How to correctly pass mold options

[glitsj16]

Hi. I've been playing with mold on a Arch Linux box for a while now. Works fantastic. I noticed 2.33.0 got a new --separate-debug-file option that could bring a nice speed-gain and I wanted to test that.

The release notes mentions --separate-debug-info, and that confused me at first. Running mold --help indicates this option is actually called --separate-debug-file, as can be seen here.

On the Arch wiki page for mold it is advised to append -fuse-ld=mold to LDFLAGS in /etc/makepkg.conf. Which is how I've been running mold for a while now.

My question: what would be the correct/proper way to pass the --separate-debug-file option in such a setup?

TIA

[rui314]

I fixed the typo in the release notes. Thank you for letting me know!

You are not supposed to directly invoke the linker. Usually it is invoked through the compiler frontend (cc, gcc or clang). Try to add -Wl,--separate-debug-file to your command option. The compiler frontend recognizes -Wl, as a linker option and pass the string that follows it to the linker.

[glitsj16]

Excellent. Passing -Wl,--separate-debug-file in Arch's makepkg.conf did the trick.

Thank you for the speedy reply and the wonderful work on mold.

[rgwood]

In case anyone's looking to enable this for Rust, I think adding "-C", "link-arg=-Wl,--separate-debug-file" to config.toml is the way to do it. For example:

[target.x86_64-unknown-linux-gnu]
linker = "clang"
rustflags = ["-C", "link-arg=-fuse-ld=/home/linuxbrew/.linuxbrew/bin/mold", "-C", "link-arg=-Wl,--separate-debug-file"]