reuse cargo check/build build.rs results?

[Dushistov]

One of crate that I use inside workspace is fork of servo skia.

Ok, workspace looks like is not really supported (I mean idea to build crates only once per workspace), according to #730 .

But even if I use servo skia as standalone crate,
without any workspace, then rls actually rebuild huge c++ library again:

target/rls/debug/build/servo-skia-6107f1eccc85d461/out/lib/libskia.a
target/rls/debug/build/servo-skia-6107f1eccc85d461/out/build/libskia.a
target/debug/build/servo-skia-6107f1eccc85d461/out/lib/libskia.a
target/debug/build/servo-skia-6107f1eccc85d461/out/build/libskia.a

as can you see cargo check / cargo build shares one directory: target/debug,
and rls use another one target/rls and rebuild c++ library again, because of building of skia is part of build.rs.

Is it possible to reuse results of build.rs from target/debug?

[nrc]

We basically can't share data between RLS and non-RLS because the RLS builds are done with a custom compiler and with different flags. Even if we did try to unify the two, it could mean that a user could cause there CLI use of Cargo to rebuild due to the RLS needing to rebuild or vice versa (and also there mightbe changes that the RLS doesn't know about so doesn't rebuild when it should). All in all, it seems much simpler if we keep builds separate. It is pretty annoying when it means artefacts like this can't be shared.