llvm types for erasure, function pointer

crates/compiler/gen_llvm/src/llvm/erased.rs

@@ -0,0 +1,22 @@
+use inkwell::{
+    types::{BasicTypeEnum, StructType},
+    AddressSpace,
+};
+
+use super::build::Env;
+
+/// Erased is laid out like
+///
+/// ```text
+/// struct Erased {
+///     value: void*,
+///     callee: void*,
+///     refcounter: void*,
+/// }
+/// ```
+pub fn basic_type<'a, 'ctx>(env: &Env<'a, 'ctx, '_>) -> StructType<'ctx> {
+    let ptr_ty = env.context.i8_type().ptr_type(AddressSpace::default());
+
+    env.context
+        .struct_type(&[ptr_ty.into(), ptr_ty.into(), ptr_ty.into()], false)
+}