expand comment

Author: mkovaxx

crates/anodized-core/src/instrument/impls.rs

@@ -12,7 +12,10 @@ use crate::{
 };
 
 impl Mode {
-    /// Expand impl items.
+    /// Expand items inside an inherent impl.
+    ///
+    /// Reasons why impl functions must be treated differently from free-standing functions:
+    /// - The `__anodized_split_*` function must be qualified as `Self::` inside an impl.
     pub fn instrument_impl(&self, spec: DataSpec, mut the_impl: ItemImpl) -> Result<ItemImpl> {
         if the_impl.trait_.is_some() {
             return Err(make_item_error(&the_impl, "trait impl"));