use std::env; #[cfg(miri)] compile_error!("`miri` cfg should not be set in build script"); fn main() { // Cargo calls `miri --print=cfg` to populate the `CARGO_CFG_*` env vars. // Make sure that the "miri" flag is not set since we are building a procedural macro crate. assert!(env::var_os("CARGO_CFG_MIRI").is_none()); }