fix: don't make MissingMatchArms diagnostic for empty match body

crates/hir/src/lib.rs

@@ -1914,7 +1914,8 @@ impl DefWithBody {
                             if let ast::Expr::MatchExpr(match_expr) =
                                 &source_ptr.value.to_node(&root)
                             {
-                                if let Some(scrut_expr) = match_expr.expr() {
+                                match match_expr.expr() {
+                                    Some(scrut_expr) if match_expr.match_arm_list().is_some() => {
                                         acc.push(
                                             MissingMatchArms {
                                                 scrutinee_expr: InFile::new(
@@ -1926,6 +1927,8 @@ impl DefWithBody {
                                             .into(),
                                         );
                                     }
+                                    _ => {}
+                                }
                             }
                         }
                         Err(SyntheticSyntax) => (),

crates/ide-diagnostics/src/handlers/missing_match_arms.rs

@@ -25,6 +25,18 @@ mod tests {
         crate::tests::check_diagnostics(ra_fixture)
     }
 
+    #[test]
+    fn empty_body() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match 0;
+         //^ error: Syntax Error: expected `{`
+}
+"#,
+        );
+    }
+
     #[test]
     fn empty_tuple() {
         check_diagnostics_no_bails(