How to reuse pre-built crate library across multiple projects/apps?

[avkonst]

I am trying to speed up the build when many of my app projects have many of the shared libraries. These apps and libs are not necessary in the same repo.

I would like to achieve the following:

Let's say I have lib1, app1 and app2 cargo.toml based projects.
First, I would like to go and cargo build lib1. It would save build output in lib1/target folder.
Next I would like to go and build app1 project, which uses lib1 crate. However, I do not want cargo build for the app1 to build lib1 again. At very most, I want it to only copy the pre-built result from lib1/target folder to app1/target.
app2 has the same dependency to lib1, and I want the same 'reuse of prebuilt lib1' during building of the app2.

I am aware about cargo workspaces, but it does not allow me to do what I want, because app1 and app2 would be in different workspaces as such.

I am aware that I can publish to a crate registry, however, it stops iterative development when lib1 and app1 needs to be modified simultaneously and many publishing actions there is not a good idea. Although, it could work as a workaround if I could publish lib1 to a local folder registry, if it is even possible.

Could you please point me in the right direction what tools and configs to use to achieve the above?

[Michael-F-Bryan]

@avkonst

Could you please point me in the right direction what tools and configs to use to achieve the above?

I would use sccache for this. You can think of it as having a shared target/ folder across your entire computer.

[avkonst]

Thanks. I will explore this option. What I do not like about it is that it will reevaluate if lib1 needs to be built when I build app1 or app2 let's say. I do not want this analysis happening when I build apps because there are quite a lot of libs and we know some have many and deep shared dependencies.

But the tool is certainly good to optimize builds of individual projects, like lib1 in my example