Is this the main benefit after Fast Compiles is enabled?

[dominikj111]

I was setting the fast compiles on my MacOS machine.
First impression wasn't really positive as I've spent couple hours to sort it out.

I carried on as written in Bevy documentation and did bash profile tweaks as documented in the llvm package installation.

export PATH="/usr/local/opt/llvm/bin:$PATH"
export LDFLAGS="-L/usr/local/opt/llvm/lib -L/usr/local/opt/llvm/lib/c++ -Wl,-rpath,/usr/local/opt/llvm/lib/c++"
export CPPFLAGS="-I/usr/local/opt/llvm/include"

I summarised the process on reddit.

On the end I was missing the last step which was to set the rustflags in the config.toml file. And this step is missing in the documentation and I think it is crucial.

After 20 trials of the cargo build --target x86_64-apple-darwin with rustflags = ["-C", "link-arg=-fuse-ld=lld"] and without, the average build time with the rustflags was 0.94s and without 1.65s.

I was testing upon small "hello world" project and I think that for bigger project the difference between both times will grow.
Am I right?

Is there another way how to confirm that fast compiles works correctly?

[nicopap]

On MacOS, you could also use the mold linker, which is significantly faster than lld. The documentation is out of date and should be updated, mold works on MacOS. I suspect that now that you figured out the difficult stuff, switching to mold is relatively easy :)

The config.toml is mentioned in the page you linked, but only on the section for mold, which doesn't make sense since it's just after a paragraph saying that mold doesn't work with MacOS 🤪 I suspect it got accidentally moved at one point.

[dominikj111]

Thanks, I'll do this during a weekend and will return back :)

[dominikj111]

Written on repo you give me ...

This repository contains a free version of the mold linker. If you are looking for a commercial version that supports macOS please visit the repository of the sold linker.

So I suppose I'm done here :)