Mixing generated and static sources with rust

Rust works somewhat differently than languages like C do, it uses the filesystem hierarchy to find imports, and lacks a mechanism like C’s -I. This makes using generated sources quite difficult, as meson separates generated sources and static sources into the build and source trees.

The most obvious solution to fix this is to copy or link the static sources into the build tree so that the hierarchy looks like what rustc expects. It would be best if this could be done transparently, and only when there are generated sources as well as

[dcbaker]

Okay, it looks like the way that cargo handles this is with an environment variable (of course). Basically you add something like:

include!(concat!(env!("OUT_DIR"), "/generated.rs"));

in your source, and cargo set’s OUT_DIR to the place it puts the generated files.

That is probably workable (rust really like environment variables, so we probably need a solution for them anyway 😕), with the one caveat that we need to ensure that all of the generated sources end up in a single output directory. That’s ugly, but probably workable.

[dcbaker]

https://github.com/rust-lang/rust/issues/78913

I seem to be mis-remembering a bit of this discussion, it’s been a while. This may actually be possible.