Macro tvix_eval::spans::expr_to_span

macro_rules! expr_to_span {
    ( $type:path ) => { ... };
}

Generates a ToSpan implementation for a type implementing rowan::AstNode. This is impossible to do as a blanket implementation because rustc forbids these implementations for traits from third-party crates due to a belief that semantic versioning truly could work (it doesn’t).