mbe: Ensure repetition separator matches

Author: jrmuizel

crates/ra_mbe/src/lib.rs

@@ -256,4 +256,28 @@ impl_froms!(TokenTree: Leaf, Subtree);
         assert_expansion(&rules, "foo! { eggs Baz }", "struct Baz ;");
     }
 
+    #[test]
+    fn test_match_group_pattern_by_separator_token() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            ($ ($ i:ident),*) => ($ (
+                mod $ i {}
+            )*);
+            ($ ($ i:ident)#*) => ($ (
+                fn $ i() {}
+            )*);
+            ($ i:ident ,# $ j:ident) => (
+                struct $ i;
+                struct $ j;
+            )
+        }
+"#,
+        );
+
+        assert_expansion(&rules, "foo! { foo, bar }", "mod foo {} mod bar {}");
+        assert_expansion(&rules, "foo! { foo# bar }", "fn foo () {} fn bar () {}");
+        assert_expansion(&rules, "foo! { Foo,# Bar }", "struct Foo ; struct Bar ;");
+    }
+
 }

crates/ra_mbe/src/mbe_expander.rs

@@ -140,8 +140,12 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Option<Bindings>
             }) => {
                 while let Some(nested) = match_lhs(subtree, input) {
                     res.push_nested(nested)?;
-                    if separator.is_some() && !input.is_eof() {
-                        input.eat_punct()?;
+                    if let Some(separator) = *separator {
+                        if !input.is_eof() {
+                            if input.eat_punct()?.char != separator {
+                                return None;
+                            }
+                        }
                     }
                 }
             }