Take into account parent indent when filling trait members

crates/ra_assists/src/add_missing_impl_members.rs

@@ -74,22 +74,25 @@ pub(crate) fn add_missing_impl_members(mut ctx: AssistCtx<impl HirDatabase>) ->
     }
 
     ctx.add_action(AssistId("add_impl_missing_members"), "add missing impl members", |edit| {
-        let indent = {
+        let (parent_indent, indent) = {
             // FIXME: Find a way to get the indent already used in the file.
             // Now, we copy the indent of first item or indent with 4 spaces relative to impl block
             const DEFAULT_INDENT: &str = "    ";
             let first_item = impl_item_list.impl_items().next();
-            let first_item_indent = first_item.and_then(|i| leading_indent(i.syntax()));
-            let impl_block_indent = || leading_indent(impl_node.syntax()).unwrap_or_default();
+            let first_item_indent =
+                first_item.and_then(|i| leading_indent(i.syntax())).map(ToOwned::to_owned);
+            let impl_block_indent = leading_indent(impl_node.syntax()).unwrap_or_default();
 
-            first_item_indent
-                .map(ToOwned::to_owned)
-                .unwrap_or_else(|| impl_block_indent().to_owned() + DEFAULT_INDENT)
+            (
+                impl_block_indent.to_owned(),
+                first_item_indent.unwrap_or_else(|| impl_block_indent.to_owned() + DEFAULT_INDENT),
+            )
         };
 
         let func_bodies = missing_fns.into_iter().map(build_func_body).join("\n");
         let func_bodies = String::from("\n") + &func_bodies;
-        let func_bodies = reindent(&func_bodies, &indent) + "\n";
+        let trailing_whitespace = format!("\n{}", parent_indent);
+        let func_bodies = reindent(&func_bodies, &indent) + &trailing_whitespace;
 
         let changed_range = {
             let last_whitespace = impl_item_list.syntax().children();
@@ -104,7 +107,9 @@ pub(crate) fn add_missing_impl_members(mut ctx: AssistCtx<impl HirDatabase>) ->
         let replaced_text_range = TextUnit::of_str(&func_bodies);
 
         edit.replace(changed_range, func_bodies);
-        edit.set_cursor(changed_range.start() + replaced_text_range - TextUnit::of_str("\n"));
+        edit.set_cursor(
+            changed_range.start() + replaced_text_range - TextUnit::of_str(&trailing_whitespace),
+        );
     });
 
     ctx.build()
@@ -241,6 +246,33 @@ trait Foo {
 struct S;
 impl Foo for S {
     fn valid(some: u32) -> bool { false }<|>
+}",
+        )
+    }
+
+    #[test]
+    fn test_indented_impl_block() {
+        check_assist(
+            add_missing_impl_members,
+            "
+trait Foo {
+    fn valid(some: u32) -> bool { false }
+}
+struct S;
+
+mod my_mod {
+    impl crate::Foo for S { <|> }
+}",
+            "
+trait Foo {
+    fn valid(some: u32) -> bool { false }
+}
+struct S;
+
+mod my_mod {
+    impl crate::Foo for S {
+        fn valid(some: u32) -> bool { false }<|>
+    }
 }",
         )
     }