Thread documentation through FnSignature and CompletionItem

crates/ra_hir/src/code_model_api.rs

@@ -297,6 +297,7 @@ pub struct FnSignature {
     /// True if the first param is `self`. This is relevant to decide whether this
     /// can be called as a method.
     pub(crate) has_self_param: bool,
+    pub(crate) documentation: String,
 }
 
 impl FnSignature {
@@ -317,6 +318,10 @@ impl FnSignature {
     pub fn has_self_param(&self) -> bool {
         self.has_self_param
     }
+
+    pub fn documentation(&self) -> &String {
+        &self.documentation
+    }
 }
 
 impl Function {

crates/ra_hir/src/code_model_impl/function.rs

@@ -2,7 +2,7 @@ mod scope;
 
 use std::sync::Arc;
 
-use ra_syntax::{TreeArc, ast::{self, NameOwner}};
+use ra_syntax::{TreeArc, ast::{self, NameOwner, DocCommentsOwner}};
 
 use crate::{
     DefId, HirDatabase, Name, AsName, Function, FnSignature, Module,
@@ -72,11 +72,15 @@ impl FnSignature {
         } else {
             TypeRef::unit()
         };
+
+        let comments = node.doc_comment_text();
+
         let sig = FnSignature {
             name,
             params,
             ret_type,
             has_self_param,
+            documentation: comments,
         };
         Arc::new(sig)
     }

crates/ra_ide_api/src/completion/completion_item.rs

@@ -259,6 +259,11 @@ impl Builder {
             }
             self.insert_text_format = InsertTextFormat::Snippet;
         }
+        let sig = function.signature(ctx.db);
+        if !sig.documentation().is_empty() {
+            self.documentation = Some(sig.documentation().clone());
+        }
+
         self.kind = Some(CompletionItemKind::Function);
         self
     }