remove inherent source impls

crates/ra_ide_api/src/display/function_signature.rs

@@ -1,10 +1,11 @@
-use super::{where_predicates, generic_parameters};
-use crate::db;
 use std::fmt::{self, Display};
+
 use join_to_string::join;
 use ra_syntax::ast::{self, AstNode, NameOwner, VisibilityOwner};
 use std::convert::From;
-use hir::{Docs, Documentation};
+use hir::{Docs, Documentation, HasSource};
+
+use crate::{db, display::{where_predicates, generic_parameters}};
 
 /// Contains information about a function signature
 #[derive(Debug)]