6 files changed, 64 insertions, 0 deletions

diff --git a/crates/ra_mbe/src/lib.rs b/crates/ra_mbe/src/lib.rs
index 8e3167e55..d7462d09d 100644
--- a/crates/ra_mbe/src/lib.rs
+++ b/crates/ra_mbe/src/lib.rs
@@ -743,4 +743,23 @@ MACRO_ITEMS@[0; 40)
         );
         assert_expansion(&rules, "foo! { { 1; } }", "fn foo () {1 ;}");
     }
+
+    #[test]
+    fn test_meta() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            ($ i:meta) => (
+                #[$ i]
+                fn bar() {}
+            )
+        }
+"#,
+        );
+        assert_expansion(
+            &rules,
+            r#"foo! { cfg(target_os = "windows") }"#,
+            r#"# [cfg (target_os = "windows")] fn bar () {}"#,
+        );
+    }
 }
diff --git a/crates/ra_mbe/src/mbe_expander.rs b/crates/ra_mbe/src/mbe_expander.rs
index a74e477d6..6ada580cc 100644
--- a/crates/ra_mbe/src/mbe_expander.rs
+++ b/crates/ra_mbe/src/mbe_expander.rs
@@ -166,6 +166,11 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
                                 input.eat_block().ok_or(ExpandError::UnexpectedToken)?.clone();
                             res.inner.insert(text.clone(), Binding::Simple(block.into()));
                         }
+                        "meta" => {
+                            let meta =
+                                input.eat_meta().ok_or(ExpandError::UnexpectedToken)?.clone();
+                            res.inner.insert(text.clone(), Binding::Simple(meta.into()));
+                        }
                         "item" => {
                             let item =
                                 input.eat_item().ok_or(ExpandError::UnexpectedToken)?.clone();
diff --git a/crates/ra_mbe/src/subtree_parser.rs b/crates/ra_mbe/src/subtree_parser.rs
index 2b11186c4..5d5557113 100644
--- a/crates/ra_mbe/src/subtree_parser.rs
+++ b/crates/ra_mbe/src/subtree_parser.rs
@@ -50,6 +50,10 @@ impl<'a> Parser<'a> {
         self.parse(ra_parser::parse_block)
     }
 
+    pub fn parse_meta(self) -> Option<tt::TokenTree> {
+        self.parse(ra_parser::parse_meta)
+    }
+
     pub fn parse_item(self) -> Option<tt::TokenTree> {
         self.parse(ra_parser::parse_item)
     }
diff --git a/crates/ra_mbe/src/tt_cursor.rs b/crates/ra_mbe/src/tt_cursor.rs
index d700aad69..04bb6b563 100644
--- a/crates/ra_mbe/src/tt_cursor.rs
+++ b/crates/ra_mbe/src/tt_cursor.rs
@@ -109,6 +109,11 @@ impl<'a> TtCursor<'a> {
         parser.parse_block()
     }
 
+    pub(crate) fn eat_meta(&mut self) -> Option<tt::TokenTree> {
+        let parser = Parser::new(&mut self.pos, self.subtree);
+        parser.parse_meta()
+    }
+
     pub(crate) fn eat_item(&mut self) -> Option<tt::TokenTree> {
         let parser = Parser::new(&mut self.pos, self.subtree);
         parser.parse_item()
diff --git a/crates/ra_parser/src/grammar.rs b/crates/ra_parser/src/grammar.rs
index 7bae0bc7b..13c50c79c 100644
--- a/crates/ra_parser/src/grammar.rs
+++ b/crates/ra_parser/src/grammar.rs
@@ -99,6 +99,33 @@ pub(crate) fn block(p: &mut Parser) {
     expressions::block(p);
 }
 
+// Parse a meta item , which excluded [], e.g : #[ MetaItem ]
+pub(crate) fn meta_item(p: &mut Parser) {
+    fn is_delimiter(p: &mut Parser) -> bool {
+        match p.current() {
+            L_CURLY | L_PAREN | L_BRACK => true,
+            _ => false,
+        }
+    }
+
+    if is_delimiter(p) {
+        items::token_tree(p);
+        return;
+    }
+
+    let m = p.start();
+    while !p.at(EOF) {
+        if is_delimiter(p) {
+            items::token_tree(p);
+            break;
+        } else {
+            p.bump();
+        }
+    }
+
+    m.complete(p, TOKEN_TREE);
+}
+
 pub(crate) fn item(p: &mut Parser) {
     items::item_or_macro(p, true, items::ItemFlavor::Mod)
 }
diff --git a/crates/ra_parser/src/lib.rs b/crates/ra_parser/src/lib.rs
index 1e6a00642..4787b5b9e 100644
--- a/crates/ra_parser/src/lib.rs
+++ b/crates/ra_parser/src/lib.rs
@@ -98,6 +98,10 @@ pub fn parse_block(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink)
     parse_from_tokens(token_source, tree_sink, grammar::block);
 }
 
+pub fn parse_meta(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+    parse_from_tokens(token_source, tree_sink, grammar::meta_item);
+}
+
 /// Parse given tokens into the given sink as an item
 pub fn parse_item(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
     parse_from_tokens(token_source, tree_sink, grammar::item);