On riscv64gc linux, split-debuginfo ="unpacked" caused error: A dwo section may not contain relocations

[kxxt]

Problem

On riscv64gc linux, split-debuginfo ="unpacked" caused error: A dwo section may not contain relocations.

• For rust > 1.64, this error occurs.
• For rust <=1.64, cargo didn't pass -C split-debuginfo=unpacked flag to rustc.
  • For rust 1.64, a segmentation fault happens in rustc.
  • For rust < 1.64, it builds fine

I think the behavior of rust < 1.64 is correct.

Steps

The following steps:

cargo new failure
cd failure
echo "[profile.dev]" >> Cargo.toml
echo 'split-debuginfo = "unpacked"' >> Cargo.toml
cargo build

caused the following failure:

Compiling failure v0.1.0 (/root/failure)
error: A dwo section may not contain relocations

error: could not compile `failure` due to previous error

Possible Solution(s)

No response

Notes

Related: llvm/llvm-project#56642

Version

cargo 1.67.1 (8ecd4f20a 2023-01-10)
release: 1.67.1
commit-hash: 8ecd4f20a9efb626975ac18a016d480dc7183d9b
commit-date: 2023-01-10
host: riscv64gc-unknown-linux-gnu
libgit2: 1.5.0 (sys:0.16.0 vendored)
libcurl: 7.86.0-DEV (sys:0.4.59+curl-7.86.0 vendored ssl:OpenSSL/1.1.1q)
os: Linux [64-bit]

[ehuss]

Transferred to rust-lang/rust, since this looks to be a compiler issue.

[jyn514]

@ehuss llvm/llvm-project#56642 (comment) says that LLVM doesn't support this combination of flags. It's unclear to me whether it's impossible or just not implemented yet, but in the meantime, cargo should probably stop passing -C split-debuginfo to proc-macros? there's some mention of -mrelax in the upstream issue, I'm not sure how that's related.

[ehuss]

The report above doesn't mention proc-macros. It seems to happen for normal binaries. The following seems to fail for me:

rustc foo.rs -C split-debuginfo=unpacked -C debuginfo=2 --target riscv64gc-unknown-linux-gnu

If split-debuginfo isn't supported on this target, then rustc should report that it isn't supported (Cargo already tests for this). I believe that is defined by the supported_split_debuginfo field in the target definition.

[VorpalBlade]

I'm getting the same issue with split-debuginfo = "packed" when cross compiling for riscv64gc-unknown-linux-gnu, it seems to be all values except off that causes issues.