m5stack-core 0.6.1

// SPDX-License-Identifier: MIT OR Apache-2.0
//! Build-time guard: PSRAM needs an optimizing build.
//!
//! Cargo injects both vars below into every build script automatically —
//! `OPT_LEVEL` from the active profile, `CARGO_FEATURE_PSRAM` iff a downstream
//! crate turned on the `psram` feature. Nothing here has to be set by hand.
//!
//! We observe *this crate's* opt-level. With a normal unified profile that is
//! the same level the application is built at, so the check is exact for the
//! common footgun (`cargo build` with no optimization). It could only diverge
//! if someone deliberately pins a per-package profile override for this crate.

fn main() {
    // The examples are firmware images and need esp-hal's linker script.
    //
    // Emitted ONLY when `examples/` is present, which means: in this repo, never
    // in the published crate. Cargo does not ignore this instruction when the
    // package has no example target — it REJECTS it ("invalid instruction ...
    // does not have a example target") and the build dies before any code is
    // compiled. `[package] include` omits `examples/`, so every crates.io
    // consumer of 0.6.0 hit that, on any feature set and any target.
    //
    // It cannot be caught by `cargo package`, `cargo publish --dry-run`, or CI:
    // all of them build a tree that still has examples. Only consuming the
    // packaged crate does.
    if std::path::Path::new("examples").is_dir() {
        println!("cargo:rustc-link-arg-examples=-Tlinkall.x");
    }
    let psram = std::env::var_os("CARGO_FEATURE_PSRAM").is_some();
    let opt0 = std::env::var("OPT_LEVEL").as_deref() == Ok("0");
    if psram && opt0 {
        println!(
            "cargo::error=m5stack-core `psram` feature requires opt-level > 0: PSRAM SPI \
             timing calibration is unreliable at opt-level 0. Set opt-level in your [profile.*]."
        );
    }
}