z" "now" "-O1" "--strip-debug" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crtendS.o" "/usr/local/rustup/toolchains/1.81.0-x86_64-unknown-linux-musl/lib/rustlib/x86_64-unknown-linux-musl/lib/self-contained/crtn.o"
  = note: rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_abbrev) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_loclists) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_aranges) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(write.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(write.lo):(.debug_abbrev) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(unlinkat.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_line) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(write.lo):(.debug_loclists) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(sync.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(unlinkat.lo):(.debug_abbrev) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(sync.lo):(.debug_abbrev) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_str) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(sync.lo):(.debug_aranges) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(writev.lo):(.debug_line_str) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(write.lo):(.debug_aranges) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(symlink.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(setxid.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(setxid.lo):(.debug_abbrev) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: /usr/lib/libc.a(setgid.lo):(.debug_info) is compressed with ELFCOMPRESS_ZLIB, but lld is not built with zlib support
          rust-lld: error: too many errors emitted, stopping now (use --error-limit=0 to see all errors)


error: could not compile `init` (bin "init") due to 1 previous error

I think that could be fixed by enabling LLVM_ENABLE_ZLIB CMake option by default.

[bjorn3]

The error seems to suggest this is about zlib compressed debuginfo, nothing related to staticlibs.

[vadorovsky]

The error seems to suggest this is about zlib compressed debuginfo, nothing related to staticlibs.

Fair, sorry for misleading title and description. I think that fix would still remain the same (enabling zlib in LLVM builds).

[lqd]

As you discovered, -Clinker is not the expected way to use rust-lld on the linux targets: using a C/C++ compiler as the linker driver will avoid the library issues.

Support is not as principled as when we enable zstd compression statically on select targets, zlib compression is more hit-or-miss depending on the builder and local configs. But saying it's not enabled at all is also incomplete. It's maybe not yet enabled on the -musl builder though.

See for example, on the latest x86_64-unknown-linux-gnu nightly:

$ rustc -Vv
rustc 1.83.0-nightly (adf8d168a 2024-09-08)
binary: rustc
commit-hash: adf8d168af9334a8bf940824fcf4207d01e05ae5
commit-date: 2024-09-08
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

$ ldd $(rustup which rustc) | grep libz
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007ffff7bfe000)

And an example showing it working, on a helloworld:

$ cargo clean -q && RUSTFLAGS="-Zdebuginfo-compression=zlib" cargo build -q && readelf -t target/debug/helloworld | grep Z
       ZLIB, 0000000000001d67, 1
       ZLIB, 00000000000f722e, 1
       ZLIB, 00000000000072b0, 1
       ZLIB, 00000000000a1660, 1
       ZLIB, 00000000001481db, 1
       ZLIB, 0000000000063e78, 1

Remember that we use rust-lld by default on this target (and thus this example would also work without using the rustc -Z flag, and using a link arg: -Clink-arg=-Wl,--compress-debug-sections=zlib).

$ readelf -p .comment target/debug/helloworld

String dump of section '.comment':
  [     1]  Linker: LLD 19.1.0 (/checkout/src/llvm-project/llvm 2b259b3c201f939f2ed8d2fb0a0e9b37dd2d1321)
  [    5f]  GCC: (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
  [    8a]  rustc version 1.83.0-nightly (adf8d168a 2024-09-08)

So rust-lld is built with zlib support here, as you can see.

[khuey]

I didn't test #130471 but it should fix this