8 files changed, 49 insertions, 27 deletions

diff --git a/crates/mbe/src/benchmark.rs b/crates/mbe/src/benchmark.rs
index ba814a2e1..38707ffa5 100644
--- a/crates/mbe/src/benchmark.rs
+++ b/crates/mbe/src/benchmark.rs
@@ -65,7 +65,7 @@ fn macro_rules_fixtures_tt() -> FxHashMap<String, tt::Subtree> {
         .filter_map(ast::MacroRules::cast)
         .map(|rule| {
             let id = rule.name().unwrap().to_string();
-            let (def_tt, _) = ast_to_token_tree(&rule.token_tree().unwrap()).unwrap();
+            let (def_tt, _) = ast_to_token_tree(&rule.token_tree().unwrap());
             (id, def_tt)
         })
         .collect()
diff --git a/crates/mbe/src/expander.rs b/crates/mbe/src/expander.rs
index 3197c834c..bfef7f73d 100644
--- a/crates/mbe/src/expander.rs
+++ b/crates/mbe/src/expander.rs
@@ -159,8 +159,7 @@ mod tests {
         let macro_definition =
             source_file.syntax().descendants().find_map(ast::MacroRules::cast).unwrap();
 
-        let (definition_tt, _) =
-            ast_to_token_tree(&macro_definition.token_tree().unwrap()).unwrap();
+        let (definition_tt, _) = ast_to_token_tree(&macro_definition.token_tree().unwrap());
         crate::MacroRules::parse(&definition_tt).unwrap()
     }
 
@@ -169,8 +168,7 @@ mod tests {
         let macro_invocation =
             source_file.syntax().descendants().find_map(ast::MacroCall::cast).unwrap();
 
-        let (invocation_tt, _) =
-            ast_to_token_tree(&macro_invocation.token_tree().unwrap()).unwrap();
+        let (invocation_tt, _) = ast_to_token_tree(&macro_invocation.token_tree().unwrap());
 
         expand_rules(&rules.rules, &invocation_tt)
     }
diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index e74f8cf3f..3af5bc18b 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -220,9 +220,11 @@ impl MacroDef {
             while src.len() > 0 {
                 let rule = Rule::parse(&mut src, true)?;
                 rules.push(rule);
-                if let Err(()) = src.expect_char(';') {
+                if let Err(()) = src.expect_any_char(&[';', ',']) {
                     if src.len() > 0 {
-                        return Err(ParseError::Expected("expected `;`".to_string()));
+                        return Err(ParseError::Expected(
+                            "expected `;` or `,` to delimit rules".to_string(),
+                        ));
                     }
                     break;
                 }
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index 9d433b3b0..9ba98f7fb 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -43,18 +43,18 @@ pub struct TokenMap {
 
 /// Convert the syntax tree (what user has written) to a `TokenTree` (what macro
 /// will consume).
-pub fn ast_to_token_tree(ast: &impl ast::AstNode) -> Option<(tt::Subtree, TokenMap)> {
+pub fn ast_to_token_tree(ast: &impl ast::AstNode) -> (tt::Subtree, TokenMap) {
     syntax_node_to_token_tree(ast.syntax())
 }
 
 /// Convert the syntax node to a `TokenTree` (what macro
 /// will consume).
-pub fn syntax_node_to_token_tree(node: &SyntaxNode) -> Option<(tt::Subtree, TokenMap)> {
+pub fn syntax_node_to_token_tree(node: &SyntaxNode) -> (tt::Subtree, TokenMap) {
     let global_offset = node.text_range().start();
     let mut c = Convertor::new(node, global_offset);
-    let subtree = c.go()?;
+    let subtree = c.go();
     c.id_alloc.map.entries.shrink_to_fit();
-    Some((subtree, c.id_alloc.map))
+    (subtree, c.id_alloc.map)
 }
 
 // The following items are what `rustc` macro can be parsed into :
@@ -108,7 +108,7 @@ pub fn parse_to_token_tree(text: &str) -> Option<(tt::Subtree, TokenMap)> {
         },
     };
 
-    let subtree = conv.go()?;
+    let subtree = conv.go();
     Some((subtree, conv.id_alloc.map))
 }
 
@@ -319,21 +319,18 @@ trait SrcToken: std::fmt::Debug {
 trait TokenConvertor {
     type Token: SrcToken;
 
-    fn go(&mut self) -> Option<tt::Subtree> {
+    fn go(&mut self) -> tt::Subtree {
         let mut subtree = tt::Subtree::default();
         subtree.delimiter = None;
         while self.peek().is_some() {
             self.collect_leaf(&mut subtree.token_trees);
         }
-        if subtree.token_trees.is_empty() {
-            return None;
-        }
         if subtree.token_trees.len() == 1 {
             if let tt::TokenTree::Subtree(first) = &subtree.token_trees[0] {
-                return Some(first.clone());
+                return first.clone();
             }
         }
-        Some(subtree)
+        subtree
     }
 
     fn collect_leaf(&mut self, result: &mut Vec<tt::TokenTree>) {
@@ -861,7 +858,7 @@ mod tests {
         // - T!['}']
         // - WHITE_SPACE
         let token_tree = ast::TokenTree::cast(token_tree).unwrap();
-        let tt = ast_to_token_tree(&token_tree).unwrap().0;
+        let tt = ast_to_token_tree(&token_tree).0;
 
         assert_eq!(tt.delimiter_kind(), Some(tt::DelimiterKind::Brace));
     }
@@ -870,7 +867,7 @@ mod tests {
     fn test_token_tree_multi_char_punct() {
         let source_file = ast::SourceFile::parse("struct Foo { a: x::Y }").ok().unwrap();
         let struct_def = source_file.syntax().descendants().find_map(ast::Struct::cast).unwrap();
-        let tt = ast_to_token_tree(&struct_def).unwrap().0;
+        let tt = ast_to_token_tree(&struct_def).0;
         token_tree_to_syntax_node(&tt, FragmentKind::Item).unwrap();
     }
 }
diff --git a/crates/mbe/src/tests.rs b/crates/mbe/src/tests.rs
index 6da18ecf4..3698ff3f0 100644
--- a/crates/mbe/src/tests.rs
+++ b/crates/mbe/src/tests.rs
@@ -29,8 +29,7 @@ macro_rules! impl_fixture {
                 let macro_invocation =
                     source_file.syntax().descendants().find_map(ast::MacroCall::cast).unwrap();
 
-                let (invocation_tt, _) = ast_to_token_tree(&macro_invocation.token_tree().unwrap())
-                    .ok_or_else(|| ExpandError::ConversionError)?;
+                let (invocation_tt, _) = ast_to_token_tree(&macro_invocation.token_tree().unwrap());
 
                 self.rules.expand(&invocation_tt).result()
             }
@@ -101,7 +100,7 @@ macro_rules! impl_fixture {
                         .descendants()
                         .find_map(ast::TokenTree::cast)
                         .unwrap();
-                    let mut wrapped = ast_to_token_tree(&wrapped).unwrap().0;
+                    let mut wrapped = ast_to_token_tree(&wrapped).0;
                     wrapped.delimiter = None;
                     wrapped
                 };
@@ -151,7 +150,7 @@ pub(crate) fn parse_macro_error(ra_fixture: &str) -> ParseError {
 
 pub(crate) fn parse_to_token_tree_by_syntax(ra_fixture: &str) -> tt::Subtree {
     let source_file = ast::SourceFile::parse(ra_fixture).ok().unwrap();
-    let tt = syntax_node_to_token_tree(source_file.syntax()).unwrap().0;
+    let tt = syntax_node_to_token_tree(source_file.syntax()).0;
 
     let parsed = parse_to_token_tree(ra_fixture).unwrap().0;
     assert_eq!(tt, parsed);
@@ -164,7 +163,7 @@ fn parse_macro_rules_to_tt(ra_fixture: &str) -> tt::Subtree {
     let macro_definition =
         source_file.syntax().descendants().find_map(ast::MacroRules::cast).unwrap();
 
-    let (definition_tt, _) = ast_to_token_tree(&macro_definition.token_tree().unwrap()).unwrap();
+    let (definition_tt, _) = ast_to_token_tree(&macro_definition.token_tree().unwrap());
 
     let parsed = parse_to_token_tree(
         &ra_fixture[macro_definition.token_tree().unwrap().syntax().text_range()],
@@ -181,7 +180,7 @@ fn parse_macro_def_to_tt(ra_fixture: &str) -> tt::Subtree {
     let macro_definition =
         source_file.syntax().descendants().find_map(ast::MacroDef::cast).unwrap();
 
-    let (definition_tt, _) = ast_to_token_tree(&macro_definition.body().unwrap()).unwrap();
+    let (definition_tt, _) = ast_to_token_tree(&macro_definition.body().unwrap());
 
     let parsed =
         parse_to_token_tree(&ra_fixture[macro_definition.body().unwrap().syntax().text_range()])
diff --git a/crates/mbe/src/tests/expand.rs b/crates/mbe/src/tests/expand.rs
index 8951f3813..e02d038b6 100644
--- a/crates/mbe/src/tests/expand.rs
+++ b/crates/mbe/src/tests/expand.rs
@@ -663,6 +663,21 @@ macro foo {
 }
 
 #[test]
+fn test_macro_2_0_panic_2015() {
+    parse_macro2(
+        r#"
+macro panic_2015 {
+    () => (
+    ),
+    (bar) => (
+    ),
+}
+"#,
+    )
+    .assert_expand_items("panic_2015!(bar);", "");
+}
+
+#[test]
 fn test_path() {
     parse_macro(
         r#"
diff --git a/crates/mbe/src/tests/rule.rs b/crates/mbe/src/tests/rule.rs
index bf48112b3..5c61a98fd 100644
--- a/crates/mbe/src/tests/rule.rs
+++ b/crates/mbe/src/tests/rule.rs
@@ -44,6 +44,6 @@ fn parse_macro_arm(arm_definition: &str) -> Result<crate::MacroRules, ParseError
     let macro_definition =
         source_file.syntax().descendants().find_map(ast::MacroRules::cast).unwrap();
 
-    let (definition_tt, _) = ast_to_token_tree(&macro_definition.token_tree().unwrap()).unwrap();
+    let (definition_tt, _) = ast_to_token_tree(&macro_definition.token_tree().unwrap());
     crate::MacroRules::parse(&definition_tt)
 }
diff --git a/crates/mbe/src/tt_iter.rs b/crates/mbe/src/tt_iter.rs
index 319a40f2a..195b8cf30 100644
--- a/crates/mbe/src/tt_iter.rs
+++ b/crates/mbe/src/tt_iter.rs
@@ -34,6 +34,17 @@ impl<'a> TtIter<'a> {
         }
     }
 
+    pub(crate) fn expect_any_char(&mut self, chars: &[char]) -> Result<(), ()> {
+        match self.next() {
+            Some(tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: c, .. })))
+                if chars.contains(c) =>
+            {
+                Ok(())
+            }
+            _ => Err(()),
+        }
+    }
+
     pub(crate) fn expect_subtree(&mut self) -> Result<&'a tt::Subtree, ()> {
         match self.next() {
             Some(tt::TokenTree::Subtree(it)) => Ok(it),