Add needed file

crates/compiler/mono/src/layout/erased.rs

@@ -0,0 +1,55 @@
+use roc_target::TargetInfo;
+
+/// The layout of an erasure.
+///
+/// A type-erased value consists of three fields at runtime:
+///
+/// ```
+/// {
+///   // the material value being erased.
+///   // if the erasure is a function, this is the captured environment, or null.
+///   value: void*,
+///
+///   // if the erasure is a function, the function pointer, or null otherwise.
+///   callee: void*,
+///
+///   // the refcounter for the material value, or null if there is no material value.
+///   refcounter: void*,
+/// }
+/// ```
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Erased;
+
+impl Erased {
+    pub fn safe_to_memcpy(&self) -> bool {
+        false
+    }
+
+    pub fn stack_size_without_alignment(&self, target_info: TargetInfo) -> u32 {
+        (target_info.ptr_width() as u32) * 3
+    }
+
+    pub fn alignment_bytes(&self, target_info: TargetInfo) -> u32 {
+        target_info.ptr_width() as u32
+    }
+
+    pub fn allocation_alignment_bytes(&self, target_info: TargetInfo) -> u32 {
+        target_info.ptr_width() as u32
+    }
+
+    pub fn is_refcounted(&self) -> bool {
+        // The refcounter may not be present, but we don't know that statically.
+        // So assume we always refcount, and the implementor of the refcount function
+        // can no-op if it's not needed.
+        true
+    }
+
+    pub fn to_doc<'b, D, A>(&self, alloc: &'b D) -> ven_pretty::DocBuilder<'b, D, A>
+    where
+        D: ven_pretty::DocAllocator<'b, A>,
+        D::Doc: Clone,
+        A: Clone,
+    {
+        alloc.text("?Erased")
+    }
+}