2 files changed, 100 insertions, 24 deletions

diff --git a/crates/ra_assists/src/add_missing_impl_members.rs b/crates/ra_assists/src/add_missing_impl_members.rs
index 4435c4b5d..e13f54c4f 100644
--- a/crates/ra_assists/src/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/add_missing_impl_members.rs
@@ -9,7 +9,35 @@ use ra_fmt::{leading_indent, reindent};
 
 use itertools::Itertools;
 
-pub(crate) fn add_missing_impl_members(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+enum AddMissingImplMembersMode {
+    DefaultMethodsOnly,
+    NoDefaultMethods,
+}
+
+pub(crate) fn add_missing_impl_members(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    add_missing_impl_members_inner(
+        ctx,
+        AddMissingImplMembersMode::NoDefaultMethods,
+        "add_impl_missing_members",
+        "add missing impl members",
+    )
+}
+
+pub(crate) fn add_missing_default_members(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    add_missing_impl_members_inner(
+        ctx,
+        AddMissingImplMembersMode::DefaultMethodsOnly,
+        "add_impl_default_members",
+        "add impl default members",
+    )
+}
+
+fn add_missing_impl_members_inner(
+    mut ctx: AssistCtx<impl HirDatabase>,
+    mode: AddMissingImplMembersMode,
+    assist_id: &'static str,
+    label: &'static str,
+) -> Option<Assist> {
     let impl_node = ctx.node_at_offset::<ast::ImplBlock>()?;
     let impl_item_list = impl_node.item_list()?;
 
@@ -35,6 +63,10 @@ pub(crate) fn add_missing_impl_members(mut ctx: AssistCtx<impl HirDatabase>) ->
         trait_fns
             .into_iter()
             .filter(|t| def_name(t).is_some())
+            .filter(|t| match mode {
+                AddMissingImplMembersMode::DefaultMethodsOnly => t.body().is_some(),
+                AddMissingImplMembersMode::NoDefaultMethods => t.body().is_none(),
+            })
             .filter(|t| impl_fns.iter().all(|i| def_name(i) != def_name(t)))
             .collect()
     };
@@ -42,7 +74,7 @@ pub(crate) fn add_missing_impl_members(mut ctx: AssistCtx<impl HirDatabase>) ->
         return None;
     }
 
-    ctx.add_action(AssistId("add_impl_missing_members"), "add missing impl members", |edit| {
+    ctx.add_action(AssistId(assist_id), label, |edit| {
         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
@@ -103,11 +135,13 @@ fn build_func_body(def: &ast::FnDef) -> String {
     let mut buf = String::new();
 
     for child in def.syntax().children() {
-        if child.kind() == SyntaxKind::SEMI {
-            buf.push_str(" { unimplemented!() }")
-        } else {
-            child.text().push_to(&mut buf);
-        }
+        match (child.prev_sibling().map(|c| c.kind()), child.kind()) {
+            (_, SyntaxKind::SEMI) => buf.push_str(" { unimplemented!() }"),
+            (_, SyntaxKind::ATTR) | (_, SyntaxKind::COMMENT) => {}
+            (Some(SyntaxKind::ATTR), SyntaxKind::WHITESPACE)
+            | (Some(SyntaxKind::COMMENT), SyntaxKind::WHITESPACE) => {}
+            _ => child.text().push_to(&mut buf),
+        };
     }
 
     buf.trim_end().to_string()
@@ -180,8 +214,7 @@ struct S;
 
 impl Foo for S {
     fn bar(&self) {}
-    fn foo(&self) { unimplemented!() }
-    fn baz(&self) -> u32 { 42 }<|>
+    fn foo(&self) { unimplemented!() }<|>
 }",
         );
     }
@@ -193,7 +226,7 @@ impl Foo for S {
             "
 trait Foo { fn foo(&self); }
 struct S;
-impl Foo for S {<|>}",
+impl Foo for S { <|> }",
             "
 trait Foo { fn foo(&self); }
 struct S;
@@ -232,8 +265,8 @@ impl Foo for S { <|> }",
     }
 
     #[test]
-    fn test_ignore_unnamed_trait_members() {
-        check_assist(
+    fn test_ignore_unnamed_trait_members_and_default_methods() {
+        check_assist_not_applicable(
             add_missing_impl_members,
             "
 trait Foo {
@@ -242,15 +275,6 @@ trait Foo {
 }
 struct S;
 impl Foo for S { <|> }",
-            "
-trait Foo {
-    fn (arg: u32);
-    fn valid(some: u32) -> bool { false }
-}
-struct S;
-impl Foo for S {
-    fn valid(some: u32) -> bool { false }<|>
-}",
         )
     }
 
@@ -260,7 +284,7 @@ impl Foo for S {
             add_missing_impl_members,
             "
 trait Foo {
-    fn valid(some: u32) -> bool { false }
+    fn valid(some: u32) -> bool;
 }
 struct S;
 
@@ -269,15 +293,66 @@ mod my_mod {
 }",
             "
 trait Foo {
-    fn valid(some: u32) -> bool { false }
+    fn valid(some: u32) -> bool;
 }
 struct S;
 
 mod my_mod {
     impl crate::Foo for S {
-        fn valid(some: u32) -> bool { false }<|>
+        fn valid(some: u32) -> bool { unimplemented!() }<|>
+    }
+}",
+        )
+    }
+
+    #[test]
+    fn test_with_docstring_and_attrs() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+#[doc(alias = "test alias")]
+trait Foo {
+    /// doc string
+    #[must_use]
+    fn foo(&self);
+}
+struct S;
+impl Foo for S {}<|>"#,
+            r#"
+#[doc(alias = "test alias")]
+trait Foo {
+    /// doc string
+    #[must_use]
+    fn foo(&self);
+}
+struct S;
+impl Foo for S {
+    fn foo(&self) { unimplemented!() }<|>
+}"#,
+        )
     }
+
+    #[test]
+    fn test_default_methods() {
+        check_assist(
+            add_missing_default_members,
+            "
+trait Foo {
+    fn valid(some: u32) -> bool { false }
+    fn foo(some: u32) -> bool;
+}
+struct S;
+impl Foo for S { <|> }",
+            "
+trait Foo {
+    fn valid(some: u32) -> bool { false }
+    fn foo(some: u32) -> bool;
+}
+struct S;
+impl Foo for S {
+    fn valid(some: u32) -> bool { false }<|>
 }",
         )
     }
+
 }
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 871b37f58..fc36e8cc9 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -112,6 +112,7 @@ fn all_assists<DB: HirDatabase>() -> &'static [fn(AssistCtx<DB>) -> Option<Assis
         remove_dbg::remove_dbg,
         auto_import::auto_import,
         add_missing_impl_members::add_missing_impl_members,
+        add_missing_impl_members::add_missing_default_members,
     ]
 }