Incompatibility with mold linker

[brson]

I recently tried to cargo install a crate (cargo-contract) that relies on dylint-link and it failed due to interactions with the recommended configuration for using the mold linker.

Mold is configured by putting this in ~/.cargo/config.toml:

[target.x86_64-unknown-linux-gnu]
linker = "clang"
rustflags = ["-C", "link-arg=-fuse-ld=/path/to/mold"]

This is a global configuration saying to use clang as the linker, and clang understands the -fuse-ld argument.

dylint-link though invokes cc, which on my system is gcc and I see the following error:

     Compiling memchr v2.4.1
  error: linking with `dylint-link` failed: exit status: 1
  ...
    = note: cc: error: unrecognized command line option '-fuse-ld=/usr/local/bin/mold'

It's not immediately obvious to me how to change dylint-link to handle this situation.

[smoelius]

I think dylint-link could check for the existence of ~/.cargo/config.toml, and whether there is an applicable setting in there.

I.e., if something like this appears, then invoke clang instead of cc:

[target.x86_64-unknown-linux-gnu]
linker = "clang"

Does that sound reasonable?

[brson]

That sounds like it would work for my use case at least, and a good start. It may not be foolproof - there may for example be other locations where cargo might be looking for .cargo/config, or otherways to communicate to rustc/cargo which linker to use.

Thanks for the quick response.

[smoelius]

@brson I just published a new version that I think should address the problem.

Could I impose upon you to test the new version before we close this issue?

[brson]

@smoelius yes, the new version works for me. Here is what I ran

cargo install dylint-link cargo-dylint
cargo install cargo-contract

Thanks!

[smoelius]

Thank you!