Extract doc-comment on plugin functions.

codegen/src/function.rs

@@ -282,6 +282,8 @@ pub struct ExportedFn {
     mut_receiver: bool,
     params: ExportedFnParams,
     cfg_attrs: Vec<syn::Attribute>,
+    #[cfg(feature = "metadata")]
+    comment: String,
 }
 
 impl Parse for ExportedFn {
@@ -404,6 +406,8 @@ impl Parse for ExportedFn {
             mut_receiver,
             params: Default::default(),
             cfg_attrs,
+            #[cfg(feature = "metadata")]
+            comment: Default::default(),
         })
     }
 }
@@ -503,6 +507,16 @@ impl ExportedFn {
         }
     }
 
+    #[cfg(feature = "metadata")]
+    pub fn comment(&self) -> &str {
+        &self.comment
+    }
+
+    #[cfg(feature = "metadata")]
+    pub fn set_comment(&mut self, comment: String) {
+        self.comment = comment
+    }
+
     pub fn set_cfg_attrs(&mut self, cfg_attrs: Vec<syn::Attribute>) {
         self.cfg_attrs = cfg_attrs
     }