3 files changed, 10 insertions, 8 deletions

diff --git a/crates/ra_assists/src/handlers/add_custom_impl.rs b/crates/ra_assists/src/handlers/add_custom_impl.rs
index b67438b6b..ebdf00e67 100644
--- a/crates/ra_assists/src/handlers/add_custom_impl.rs
+++ b/crates/ra_assists/src/handlers/add_custom_impl.rs
@@ -1,10 +1,10 @@
+use itertools::Itertools;
 use ra_syntax::{
     ast::{self, AstNode},
     Direction, SmolStr,
     SyntaxKind::{IDENT, WHITESPACE},
     TextRange, TextSize,
 };
-use stdx::SepBy;
 
 use crate::{
     assist_context::{AssistContext, Assists},
@@ -61,9 +61,9 @@ pub(crate) fn add_custom_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<
             .filter(|t| t != trait_token.text())
             .collect::<Vec<SmolStr>>();
         let has_more_derives = !new_attr_input.is_empty();
-        let new_attr_input = new_attr_input.iter().sep_by(", ").surround_with("(", ")").to_string();
 
         if has_more_derives {
+            let new_attr_input = format!("({})", new_attr_input.iter().format(", "));
             builder.replace(input.syntax().text_range(), new_attr_input);
         } else {
             let attr_range = attr.syntax().text_range();
diff --git a/crates/ra_assists/src/handlers/generate_impl.rs b/crates/ra_assists/src/handlers/generate_impl.rs
index d9b87c9c0..7162dc184 100644
--- a/crates/ra_assists/src/handlers/generate_impl.rs
+++ b/crates/ra_assists/src/handlers/generate_impl.rs
@@ -1,5 +1,6 @@
+use itertools::Itertools;
 use ra_syntax::ast::{self, AstNode, GenericParamsOwner, NameOwner};
-use stdx::{format_to, SepBy};
+use stdx::format_to;
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 
@@ -50,7 +51,7 @@ pub(crate) fn generate_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()
                     .filter_map(|it| it.name())
                     .map(|it| it.text().clone());
 
-                let generic_params = lifetime_params.chain(type_params).sep_by(", ");
+                let generic_params = lifetime_params.chain(type_params).format(", ");
                 format_to!(buf, "<{}>", generic_params)
             }
             match ctx.config.snippet_cap {
diff --git a/crates/ra_assists/src/handlers/generate_new.rs b/crates/ra_assists/src/handlers/generate_new.rs
index b84aa24b6..32dfed274 100644
--- a/crates/ra_assists/src/handlers/generate_new.rs
+++ b/crates/ra_assists/src/handlers/generate_new.rs
@@ -1,9 +1,10 @@
 use hir::Adt;
+use itertools::Itertools;
 use ra_syntax::{
     ast::{self, AstNode, GenericParamsOwner, NameOwner, StructKind, VisibilityOwner},
     T,
 };
-use stdx::{format_to, SepBy};
+use stdx::format_to;
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 
@@ -52,8 +53,8 @@ pub(crate) fn generate_new(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
         let params = field_list
             .fields()
             .filter_map(|f| Some(format!("{}: {}", f.name()?.syntax(), f.ty()?.syntax())))
-            .sep_by(", ");
-        let fields = field_list.fields().filter_map(|f| f.name()).sep_by(", ");
+            .format(", ");
+        let fields = field_list.fields().filter_map(|f| f.name()).format(", ");
 
         format_to!(buf, "    {}fn new({}) -> Self {{ Self {{ {} }} }}", vis, params, fields);
 
@@ -102,7 +103,7 @@ fn generate_impl_text(strukt: &ast::Struct, code: &str) -> String {
             .map(|it| it.text().clone());
         let type_params =
             type_params.type_params().filter_map(|it| it.name()).map(|it| it.text().clone());
-        format_to!(buf, "<{}>", lifetime_params.chain(type_params).sep_by(", "))
+        format_to!(buf, "<{}>", lifetime_params.chain(type_params).format(", "))
     }
 
     format_to!(buf, " {{\n{}\n}}\n", code);