4 files changed, 49 insertions, 4 deletions

diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index f06191963..4ac1d6334 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -43,6 +43,7 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         T!['('],
         T!['{'],
         T!['['],
+        L_DOLLAR,
         T![|],
         T![move],
         T![box],
@@ -248,7 +249,12 @@ fn lambda_expr(p: &mut Parser) -> CompletedMarker {
             p.error("expected `{`");
         }
     }
-    expr(p);
+
+    if p.at_ts(EXPR_FIRST) {
+        expr(p);
+    } else {
+        p.error("expected expression");
+    }
     m.complete(p, LAMBDA_EXPR)
 }
 
@@ -438,7 +444,7 @@ fn match_arm(p: &mut Parser) -> BlockLike {
     // }
     attributes::outer_attributes(p);
 
-    patterns::pattern_list_r(p, TokenSet::empty());
+    patterns::pattern_list_r(p, TokenSet::EMPTY);
     if p.at(T![if]) {
         match_guard(p);
     }
diff --git a/crates/ra_parser/src/grammar/items.rs b/crates/ra_parser/src/grammar/items.rs
index 370990e21..6e23d9b72 100644
--- a/crates/ra_parser/src/grammar/items.rs
+++ b/crates/ra_parser/src/grammar/items.rs
@@ -33,7 +33,7 @@ pub(super) enum ItemFlavor {
 
 pub(super) const ITEM_RECOVERY_SET: TokenSet = token_set![
     FN_KW, STRUCT_KW, ENUM_KW, IMPL_KW, TRAIT_KW, CONST_KW, STATIC_KW, LET_KW, MOD_KW, PUB_KW,
-    CRATE_KW, USE_KW
+    CRATE_KW, USE_KW, MACRO_KW
 ];
 
 pub(super) fn item_or_macro(p: &mut Parser, stop_on_r_curly: bool, flavor: ItemFlavor) {
@@ -249,6 +249,11 @@ fn items_without_modifiers(p: &mut Parser, m: Marker) -> Result<(), Marker> {
             // }
             adt::struct_def(p, m);
         }
+        // test pub_macro_def
+        // pub macro m($:ident) {}
+        T![macro] => {
+            macro_def(p, m);
+        }
         IDENT if p.at_contextual_kw("union") && p.nth(1) == IDENT => {
             // test union_items
             // union Foo {}
@@ -379,6 +384,29 @@ pub(crate) fn mod_item_list(p: &mut Parser) {
     m.complete(p, ITEM_LIST);
 }
 
+// test macro_def
+// macro m { ($i:ident) => {} }
+// macro m($i:ident) {}
+fn macro_def(p: &mut Parser, m: Marker) {
+    p.expect(T![macro]);
+    name_r(p, ITEM_RECOVERY_SET);
+    if p.at(T!['{']) {
+        token_tree(p);
+    } else if !p.at(T!['(']) {
+        p.error("unmatched `(`");
+    } else {
+        let m = p.start();
+        token_tree(p);
+        match p.current() {
+            T!['{'] | T!['['] | T!['('] => token_tree(p),
+            _ => p.error("expected `{`, `[`, `(`"),
+        }
+        m.complete(p, TOKEN_TREE);
+    }
+
+    m.complete(p, MACRO_DEF);
+}
+
 fn macro_call(p: &mut Parser) -> BlockLike {
     assert!(paths::is_use_path_start(p));
     paths::use_path(p);
diff --git a/crates/ra_parser/src/grammar/patterns.rs b/crates/ra_parser/src/grammar/patterns.rs
index f5d12278c..422a4e3dc 100644
--- a/crates/ra_parser/src/grammar/patterns.rs
+++ b/crates/ra_parser/src/grammar/patterns.rs
@@ -50,7 +50,7 @@ pub(super) fn pattern_r(p: &mut Parser, recovery_set: TokenSet) {
         //     let m!(x) = 0;
         // }
         if lhs.kind() == PATH_PAT && p.at(T![!]) {
-            let m = lhs.precede(p);
+            let m = lhs.undo_completion(p);
             items::macro_call_after_excl(p);
             m.complete(p, MACRO_CALL);
         }
diff --git a/crates/ra_parser/src/grammar/type_params.rs b/crates/ra_parser/src/grammar/type_params.rs
index 34406b5bd..50e4900c3 100644
--- a/crates/ra_parser/src/grammar/type_params.rs
+++ b/crates/ra_parser/src/grammar/type_params.rs
@@ -25,6 +25,7 @@ fn type_param_list(p: &mut Parser) {
         match p.current() {
             LIFETIME => lifetime_param(p, m),
             IDENT => type_param(p, m),
+            CONST_KW => type_const_param(p, m),
             _ => {
                 m.abandon(p);
                 p.err_and_bump("expected type parameter")
@@ -62,6 +63,16 @@ fn type_param(p: &mut Parser, m: Marker) {
     m.complete(p, TYPE_PARAM);
 }
 
+// test const_param
+// struct S<const N: u32>;
+fn type_const_param(p: &mut Parser, m: Marker) {
+    assert!(p.at(CONST_KW));
+    p.bump(T![const]);
+    name(p);
+    types::ascription(p);
+    m.complete(p, CONST_PARAM);
+}
+
 // test type_param_bounds
 // struct S<T: 'a + ?Sized + (Copy)>;
 pub(super) fn bounds(p: &mut Parser) {