Put airports behind a feature flag

That flag, "airports", is part of the default feature set.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "vatsim_utils"
-version = "0.4.0"
+version = "0.5.0"
 edition = "2021"
 authors = ["Celeo <mattboulanger@fastmail.com>"]
 description = "Utilities to interact with VATSIM data"
@@ -23,3 +23,8 @@ reqwest = { version = "0.11.11", features = ["json"] }
 serde = { version = "1.0.142", features = ["derive"] }
 serde_json = "1.0.83"
 thiserror = "1.0.32"
+
+
+[features]
+default = ["airports"]
+airports = []

src/distance.rs

@@ -116,7 +116,6 @@ pub static AIRPORTS_MAP: Lazy<HashMap<&'static str, Airport>> = Lazy::new(|| {
 ///
 /// assert_eq!(distance.round() as i64, 95);
 /// ```
-#[must_use]
 pub fn haversine(lat1: f64, lon1: f64, lat2: f64, lon2: f64) -> f64 {
     let r = 6371e3;
     let φ1 = (lat1 * PI) / 180_f64;

src/lib.rs

@@ -16,6 +16,7 @@
     unused_results
 )]
 
+#[cfg(feature = "airports")]
 pub mod distance;
 pub mod errors;
 pub mod live_api;