3 files changed, 21 insertions, 1 deletions

diff --git a/src/grammar.ron b/src/grammar.ron
index 67022b296..a73e4e1f1 100644
--- a/src/grammar.ron
+++ b/src/grammar.ron
@@ -138,6 +138,7 @@ Grammar(
 
         // atoms
         "TUPLE_EXPR",
+        "PAREN_EXPR",
         "PATH_EXPR",
         "LAMBDA_EXPR",
         "IF_EXPR",
diff --git a/src/grammar/expressions/atom.rs b/src/grammar/expressions/atom.rs
index 6a0d47d82..4eb638c3c 100644
--- a/src/grammar/expressions/atom.rs
+++ b/src/grammar/expressions/atom.rs
@@ -60,12 +60,29 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<CompletedMark
     Some(done)
 }
 
+// test tuple_expr
+// fn foo() {
+//     ();
+//     (1);
+//     (1,);
+// }
 fn tuple_expr(p: &mut Parser) -> CompletedMarker {
     assert!(p.at(L_PAREN));
     let m = p.start();
     p.expect(L_PAREN);
+
+    let mut saw_comma = false;
+    let mut saw_expr = false;
+    while !p.at(EOF) && !p.at(R_PAREN) {
+        saw_expr = true;
+        expr(p);
+        if !p.at(R_PAREN) {
+            saw_comma = true;
+            p.expect(COMMA);
+        }
+    }
     p.expect(R_PAREN);
-    m.complete(p, TUPLE_EXPR)
+    m.complete(p, if saw_expr && !saw_comma { PAREN_EXPR } else { TUPLE_EXPR })
 }
 
 // test lambda_expr
diff --git a/src/syntax_kinds/generated.rs b/src/syntax_kinds/generated.rs
index 8dfeb2b82..fe1a6694c 100644
--- a/src/syntax_kinds/generated.rs
+++ b/src/syntax_kinds/generated.rs
@@ -128,6 +128,7 @@ pub enum SyntaxKind {
     STRUCT_PAT,
     TUPLE_PAT,
     TUPLE_EXPR,
+    PAREN_EXPR,
     PATH_EXPR,
     LAMBDA_EXPR,
     IF_EXPR,
@@ -353,6 +354,7 @@ impl SyntaxKind {
             STRUCT_PAT => &SyntaxInfo { name: "STRUCT_PAT" },
             TUPLE_PAT => &SyntaxInfo { name: "TUPLE_PAT" },
             TUPLE_EXPR => &SyntaxInfo { name: "TUPLE_EXPR" },
+            PAREN_EXPR => &SyntaxInfo { name: "PAREN_EXPR" },
             PATH_EXPR => &SyntaxInfo { name: "PATH_EXPR" },
             LAMBDA_EXPR => &SyntaxInfo { name: "LAMBDA_EXPR" },
             IF_EXPR => &SyntaxInfo { name: "IF_EXPR" },