3 files changed, 6 insertions, 2 deletions

diff --git a/crates/ra_parser/src/grammar.rs b/crates/ra_parser/src/grammar.rs
index f94702e97..c9941fe93 100644
--- a/crates/ra_parser/src/grammar.rs
+++ b/crates/ra_parser/src/grammar.rs
@@ -129,7 +129,9 @@ fn opt_alias(p: &mut Parser) {
     if p.at(AS_KW) {
         let m = p.start();
         p.bump();
-        name(p);
+        if !p.eat(UNDERSCORE) {
+            name(p);
+        }
         m.complete(p, ALIAS);
     }
 }
diff --git a/crates/ra_parser/src/grammar/items/use_item.rs b/crates/ra_parser/src/grammar/items/use_item.rs
index 5111d37eb..b36612726 100644
--- a/crates/ra_parser/src/grammar/items/use_item.rs
+++ b/crates/ra_parser/src/grammar/items/use_item.rs
@@ -76,6 +76,7 @@ fn use_tree(p: &mut Parser) {
                     //  yet::another::path,
                     //  running::out::of::synonyms::for_::different::*
                     // };
+                    // use Trait as _;
                     opt_alias(p);
                 }
                 COLONCOLON => {
diff --git a/crates/ra_parser/src/grammar/params.rs b/crates/ra_parser/src/grammar/params.rs
index a70f067f9..d027578b6 100644
--- a/crates/ra_parser/src/grammar/params.rs
+++ b/crates/ra_parser/src/grammar/params.rs
@@ -83,9 +83,10 @@ fn value_parameter(p: &mut Parser, flavor: Flavor) {
 
             // test trait_fn_placeholder_parameter
             // trait Foo {
-            //     fn bar(_: u64);
+            //     fn bar(_: u64, mut x: i32);
             // }
             if (la0 == IDENT || la0 == UNDERSCORE) && la1 == COLON
+                || la0 == MUT_KW && la1 == IDENT && la2 == COLON
                 || la0 == AMP && la1 == IDENT && la2 == COLON
                 || la0 == AMP && la1 == MUT_KW && la2 == IDENT && la3 == COLON
             {