1 files changed, 52 insertions, 0 deletions
diff --git a/third_party/rust/wasm-encoder/src/component/start.rs b/third_party/rust/wasm-encoder/src/component/start.rs
new file mode 100644
index 0000000000..d4b60e1dfc
--- /dev/null
+++ b/third_party/rust/wasm-encoder/src/component/start.rs
@@ -0,0 +1,52 @@
+use crate::{ComponentSection, ComponentSectionId, Encode};
+
+/// An encoder for the start section of WebAssembly components.
+///
+/// # Example
+///
+/// ```
+/// use wasm_encoder::{Component, ComponentStartSection};
+///
+/// let start = ComponentStartSection { function_index: 0, args: [0, 1], results: 1 };
+///
+/// let mut component = Component::new();
+/// component.section(&start);
+///
+/// let bytes = component.finish();
+/// ```
+#[derive(Clone, Debug)]
+pub struct ComponentStartSection<A> {
+    /// The index to the start function.
+    pub function_index: u32,
+    /// The arguments to pass to the start function.
+    ///
+    /// An argument is an index to a value.
+    pub args: A,
+    /// The number of expected results for the start function.
+    ///
+    /// This should match the number of results for the type of
+    /// the function referenced by `function_index`.
+    pub results: u32,
+}
+
+impl<A> Encode for ComponentStartSection<A>
+where
+    A: AsRef<[u32]>,
+{
+    fn encode(&self, sink: &mut Vec<u8>) {
+        let mut bytes = Vec::new();
+        self.function_index.encode(&mut bytes);
+        self.args.as_ref().encode(&mut bytes);
+        self.results.encode(&mut bytes);
+        bytes.encode(sink);
+    }
+}
+
+impl<A> ComponentSection for ComponentStartSection<A>
+where
+    A: AsRef<[u32]>,
+{
+    fn id(&self) -> u8 {
+        ComponentSectionId::Start.into()
+    }
+}