Make single line pattern matching void expression

Instead of returning `nil`, raise a syntax error if its value is
used.  [Feature #16355]

1 files changed, 11 insertions, 0 deletions

diff --git a/parse.y b/parse.y
index c1df3060bd..15c9b419d7 100644
--- a/parse.y
+++ b/parse.y
@@ -10740,6 +10740,17 @@ value_expr_check(struct parser_params *p, NODE *node)
 	  case NODE_RETRY:
 	    return void_node ? void_node : node;
 
+	  case NODE_CASE3:
+	    if (!node->nd_body || nd_type(node->nd_body) != NODE_IN) {
+		compile_error(p, "unexpected node");
+		return NULL;
+	    }
+	    if (node->nd_body->nd_body) {
+		return NULL;
+	    }
+	    /* single line pattern matching */
+	    return void_node ? void_node : node;
+
 	  case NODE_BLOCK:
 	    while (node->nd_next) {
 		node = node->nd_next;