2 files changed, 11 insertions, 6 deletions

diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index 66a769c73..dbb3853d0 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -6,7 +6,6 @@ use ra_syntax::{
     ast::{self, ArgListOwner},
     algo::find_node_at_offset,
 };
-use hir::Docs;
 
 use crate::{FilePosition, CallInfo, FunctionSignature, db::RootDatabase};
 
@@ -27,7 +26,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
     let fn_def = ast::FnDef::cast(fn_def).unwrap();
     let function = hir::source_binder::function_from_source(db, symbol.file_id, fn_def)?;
 
-    let mut call_info = CallInfo::new(db, function, fn_def)?;
+    let mut call_info = CallInfo::new(db, function);
 
     // If we have a calling expression let's find which argument we are on
     let num_params = call_info.parameters().len();
@@ -107,11 +106,10 @@ impl<'a> FnCallNode<'a> {
 }
 
 impl CallInfo {
-    fn new(db: &RootDatabase, function: hir::Function, node: &ast::FnDef) -> Option<Self> {
-        let doc = function.docs(db);
-        let signature = FunctionSignature::from(node).with_doc_opt(doc);
+    fn new(db: &RootDatabase, function: hir::Function) -> Self {
+        let signature = FunctionSignature::from_hir(db, function);
 
-        Some(CallInfo { signature, active_parameter: None })
+        CallInfo { signature, active_parameter: None }
     }
 
     fn parameters(&self) -> &[String] {
diff --git a/crates/ra_ide_api/src/display.rs b/crates/ra_ide_api/src/display.rs
index 4ce362ebb..c05d59689 100644
--- a/crates/ra_ide_api/src/display.rs
+++ b/crates/ra_ide_api/src/display.rs
@@ -5,6 +5,7 @@ use std::fmt::{self, Display};
 use join_to_string::join;
 use ra_syntax::ast::{self, AstNode, NameOwner, VisibilityOwner, TypeParamsOwner};
 use std::convert::From;
+use hir::Docs;
 
 /// Contains information about a function signature
 #[derive(Debug)]
@@ -30,6 +31,12 @@ impl FunctionSignature {
         self.doc = doc;
         self
     }
+
+    pub(crate) fn from_hir(db: &db::RootDatabase, function: hir::Function) -> Self {
+        let doc = function.docs(db);
+        let (_, ast_node) = function.source(db);
+        FunctionSignature::from(&*ast_node).with_doc_opt(doc)
+    }
 }
 
 impl From<&'_ ast::FnDef> for FunctionSignature {