Add #[must_use]

src/fn_register.rs

@@ -30,6 +30,7 @@ pub struct Mut<T>(T);
 
 /// Dereference into DynamicWriteLock
 #[inline(always)]
+#[must_use]
 pub fn by_ref<T: Variant + Clone>(data: &mut Dynamic) -> DynamicWriteLock<T> {
     // Directly cast the &mut Dynamic into DynamicWriteLock to access the underlying data.
     data.write_lock::<T>()
@@ -38,6 +39,7 @@ pub fn by_ref<T: Variant + Clone>(data: &mut Dynamic) -> DynamicWriteLock<T> {
 
 /// Dereference into value.
 #[inline(always)]
+#[must_use]
 pub fn by_value<T: Variant + Clone>(data: &mut Dynamic) -> T {
     if TypeId::of::<T>() == TypeId::of::<&str>() {
         // If T is `&str`, data must be `ImmutableString`, so map directly to it
@@ -63,24 +65,30 @@ pub fn by_value<T: Variant + Clone>(data: &mut Dynamic) -> T {
 /// Trait to register custom Rust functions.
 pub trait RegisterNativeFunction<Args, Result> {
     /// Convert this function into a [`CallableFunction`].
+    #[must_use]
     fn into_callable_function(self) -> CallableFunction;
     /// Get the type ID's of this function's parameters.
+    #[must_use]
     fn param_types() -> Box<[TypeId]>;
     /// _(METADATA)_ Get the type names of this function's parameters.
     /// Exported under the `metadata` feature only.
     #[cfg(feature = "metadata")]
+    #[must_use]
     fn param_names() -> Box<[&'static str]>;
     /// _(METADATA)_ Get the type ID of this function's return value.
     /// Exported under the `metadata` feature only.
     #[cfg(feature = "metadata")]
+    #[must_use]
     fn return_type() -> TypeId;
     /// _(METADATA)_ Get the type name of this function's return value.
     /// Exported under the `metadata` feature only.
     #[cfg(feature = "metadata")]
+    #[must_use]
     fn return_type_name() -> &'static str;
 }
 
 #[inline(always)]
+#[must_use]
 fn is_setter(_fn_name: &str) -> bool {
     #[cfg(not(feature = "no_object"))]
     if _fn_name.starts_with(crate::engine::FN_SET) {